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The IC 342/Maffei Group Revealed

Ronald J. Buta – University of Alabama Marshall L. McCall – York University, Canada

Deposited 06/11/2019

Citation of published version:

Buta, R., McCall, M. (1999): The IC 342/Maffei Group Revealed. The Astrophysical Journal Supplement Series, 124(1). DOI: 10.1086/313255

© 1999. The American Astronomical Society. All rights reserved.

THE ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 124:33È93, 1999 September ( 1999. The American Astronomical Society. All rights reserved. Printed in U.S.A.

THE IC 342/MAFFEI GROUP REVEALED RONALD J. BUTA1 University of Alabama Department of Physics and Astronomy, Tuscaloosa, AL 35487-0324; buta=sarah.astr.ua.edu AND MARSHALL L. MCCALL1,2 York University Department of Physics and Astronomy, 4700 Keele Street, Toronto, Ontario, Canada, M3J 1P3; mccall=yorku.ca Received 1998 November 30; accepted 1999 April 27

ABSTRACT Deep wide-Ðeld CCD images in the optical and near-infrared have been acquired for 14 of the 16 known or suspected members of the IC 342/Ma†ei Group of galaxies, one of the closest groups to the Milky Way, and probably the closest group to M31. Because of their low Galactic latitude, all galaxies are heavily extinguished, and myriads of foreground stars are superimposed. A sophisticated algorithm built around DAOPHOT has been developed which successfully removes the foreground stars, making possible comprehensive morphological and photometric studies. The cleaned near-infrared images reveal the true morphology and extent of many of the galaxies for the Ðrst time, three of which are among the largest in the northern sky. Besides surface brightness proÐles, precise total magnitudes and colors have been measured. Many of the results represent substantial revisions to previous estimates. The data will make possible new determinations of the distances and masses of the galaxies, which are crucial for evaluating the impact the group may have had upon the dynamical evolution of the Local Group. Subject headings: galaxies: clusters: individual (IC 342/Ma†ei) È galaxies: photometry È galaxies: structure È infrared: galaxies

1. INTRODUCTION ellipse Ðts to isophotes, orientations, and spheroid and disk properties. In a separate paper, we will undertake a com- The IC 342/Ma†ei Group is a loose grouping of more prehensive analysis of foreground extinctions, which may be than a dozen galaxies located behind the Milky Way near up to a factor of 100 in the V band for several group the northern intersection of the Galactic and supergalactic members, and then derive distances using a variety of well- planes. The group is thought to be one of the most impor- established techniques. tant within 5 Mpc of the Milky Way and may contain the In ° 2, we present some background information to place nearest normal giant elliptical. Yet, deÐnitive estimates of our observations into proper perspective. Following this, in its total mass and population have never been obtained, ° 3, we discuss the processing and calibration of the Schmidt owing to severe extinction and the superposition of myriads images. In ° 4, we describe how images were cleaned, includ- of foreground stars. To date, the best available estimates for ing the method developed to eliminate foreground stars, the distance are in the range of 2È4 Mpc. If correct, dynami- which posed a formidable obstacle to photometry for most cal studies suggest that the two dominant members, IC 342 of our sample galaxies. An atlas of the galaxies, showing and Ma†ei 1, may have interacted with the Local Group as morphology before and after elimination of Ðeld stars, is recently as eight billion years ago. Clearly, the group merits presented in ° 5. Surface photometry, including the deriva- far more attention than it has received. tion of global photometric parameters, is covered in ° 6. A This paper provides, in some cases for the Ðrst time, stan- detailed discussion of each galaxy, including an analysis of dard global photometric parameters for 14 of the 16 known the surface photometry, is presented in ° 7. Other extended or suspected members of the IC 342/Ma†ei Group, to set sources in the vicinity of the galaxies are described in ° 8. the stage for determining an accurate distance to the group Finally, a brief summary is presented in ° 9. and to evaluate its possible inÑuence on the Local Group in the past. The photometry we present is based on CCD 2. BACKGROUND imaging surveys carried out with the 0.6/0.9 m Burrell- Schmidt Telescope of Kitt Peak National Observatory in 2.1. Census 1992 and 1995. In two previous papers (McCall & Buta The IC 342/Ma†ei Group is located near the northern 1995, 1997), we presented preliminary information on three intersection of the Galactic and supergalactic planes in new probable members of the group identiÐed on our the Galactic coordinate range 129¡ ¹ l ¹ 149¡, survey images. This paper presents our Ðnal results for these [1¡ ¹ b ¹ 16¡. The current census stands at 16 known or galaxies and 11 others, encompassing morphologies, total suspected members, most of which are late-type dwarfs (see magnitudes and color indices, surface brightness proÐles, Krismer, Tully, & Gioia 1995). Table 1 gives the dates of discovery, morphologies (from this paper), heliocentric 1 Visiting Astronomer, Kitt Peak National Observatory, National radial velocities, and positions. In this table, the galaxies are Optical Astronomy Observatories, which is operated by the Association of listed in order of right ascension, but in subsequent tables Universities for Research in Astronomy, Inc., under cooperative agreement and Ðgures they will be listed in alphabetical order to ease with the National Science Foundation. Observations made with the Burrell Schmidt of the Warner and Swasey Observatory, Case Western Ðnding. Figure 1 displays the locations of the galaxies in Reserve University. Galactic coordinates (see also Fig. 1 of Krismer et al. 1995 2 Please direct all correspondence to: Marshall McCall. and of Karachentsev et al. 1997). The group extends 33 34 BUTA & MCCALL Vol. 124

TABLE 1 KNOWN AND SUSPECTED MEMBERS OF THE IC 342/MAFFEI GROUP

v_ l bLB Object Discovery Type (km s~1) R.A. (1950) Decl. (1950) (deg) (deg) (deg) (deg) References (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

Cassiopeia 1 ...... 1995 IAB(s)m ]35 02 02 05.0 ]68 46 18.0 129.57 ]7.11 6.28 ]8.48 D1,V1,C1 MB1...... 1995 IBm ]189 02 31 52.1 ]59 09 39.7 135.85 [0.85 358.98 ]1.41 D2,V2,C2 Maffei 1 ...... 1968 E3 [87 02 32 50.7 ]59 26 16.4 135.86 [0.55 359.29 ]1.44 D3,V3,C2 MB2...... 1995 I? ? 02 33 16.1 ]59 01 12.8 136.07 [0.91 358.95 ]1.19 D2,V4,C2 Maffei 2 ...... 1968 SAB(rs)bc [23 02 38 08.0 ]59 23 24.0 136.50 [0.33 359.58 ]0.83 D3,V5,C3 Dwingeloo 2 ...... 1995 Im ]91 02 50 19.1 ]58 48 07.0 138.16 [0.19 359.90 [0.81 D4,V6,C4 MB3...... 1997 dSph ? 02 51 53.2 ]58 39 30.0 138.41 [0.23 359.89 [1.06 D5,V4,C4 Dwingeloo 1 ...... 1994 SB(s)cd ]108 02 53 01.9 ]58 42 38.0 138.52 [0.11 0.02 [1.15 D6,V6,C4 IC342...... 1895 SA(s)cd ]25 03 41 58.6 ]67 56 26.0 138.17 ]10.58 10.60 ]0.37 D7,V7,C3 UGCA 86...... 1974 SAB(s)m ]80 03 54 59.2 ]66 59 56.6 139.76 ]10.65 10.85 [1.17 D8,V8,C5 Camelopardalis Aa ...... 1994 I/dSph ? 04 19 26.7 ]72 41 27.0 137.25 ]16.20 16.09 ]1.87 D9,V4,C6 NGC 1569 ...... 1789 I (Amorphous) [77 04 26 05.8 ]64 44 18.0 143.68 ]11.24 11.91 [4.92 D10,V9,C3 NGC 1560 ...... 1885 Sd [36 04 27 08.2 ]71 46 29.0 138.37 ]16.02 16.03 ]0.79 D11,V10,C3 UGCA 92...... 1974 IBm [95 04 27 25.9 ]63 30 22.4 144.71 ]10.51 11.32 [6.01 D8,V8,C5 Camelopardalis Ba ...... 1997 I ]75 04 48 03.3 ]67 01 02.0 143.38 ]14.42 15.04 [4.21 D12,V11,C7 UGCA 105 ...... 1974 SAB(s)m ]113 05 09 35.2 ]62 31 19.6 148.52 ]13.66 14.99 [9.25 D8,V8,C5

NOTES.ÈCol. (1): Name of galaxy, in order of right ascension. Col. (2): Date of publication of discovery. Col. (3): Revised Hubble type, based upon images presented in this paper where available. For Cam A and Cam B, types are based upon the judgment of the authors on the basis of published data (see text). Col. (4): Heliocentric radial velocity, in km s~1. Col. (5): Right ascension, epoch 1950, in units of hours, minutes, and seconds. Col. (6): Declination, epoch 1950, in units of degrees, arcminutes, and arcseconds. Col. (7): Galactic longitude. Col. (8): Galactic latitude. Col. (9): supergalactic longitude. Col. (10): supergalactic latitude. Col. (11): References to discovery, velocity, and coordinates. a Not observed for this paper. REFERENCES.ÈDiscovery: (D1) Weinberger 1995 (but also note Blitz et al. 1982); (D2) McCall & Buta 1995; (D3) Ma†ei 1968; (D4) Verheijen, Burton, & Kraan-Korteweg 1995; (D5) McCall & Buta 1997; (D6) Kraan-Korteweg et al. 1994, and Huchtmeier et al. 1995; (D7) Dreyer 1895, based upon a communication from W. F. Denning; (D8) Nilson 1974; (D9) Karachentsev 1994; (D10) Herschel 1789; (D11) Tempel 1885; (D12) Huchtmeier et al. 1997. Heliocentric Radial Velocityv_ : (V1) Huchtmeier et al. 1995; (V2) McCall, Buta, & Huchtmeier 1995, and Huchtmeier & van Driel 1996; (V3) McCall et al. 1999; (V4) Not measured; (V5) Hurt et al. 1996; (V6) Burton et al. 1996; (V7) Newton 1980a; (V8) Huchtmeier & Richter 1986; (V9) Reakes 1980; (V10) Broeils 1992; (V11) Huchtmeier et al. 1997. Coordinates: (C1) Huchtmeier et al. 1995; (C2) McCall & Buta 1995; (C3) de Vaucouleurs et al. 1991; (C4) McCall & Buta 1997; (C5) this paper; (C6) Karachentseva & Karachentsev 1998; (C7) Huchtmeier et al. 1997. along the supergalactic plane from the Galactic plane, The group is displaced by only 30¡ from M31; considering where members are most heavily obscured, toward the distances, it is likely the nearest to M31. concentration of galaxies around M81. It is a member of In B, the apparently brightest members of the group are what Tully (1982) refers to as the Canes Venatici Cloud. the Scd spiral IC 342, the peculiar amorphous galaxy NGC 1569, and the edge-on Magellanic system NGC 1560, which were discovered in the 18th and 19th centuries. These three objects have received the most attention and are actually rather well studied. Three faint dwarfs in the region, UGCA NGC 1560 @@ 86, 92, and 105, were discovered by Nilson (1974). The true Camelopardalis B 15 Camelopardalis A extent of the group was not really recognized until the dis- @ @ covery of Ma†ei 1 and 2 in 1968 (Ma†ei 1968), now recog- UGCA 105 ' nized as an elliptical and Sbc spiral, respectively. The most NGC 1569 ' ': IC342 'in., @ recent additions are Cam A (Karachentsev 1994), Cam B I!! @ @ \@ (Huchtmeier, Karachentsev, & Karachentseva 1997), Cas 1 C) 10 ., UGCA86 : UGCA92 (Weinberger 1995; Huchtmeier et al. 1995), Dwingeloo 1 :E,., ' ,, ' Cassiopeia 1 (Kraan-Korteweg et al. 1994; Huchtmeier et al. 1995), ' @ ' Dwingeloo 2 (Verheijen, Burton, & Kraan-Korteweg 1995; ~ '' Supergalactic Plane Burton et al. 1996), MB 1 and MB 2 (McCall & Buta 1995; 5 '' McCall, Buta, & Huchtmeier 1995), and MB 3 (McCall & (!)I ' Buta 1997). The Ðrst two galaxies discovered by McCall & '' Buta (1995) are probable dwarf companions of Ma†ei 1 ~l~ctic Dwingeloo 1 ~ Maffei 2 (although the status of the second remains uncertainÈsee 0 ------· (t)·------MB 3 : +

Ma†ei 2 may be close in luminosity (see McCall & Buta Spinrad et al. (1971, 1973) derived the Ðrst estimates of 1996). A more deÐnitive statement concerning this issue will the amount of extinction toward Ma†ei 1 and 2 by compar- be presented in a separate paper. Although Dwingeloo 1 ing the nuclear spectra with spectra of the spheroid of M31 was purported to be a large galaxy at the time of its dis- and giant ellipticals like NGC 3379. In visual light, Ma†ei 1 covery, it is substantially less luminous than the other three was found to be extinguished by 5.2 mag and Ma†ei 2 by 6.3 galaxies, being more akin to M33. mag. Additional members of the IC 342/Ma†ei Group will no Spinrad et al. (1971) made a rough estimate of the dis- doubt be found as the region is more intensively scrutinized. tance to Ma†ei 1 using a measurement of the core radius, an Several surveys of the area around Ma†ei 1 and 2 have been eyeball estimate of the central velocity dispersion, an made recently (Weinberger, Saurer, & Seeberger 1995; Hau inferred total magnitude, and an assumed mass-to-light et al. 1995; Lercher, Kerber, & Weinberger 1996; Iwata et ratio. The result, 1 Mpc, which was evaluated to be within a al. 1997; Saurer, Seeberger, & Weinberger 1997; Henning et factor of 2 of the true distance, prompted them to suggest al. 1998; Buta & McCall, in preparation). Lahav et al. (1998) that the galaxy might be an unbound member of the Local have suggested that a particularly good candidate for mem- Group. bership is the edge-on system C11J7 discovered by Hau et The extinction toward Ma†ei 1 was a subject of contro- al. (1995). Many papers concerning other current work on versy. Various methods involving foreground stars consis- identifying and studying galaxies in the ““ Zone of tently gave visual extinctions less than about 4 mag. Buta & Avoidance ÏÏ appear in the proceedings of the meeting, McCall (1983) evaluated these methods and made two new ““ Unveiling Large-Scale Structures Behind the Milky Way ÏÏ estimates of the extinction independent of Spinrad et al. (Balkowski & Kraan-Korteweg 1994). (1971). First, they measured the total column density of gas in the direction of the galaxy, which was known to correlate 2.2. Major Galaxies well with the total visual extinction by dust (Savage & ^ 2.2.1. IC 342 Mathis 1979). The result forAV was 4.9 0.4 mag. Second, IC 342 was discovered by W. F. Denning in the 1890Ïs they carried out photoelectric photometry of the inner (Dreyer 1895), and one of the best photographs was region of the galaxy, from which they were able to derive published long ago by Hubble (1936). It is a large late-type B[V . Comparing the measurement with the known intrin- spiral close to face-on. sic colors of elliptical galaxies,AV was estimated to be By measuring its tilt (25¡ ^ 3¡), Newton (1980a, 1980b) 5.3 ^ 0.4 mag. Together, the results conÐrmed the estimate revealed that IC 342 is rotating at a rate typical of a giant of Spinrad et al. (1971). spiral. However, its distance was uncertain. Until 1989, dis- Based on a large extrapolation of the V -band photoelec- tance estimates for IC 342 ranged from 1.5 to 8 Mpc, pri- tric growth curve, Buta & McCall (1983) estimated the total marily because of uncertainty in the extinction (McCall visual magnitude of Ma†ei 1 to be 11.4 mag. This led to a `1.3 1989). Circumstantial evidence suggested that the distance distance of2.1~0.8 Mpc, based upon the relationship was on the low side of this range. For example, Hodge & between luminosity and central velocity dispersion Kennicutt (1983) counted more H II complexes in IC 342 observed for elliptical galaxies in visual light (de Vaucou- than in any other spiral except M81, indicating some beneÐt leurs & Olson 1982). The corresponding absolute magni- from higher spatial resolution accompanying proximity to tude in V was [20.4, close to that of the Milky Way. the Milky Way. Also, the high Ñux observed for many Membership in the Local Group seemed to be ruled out. molecular lines (e.g., Henkel, Mauersberger, & Schilke Instead, the galaxy appeared to be located in what was 1988) hinted that the galaxy was nearby. known at the time as the Ursa Major-Camelopardalis Spectra of constituent H II regions by McCall, Rybski, & Cloud (Bottinelli et al. 1971), of which IC 342 was also a Shields (1985) led to the realization that IC 342 was extin- part. guished by 2.4 mag in V , much more than previously More recently, by measuring surface brightness Ñuctua- thought (McCall 1986, 1989). The result was subsequently tions in the K@ passband, Luppino & Tonry (1993) esti- conÐrmed by Madore & Freedman (1992), who examined mated the distance to Ma†ei 1 to be 4.2 ^ 0.5 Mpc. the color of the blue plume in the HR diagram of an arm Although ostensibly a better method of getting the distance Ðeld. The new estimate for the extinction forced a revision than any of the other methods so far applied (see Jacoby et of nearly all previous distance estimates (McCall 1989). The al. 1992), the result may be compromised by practical prob- resulting mean was only 1.8 Mpc (with a standard deviation lems unique to the Ðeld of Ma†ei 1. SpeciÐcally, the severe of 0.3 Mpc), implying that the luminosity in B was [20.2, contamination of the Ðeld by faint foreground stars and similar to that of the Milky Way. Given the size of the variations in the galaxy-subtracted background introduced galaxy and its proximity to M31, it was realized that IC 342 by the dust lanes may have seriously a†ected the determi- (along with Ma†ei 1) might have played a signiÐcant role in nation of the Ñuctuation magnitude (see Jensen, Tonry, & the evolution of the Local Group (see below). Luppino 1998). Evidence that there may be a problem is suggested by the fact that the Ñuctuation magnitude bright- 2.2.2. Ma†ei 1 and 2 ens by 0.46 mag going from a radius of 6A to 62A, which is In 1968, Ma†ei (1968) discovered two heavily reddened opposite to what would be expected if there had been a extended sources in the same general area as IC 342, which relatively recent episode of star formation focussed on the he suspected to be galaxies. Spinrad et al. (1971, 1973) veri- center, or if there were a signiÐcant population of globular Ðed that both were galaxies, and identiÐed the Ðrst as a clusters. giant elliptical and the second as an intermediate-type It is very likely that Ma†ei 1 is the nearest normal giant spiral. These classiÐcations are conÐrmed in this paper. elliptical galaxy to the Local Group and may, in terms of The galaxies became known as Ma†ei 1 and Ma†ei 2, mass, be the dominant member of the IC 342/Ma†ei Group. respectively. Even if Ma†ei 1 were as distant as 4 Mpc, it would still be a 36 BUTA & MCCALL Vol. 124 very important object. Giant elliptical galaxies are rare member from each (which ultimately became IC 342 and among most of the nearby groups cataloged by de Vaucou- Ma†ei 1) and the merger of the remaining member of each leurs (1975). If Ma†ei 1 is the nearest giant elliptical, then it with M31. Besides conÐrming that the results of conven- presents an opportunity to study the core of such a galaxy tional Local Group timing are unreliable, they suggested at unprecedented resolution. that timing of the enlarged system (basically the four-body In principle, a good distance for Ma†ei 2 could have been system of the Milky Way, M31, Ma†ei 1, and IC 342) might gained through application of the Tully-Fisher relation, yield improved estimates for the total mass and age. Of because 21 cm radiation has been readily detectable (e.g., course, the primary deÐciency of the model is that it does Hurt, Turner, & Ho 1996). Unfortunately, the apparent not explicitly predict the existence of any other large gal- total magnitude of the galaxy has never been measured. axies in the same direction as IC 342 and Ma†ei 1 (at the Thus, the distance has remained extremely uncertain. Bot- time, the location and size of Ma†ei 2 were not known, and tinelli et al. (1971) obtained distance estimates ranging from Dwingeloo 1 was not discovered yet), although it could be 2 to 6 Mpc by comparing the H I properties with those of argued that dwarfs might have arisen from tidal disruption other galaxies of comparable type. Spinrad et al. (1973) of the interacting systems. derived a value of 5 ^ 2 Mpc on the basis of the sizes of constituent H II regions. It is probably best to regard the 2.4. Reasons for this Study last estimate as an upper limit, because the heavy extinction To fully evaluate models which attempt to use the makes the nebulae look smaller than they would appear in a motions of neighbors of the Milky Way to arrive at the age galaxy at a comparable distance but at a higher galactic of the universe and the local density of dark matter latitude. (Valtonen et al. 1993; Byrd et al. 1994; Peebles 1995), and to Distances to Ma†ei 1 and 2 remain so uncertain that a develop improvements, it is imperative not only to complete physical connection between the two galaxies cannot be the census of galaxies in the IC 342/Ma†ei Group, but to ruled out. If Ma†ei 2 and Ma†ei 1 were at comparable have complete and reliable data for each constituent. As distances, it is likely that the luminosity of Ma†ei 2 would noted by Krismer et al. (1995), any successful model must be approach that of Ma†ei 1 (McCall & Buta 1996). Although able to account for the current placement of all members of Ma†ei 2 appears fainter, it is more heavily extinguished. A the group, not just Ma†ei 1 and IC 342. comprehensive examination of the intrinsic properties of Total colors, magnitudes, and sizes of group members are the members of the IC 342/Ma†ei Group will be presented essential to reÐning estimates of extinction, distance, and in a separate paper. luminosity. In addition, surface photometry of the larger members is needed to determine relative masses and inter- 2.3. Relevance to L ocal Group T iming action radii for n-body simulations. Kahn & Woltjer (1959) and Lynden-Bell (1981) have Presently, apparent photometric data for most of the gal- shown that the distances and motions of nearby galaxies axies is anchored to photography (or worse). Existing aper- may be used to constrain the total mass of the M31ÈMilky ture photometry is often suspect because of contamination Way pair and the dynamical age of the Local Group. The by foreground stars, or so limited in scope that profound latter has been interpreted as an independent estimate for extrapolations must be made to derive integrated proper- the age of the universe. The method, known as ““ Local ties. In addition, the sizes of all galaxies in the group are Group timing,ÏÏ hinges upon the assumption that M31 and extremely uncertain due to the heavy obscuration (the three the Milky Way separated from the Hubble Ñow soon after largest are at least 15@È30@ across). The research presented formation and have behaved dynamically like an isolated here overcomes all of these problems and provides for the binary ever since, with the consequence that the Milky Way Ðrst time a homogeneous and reliable set of fundamental has turned in its orbit and is now falling back toward M31. data, which should Ðnally make it possible to pinpoint the McCall (1986, 1987, 1989) noticed that the modern role that the IC 342/Ma†ei Group has played in our own revision to the extinction of IC 342 moved the galaxy into a history. position only 1.3 Mpc from M31. This led to the realization that Ma†ei 1 might be comparably close. Relative mass-to- 3. OBSERVATIONS, REDUCTIONS, AND CALIBRATIONS light ratios indicated that the present gravitational acceler- ation of M31 by IC 342 and Ma†ei 1 is signiÐcant with 3.1. Observations and Reductions for V and I respect to that due to the Milky Way. Considering the Except for Cam A and Cam B, all of the galaxies listed in present rate of recession of the two galaxies from M31, their Table 1 were observed. The main observations were carried past dynamical inÑuence on the Local Group must have out with the 0.6/0.9 m Burrell Schmidt telescope at Kitt been even greater. In other words, the dominant members Peak National Observatory during the period 1995 of the IC 342/Ma†ei Group may be massive enough and November 11È16 (UT). All images were acquired with a near enough to the Local Group to have had an inÑuence Tektronix 2048 ] 2048 CCD camera, for which pixel sizes on local history (McCall 1986, 1987, 1989; Valtonen et al. were 21 km square. The CCD was fed an f/3.5 beam. Using 1993; Dunn & LaÑamme 1993; Peebles 1990, 1994), thereby medium brightness stars from the Space Telescope Science calling into question the binary hypothesis of Local Group Institute Guide Star Catalog, we determined the exact scale timing (see, e.g., Peebles 1995). of the images to be2A.028 ^ 0A.001 per pixel, so the frames Valtonen et al. (1993) interpreted the high speeds of IC covered 69@ ] 69@ on the sky. The readout noise was only 342 and Ma†ei 1 relative to M31 and the current approach 3 e~ pixel~1, so exposures were sky-noise dominated. The of M31 toward the Milky Way to indicate that an encoun- gain setting was 3.75 electrons per ADU. ter took place 5 to 8 billion years ago. They proposed that Images were acquired in V (KPNO Ðlter 1542, central two primordial binaries encountered the progenitor of M31 wavelengthj \ 5436 AŽ , full width at half-maximum \ c Ž \ and that the ensuing interactions led to the ejection of one FWHM 1004A), Cousins I (KPNO Ðlter 1539, jc No. 1, 1999 IC 342/MAFFEI GROUP REVEALED 37

TABLE 2 OBSERVING LOG

E†ective Number of Object Filter Air Mass UT Date Frames Minutes/Frame

Cassiopeia 1 ...... I 1.434 1995 Nov 12 6 5 Cassiopeia 1 ...... V 1.510 1995 Nov 14 6 5 Dwingeloo 1 ...... I 1.151 1995 Nov 11 5 5 Dwingeloo 1 ...... V 1.282 1995 Nov 14 6 5 Dwingeloo 1 ...... Ha 1.499 1995 Nov 16 1 10 IC342...... I 1.271 1995 Nov 12 6 5 IC342...... V 1.286 1995 Nov 14 5 5 IC342...... B 1.237 1992 Oct 26 2 10 IC342...... Ha 1.501 1995 Nov 16 2 10 Maffei 1 ...... I (1) 1.303 1995 Nov 11 6 5 Maffei 1 ...... I (2) 1.156 1995 Nov 15 6 5 Maffei 1 ...... V 1.332 1995 Nov 14 6 5 Maffei 1 ...... B 1.146 1992 Oct 26 3 10 Maffei 1 ...... Ha 1.297 1995 Nov 16 2 10 Maffei 2 ...... I 1.211 1995 Nov 11 6 5 Maffei 2 ...... V 1.186 1995 Nov 14 6 5 Maffei 2 ...... B 1.274 1992 Oct 26 2 15 Maffei 2 ...... Ha 1.487 1995 Nov 16 1 10 NGC 1560 ...... I 1.303 1995 Nov 12 6 5 NGC 1560 ...... V 1.560 1995 Nov 14 3 5 NGC 1569 ...... I 1.306 1995 Nov 12 4 5 NGC 1569 ...... V 1.426 1995 Nov 14 3 5 UGCA 86...... I 1.262 1995 Nov 15 5 5 UGCA 86...... V 1.320 1995 Nov 14 6 5 UGCA 92...... I 1.207 1995 Nov 15 6 5 UGCA 92...... V (1) 1.174 1995 Nov 14 6 5 UGCA 92...... V (2) 1.189 1995 Nov 14 6 5 UGCA 92...... Ha 1.498 1995 Nov 16 1 15 UGCA 105 ...... I 1.323 1995 Nov 15 6 5 UGCA 105 ...... V 1.232 1995 Nov 14 6 5 M81...... I 1.257 1995 Nov 16 1 1 M81...... V 1.259 1995 Nov 16 1 1

Ž \ Ž \ 8244A,A FWHM 1954), Ha (KPNO Ðlter 1563, jc acquired in Cousins I over two nights (November 12 and 6573AŽ ,A FWHM \ 67Ž ), and a continuum band adjacent 15), and three in V on one night (November 14). Scattered \ Ž \ Ž to Ha (KPNO Ðlter 1494,jc 6658 A,A FWHM 84 ). moonlight impacted some of our observations either as a Through each broadband Ðlter, sequences of Ðve or six 5 background gradient or as streaks. To minimize the minute exposures were taken. The shortness of the expo- problem, we positioned the dome slit to prevent moonlight sures was motivated by the need to minimize the number of from directly falling on the front end of the telescope. saturated stars in the very crowded Ðelds under study and Reductions for each night were carried out using IRAF.4 to facilitate the removal of cosmic ray events. Because of Bias corrections were made using an overscan zone 32 slight Ðeld distortion, no dithering was done between suc- columns wide in each image and a zero correction frame for cessive images. To minimize Ðlter positioning errors and the night constructed from the combination of two sets of improve Ñat-Ðelding, we observed with only one broadband 11 bias frames acquired at the beginning and end of the Ðlter per night. One or two Ha exposures, each of 10È15 night. The dark current was determined to be small and minutes duration, were acquired for Dwingeloo 1, IC 342, showed no pattern, therefore no dark correction was made. Ma†ei 1, Ma†ei 2, and UGCA 92. In each case, an obser- Considerable care was taken to ensure accurate Ñat- vation of equal duration was made through the continuum Ðelding over the entire Ðeld of the CCD. Dome Ñat Ðelds Ðlter.3 could not be used because it was not possible to employ A log of the observations is given in Table 2. In addition exposures long enough to quench the shutter pattern when to the galaxies in the IC 342/Ma†ei Group, we also made using the lighting system required to evenly illuminate the short (60 s) exposures of M81 in V and I to provide an screen. Instead, twilight images acquired at the beginning of external check on our surface photometry. Besides the usual each night (when the Moon was below the horizon) were calibration images, jittered 10 minute exposures of a employed to remove pixel-to-pixel variations in response. ““ blank ÏÏ Ðeld at relatively high Galactic latitude The individual twilight Ñats were combined using the IRAF [a(1950) \ 01h42m15s, d(1950) \ 14¡07@41@@] were acquired task FLATCOMBINE with the option CCDCLIP to after dark to facilitate Ñat-Ðelding. A total of six frames was

4 IRAF is distributed by the National Optical Astronomy Observa- 3 Results from the analysis of the Ha and continuum images will be tories, which is operated by the Association of Universities for Research in presented in detail in a separate paper. Astronomy, Inc., under contract to the National Science Foundation. 38 BUTA & MCCALL Vol. 124 remove Ðeld stars. Although faint residuals of some of these for electronic improvements that came in the later run. The stars remained, their e†ect on the Ñat-Ðelded images was preprocessing of the images (bias correction, twilight Ñat- small. Ðelding) was basically the same as for the 1995 data, with All frames of the blank Ðeld acquired through a given the di†erence that no ““ blank sky ÏÏ Ðeld was observed to Ðlter were combined to create an illumination correction improve Ñat-Ðelding. Also, only two frames of 10 and 15 image relative to the twilight Ñat suitable for removing low- minutes each were obtained for IC 342 and Ma†ei 2, respec- frequency variations in response. In the process of checking tively, so that cosmic ray removal was less automatic for the illumination correction by Ñattening the individual dark these galaxies. The B-band images are extremely useful for sky images, it was discovered that subtle large-scale pat- evaluating reddenings, especially for Ma†ei 1 and 2. terns were left that di†ered from image to image. These patterns were seen in the I Ðlter, but not in the V Ðlter, 3.3. Calibrations suggesting that they were caused by spatial 0.8 km varia- Images were calibrated using observations of several tions in the airglow on scales less than1¡.2. For the three Ðelds from Landolt (1992). Because of the large Ðeld of view blank Ðeld images obtained on 1995 November 15, the of the Schmidt frames, we were able to use nearly every amplitude of these variations was typically 1% or less. The standard star in each Landolt Ðeld. combined illumination image in I averaged out the varia- The Landolt Ðelds were chosen to include the widest tions to an extent that our illumination correction image range of V [I colors possible, because of the severe was not seriously compromised by them. Similarly, by com- reddening of many of the galaxies in our sample. The best bining up to Ðve or six images of each galaxy, variations Ðeld for our purposes was Selected Area 110, where V [I local to the galaxy frames would have averaged out also, ranges from 0.353 to 2.856. This range almost extends far minimizing or eliminating their impact on our surface enough to include Ma†ei 1 and 2, for which V [I + 3.1. photometry. On the best three of our six nights of 1995, we imaged It is difficult to assess the Ðnal accuracy of our Ñat- four di†erent Landolt Ðelds, each at least two times with Ðelding for many of our sample galaxies because some Ðelds di†erent exposures to balance the brighter and fainter stars. show glowing foreground material and possibly variable One Ðeld was observed at both high and low air mass to extinction. Based on our analysis of the blank Ðeld images, obtain accurate extinction coefficients. The range of air we estimate that our Ñat-Ðelding is good to better than mass observed was 1.2È2.3. 0.5% for low-frequency features and much better than this Except for the V band on the night of November 16, for high-frequency features. natural magnitudes were measured with the IRAF task After Ñattening, we combined the galaxy images in each PHOT using an aperture 14A in diameter, the same as used observing sequence. This was performed using the IRAF by Landolt (1992) for most of his photoelectric obser- task IMCOMBINE with a rejection option to remove vations. (An aperture of 18A was used for the November 16 cosmic rays and occasional satellite or meteor streaks. First, V -band calibration owing to a slight focus error.) Since only each image was shifted to the coordinate system of one one Ðlter was used on most of the nights, we applied the image chosen to be the reference image. The IRAF task PHOTCAL package in IRAF to arrive at the following IMALIGN was used for this purpose, using a Ðle of star relations: positions on the reference image. Because skies were photo- \ ] ] [ 2] ] [ metric, each individual shifted image was scaled according v V v0 v1(V I) v2 x v3(V I) , (1) to its air mass relative to the reference image in the i \ I ] i ] i (V [I)2]i x ] i (V [I) , (2) sequence. Before combining, a zero level o†set was removed 0 1 2 3 from each image to make the background levels equal. where V , I, and V [I are from Landolt (1992), v and i are Then, the o†set for the reference image was added back to the natural magnitudes scaled to 1 s exposures, x is the air the combined image. This procedure gave us a combined mass, andv0, v1, v2, v3 andi0, i1, i2, i3 are coefficients image with a cosmic signal and background level appropri- derived by least squares (see Stetson 1990). The results are ate to a well-deÐned air mass. Galaxy images then were listed in Table 3. cleaned of all stars and artifacts (see ° 4). All surface photo- On our best night, the standard deviation of the I-band metry was performed on the combined and cleaned images. calibration was 0.038 mag. For the V -band calibration, the Some of the I-band images of NGC 1560 and NGC 1569 best night gave a standard deviation of 0.026 mag. The were compromised by thin clouds (easily visible in the larger scatter in I may be attributable to the brighter sky moonlight). Before combining, the a†ected images were background. On other nights, when we obtained fewer stan- scaled to the unobscured ones using factors determined dards due to partial cloudiness, we used mean color coeffi- from photometry of a common set of stars. cients from the good nights and solved for zero points (and extinction coefficients if necessary). 3.2. Observations and Reductions for B As a check on how much light lay outside the adopted Observations of IC 342, Ma†ei 1, and Ma†ei 2 were aperture for photometry, we remeasured stars observed on obtained in B, V , and I with the Burrell-Schmidt on 1992 1995 November 15 with a 20A aperture. The color coeffi- \[ ^ \ October 26 (UT). The log is included in Table 2. Unfor- cients obtained werei1 0.0143 0.0050 and i3 tunately, only the B-band images could be Ñat-Ðelded well 0.0118 ^ 0.0142, compared with i \[0.0140 ^ 0.0042 \ ^ 1 enough to be used for surface photometry. Imperfect repo- andi3 0.0105 0.0117 for a 14A diameter aperture. The sitioning of the Ðlter wheel compromised the images in V results for the two apertures agree within the uncertainties, and I (a problem identiÐed by NOAO sta† after our 1992 but mean errors for the 20A measurements are larger, prob- run, and then supposedly Ðxed, but nevertheless the reason ably due to inclusion of faint companions and more sky why we chose to use only one Ðlter per night during the light. If the color and extinction coefficients are Ðxed at the 1995 run). The same CCD setup was used as in 1995, except values in Table 3, then the zero point for the 20A calibration No. 1, 1999 IC 342/MAFFEI GROUP REVEALED 39

TABLE 3 STANDARD STAR CALIBRATIONS

Number UT Date PHOTCAL Solution rms of Stars

1992 Oct 26 ...... b \ B [ (18.6928 ^ 0.0161) [ (0.04406 ^ 0.00780)(B[V )2](0.2893 ^ 0.0094)x ] (0.0595 ^ 0.0184)(B[V ) 0.036 116

1995 Nov 11 ...... i \ I [ (19.4584 ^ 0.0099) [ (0.01545 ^ 0.00442)(V [I)2](0.0476 ^ 0.0042)x ] (0.0157 ^ 0.0124)(V [I) 0.038 275

1995 Nov 12 ...... i \ I [ (19.4715 ^ 0.0036) [ 0.0147(V [I)2]0.050x ] 0.0131(V [I) 0.051 155

1995 Nov 14 ...... v \ V [ (19.5780 ^ 0.0074) [ (0.00696 ^ 0.00278)(V [I)2](0.1288 ^ 0.0038)x [ (0.0181 ^ 0.0076)(V [I) 0.026 304

1995 Nov 14 ...... v \ V [ (19.5772 ^ 0.0074) [ (0.00962 ^ 0.00396)(B[V )2](0.1277 ^ 0.0040)x [ (0.0193 ^ 0.0088)(B[V ) 0.026 304

1995 Nov 15 ...... i \ I [ (19.4615 ^ 0.0104) [ (0.01398 ^ 0.00416)(V [I)2](0.0531 ^ 0.0050)x ] (0.0105 ^ 0.0117)(V [I) 0.041 272

1995 Nov 16 ...... v \ V [ (19.5847 ^ 0.0032) [ 0.007(V [I)2]0.129x [ 0.018(V [I) 0.020 64

1995 Nov 16 ...... i \ I [ (19.4938 ^ 0.0250) [ (0.04985 ^ 0.02041)(V [I)2]0.05x ] (0.0960 ^ 0.0471)(V [I) 0.034 64 changes to 19.4948, which is only 0.033 mag larger than for determine B[V colors, it was necessary to compute a cali- 14A. bration formula for V for the night of 1995 November 14 The calibration of the 1992 B-band observations was per- with B[V as an independent variable (rather than V [I). formed in a similar manner to the 1995 observations. Four The following relations were used: standard star Ðelds were observed (three of them the same \ ] ] [ 2] ] [ as in 1995) covering a wide range in color and air mass. To b B b0 b1(B V ) b2 x b3(B V ) , (3) \ ] ] [ 2] ] [ v V v0 v1(B V ) v2 x v3(B V ) . (4) Even though separate observing runs are involved, it is perfectly feasible to combine these formulae since the stan- I>. dard magnitudes, rather than the natural magnitudes, are ;;" "'"' I>. I>. I>. I>. I>. I>. the independent variables. The resulting coefficients are ~ listed in Table 3. A test was made to determine if the B-band I>. rb • ,,. . I>. calibration formula required a second-order extinction cor- • • rection, but the term was found not to be signiÐcant. The • standard deviation of the B-band calibration was 0.036 mag.

<3 I>. I>. 3.4. External Checks X I>. I>. Photoelectric multiaperture photometry is available for 'ii" <3 ::,.'.' 0 X Ðve group members and M81 from Longo & de Vaucou- I>. J. leurs (1983), Buta & McCall (1983), de Vaucouleurs & I>. fl Longo (1988), and H. G. Corwin (1993, private communication). Figure 2 compares simulated aperture photometry of the galaxies in our images with the published photoelectric results. The plots show the di†erences .5 I>. between the published B, V and I magnitudes and the fully transformed magnitudes calculated from our CCD images ~ <3 (m ) as a function of the aperture diameter A. It should be ;;" X calc ,-," noted that our magnitudes are derived from our cleaned 0 'X J. images (see ° 4), but observers who obtained the photoelec- tric photometry could only remove speciÐc stars. Thus, -.5 comparisons for small apertures give the best idea of the quality of our zero-point determinations. .5 1 1.5 2 A numerical comparison of the magnitude di†erences in logA(0.'1) all three Ðlters is given in Table 4. For A ¹ 60@@, the mean di†erences in B and V are less than ^0.05 mag, indicating IG F . 2.ÈComparison of simulated circular aperture photometry (mcalc) satisfactory agreement. In I, there are no data for apertures with published photoelectric values in Longo & de Vaucouleurs (1983), less than 60A in diameter available, but the two smallest Buta & McCall (1983), de Vaucouleurs & Longo (1988), and H. G. Corwin apertures give a mean di†erence of only 0.067 ^ 0.048 mag. (1993, private communication). Magnitude di†erences are plotted against the aperture diameter. The symbols refer to di†erent galaxies as follows: For all three Ðlters, a larger standard deviation results if all vertical open triangles, IC 342; Ðlled circles, Ma†ei 1; crosses, NGC 1560; apertures are considered, due mainly to the imperfections of open circles, NGC 1569; pluses, UGCA 105; horizontal open triangles, M81. foreground star removal from large-aperture photoelectric 40 BUTA & MCCALL

TABLE 4 COMPARISON OF PHOTOELECTRIC AND CCD APERTURE PHOTOMETRY

[ Filter Aperture Range SPhotoelectric CCDTp1 N (1) (2) (3) (4) (5)

B ...... A ¹ 60@@ [0.043 0.086 11 V ...... A ¹ 60@@ 0.028 0.051 20 I ...... A ¹ 80@@ 0.067 0.067 2 B ...... All A [0.030 0.271 32 V ...... All A 0.046 0.200 61 I ...... All A 0.159 0.145 12

NOTES.ÈCol. (1): Name of Ðlter. Col. (2): Range of aperture diameters used in photoelectric photometry, in arcseconds. Col. (3): Mean di†erence between aperture magnitudes derived from photoelectric photometry and corresponding aperture magnitudes derived from CCD photometry. Col. (4): Standard deviation of magnitude di†erences. Col. (5): Number of photoelec- tric measurements. photometry. This problem is particularly severe for Ma†ei 1 able pieces and then put them back together once stars were in B. We conclude that zero points for all three of our Ðlters removed. have been determined to an accuracy of 0.05 mag or better. Also, when this project was begun, DAOPHOT could not Ðt properly a crowded Ðeld of stars on a variable back- 4. CLEANING OF IMAGES ground, such as that presented by an unresolved galaxy. In our Ðelds, groups were so large in extent relative to the 4.1. Overview galaxies that the ““ sky ÏÏ changed signiÐcantly across them. Because of the location of our sample galaxies close to the Yet, DAOPHOT Ðtted all stars in a group using the same Galactic plane, and our sensitivity to cool and highly background level. In response to our concerns, L. Davis reddened stars, the number of foreground stars on our (NOAO 1993, private communication) implemented a criti- images is extremely large (almost 100,000 on a few of the cal change which enabled the sky to be deÐned for individ- images). In order to isolate isophotes and carry out accurate ual stars, thus making possible good Ðts on a variable surface photometry, it was essential to remove as many of background. In addition, after a Ðrst run of DAOPHOT these stars as possible. Fortunately, most stars could be (speciÐcally, the DAOPHOT tasks DAOFIND and subtracted by deriving proÐle parameters via crowded-Ðeld ALLSTAR), we Ñattened the background as much as pos- photometry. However, bright stars and their artifacts, such sible by subtracting from the original image a median- as halos, di†raction spikes, or saturation overÑows, smoothed version of the star-free galaxy image. Then, required special attention. As well, in many of the images a Ðnding, Ðtting, and subtracting were repeated. Ðxed pattern of stripes was just visible above the sky, pre- An IRAF script was created to handle all aspects of sumably due to some instability in the electronics. To stellar photometry, including subdividing the image, Ðnding enable surface photometry down to the faintest possible the stars, carrying out initial photometry, Ñattening the isophotes, this pattern also had to be removed. background, Ðtting the stars, subtracting the stars, and A detailed Ñow chart showing the entire procedure for reassembling the star-subtracted subsections. This was cleaning images is given in Figure 3. The stream of tasks is called KILLALL. The procedure for removing stars from displayed by the connected square boxes on the left. Names any given subsection is illustrated in the Ñow chart in of the software tasks employed are capitalized. Input and Figure 4. Tasks are identiÐed in square boxes, and decisions output are speciÐed by the rounded boxes on the right. are marked by the diamonds. Input and output are speciÐed Input to particular tasks is indicated by bold black arrows. in rounded boxes. The Ñow of logic is displayed by thin Output from tasks is indicated by the wide grey arrows. black arrows. Input to speciÐc tasks is indicated by bold Except for KILLALL, RMPAT, and GALPHOT, all tasks black arrows. Output from a task is indicated by a thick are a part of IRAF or the IRAF implementation of grey arrow. Everywhere, names of employed software tasks DAOPHOT. Further details are given below. are capitalized. All tasks are a part of IRAF or the IRAF After evaluating several di†erent methods, we decided to implementation of DAOPHOT. use DAOPHOT (Stetson 1987, 1992) to Ðt the stellar pro- What follows is a brief verbal summary of the steps taken Ðles and subtract o† the stars. Even though the proÐles were to clean the images. Details regarding key aspects of the undersampled, experiments showed that DAOPHOT could process are given in subsections below. adeptly remove fainter stars, despite the severe crowding. For any particular image, cleaning began with a run of Noticeable residuals remained in the cores of the brightest KILLALL. The image was subdivided into 512 ] 512 sub- unsaturated stars, but they could be eradicated quickly and sections, each with a border 40 pixels wide. For each sub- accurately through noninteractive editing. section, stars were identiÐed with DAOFIND using a 5 p Unfortunately, the IRAF implementation of DAOPHOT detection threshold. Next, the stars were Ðtted with was incapable of handling more than 50,000 stars at a time, ALLSTAR using a Ðxed analytical psf (Mo†at25), and then or more than 100 stars in a group at a time. Although subtracted from the original image. Four passes through ALLSTAR (but not NSTAR) could deal with the group size DAOFIND and ALLSTAR were necessary, the Ðrst to limit through dynamic grouping, to handle the total star enable subtraction of the galaxy, and the next three to single limit it was necessary to break images into more manage- out as many stars as possible, especially in blends. The Ðrst Procedure for Cleaning Images ------... PSF Image: Reduced Assume PSF is constant Moffat25. Use a few stars to constrain the parameters. PSF: Initial estimate

KII..LALL Image: No stars, I Identify and remove stars, threshold 5cr. Catalogue: All stars, 1

PSELECT Select PSF candidates by magnitude. Catalogue: PSF candidates

SUBSTAR Subtract all but PSF candidates. Image: PSF candidates only

PSF Define variable PSF using best PSF candidates. PSF: Best variable

KILLALL Image: No stars, 2 Identify and remove stars, threshold 5cr. Catalogue: All stars, 2

PSELECT Select unsaturated stars with visible residuals. Catalogue: unsaturated bright stars

IMEDIT Non-interactively, remove residuals of Image: No spots unsaturated stars.

RMPAT Subtract any fixed pattern of horizontal stripes left Image: No stripes by CCD electronics.

KILLALL Image: No pepper Identify and remove stars, threshold 3cr. Catalogue: All stars, 3

IMCOPY and AD DST AR Return galaxy constituents removed by KILLALL Image: Restored galaxy

IMEDIT Interactively edit or mask saturated stars, haloes, Image: Final, cleaned and masked spikes, and enlarged spots.

GALPHOT Begin surface photometry.

FIG. 3.ÈFlow chart illustrating how images were cleaned of stars and blemishes KILLALL Image: 2048x2048, 1-----~ IMCOPY reduced. Extract 512x512 section and border 40 pixels wide. SUBSTAR Subtract all stars in pre-existing ALLSTAR catalogue from image using old Image for passes 1 Yes PSF. and 2: Original.

MEDIAN 15x15 median filter the star-subtracted DAOFIND image. Locate stars. IMARITH PHOT Subtract zeroed median image from Determine initial star-subtracted image estimates for to derive pure sky. magnitudes.

FITSKY ALLSTAR Determine the sky Fit all stars at once for each star from the Image for passes 3 using input PSF, pure sky image. and 4: Fitted stars with sky determined substracted. individually for each star. IMARITH Subtract zeroed median image from original image to MEDIAN remove galaxy. 15x15 median filter ~-Y_e_s---L the star-subtracted image. ALLSTAR Fit all stars in galaxy-subtracted image using latest IMARITH PAPPEND PSF and initial Subtract zeroed Augment master estimates for median image from PHOT catalogue. magnitudes from original image to pre-existing remove galaxy. ALLSTAR catalogue.

No SUBSTAR IMCOPY Subtract fitted stars Copy star-subtracted from original image 512x512 subsection using latest PSF. to container for whole image.

FIG. 4.ÈFlow chart illustrating in detail how stars were removed from the images IC 342/MAFFEI GROUP REVEALED 43 version of a ““ star-free ÏÏ image of the galaxy was created by to be 3 pixels and the matching radius (MATCHRAD) 2 reassembling the star-subtracted subsections, and a master pixels. The sky annulus was adopted to have an inner radius catalog of stars was created by appending catalogs for each of 8 pixels and a width of 8 pixels. subsection. A galaxy-free image of the Ðeld was created by For initial Ðts, a constant psf was determined from the median-Ðltering the star-free image, and subtracting it from I-band image of Ma†ei 1 obtained on 1995 November 15. the original image. Using PSELECT, stars within a speciÐc This was done in two steps using six stars concentrated magnitude range were identiÐed as being the most suitable around the center of the Ðeld. Each of the six stars was free for determining an improved psf. The psf stars (as many as a of contamination within the Ðtting radius, but had faint hundred) were isolated by using SUBSTAR to subtract o† companions within the psf radius. These faint companions all but the psf stars from the original image. Then, an accu- were not always found in an initial run of DAOFIND, so rate variable psf was derived. All stars on the galaxy-free had to be added by hand to the PSF input Ðle. In the Ðrst image appearing in the master catalog were then reÐtted step, the six stars were used with companions to get an subsection by subsection using the revised psf. The second initial estimate for the psf. Then, the faint companions were version of a ““ star-free ÏÏ image of the galaxy was created by Ðtted with this psf and subtracted o†. In the second step, the reassembling the improved star-subtracted subsections. six cleaned stars were used to improve the psf. The result The resulting star-free image retained many blemishes, so was called ““ bestpsf.ÏÏ further processing was necessary. Besides being summarized Initial attempts at star removal using bestpsf revealed in Figure 3, the steps are illustrated with six images of Cas 1 that the psf varied subtly from galaxy to galaxy. Further- in Figure 5 (all displayed using linear, as against logarith- more, residuals were enhanced in the corners of the images, mic, units for surface brightness). Residuals for the brighter revealing that the psf varied across the CCD. Thus, to unsaturated stars, called ““ spots,ÏÏ were eliminated through improve star removal, it was necessary to Ðt each image noninteractive editing. Then, a faint residual pattern of using a variable psf tailored to that image. horizontal stripes was removed by a process involving It was determined that ““ bestpsf ÏÏ was suitable as an median Ðltering. The detection threshold speciÐed for the initial psf for all of the images, including the V -band images. Ðrst run of KILLALL was so high that many faint stars still For a given image, KILLALL was used Ðrst with ““ bestpsf ÏÏ ““ peppered ÏÏ the image. These were removed by passing all to compile a master catalog of foreground stars. Then, using of the cleaned subsections through KILLALL, but with the PSELECT, a set of bright candidate psf stars in a limited detection threshold reduced to 3 p. Remaining blemishes magnitude range was pinpointed (““ natural ÏÏ magnitude were either masked or edited by hand. range [12.0 to [13.5 for the uniform 300 s exposures Although resolved structures generally survived the obtained). The output Ðle from PSELECT was used in the cleaning process intact, for a few galaxies, such as IC 342, DAOPHOT task SUBSTAR as an exclusionary Ðle (exÐle). unresolved components of OB associations were sometimes SUBSTAR was used to subtract all of the stars found by removed. Sharp nuclei, such as those of Ma†ei 1 and Ma†ei KILLALL except the candidate psf stars. Then, the task 2, also were Ðtted and subtracted. Wherever any such PSF was applied interactively to the output image from problem was recognizable, the missing component was SUBSTAR. Each candidate star was inspected on the image added back to the cleaned image using the parameters of and on a grid map. The procedure usually left sufficient the Ðt listed in ALLSTARÏs star catalog. However, the fore- numbers of stars all across the Ðeld to map the psf to second ground star problem was so severe that it is almost certain order (VARORDER \ 2 in DAOPARS). With the that some removed components could not be Ñagged. improved psf, KILLALL was applied to the original image Nevertheless, it is felt that the accuracy of global photo- again to reÐt and subtract all of the stars in the master metry would not be impaired signiÐcantly, as the amount of catalog. light lost from subtracted features would have been a tiny fraction of that from a whole galaxy. 4.3. De-Spotting Using KILLALL with a variable psf left each galaxy 4.2. PSF Determination image largely devoid of foreground stars but with many Critical to the star removal was accurate modeling of the cosmetic defects. One problem was that bright unsaturated point spread function (psf). We used the DAOPHOT task stars left small patches of residuals, called ““ spots,ÏÏ about PSF for this purpose, initially following the ““ Guide to 3È4 pixels in radius (see Fig. 5b). These were a consequence Computing a PSF in a Crowded Field ÏÏ provided in the of undersampling. The process of eliminating them is help package for this task. The psf determination involved referred to as ““ de-spotting.ÏÏ two main steps: (1) determining an initial constant PSF Noticeable spots remained only for stars brighter than a from a few stars to be used for an initial run of cleaning; and speciÐc magnitude and could be easily pinpointed from the (2) determining the Ðnal variable psf from 40 or more stars master catalog of KILLALL using PSELECT. To remove across the whole Ðeld of an image. the spots in an image, we used the IRAF task IMEDIT Because of the large pixel size(2A.03), the psf was under- noninteractively with an input Ðle containing the locations sampled on the Schmidt images; the FWHM of stellar pro- of all of the spots. Each spot was eliminated by inter- Ðles averaged only about 2 pixels over most of the images. polating a plane Ðtted to pixels in an annulus 2 pixels wide The option ““ auto ÏÏ in DAOPARS was used to determine around the spot. Appropriate noise was added to the inter- the best analytic function to employ. After considerable polations using a measurement of the noise in the image. testing, we adopted the three-parameter ““ Mo†at25 ÏÏ func- The de-spotted image of Cas 1 is shown in Figure 5c. tion, which is described in detail in the help package for De-spotting eliminated the vast majority of spots very well. DAOPARS. Using IMEXAMINE, the critical psf radius However, it occasionally created new, bigger spots, if two (PSFRAD) was determined to be 8 pixels for the brightest original spots were close together or if there were something unsaturated stars. The Ðtting radius (FITRAD) was taken substantial in the IMEDIT annulus that contaminated the FIG. 5.ÈSteps in the cleaning of Cas 1: (a) the initial image with foreground stars; (b) image arising from a full run of KILLALL with a 5 p detection threshold and variable psf, showing residual spots and faint stripes; (c) de-spotted image created after running IMEDIT in noninteractive mode; (d) de-striped image created by RMPAT; (e) de-peppered image created after running KILLALL again, but with a 3 p detection threshold; ( f ) Ðnal image used for surface photometry created after interactive editing and masking. IC 342/MAFFEI GROUP REVEALED 45 interpolation. These were later removed interactively using polating a plane. However, some extremely bright stars IMEDIT. showed artifacts extending from 15 to 75 pixels from their centers. If such features were superimposed on the galaxy, 4.4. De-Striping interpolation would not necessarily work. Instead, they After star removal, very faint horizontal stripes were were masked. We set VALUE in IMEDIT to a Ðxed large revealed in the I-band images, especially of the fainter gal- number (greater than any of the actual intensities in the axies in our sample. Stripes are barely visible crossing image). Both circular and rectangular masks were used as directly through the image of Cas 1 in Figures 5b and 5c. needed. The surface photometry package we employed (see The amplitude of the stripes was typically 0.1% of the sky in ° 6.2) was able to Ñag and ignore masked areas. I. None of the V -band images showed the stripes. The ATLAS OF GROUP MEMBERS precise alignment with the rows and the correlation with the 5. signal suggests that the origin was a signal-dependent insta- Our KPNO Burrell-Schmidt images are the deepest ever bility in the CCD electronics. The process of eliminating the obtained of the members of the IC 342/Ma†ei Group. Also, stripes is referred to as ““ de-striping.ÏÏ none of the galaxies have been seen ever before without To remove the stripes from the I-band images, we created foreground stars superimposed. Given these facts, we felt it a special routine outside of IRAF, called RMPAT, which was appropriate to present images for all of the galaxies extracted and subtracted the pattern. Each de-spotted before and after cleaning. These are displayed in alphabeti- image was boxcar smoothed with a window large enough to cal order in Figures 6È22. Most are in the I band. Also, median out the stripes. The inÑuence of stars was removed most are logarithmic, having been converted to units of mag by rejecting deviant pixels. The resulting Ñat image was arcsec~2. The exceptions are Figures 10 (left) and 12, which subtracted from the original, exposing the true amplitude of show surface brightnesses in linear units. Comments on the stripes with respect to sky. Then, a single column vector each galaxy are given in ° 7 below. describing the variations in the background signal from row Caution must be exercised in interpreting the cleaned to row was created by computing the median of all of the images. Some features are artifacts of the cleaning process. pixels in each row. This vector was then subtracted from The artifacts are sometimes obvious, as in the cleaned image every column of the original de-spotted image. of IC 342, but sometimes are not. Also, although we tried to The de-striped image of Cas 1 is shown in Figure 5d. The restore stellar associations removed by the cleaning process, procedure was successful in reducing the amplitude of the some may still be missing. The best way to use the cleaned stripes to a level below the sky noise. images is to refer to the uncleaned images to establish the reliability of small details. The cleaned images are best for 4.5. De-Peppering showing large-scale structures. Although KILLALL removed most of the foreground 6. SURFACE PHOTOMETRY stars from an image, large numbers of very faint stars (not easily seen on the uncleaned images) still ““ peppered ÏÏ the 6.1. Overview Ðeld. These stars had been missed because the Ðnding For each galaxy, surface photometry was performed on threshold (in FINDPARS) had been set to 5 p, where p is an the cleaned images, both V and I. First, free ellipses were estimate of the background noise level (SIGMA in Ðtted to the observed isophotes in order to examine the DATAPARS). The problem can be seen in the image of Cas radial variations in shape and orientation and to determine 1 displayed in Figure 5d. The process of removing remain- the center, inclination, and photometric major axis position ing foreground stars is referred to as ““ de-peppering.ÏÏ angle of the galaxy. Second, Ðxed ellipses with the center, To eliminate the faintest stars, each cleaned image was shape, and orientation of the galaxy (as determined from the passed through KILLALL, with the Ðnding threshold analysis of the free ellipses) were Ðtted to determine surface reduced to 3 p. Unfortunately, this procedure sometimes brightness proÐles, length scales, and total magnitudes and eliminated features intrinsic to the galaxies, such as in the color indices. case of Ma†ei 2, NGC 1560, NGC 1569, and UGCA 105. Subtracted galaxy features were restored using the 6.2. Fits of Free Ellipses and the Derivation of DAOPHOT task ADDSTAR. Images of IC 342 could not Orientation Parameters be de-peppered, because signiÐcant quantities of light were 6.2.1. Software removed from the patchy spiral arms, even in the I band. How the shape and orientation of isophotes vary with For this galaxy, the pepper was left as part of the sky level. radius conveys information about the intrinsic geometry of The de-peppered image of Cas 1 is shown in Figure 5e. a galaxy. Such information is particularly important for galaxies in the IC 342/Ma†ei Group, because numerous 4.6. Editing and Masking authors have expressed a view that there have been tidal Although KILLALL removed most of the contaminating interactions among members. foreground stars, and de-spotting removed any residuals, For each galaxy in our sample, the shape and orientation there were usually still hundreds of remaining features on of isophotes were derived using the GALPHOT package, each processed image. These took the form of saturated which was developed within the IRAF framework by stars, halos of these stars, spikes, enlarged spots from W. Freudling of the European Southern Observatory. IMEDIT de-spotting, and foreground Galactic material. GALPHOT provides a modiÐed version of the ellipse- The Ðnal cleaning phases involved both interactive and Ðtting algorithm of Jedrzejewski (1987). JedrzejewskiÏs noninteractive runs of IMEDIT in which remaining arti- method was originally developed for ellipticals, which have facts were either replaced or masked. monotonically declining brightness proÐles, but FreudlingÏs Features not much larger than about 10 pixels in radius modiÐcations make possible studies of less regular galaxy could be reliably replaced. This was accomplished by inter- types. 46

FIG. 6.ÈI-band images of Cas 1: (left) original; (right) cleaned. On this and all remaining atlas images, north is at the top and east is to the left. Images have been sky-subtracted and converted to units of mag arcsec~2. The scale bar at lower left in the left panel is 1@ in length. . . .. ,.. t ... '•. . ,. '! • •...... • • ...... •. -~. • . .. .. • .. .. : . ... • . . - . .. ,~, •·· ...... ~ .. . ~ ••. ... 1•. ... }. ' . :-,,. I ,.. ; ...... ; ...... ,&...... •· .. . • \ . . ~!.- ... . - . • . . • • • ...... • • ·. • .... . •. . • I ·•· ~,• . • ~• . . -. -· . . • ••• • • . . ; ...... •: . - .••• · . •-•· -~.· ' • --: : - _ •1 ... . ·:·,· . .. •.•..• ...... •-1.•. - ... • • .. . • .. . : ~ . ,,_ . . '-.. ... , ~..... •• ... - . . •· ~ .. .. ~- : . •• ...... • •··· •. • • • . •·-• : ; . ~ ...... • - . . . . • • ·••:•i.. . ' . .. • • • . .. .. ,. . t.. .,,. .. .,,. r - .. • ' . • .... ·, ...... , J . • ...... • !. . : .. • .• ·• . . · . • . . . • •- .., •. . -~·-· ...... - ••. . ;. • ' . . • ' . • . ... •...... •.. • ,. •· . . . . -,.~.. : _. .. .. ~ • . . ·--;. .. .. -, •• .•. ... •• •.. . .f .... . • • ·.'., 4 • . '. • =•~ ... •· . ••..• .•, ,...... •· . I .... . •· • .. • • • .• -. . : •• . • . •... •'. : . . . ,.:-:~,· ·: - ...... ,· . J·•-• . •.~. . . ' • ,. .. ~ · •V.' ' • - ...... ,., •; .• . "'1, , . .,_ , ...... ; •• ... • _. . ,. .:..,·.·: . . . • 47 ...... • • . • : "' :,. . • • , . - .. . :. ~ • . • .. . ·•..;, ..... /. . •. . .. ,. .• •·· ._.. ·•. . , .... . , . . . • • ~ ...... , . • ••• •· •.. . . i ...... • . .• ·-, • • • • • • .. . . • • . . l ... • ,. . ·. .. .,.,~ '/ .. • • ~: ... ~ .. . . ._-. ··.I' lf"•.. •'... "' . - .. " . • • .. ·• .., . ·•...... - • . ,.. .. ·· ...... •: . . . • .. •. . .,,.. , A . '- ...... · . . ..,, . .. • • ·•• . ,...... , . . -• . • 4l . .. . .· ...... • ~...... • · . -~- .-. . .. .• ...... ,, ~·- . ... . •· ·~ •-., . ·,.'\ •• • • , . -.·;_.·. . :. . ~- ...... -. . • • • . ._y.l ,-.,.;'. , . . -- .. . ~ . - . . . . , . . •- •A•:. .. . . •L ·· . .•. . ,,., . . .. ., . . • •.: . . . . ,· \ •···;- · · . ·•., ., ' . • . .. •.. .•. .,...... •. .. . •' t• ...... • • . ·~ .. . - - ... • • • . ,.. • , . ·• .. . • •. . . ',: ; -., ~- . . .- -• .. ., . . . .·. .. . · • ' • .. · • . . ~-: ·~ . ... - .. . .. :.__ • • .. .. • .. . . ·· • -. •. .• ~. .. a. . -. . - · . • , 1 .. I . • , .

FIG. 7.ÈI-band images of Dwingeloo 1: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 5@ in length. 48

FIG. 8.ÈI-band images of Dwingeloo 2: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 1@ in length. 49

FIG. 9.ÈI-band images of IC 342: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 3@ in length. 50

FIG. 10.È(L eft) Deep negative print of the cleaned I-band image of IC 342, showing glowing foreground material to the east of the galaxy and possible evidence for a tidal interaction to the southwest. The circular spots represent masked regions that were replaced with zero intensity by program SPHOT, but for which the mean surrounding sky level was di†erent from zero. The scale bar at lower left is 10@ in length. (Right) V [I color index map of IC 342. Colors range from 0.6 to 2.6, with bluer features dark and redder features light. The scale of this image is the same as of those in Fig. 9. , .. . .•1· • . "' . .... • ,, , ·• . • . ... -· .. ., • . •• . . , -~. . • • .• . ,., ~ ·- • .... . ·.• ·, • , •1 ' .. --~ • . .. •:"" • "· -- .. ' · .. •· ·.• :, • .. - ...... • • 'F' Ir . . • • . • -~ ...... •~ • .. 4;" ·• ...... ·,~- • • . • - ... ~ . . .. , - - • • • I . \ : . ' ,,, . · •'';-=• .. ... ·., • . ' .. . , • - ·•·. . ' • 51 .. ... \. . . - ,. l •• . ~ ;. . . . . ·•· . . • • . • ,,._ .1•.·. . .. ,1~ •• . - •· ...... JI . - . ~ .. . ~ . • I •. :- •• . 'I •' • ... . . ' ...... ·• .. ,,:, . :· . , ;. . . • . ' . . . . •. • ••:~ .. , • • ~ . . .•. ·( ·, : • .~ . .. ; L .. •• ... . ··~:, _' ,,,. • • ., . . • . .. • ' ...... • ., ,it: • • -~ . ;...... ; . ••• • 'T,' t. '• • . • , :> .• .. .. • . • .. .. . • . • : f . . . :t • ... •

FIG. 11.ÈI-band images of Ma†ei 1: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 3@ in length. 52

FIG. 12.ÈI-band images of the inner8.65@ ] 8.65@ region of Ma†ei 1 showing the residuals of the observed light distribution about a model constructed from Ðts of free ellipses to the cleaned image. The di†erence image in the left panel includes the foreground stars, while the one at right is based on the cleaned image. Dark areas are regions of negative residuals and are probably caused by dust. \• . . ·.·:- •· • • ...... · • -.,-,__J • . . . ' -~ ., , .. ... -. . .. • • ...... - • • ,· . • . • . . • •• .. · . • . : , • . ... , • • _ • .. . • ·• . .· ... .. ; ., . . •• • • • . • . • . .. •4 ; . . ••• • . •· -: • •• . .. • ,, ..,f..''f'\,..,_: .. . •1 • . .. -"- . . . • : • . •· . ·· -•. • ...... • • . • . ,· . •,-,, • . .. ·. " '. • • .,.~ . ,. ~ . • ..... , .. ~ ,_ '1• • . r , ...... _-_ :: • • .. ,. . • • . , ., - . . . . . • •· . ··•• . " ,. " . - 53 . .•" ., .. ~ ... ,• .. - .. • . .•...... • ' • . . .)'"F.'. • • . ~- ' . r .·• . -· .. ··~ ...... •' , ...... ,. ... . ~ .. .. ·· • I .:, • ~ • . . : ' ...... • - • • . • . • .. • • .. - ...... -~ • .- • . ,: .f· -,·;...... ·· ;._~- ,_ • ., ...... •. , t . ... · . .. .. • •· . ·· . .. . . " . • :­ _ . , ...... '-:. ~- :- . . • . .. • , -·•· )· • ..... ,,. , ' • . . • .

FIG. 13.ÈI-band images of Ma†ei 2: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 5@ in length. FIG. 14.ÈDeep negative prints of cleaned images of Ma†ei 1 (top two panels) and Ma†ei 2 (bottom two panels) showing low surface brightness isophotes in two passbands. Images in B are on the left, and images in I are on the right. Note especially the complex foreground nebulosity to the north and east of Ma†ei 1 seen in the I band. The Ðeld shown for Ma†ei 1 is34.6@ square, and that for Ma†ei 2 is 17.3@ square. The nuclei of both galaxies are exactly centered in each frame, in order to highlight the apparent asymmetry in the outer I-band isophotes of Ma†ei 1 and the symmetry of the outer I-band isophotes of Ma†ei 2, as compared to the inner regions. Ma†ei 1Ïs companion galaxy MB 1 can be seen below and right of the center in the upper right panel. A bright foreground star is seen near the top of the B-band image of Ma†ei 2; this star has been removed from the I-band image. Some artifacts of cleaning also are visible in both images of Ma†ei 1.

54 . . •· (! ,ft. • . i. . .. . • .; .. . ~ -· ~ • ~ . . . -~ • ... • ... ~. . . _· - . : . ·• . " "' 1'L . . fl . .·: • . ~~· ' " • . -~ ... .,_ . . . • . • . • .r.... :.__-.!•_'_Jill_•• . t + ·~ ,...•. .• • _ ... ,- . ~ , . .. ~ , - . :.~~- • • ,· . , - . • • ,- . ~--~· , ... .., , !'.;.: •· - ~ • ,. ·· • . • • ~ •• ~. ·• - • •• :1. l ' I ~ • ;t ~ ·~~~: . • . .. • . ~ ~~- -,_'-:., ~L •..• ,,,. , ,-. .l'111 w.. - • W' . - ,. ___ ,=- -~ - r. I. ... ·, , . ·· ' - • II ; • -· -$. . . L __ ""':' . . • • T _ ... ~ ,,. : ~-·· •~·• - I • '• , . _·_ . '. •, · . _,. •• ·, -~~ - ·· .;1S• l. ' ~ ' . .. ~ I~-. 55 f • •• .. - ·• ... ·~~- - - • '. L i,• • - •t ' - ' ,- • • - . (II-· ...,t .. • A · It ; . • . , . ;"~l -.. . ·. .... r , .. • • .... ,~ . .. .:...... "· • • •• . • •• ... -~ •~ . - . . • ~ ~ • - .... , •I. 1 • •" . ~ • 1 ~.; • . . -_ ·= • • - . • .... I • ,· ~; •· . ' :)_ •. ~ .. • " · • . . -- .•. r •• \ . : " • . • . . - •- . • • • -- • .. . • I ,., I 4 , • . • ~• -~ _ . · •• ...... • _., . .. .. ' _ <..• .,. • 1'.. . . ~. . ~ .. ••• . , ' ... • · . •

FIG. 15.ÈI-band images of MB 1: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 2@ in length. J ,• J • • ' ·- • - ~ II, .. 'I • • • • • • • I • I I • - • • •' • " f p • • • ' • . .. . ;/I • • - ...... ~. - - 'I ~ .. . r., .. • • • II ~,. • • • - - • I • ,• • • I ·J . •~; -- - • • • .- ...... I• • " • •• .. ••• ,.: -- ••• t· ... ,· .. -. · • . • ;_• ._ . -r' I ... I • I • ( . •• •I • • • • •• - ~ . > ,. •. - .. I - i • if • • • " _1: • • •,.. . . • . •r~ •- • • . - • • . • .. .. •:.a. • • • I ""T .., ,•• :." •- • • • . .). • •• ~- - ,-. -I fi J - • • • • • •, ,. .,. •." :g.• • • ...... • =..t.:,. p,T 56 ,-'a,1 T ... _ • .. }. ~ • ... •, ..,; ,.. I •• •• : . •: I .. • _. - • .. ~ . . J I · • . .. . . I • • I • •, . . • • . . . I . ,.. • • :.::• -. • • . . 5 •• • ... I • I -- ...... •• I• • • - ,•; I_ .. • · . •y• ••• •• - . .·, .. •,11 . .. I . • . Ir .

FIG. 16.ÈI-band images of MB 2: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 1@ in length. 57

FIG. 17.ÈI-band images of MB 3: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 1@ in length. ••• ;, • • . • • • . •• . . • • ' I- • . (I;...... I '• .,; • • . , "•. . . .; .. . ,,. • . . • t ·­ • : · . . • . . I • . I 58 •· •· · .. , ~ ~- . . . . • • . , . " . . ' •• . • " ., - · .. •...... ·:1-: . •• • • ' : ~ . ..J,.,· . . • . · . • . • · ' . ! : ...... : • • . - . -~· . ·• . ~· .. ). . . - . ·

FIG. 18.ÈI-band images of NGC 1560: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 3@ in length. 59

FIG. 19.ÈI-band images of NGC 1569: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 2@ in length. 60

FIG. 20.ÈI-band images of UGCA 86: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 3@ in length. 61

FIG. 21.ÈI-band images of UGCA 92: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 1@ in length. . ' j . • ..... , ,.....__I' • ' • • . •• .. •• l , .. ~ • • ...... , • • • • • . .. . . • / . ' ! ~ A . • , fl . • .. . • •. . • • .. . • • • • . • • • • . • . • • ' . • • ! . . • . . . • . • • • •• .• •• . . . • . ·.e . •••• • . . . ., .... , • " :. ! ·. - • . : ... , .. . • . • . . ' • • . . . . - !' . , • . ~ .. • . • . • I •• , \ . • Ji...... • ~ . "' • . •· ...... •• - •· . . . -•· ...... ,. .. . ! •. :_ -~ , • _., •• . .: •:•. p...... • . · • .. . -~ __ . • ~ • • • • • .,~ .tl • ...... • · . ., . • • ,. . ' ••• _,, -·,. , .. • .. 4liir-. '"-' ; ~~-:. ... .• .. • . • •• ·. . " # ~ ~ • •. .. •• ...... • . "' • • • · • • • • • • . . • • . - • . . • . . •• • . ~ .. ~- .•· • ·- . •.. J . • • . . • • • . ~ . • • • .

FIG. 22.ÈI-band images of UGCA 105: (left) original; (right) cleaned. The scale bar at lower left in the left panel is 2@ in length. IC 342/MAFFEI GROUP REVEALED 63

6.2.2. Sky Subtraction ELLIPSE Ðtted outward from the MARKGAL position, The GALPHOT task SKYSUB was used to determine and then inward. Outward, it normally stopped when the the sky level appropriate to the Ðeld of each galaxy. In isophote intensity was less than 10 ADU, i.e., once the noise SKYSUB, a display of the image and a cursor allow speciÐ- became sufficiently high compared to the signal that Ðts cation of the corners of boxes sampling the sky at locations became unstable. If it could not make a reliable Ðt within all over the Ðeld. Once satisfactory sky samples were deter- the speciÐed number of allowed iterations (usually 100), it mined, they were Ðtted with a horizontal plane. Although would use the parameters from the previous best-Ðtting SKYSUB uses the IRAF task IMSURFIT to Ðt the Ðnal ellipse and compute the average surface brightness along sky level, and in principle can Ðt a more complicated surface that ellipse for the given radius. The GALPHOT task (such as a tilted plane), it proved to be impractical, and, we PLOTELL was used to interactively examine how well the feel, unnecessary, to Ðt other than a constant sky level in Ðtted ellipses matched the appearance of the galaxy. most cases. The sky boxes used were uniformly distributed The output of SPHOT is a table of Ðtted parameters and around a given galaxy in a pattern resembling its shape. We a ““ clean ÏÏ image where any masks present have been inter- normally used 30È50 such boxes, depending on the angular polated over using the best-Ðtting ellipses. These ““ clean ÏÏ size of the galaxy. Boxes were dispersed among masked images were used for the Ðnal surface photometry. To regions where necessary. Care was taken not to place the improve the appearance of replaced masks in the periph- boxes unnecessarily far from any galaxy, because many eries of some of the disk galaxies in our sample, we used the Ðelds were contaminated in places with foreground nebu- GALPHOT task TOTMAG, which exponentially extrapo- losity of low surface brightness. We generally placed the lated Ðtted proÐles down to a speciÐed surface brightness boxes at about twice the radius of the very faintest isophote level or speciÐed radius using the mean position angle and we could see on the image display. ellipticity of several outer isophotes. Points used to deÐne SKYSUB could be used in a practical manner for all of the extrapolations were determined interactively using the the galaxies in our sample except Ma†ei 1. The background GALPHOT task MARKDISK. around Ma†ei 1 includes obvious foreground nebulosity covering a large area. For this Ðeld, we estimated the sky level using the IRAF tasks FITSKYPARS and PHOT. The 6.2.4. Axis Ratios and Position Angles sky level was estimated for both the V and I images as the Plots of the axis ratio q and the photometric major axis mode of pixel values within a circular annulus having an position angle / as a function of the length of the semimajor inner radius of 550 pixels (1115A) and a width of 100 pixels axis are displayed for each sample galaxy in Figure 23. (203A). Position angles, which are for epoch 1950, were determined using local positional standards. For I-band images, stars 6.2.3. Fitting of Ellipses from the STScI Guide Star Catalog were employed. Devi- The Ðtting of free ellipses required the GALPHOT tasks ations from the equatorial system amounted to 3¡ to 4¡. MARKGAL, SPHOT, and ELLIPSE. With MARKGAL, Several V -band images were analyzed in the same manner we interactively chose points on an initial ellipse to be used and determined to require the same corrections as the as the starting guess for the main ellipse-Ðtting task, I-band images. ELLIPSE. The starting ellipse was usually selected to lie in Note that some points in the plots are not independent of a zone of intermediate surface brightness, because the best other points because, as noted above, if ELLIPSE failed to Ðt would be used as the initial guess for zones at both converge to a Ðt of an isophote after a speciÐed number of smaller and larger radii. In the case of a spiral with a lot of iterations, it adopted the derived center, shape, or orienta- structure, ELLIPSE failed to Ðnd the nucleus if we started tion of the isophote previously Ðtted and simply solved for too far out. For IC 342, for example, we had to start the the surface brightness alone or the remaining parameters. ellipse Ðtting close to the center inside the main spiral arms. The orientation parameters which we believe to be most Each isophote was Ðtted by Fourier analyzing the devi- reÑective of the true orientation of each galaxy in space are ations from an ellipse at a given prechosen radius and iter- listed in Table 5. Except for Ma†ei 1, these were determined atively determining the best-Ðtting center, axis ratio, and by averaging the values of q and / derived for the outer major axis position angle (see Jedrzejewski 1987). The pre- isophotes. For Ma†ei 1, the axis ratios and position angles chosen radii were stepped both inward and outward from were averaged over all radii. For Ma†ei 1, Ma†ei 2, the starting radius (deÐned by MARKGAL) by a uniform Dwingeloo 1, Dwingeloo 2, MB 1, MB 2, and MB 3, the scale factor of 1.1. averages are based upon surface photometry in the I band We note that miscentering of the outer isophotes was not only, because the V band su†ers serious extinction. For the uncommon in our sample galaxies and was particularly remaining sample galaxies, the averages are based on ellipse prominent for Ma†ei 1 and IC 342. The latter galaxy shows Ðts in both V and I. obvious tidal distortion at large radii. We are uncertain Five galaxies in the IC 342/Ma†ei Group have been whether the miscentering of Ma†ei 1Ïs isophotes is real or interferometrically mapped at 21 cm. Fits to the velocity due to foreground star or glowing dust complications. Ðelds have provided estimates of the kinematic inclination The task SPHOT allowed speciÐcation of masks, i.e., and the position angle of the kinematic line of nodes. They regions which would not be used in the iterations for the are summarized in Table 6. For direct comparison, the incli- best-Ðtting ellipses. A preliminary zero point for each image nations and position angles resulting from our photometric also was speciÐed at this stage (the full calibration formulae study in I are included. Photometric inclinations have been in Table 3 could not be used yet, because SPHOT and computed from SqT and an adopted intrinsic axis ratio q0 ELLIPSE operate on only one image at a time). It was (i.e., the axis ratio for i \ 90¡) using (Hubble 1926) computed using the known air mass for each image, a rough 2[ 2 estimate of the V [I color index of the galaxy, the solid 2 \ SqT q0 cos i [ 2 . (5) angle subtended by each pixel, and the exposure time. 1 q0 TABLE 5 TOTAL MAGNITUDES,COLORS, AND ORIENTATION PARAMETERS

[ [ SqT /(1950) BT VT IT (B V )T (V I)T Object s.e. s.e. s.e. s.e. s.e. s.e. s.e. (1) (2) (3) (4) (5) (6) (7) (8)

Cassiopeia 1 ...... 0.760 93.5 . . . 13.97 11.98 . . . 1.99 0.010 1.5 . . . 0.08 0.05 . . . 0.10 Dwingeloo 1 ...... 0.699 110.7 . . . 13.08 10.33 . . . 2.75 0.002 2.0 . . . 0.13 0.07 . . . 0.15 Dwingeloo 2 ...... 0.473 71.7 . . . 16.21 13.71 . . . 2.50 0.090 2.4 . . . 0.15 0.09 . . . 0.18 IC342...... 0.873 86.5 9.37 8.31 6.68 1.06 1.63 0.004 1.6 0.03 0.03 0.03 0.04 0.04 Maffei 1 ...... 0.729 83.9 13.47 11.14 8.06 2.33 3.08 0.007 0.7 0.09 0.06 0.04 0.12 0.07 Maffei 2 ...... 0.421 23.0 14.77 12.41 9.29 2.36 3.12 0.005 0.7 0.29 0.08 0.06 0.32 0.10 MB1...... 0.470 106.9 . . . 15.17 12.85 . . . 2.32 0.010 8.4 . . . 0.17 0.07 . . . 0.18 MB2...... 0.714 40.7 . . . 16.72 14.87 . . . 1.85 0.021 0.4 . . . 0.15 0.05 . . . 0.16 MB3...... 0.425 86.7 . . . 17.33 14.47 . . . 2.86 0.067 3.5 . . . 0.11 0.10 . . . 0.14 NGC 1560 ...... 0.216 20.6 . . . 11.27 10.26 . . . 1.01 0.010 0.1 . . . 0.02 0.03 . . . 0.03 NGC 1569 ...... 0.503 119.3 . . . 11.06 9.84 . . . 1.22 0.016 1.1 . . . 0.02 0.02 . . . 0.03 UGCA 86...... 0.800 26.8 . . . 11.89: 10.40 . . . 1.49: 0.018 1.8 . . . 0.07 0.07 . . . 0.10 UGCA 92...... 0.554 74.1 . . . 14.20 12.62 . . . 1.58 0.011 2.6 . . . 0.05 0.11 . . . 0.13 UGCA 105 ...... 0.645 179.2 . . . 11.48 10.41 . . . 1.07 0.016 3.1 . . . 0.03 0.06 . . . 0.07 M81...... 0.595 160.1 . . . 6.92 5.65 . . . 1.27 0.010 0.4 . . . 0.04 0.08 . . . 0.09

NOTES.ÈCol. (1): Name of galaxy, in alphabetical order. Col. (2): Mean axis ratio of outer isophotes (and standard error of mean) derived by Ðtting free ellipses. Values are means for V and I, except for the Ma†ei, Dwingeloo, and MB galaxies, for which measurements were restricted to I because of the heavy extinction. Col. (3): Mean position angle of outer isophotes (and standard error of mean) derived by Ðtting free ellipses, measured eastward from north (epoch 1950). Values are means for V and I, except for the Ma†ei, Dwingeloo, and MB galaxies, for which measurements were restricted to I because of the heavy extinction. Col. (4): Estimated total magnitude in B (and standard error of mean) derived from Ðts of ellipses with axis ratios and orientations Ðxed at values speciÐed in cols (2) and (3), respectively. Col. (5): Estimated total magnitude in V (and standard error of mean) derived from Ðts of ellipses with axis ratios and orientations Ðxed at the values speciÐed in cols. (2) and (3), respectively. Col. (6): Estimated total magnitude in I (and standard error of mean) derived from Ðts of ellipses with axis ratios and orientations Ðxed at the values speciÐed in cols. (2) and (3), respectively. Col. (7): Estimated total B[V color (and standard error of mean) derived from Ðts of ellipses with axis ratios and orientations Ðxed at the values speciÐed in cols. (2) and (3), respectively. Col. (8): Estimated total V [I color (and standard error of mean) derived from Ðts of ellipses with axis ratios and orientations Ðxed at the values speciÐed in cols. (2) and (3), respectively.

TABLE 6 COMPARISON OF RADIO AND OPTICAL ORIENTATION PARAMETERS

H I Kinematic I Band H I Kinematic I Band Position Angle Position Angle Inclination Inclinationa H I Object (deg) (deg) (deg) (deg) Reference

Dwingeloo 1 ...... 112 ^ 1 111 51 ^ 2471 Dwingeloo 2 ...... 103 ^ 57269^ 3641 IC342...... 39 ^ 38725^ 3302 Maffei 2 ...... 26 ^ 12367^ 1683 NGC 1560 ...... 21 ^ 12180854 a Based upon an intrinsic axis ratioq0 of 0.2. REFERENCES.È(1) Burton et al. 1996; (2) Newton 1980a; (3) Hurt et al. 1996; (4) Broeils 1992. IC 342/MAFFEI GROUP REVEALED 65 160

(a) Cas 1 160 (b) Dwingeloo 1 120 ••• 0 -l{) ••• q.q.q.~o. 0. 0) • .... 80 • 120 • • • 0 • • • --a. 0 • • •0 - ~• ~oo 40 0~ • 80

1 1 0 ti .8 •••• -...... 8 0 • o. ~ 0 • .0 q. • •••• II Oo 0 • • ••• • b< 0a • '-o-~ .6 • .6 •• 0 ,. • o•• .4 .4 \_..· .2 0 - 40 80 120 0 100 200 300 a (arcseconds) a (arcseconds)

120 200 (c) Dwingeloo 2 160 (d) IC 342 100 , 0 0 • 0 -l{) 120 • 0) 80 .... ••••• • • • •• •••• • 80 0 i~ ., ., . --a. 60 40 40 0

.8 1 0 0 •!i•·. !, ~ ., i • ti •• -...... 6 •• .8 .0 • • •• • • II • • b< .4 • .6 .2 .4 0 .2 0 20 40 60 80 0 200 400 600 800 a ( arcseconds) a (arcseconds)

FIG. 23.ÈOrientation of isophotes as a function of the length of the semimajor axis, based upon Ðts of free ellipses. The parameter q is the minor-to-major axis ratio, while / is the major axis position angle corrected to 1950. For most galaxies, Ðlled circles refer to I, while open circles refer to V . However, for Ma†ei 1, MB 1, and MB 2, Ðlled circles refer to the Ðrst I-band image (image 1) and open circles refer to the second (image 2) (see Table 2). For Ma†ei 1, crosses refer to the V -band image, and for UGCA 92, open circles refer to the Ðrst V -band image (image 1), and crosses refer to the second (image 2) (see Table 2). Only the I-band Ðts are shown for Dwingeloo 1, Dwingeloo 2, Ma†ei 2, and MB 3.

For all of the disk galaxies in the sample, the intrinsic axis 6.3. Fits of Fixed Ellipses and the Derivation of Global ratio was assumed to be 0.2. This value is often assumed in Photometric Parameters studies involving the Tully-Fisher relation (Aaronson, 6.3.1. Software Mould, & Huchra 1980). The additive correction of ]3¡ The principal objective of our study has been to measure advocated by Aaronson, Mould, & Huchra (1980) was not accurate total magnitudes and color indices of each galaxy applied because each photometric axis ratio is based on an in the IC 342/Ma†ei Group. One way of deriving a total average over a range of surface brightnesses in the outer magnitude is to use TOTMAG to extrapolate the surface parts of a galaxy, rather than on a single isophote brightness proÐle constructed from the free ellipses Ðtted by (Schommer et al. 1993). GALPHOT. However, the extrapolation can be large, 66 BUTA & MCCALL Vol. 124

80 120 (e) Maffei 1 (f) Maffei 2

0 -u:, 0) )()( )( 40 ___..... 80 --•~~------• • -s- o e i •• • • • i ~ e • o 0 0

40

1 .8 ~ .8 •••• • • .6 .0 m111 o O o -o-•---- • ••••• 'II ' ...... • b< .6 .4 ••• • • • .4 .2 .2 0 0 200 400 600 0 100 200 300 400 a (arcseconds) a ( arcseconds) 180 160 0 (g) MB 1 80 (h) MB 2

0 -u:, 140 0 0) 0 ___..... 0 ••••••• 120 ,'A8 . 40 • • 0 -s- " .... • • • • 0 • O O O O 0 IIICCOOOOOO O O ~ e O 100 0 0 0

80 0 1 .8 .8 ••• • ~ .6 •0 •0 .0 .6 'II 0 b< .4 .4 0 .2 ••••••• .2 0 0 20 40 60 80 100 0 10 20 30 40 50 a (arcseconds) a (arcseconds) FIG. 23.ÈContinued because the number of degrees of freedom of Ðtted ellipses is analyses of the intensity distribution, was used to compute so great that the range of radius over which Ðts converge elliptically averaged surface brightness proÐles from the may be signiÐcantly less than the range over which the cleaned and already sky-subtracted images by averaging the galaxy is detected. A proÐle constructed from Ðts of ellipses intensities within elliptical annuli having a common center with a Ðxed center, shape, and orientation, which gives what and a shape and orientation constrained by the GALPHOT we will call the elliptically averaged surface brightness as a results. If a clear nucleus were present in a galaxy, it was function of radius, is capable of being extended to larger chosen as the center of all ellipses. If not, the average of the radii. A superior total magnitude can be derived from such centers of the outer isophotes derived by ELLIPSE was a proÐle, because less of an extrapolation is required. It is adopted. Intensity averages were carried out in annuli 4A to advantageous, too, that Ðxed ellipses can be constrained to 10A in width (called the STEP), depending on the size of the be centered on the nucleus, whereas free ellipses Ðtting outer galaxy. Within a given annulus, allowance was made for isophotes may be signiÐcantly miscentered. partial pixels by dividing pixels near the boundaries into 25 Since the GALPHOT version of ELLIPSE was not subpixels and computing a weight. designed to integrate Ñuxes within Ðxed ellipses, we used our own software, NEWFOURAN, for this purpose. For 6.3.2. Surface Brightness and Color Index ProÐles each galaxy, NEWFOURAN, which also does Fourier For each galaxy, the Ðnal, fully transformed elliptically No. 1, 1999 IC 342/MAFFEI GROUP REVEALED 67 140 80

120 (i) MB 3 60 (j) NGC 1560

0 -lO 100 40 0) ..... ••• •• •••• • •• • 80 20 ••••••ca c. c. c. --s. 60 0

40 -20 1 .8

.8 .6 ...... _d .0 .6 .4 II •••• b< ••• .4 • • ••• • .2 ~~~~--. i," " r!1 .2 0 0 20 40 60 0 100 200 300 a (arcseconds) a (arcseconds) 80 160 (k) NGC 60 (1) UGCA 86 140 0 -lO 40 0) 0 0 0 • 120 (9(9~ •• ..... • • • -•••· • O O • o • 20 •.,•o o • --s. 100 0 0 80 -20 1 1 .8 0 d ••• ...... _ .8 • • •• • .0 .6 0 0 o00 0 0 0 II o. • b< • • • • .4 .6 0 .2 .4 00 0 40 80 120 160 200 0 50 100 150 200 250 300 a (arcseconds) a (arcseconds) FIG. 23.ÈContinued

averaged (i.e., Ðxed-ellipse average) surface brightnesses k was sometimes very noisy at large radii, especially for those [ V andkI and the surface color indexkV kI are plotted galaxies su†ering the largest amount of extinction. In such against radius a in Figure 24. For IC 342, Ma†ei 1, and cases, it was deemed prudent to computek using the mean [ [ I Ma†ei 2, the elliptically averaged proÐles in B and the B V ofkV kI for several inner points. In the tables (speciÐcally, color index proÐle are shown, too. The radius refers to the Tables 7 and 9), adopted colors are noted by parentheses. length of the semimajor axis of the ellipse which divides the In each table, the surface brightness and color at the area of the elliptical averaging annulus into two equal parts. center of each galaxy (a \ 0@@) are provided. The estimates ProÐles are listed in Tables 7 and 8. For comparison, Table can be fairly precise if a deÐnite nucleus is present, but for 9 gives the transformed proÐles of Ma†ei 1 derived by most galaxies they are simply an interpolation of the inten- Ðtting free ellipses. sity array at the adopted center. To accomplish transformations, we Ðrst solved quadrati- [ 6.3.3. Total Magnitudes and Color Indices cally forkV kI using the appropriate relations from Table 3. Then, surface brightnesses could be derived after allowing For each galaxy except Ma†ei 1, the total magnitude was [ for the integration time and pixel area. Note that kV kI derived by Ðtting an exponential to the outer points of the 68 BUTA & MCCALL Vol. 124

60 ,.....,.--,----,---,---r--.-....--,....--r--,--.---r---r-.,...... ,

120 (m) UGCA 92 40 (n) UGCA 105 ...... 0 lO 20 C) (II • ...... -•• i. • 80 •• )()()( xx 0 111 • • •oo -s. i Olo OI o 0 -·•~"ei•. )( ~ ~ ~ • -20

40 t--t--+--+--+-+--+--+-+-+-+-t--t--+--+----i-40 t--t--+--+-+--+--+--+-+-+-+-lt--t--t--+----i 1 1

.8 .8 • O • 0 {_ -\ )( ° .0 .6 • ••••• <. • bt •x0xe exexex ii •0 .6 • ~00000 .4 - ••• --.oeoxo'o .4 xx" .2 .2 ,__.....___..__,__.___.__.__.___.___.__ ...... __.___.___,__. 0 40 80 120 0 40 80 120 160 200 240 280 a (arcseconds) a (arcseconds)

280 240 (o) M81 ...... 200 0 lO 160 ....C) ••••••••••• ...... 120 -s. 80 40 0 1

~ .8 .0 ' ~ II .6 ~ . .. '- bt ...... •• ~ 0 .4

.2 ~~-~-~~~~~~~~~ 0 100 200 300 400 500 600 a (arcseconds) FIG. 23.ÈContinued elliptically averaged (i.e., Ðxed-ellipse average) proÐle, and where then extrapolating the Ðt to inÐnity. In all of these cases, it = a 1 was possible to deÐne an outer zone ranging in radius from *F \ 2nqP I(a)ada \ 2nq10~0.4(A`Bam)A m ] B , CB C2B2 a1 toa2, wherekI andkV declined with radius according to am (8) k \ A ] Ba . (6) and where I(a) \ 10~0.4(A`Ba), q is the mean axis ratio of the The magnitudem(a ) within an ellipse with semimajor outer disk from Table 5, and C \ 0.4 ln 10. \ ] m axis am a2 STEP/2 was computed by outwardly inte- Ma†ei 1 does not have an exponential proÐle, so a di†er- grating the Ñux within the Ðxed elliptical annuli. Integrated ent technique had to be used to estimate the total magni- magnitudes were fully transformed in the same manner as tude. We determined that the elliptically averaged proÐle the surface brightnesses, i.e., by computing V [I Ðrst and was a reasonable proÐle to use for photometry, despite the then V and I. Finally, the extrapolated total magnitude mT fact that the outer isophotes are not centered on the was derived by computing nucleus. A de Vaucouleurs r1@4 law, deÐned by \[ ~0.4m(am)] \ ] 1@4 mT 2.5 log (10 *F) , (7) k A Ba (9) No. 1, 1999 IC 342/MAFFEI GROUP REVEALED 69

22

X>CXX>C,cxx "xx xx,. (a) Cas 1 (b) Dwingeloo 1 ...... "x N "x I "x C) 24 ,.,.,, Q) Ill Xxxxxxx>ex ~~ C) "xx r-, "x "x Ill "x,. 'E,.'11." J I "xx ~ ~ 26 \. 26 sIll "\.>Iii ")I~ - x,. ~ ~\.,. 28 ~v "V 28 x~, ~ 'XX.... X' '- 30 3.5 2.5 :i 3 \.. 2 ~ 2.5 1.5 2 1 0 50 100 150 0 100 200 300 a. (arcseconds) a. ( arcseconds) 22 16

( c) Dwingeloo 2 18 (d) IC 342 ...... N xxxxxxxxxxx I ,..,, ... C) 24 20 Q) ,...,..,, Ill C) ...... ,.,. r-, Ill ''!..x I 22 -¥l!. ~ Ill 26 X "' XX XXX X ,c-.. 24 X xx "><' ~ s "x X l(.X - ~

FIG. 24.ÈElliptically averaged surface brightness and color index proÐles. In all cases, the mean intensity around an ellipse with a Ðxed center, axis ratio, and position angle is plotted against the length of the semimajor axis of the ellipse. The mean is expressed in units of mag arcsec~2, The orientation [ [ parameters adopted for each galaxy are listed in Table 5. For IC 342, Ma†ei 1, and Ma†ei 2, Ðve proÐles are shown:kB, kV, kI, kB kV, andkV kI. For the [ remaining galaxies, three proÐles are shown:kV, kI, andkV kI. Dashed or solid lines in each case show extrapolations used to get total magnitudes. was Ðtted over the rangea toa . Then, the extrapolated generally better determined in I than in V . Also, few gal- 1 2 [ total magnitudemT was derived from equation (7) with axies showed a signiÐcant radial trend inkV kI at large radii. = ~0.4(A`Bam1@4) 7 7~l \ P \ 10 (7!)y Total magnitudes and colors derived for each galaxy are *F 2nq I(a)ada 8nq 8 ; [ , am (CB) l/0 (7 l)! compiled in Table 5. Also included in this table are esti- mates of uncertainties. Each has been estimated by propa- (10) gating the errors associated with the calibration (see Table \ 1@4 \ ~0.4(A`Ba1@4) wherey CBam , I(a) 10 , and q and C are as 3), the adopted axis ratio and position angle, the scatter of before. the surface brightnesses around the Ðt used for extrapo- For some of the disk galaxies, the value of the slope B in lation, photon counting statistics, and the determination of the V band was Ðxed to be the same as that determined for the sky brightness. For each Ðlter, the e†ect of uncertainty the I band, because the outer parts of the proÐles were in the sky level was estimated via repeated trials of the 70 BUTA & MCCALL Vol. 124

16

18 20 (f) Maffei 2 ,...... _ N I 22 C) 20 Q) rn C) 24 f-, 22 «s bl) 26 «s 24 ..__,a 26 28 :::s.. 28 30 ,. :i 30 32 ~ 3.5 :::s.. 3 ,. 3 ,. -II. ,. ,. ;,.,i.,_....t"'i J.".l. ,. ,. ,.,,., ,.'?.,. -II. ,. > 2.5 2 ,.,. ,. :::s.. ~ ,. 2 ,. ~ 1 2 1/4 3 41/4 5 0 200 400 600 a (arcseconds ) a (arcseconds)

22 22 l()(ll.x a("a< (g) MB 1 (h) MB 2 ,...... _ 'l,,i><., N I 24 24 C) "3<~ )( )( )( )( )( )( )( Q) ""'""" ":tic " " rn ,.,...,.~ I " " ... C) f-, ,.,.,.lll! """"°' "'x>

3 2.5 )( )( )( )( )( 2.5 2 t )( )( )( :::s.. )( )( X X )( 2 1.5

1.5 ~~~~~~~~~~~~~~ 0 50 100 150 20 40 60 a (arcseconds) a (arcseconds) FIG. 24.ÈContinued

SKYSUB routine in GALPHOT and by considering the average distribution of surface brightness across a galaxy, it mean error in the mean sky brightness for all of the sky does not necessarily reÑect accurately the shape of the light boxes. Fortunately, because of the large Ðeld of view, the proÐle of a spheroid or disk. This is because local features, mean sky brightness can be regarded as having been well such as a bar, spiral arms, or dust lanes, contribute to the determined in every case. Good internal consistency is evi- average surface brightness computed for any radius. The denced by the fact that for each of the galaxies Ma†ei 1, MB properties of spheroid and disk components, speciÐcally 1, and MB 2, I-band magnitudes derived from two separate scale lengths and e†ective surface brightnesses, often can be nights of data agreed to within 0.10 mag. Also, the two derived more accurately by Ðtting surface brightness pro- separate V -band images of UGCA 92 derived from one Ðles along the major and minor axes. With such proÐles, it night yielded total magnitudes which di†ered by only 0.05 is possible to exclude deviations introduced by small-scale mag. features and to Ðt that part of the light which is most repre- sentative of the spheroid and/or disk components. 6.4. Derivation of Parameters Describing the Surface We extracted surface brightness proÐles in I along the Brightness ProÐles major and minor axes for most of the galaxies in our Although an elliptically averaged (i.e., Ðxed-ellipse sample. They were derived using a program outside of average) proÐle provides an excellent description of the IRAF that computes proÐles along speciÐed position No. 1, 1999 IC 342/MAFFEI GROUP REVEALED 71 20 22

)( )( )( (i) MB 3 (j) NGC 1560 )( )( )( .. )( 22 I -C) 24 )( )( )( Q) X. [I) C) .,..,..,. 1-, )( ..,. I It! )( '><..., )( 24 t:IO 26 )( )( )( )( It! )( )( )( )( ...... s X. )( )(

30 28

3.5 )( 1.5

~ )( )( 3 )( )( )( 1 ~ )( )( )( )( )( =l )( )( )( 2.5 .5 0 20 40 60 0 100 200 300 400 a (arcseconds) a (arcseconds)

22 18 .. I -C) 20 Q) [I) C) 1-, 24 It! 22 t:IO It! 24 ...... s 26 =l 26

28 2.5 2.5 2 ~ 2 ~ 1.5 =l 1.5 1 1 0 40 80 120 160 200 240 0 50 100 150 200 250 a (arcseconds) a (arcseconds) FIG. 24.ÈContinued

angles. At each radius, a surface brightness was derived via e†ective radius and e†ective surface brightness of the spher- bilinear interpolation. To improve the signal-to-noise ratio oid and/or disk along one or more axes by Ðtting the major at large radii, the program averaged intensities along an and/or minor axis proÐles directly, or by Ðtting the ellip- elliptical contour having the shape and orientation given in tically averaged proÐle and then checking the results by Table 5 and within a cone having a half angle of 5¡. superimposing the Ðt upon the major and minor axis pro- The extracted proÐles are illustrated in Figures 25 Ðles. Spheroidal components were modeled with a de Vau- through 36. For two galaxies (Ma†ei 1 and NGC 1569), the couleurs r1@4 law, and disks were modeled with an sph sph proÐles have been folded to improve precision. For the exponential. The e†ective radiusae orbe and e†ective unfolded proÐles, the di†erent sections are labeled by direc- surface brightnessksph of the spheroid and the e†ective disk disk e disk tion (NE, northeast; SW, southwest, etc.). The adopted radiusae orbe and e†ective surface brightnesske of major axis position angles are those listed in Table 5, and the disk were derived simultaneously by nonlinear least the minor axis position angles are displaced by 90¡ from squares. Each e†ective radius refers to the length of the these. semimajor axis(ae)( or semiminor axisbe) of the isophote For each galaxy in our sample, we measured values of the encompassing half the total Ñux of the model (r1@4 law or 72 BUTA & MCCALL

xxxxxxxx "xx "x (m) UGCA 92 (n) UGCA 105 "x 22 N 24 "x X,c -I "xx 0 CD xxxxxxxxx "x r/l ""xx.,. 0 "x X,c 1-, "xx l(,..,, I X,c ~"x "'bD Xxxxx 26 xxxx 24 s"' "XII< ----- ~v =l \.~ 28 26

2.5 2 :r 2 1.5 x xx >< xx x ~ Xxxxxx>

14

16 (o) M81 N -I 0 CD r/l 18 0 1-, 20 "'bD s"' ----- 22 =l 24 2.5 2 :r ~ 1.5 =l 1 X .5 0 200 400 600 800 a ( arcseconds) FIG. 24.ÈContinued exponential), and the e†ective surface brightness is the radi- a footnote to the table. ance of that isophote. Results are summarized in Tables 10, The isophotal diameterD25 and major/minor axis ratio 11, and 12, and discussed galaxy by galaxy in ° 7. R25 were derived from a least squares Ðt to the standard isophote of an ellipse centered on the nucleus. Results for 6.5. Standard Photometric Parameters in B Ma†ei 1 and Ma†ei 2 are severely a†ected by extinction. Because we have B-band data for Ma†ei 1, Ma†ei 2, and Even for IC 342, the standard isophote is within that part of IC 342, it is possible to measure fundamental parameters for the galaxy where the arms are bright, so the parameters are these galaxies which are linked to the standard isophote, uncertain. \ namely where the surface brightness iskB 25.00 mag The e†ective aperture,Ae, is the diameter of a circular arcsec~2 (see de Vaucouleurs et al. 1991). These include the aperture transmitting half the total Ñux, normally in B.In isophotal diameterD25 and the axis ratioR25. Also, it is Table 13, measurements are listed for B, V , and I. Also possible to derive e†ective apertures and e†ective colors in included for each Ðlter is a measurement of the length of the the standard system and to compare them with results major axis,De, of the elliptical aperture transmitting half based upon our data in V and I. Table 13 gives the mea- the total Ñux. For all three galaxies, the e†ective aperture surements. A brief description of each parameter is given in decreases from B to I. This indicates the presence of signiÐ- TABLE 7 I AND V [I PROFILES OF ALL SAMPLE GALAXIES DERIVED BY FITTING FIXED ELLIPSESa

[ [ [ [ a kI kV kI a kI kV kI a kI kV kI a kI kV kI Cassiopeia 1

0.00 ...... 22.49 2.12 46.04 22.86 1.81 94.02 24.04 2.02 142.01 25.31 2.38 2.83 ...... 22.63 1.93 50.04 22.95 1.80 98.02 24.18 2.11 146.01 25.59 2.42 6.32 ...... 22.64 1.81 54.04 23.01 1.82 102.02 24.31 2.09 150.01 25.85 1.71 10.20 ...... 22.59 1.84 58.03 23.12 1.86 106.02 24.39 2.13 154.01 25.95 2.24 14.14 ...... 22.66 1.84 62.03 23.19 1.93 110.02 24.43 2.18 158.01 26.15 2.03 18.11 ...... 22.66 1.85 66.03 23.29 1.98 114.02 24.63 2.17 162.01 26.24 2.18 22.09 ...... 22.66 1.84 70.03 23.42 1.97 118.02 24.69 2.23 166.01 26.25 2.60 26.08 ...... 22.69 1.83 74.03 23.50 1.99 122.02 24.93 2.41 170.01 26.23 (2.24) 30.07 ...... 22.68 1.89 78.03 23.62 2.05 126.02 25.02 2.23 174.01 26.91 2.35 34.06 ...... 22.73 1.85 82.02 23.74 2.01 130.01 25.08 2.21 178.01 26.74 2.07 38.05 ...... 22.74 1.83 86.02 23.84 1.99 134.01 25.28 2.29 ...... 42.05 ...... 22.79 1.83 90.02 23.95 2.10 138.01 25.35 2.33 ......

Dwingeloo 1

0.00 ...... 20.90 2.58 102.02 23.30 2.79 206.01 24.03 2.63 310.01 25.11 2.64 2.83 ...... 21.09 2.63 106.02 23.34 2.73 210.01 24.07 2.69 314.01 25.18 2.86 6.32 ...... 21.38 2.78 110.02 23.35 2.74 214.01 24.13 2.60 318.01 25.25 2.82 10.20 ...... 21.55 2.79 114.02 23.36 2.74 218.01 24.17 2.64 322.01 25.27 (2.82) 14.14 ...... 21.76 2.80 118.02 23.39 2.69 222.01 24.18 2.52 326.01 25.26 (2.82) 18.11 ...... 21.99 2.84 122.02 23.42 2.60 226.01 24.21 2.68 330.01 25.38 (2.82) 22.09 ...... 22.16 2.73 126.02 23.44 2.69 230.01 24.28 2.60 334.01 25.38 (2.82) 26.08 ...... 22.29 2.81 130.01 23.48 2.72 234.01 24.28 2.65 338.01 25.39 (2.82) 30.07 ...... 22.39 2.79 134.01 23.51 2.66 238.01 24.35 2.70 342.01 25.45 (2.82) 34.06 ...... 22.44 2.80 138.01 23.52 2.67 242.01 24.37 2.80 346.01 25.57 (2.82) 38.05 ...... 22.50 2.82 142.01 23.55 2.72 246.01 24.49 2.86 350.01 25.56 (2.82) 42.05 ...... 22.59 2.82 146.01 23.58 2.70 250.01 24.51 2.73 354.01 25.71 (2.82) 46.04 ...... 22.70 2.86 150.01 23.60 2.72 254.01 24.52 2.80 358.01 25.68 (2.82) 50.04 ...... 22.77 2.95 154.01 23.58 2.66 258.01 24.56 3.05 362.01 25.69 (2.82) 54.04 ...... 22.83 2.87 158.01 23.63 2.55 262.01 24.58 2.78 366.01 25.71 (2.82) 58.03 ...... 22.88 2.96 162.01 23.71 2.66 266.01 24.61 2.83 370.01 25.74 (2.82) 62.03 ...... 22.94 2.97 166.01 23.72 2.71 270.01 24.62 3.01 374.01 25.65 (2.82) 66.03 ...... 22.98 2.87 170.01 23.79 2.60 274.01 24.72 2.91 378.01 25.68 (2.82) 70.03 ...... 23.03 2.95 174.01 23.80 2.74 278.01 24.73 2.65 382.01 25.73 (2.82) 74.03 ...... 23.07 2.94 178.01 23.83 2.56 282.01 24.78 2.70 386.01 25.78 (2.82) 78.03 ...... 23.10 2.98 182.01 23.87 2.58 286.01 24.84 2.84 390.01 25.80 (2.82) 82.02 ...... 23.11 2.88 186.01 23.90 2.65 290.01 24.85 2.74 394.01 25.85 (2.82) 86.02 ...... 23.17 2.89 190.01 23.96 2.59 294.01 24.91 2.89 398.01 25.93 (2.82) 90.02 ...... 23.20 2.79 194.01 24.01 2.57 298.01 25.01 2.88 ...... 94.02 ...... 23.24 2.77 198.01 24.02 2.63 302.01 25.05 2.74 ...... 98.02 ...... 23.26 2.61 202.01 24.02 2.63 306.01 25.13 2.86 ...... Dwingeloo 2 0.00 ...... 23.49 2.70 30.07 23.62 2.91 62.03 24.35 2.38 94.02 25.31 2.71 2.83 ...... 23.58 2.73 34.06 23.63 2.57 66.03 24.43 2.23 98.02 25.50 2.55 6.32 ...... 23.71 2.49 38.05 23.67 2.71 70.03 24.59 2.27 102.02 25.64 2.87 10.20 ...... 23.69 2.76 42.05 23.76 2.76 74.03 24.76 2.14 106.02 25.92 2.32 14.14 ...... 23.66 2.65 46.04 23.82 2.69 78.03 24.79 2.33 110.02 26.29 2.56 18.11 ...... 23.69 2.77 50.04 23.88 2.49 82.02 24.98 2.26 114.02 26.29 2.56 22.09 ...... 23.77 2.93 54.04 24.02 2.54 86.02 24.98 2.30 118.02 26.41 2.56 26.08 ...... 23.73 3.06 58.03 24.13 2.55 90.02 25.14 2.21 ......

IC 342

0.00 ...... 16.07 0.94 165.08 21.16 1.70 445.03 22.31 1.56 725.02 24.19 1.60 2.83 ...... 16.38 1.20 175.07 21.21 1.69 455.03 22.35 1.55 735.02 24.29 1.62 6.32 ...... 17.57 1.46 185.07 21.26 1.68 465.03 22.40 1.53 745.02 24.40 1.62 10.20 ...... 18.42 1.74 195.06 21.26 1.67 475.03 22.44 1.54 755.02 24.50 1.63 14.14 ...... 18.83 1.85 205.06 21.28 1.68 485.03 22.50 1.54 765.02 24.57 1.60 18.11 ...... 19.09 1.88 215.06 21.28 1.68 495.02 22.58 1.52 775.02 24.66 1.57 22.09 ...... 19.28 1.88 225.06 21.31 1.67 505.02 22.64 1.53 785.02 24.75 1.56 26.08 ...... 19.44 1.87 235.05 21.32 1.66 515.02 22.67 1.54 795.02 24.82 1.54 TABLE 7ÈContinued

[ [ [ [ a kI kV kI a kI kV kI a kI kV kI a kI kV kI 30.07 ...... 19.57 1.87 245.05 21.34 1.64 525.02 22.73 1.55 805.02 24.85 1.55 34.06 ...... 19.67 1.88 255.05 21.38 1.64 535.02 22.80 1.53 815.02 24.92 1.57 38.05 ...... 19.81 1.87 265.05 21.40 1.63 545.02 22.85 1.52 825.02 25.01 1.57 42.05 ...... 19.92 1.86 275.05 21.43 1.63 555.02 22.90 1.51 835.02 25.01 1.56 46.04 ...... 20.03 1.84 285.04 21.48 1.63 565.02 22.93 1.51 845.02 25.10 1.59 50.04 ...... 20.12 1.84 295.04 21.53 1.63 575.02 23.00 1.53 855.02 25.18 1.62 54.04 ...... 20.20 1.84 305.04 21.59 1.64 585.02 23.06 1.53 865.01 25.21 1.61 58.03 ...... 20.27 1.83 315.04 21.65 1.63 595.02 23.14 1.52 875.01 25.27 1.58 62.03 ...... 20.33 1.83 325.04 21.70 1.61 605.02 23.20 1.52 885.01 25.36 1.62 66.03 ...... 20.38 1.82 335.04 21.76 1.61 615.02 23.26 1.52 895.01 25.50 1.56 70.03 ...... 20.43 1.80 345.04 21.81 1.61 625.02 23.32 1.52 905.01 25.52 1.47 74.03 ...... 20.49 1.80 355.04 21.87 1.61 635.02 23.39 1.51 915.01 25.60 1.45 85.15 ...... 20.59 1.78 365.03 21.94 1.61 645.02 23.48 1.52 925.01 25.55 1.58 95.13 ...... 20.68 1.77 375.03 21.99 1.61 655.02 23.55 1.53 935.01 25.61 1.58 105.12 ...... 20.75 1.77 385.03 22.05 1.60 665.02 23.62 1.52 945.01 25.61 1.74 115.11 ...... 20.82 1.75 395.03 22.09 1.60 675.02 23.70 1.52 955.01 25.70 1.55 125.10 ...... 20.88 1.73 405.03 22.15 1.59 685.02 23.78 1.54 965.01 25.77 1.54 135.09 ...... 20.94 1.71 415.03 22.20 1.59 695.02 23.87 1.55 975.01 25.90 1.36 145.09 ...... 21.01 1.70 425.03 22.24 1.57 705.02 23.98 1.61 985.01 25.87 1.36 155.08 ...... 21.09 1.69 435.03 22.27 1.57 715.02 24.07 1.61 995.01 25.94 1.40 Maffei 1 0.00 ...... 16.64 3.22 106.02 21.43 3.04 225.06 22.90 3.08 495.02 24.63 2.94 2.83 ...... 16.89 3.27 110.02 21.48 3.04 235.05 23.00 3.09 505.02 24.68 2.85 6.33 ...... 17.50 3.27 114.02 21.55 3.03 245.05 23.08 3.10 515.02 24.74 2.99 10.20 ...... 18.11 3.29 118.02 21.60 3.03 255.05 23.17 3.08 525.02 24.78 2.88 14.14 ...... 18.56 3.26 122.02 21.65 3.03 265.05 23.25 3.07 535.02 24.85 2.95 18.11 ...... 18.90 3.24 126.02 21.71 3.05 275.05 23.33 3.09 545.02 24.91 3.00 22.09 ...... 19.16 3.23 130.01 21.76 3.03 285.04 23.41 3.08 555.02 25.00 3.20 26.08 ...... 19.35 3.23 134.01 21.82 3.04 295.04 23.50 3.15 565.02 25.03 (3.02) 30.07 ...... 19.52 3.24 138.01 21.87 3.04 305.04 23.59 3.20 575.02 25.07 (3.02) 34.06 ...... 19.68 3.23 142.01 21.92 3.03 315.04 23.67 3.29 585.02 25.06 (3.02) 38.05 ...... 19.85 3.21 146.01 21.97 3.04 325.04 23.73 3.28 595.02 25.15 (3.02) 42.05 ...... 19.99 3.16 150.01 22.02 3.03 335.04 23.77 3.22 605.02 25.19 (3.02) 46.04 ...... 20.13 3.10 154.01 22.08 3.03 345.04 23.82 3.29 615.02 25.29 (3.02) 50.04 ...... 20.26 3.07 158.01 22.14 3.05 355.04 23.87 3.31 625.02 25.39 (3.02) 54.04 ...... 20.38 3.09 162.01 22.19 3.05 365.03 23.92 3.26 635.02 25.47 (3.02) 58.03 ...... 20.49 3.10 166.01 22.23 3.05 375.03 23.99 3.24 645.02 25.50 (3.02) 62.03 ...... 20.61 3.10 170.01 22.28 3.05 385.03 24.03 3.10 655.02 25.58 (3.02) 66.03 ...... 20.71 3.10 174.01 22.33 3.05 395.03 24.12 3.24 665.02 25.62 (3.02) 70.03 ...... 20.81 3.11 178.01 22.37 3.03 405.03 24.15 3.16 675.02 25.63 (3.02) 74.03 ...... 20.90 3.09 182.01 22.43 3.08 415.03 24.22 3.17 685.02 25.68 (3.02) 78.03 ...... 20.98 3.07 186.01 22.47 3.08 425.03 24.27 3.08 695.02 25.72 (3.02) 82.02 ...... 21.06 3.07 190.01 22.53 3.12 435.03 24.32 3.14 705.02 25.72 (3.02) 86.02 ...... 21.13 3.04 194.01 22.58 3.12 445.03 24.38 3.14 715.02 25.78 (3.02) 90.02 ...... 21.19 3.05 198.01 22.63 3.14 455.03 24.44 3.19 725.02 25.89 (3.02) 94.02 ...... 21.25 3.04 202.01 22.68 3.14 465.03 24.46 2.98 735.02 26.07 (3.02) 98.02 ...... 21.32 3.06 205.06 22.71 3.11 475.03 24.53 2.96 745.02 26.12 (3.02) 102.02 ...... 21.37 3.06 215.06 22.81 3.11 485.03 24.57 2.90 755.02 26.20 (3.02)

Maffei 2

0.00 ...... 18.61 3.33 100.08 21.64 3.15 308.03 23.77 3.11 516.02 25.53 3.28 2.83 ...... 18.72 3.44 108.07 21.71 3.14 316.02 23.82 3.01 524.02 25.64 3.04 6.32 ...... 19.12 3.47 116.07 21.80 3.15 324.02 23.89 2.93 532.02 25.82 2.77 10.20 ...... 19.55 3.47 124.06 21.87 3.15 332.02 23.97 3.01 540.02 25.92 2.76 14.14 ...... 19.92 3.39 132.06 21.96 3.18 340.02 24.03 3.13 548.02 25.93 2.77 18.11 ...... 20.15 3.32 140.06 22.02 3.15 348.02 24.06 3.08 556.01 25.87 3.09 22.09 ...... 20.28 3.29 148.05 22.09 3.17 356.02 24.15 3.14 564.01 25.89 3.10 26.08 ...... 20.40 3.22 156.05 22.17 3.15 364.02 24.22 3.15 572.01 25.93 3.55 30.07 ...... 20.51 3.22 164.05 22.25 3.19 372.02 24.22 3.14 580.01 26.10 3.33 34.06 ...... 20.61 3.21 172.05 22.35 3.18 380.02 24.25 3.03 588.01 26.02 2.83 38.05 ...... 20.70 3.18 180.04 22.43 3.18 388.02 24.26 3.02 596.01 26.12 2.48 42.05 ...... 20.78 3.17 188.04 22.54 3.20 396.02 24.30 2.97 604.01 26.17 (3.10) 46.04 ...... 20.87 3.16 196.04 22.59 3.15 404.02 24.38 2.93 612.01 26.48 (3.10) 50.04 ...... 20.95 3.16 204.04 22.68 3.20 412.02 24.47 2.91 620.01 26.53 (3.10)

74 TABLE 7ÈContinued

[ [ [ [ a kI kV kI a kI kV kI a kI kV kI a kI kV kI 54.04 ...... 21.02 3.15 212.04 22.76 3.16 420.02 24.55 2.81 628.01 26.56 (3.10) 58.03 ...... 21.11 3.14 220.04 22.85 3.16 428.02 24.60 2.88 636.01 26.63 (3.10) 62.03 ...... 21.19 3.16 228.04 22.89 3.17 436.02 24.70 2.88 644.01 26.91 (3.10) 66.03 ...... 21.26 3.16 236.03 22.98 3.11 444.02 24.77 2.87 652.01 27.13 (3.10) 70.03 ...... 21.31 3.16 244.03 23.07 3.09 452.02 24.82 2.88 660.01 27.32 (3.10) 74.03 ...... 21.36 3.15 252.03 23.17 3.00 460.02 24.93 2.95 668.01 27.11 (3.10) 78.03 ...... 21.41 3.14 260.03 23.25 3.05 468.02 25.02 3.20 676.01 27.01 (3.10) 82.02 ...... 21.46 3.13 268.03 23.36 3.08 476.02 25.13 3.20 684.01 27.10 (3.10) 86.02 ...... 21.51 3.12 276.03 23.44 3.04 484.02 25.27 3.34 692.01 27.23 (3.10) 90.02 ...... 21.55 3.14 284.03 23.52 3.12 492.02 25.28 2.94 700.01 26.90 (3.10) 94.02 ...... 21.58 3.13 292.03 23.59 3.08 500.02 25.50 3.38 ...... 98.02 ...... 21.62 3.15 300.03 23.66 3.04 508.02 25.43 2.84 ......

MB 1

0.00 ...... 22.61 2.25 42.05 23.35 2.22 86.02 24.49 2.33 130.01 25.31 2.18 2.83 ...... 22.62 2.29 46.04 23.45 2.28 90.02 24.53 2.19 134.01 25.33 2.48 6.32 ...... 22.58 2.58 50.04 23.55 2.43 94.02 24.64 2.34 138.01 25.56 2.28 10.20 ...... 22.63 2.53 54.04 23.66 2.45 98.02 24.70 2.36 142.01 25.64 2.28 14.14 ...... 22.67 2.44 58.03 23.78 2.43 102.02 24.73 2.35 146.01 25.68 2.34 18.11 ...... 22.77 2.50 62.03 23.91 2.41 106.02 24.78 2.37 150.01 25.81 2.12 22.09 ...... 22.87 2.44 66.03 24.02 2.31 110.02 24.88 2.26 154.01 25.81 2.12 26.08 ...... 22.98 2.41 70.03 24.12 2.08 114.02 25.02 2.29 158.01 26.03 1.87 30.07 ...... 23.08 2.44 74.03 24.23 2.16 118.02 25.13 2.43 ...... 34.06 ...... 23.16 2.38 78.03 24.31 2.23 122.02 25.22 2.33 ...... 38.05 ...... 23.24 2.24 82.02 24.43 2.45 126.02 25.28 2.21 ...... MB 2 0.00 ...... 24.20 2.70 18.11 24.31 2.28 38.05 24.41 1.67 58.03 26.45 1.98 2.83 ...... 24.13 1.99 22.09 24.34 2.25 42.05 24.47 1.72 62.03 26.87 1.54 6.32 ...... 24.16 2.21 26.08 24.32 1.70 46.04 24.75 1.82 ...... 10.20 ...... 24.14 2.17 30.07 24.25 1.70 50.04 25.19 1.83 ...... 14.14 ...... 24.25 2.15 34.06 24.22 1.83 54.04 25.80 1.72 ...... MB 3 0.00 ...... 22.76 2.99 22.09 23.40 2.82 46.04 24.33 3.40 70.03 25.73 (2.87) 2.83 ...... 22.72 2.70 26.08 23.51 2.78 50.04 24.46 2.87 74.03 26.05 (2.87) 6.32 ...... 22.76 2.65 30.07 23.61 2.92 54.04 24.79 3.04 78.03 26.06 (2.87) 10.20 ...... 22.96 2.81 34.06 23.75 2.89 58.03 24.99 2.71 82.02 25.98 (2.87) 14.14 ...... 23.07 3.06 38.05 23.98 2.63 62.03 25.13 2.98 ...... 18.11 ...... 23.23 2.76 42.05 24.16 2.70 66.03 25.46 (2.87) ...... NGC 1560 0.00 ...... 20.39 1.12 124.06 21.87 1.03 252.03 23.45 0.96 380.02 24.88 0.96 5.66 ...... 20.36 1.10 132.06 21.97 1.02 260.03 23.55 0.99 388.02 24.93 1.13 12.65 ...... 20.35 1.07 140.06 22.08 1.01 268.03 23.68 0.95 396.02 25.20 0.94 20.40 ...... 20.42 1.06 148.05 22.20 1.02 276.03 23.73 0.99 404.02 25.26 0.98 28.28 ...... 20.46 1.08 156.05 22.31 1.04 284.03 23.82 0.96 412.02 25.47 0.99 36.22 ...... 20.56 1.09 164.05 22.42 1.01 292.03 23.90 0.96 420.02 25.61 1.02 44.18 ...... 20.69 1.06 172.05 22.54 0.98 300.03 23.97 0.95 428.02 25.69 1.12 52.15 ...... 20.81 1.04 180.04 22.62 0.98 308.03 24.08 0.94 436.02 25.76 1.21 60.13 ...... 20.91 1.03 188.04 22.72 1.00 316.02 24.14 1.00 444.02 26.01 1.07 68.12 ...... 21.04 1.04 196.04 22.82 0.99 324.02 24.23 0.93 452.02 26.09 1.27 76.11 ...... 21.19 1.03 204.04 22.91 0.97 332.02 24.32 0.93 460.02 26.17 1.31 84.10 ...... 21.33 1.03 212.04 22.99 0.98 340.02 24.37 0.95 468.02 26.36 1.04 92.09 ...... 21.46 1.03 220.04 23.08 0.99 348.02 24.49 1.00 476.02 26.92 0.32 100.08 ...... 21.55 1.04 228.04 23.16 0.98 356.02 24.56 0.89 484.02 26.49 0.95 108.07 ...... 21.64 1.02 236.03 23.28 0.97 364.02 24.61 0.97 ...... 116.07 ...... 21.74 1.03 244.03 23.36 0.99 372.02 24.73 1.03 ...... NGC 1569 0.00 ...... 16.59 1.10 62.03 21.25 1.25 126.02 23.32 1.42 190.01 24.78 1.77 2.83 ...... 16.96 0.99 66.03 21.44 1.31 130.01 23.41 1.49 194.01 24.82 1.38

75 TABLE 7ÈContinued

[ [ [ [ a kI kV kI a kI kV kI a kI kV kI a kI kV kI 6.32 ...... 17.48 0.97 70.03 21.61 1.32 134.01 23.50 1.50 198.01 24.96 1.49 10.20 ...... 17.88 1.05 74.03 21.78 1.36 138.01 23.62 1.44 202.01 24.99 1.83 14.14 ...... 18.32 1.11 78.03 21.93 1.36 142.01 23.70 1.46 206.01 24.97 1.99 18.11 ...... 18.72 1.14 82.02 22.07 1.38 146.01 23.80 1.55 210.01 25.10 1.81 22.09 ...... 19.02 1.17 86.02 22.21 1.35 150.01 23.94 1.54 214.01 25.22 1.63 26.08 ...... 19.33 1.18 90.02 22.36 1.38 154.01 24.01 1.59 218.01 25.37 1.76 30.07 ...... 19.61 1.20 94.02 22.49 1.40 158.01 24.08 1.48 222.01 25.44 1.95 34.06 ...... 19.84 1.21 98.02 22.61 1.40 162.01 24.17 1.48 226.01 25.43 1.84 38.05 ...... 20.07 1.22 102.02 22.73 1.42 166.01 24.20 1.51 230.01 25.80 1.34 42.05 ...... 20.30 1.23 106.02 22.81 1.46 170.01 24.32 1.47 234.01 25.92 2.21 46.04 ...... 20.51 1.22 110.02 22.93 1.45 174.01 24.36 1.51 238.01 25.98 2.27 50.04 ...... 20.70 1.22 114.02 23.03 1.44 178.01 24.52 1.45 242.01 26.15 1.69 54.04 ...... 20.86 1.25 118.02 23.14 1.49 182.01 24.56 1.67 ...... 58.03 ...... 21.05 1.22 122.02 23.22 1.48 186.01 24.74 1.54 ......

UGCA 86

0.00 ...... 21.57 1.43 78.03 22.85 1.73 158.01 23.35 1.50 238.01 24.90 1.28 2.83 ...... 21.68 1.47 82.02 22.89 1.71 162.01 23.48 1.41 242.01 25.00 1.17 6.32 ...... 21.86 1.59 86.02 22.97 1.70 166.01 23.56 1.45 246.01 24.98 1.21 10.20 ...... 21.91 1.68 90.02 23.01 1.69 170.01 23.64 1.45 250.01 25.00 1.22 14.14 ...... 21.94 1.71 94.02 23.05 1.68 174.01 23.72 1.44 254.01 25.08 1.23 18.11 ...... 22.01 1.69 98.02 23.05 1.67 178.01 23.84 1.38 258.01 25.12 1.17 22.09 ...... 22.09 1.74 102.02 23.10 1.67 182.01 23.92 1.40 262.01 25.23 1.08 26.08 ...... 22.18 1.72 106.02 23.15 1.62 186.01 24.03 1.33 266.01 25.38 0.99 30.07 ...... 22.23 1.73 110.02 23.21 1.61 190.01 24.09 1.37 270.01 25.36 1.13 34.06 ...... 22.26 1.75 114.02 23.24 1.61 194.01 24.21 1.30 274.01 25.43 0.97 38.05 ...... 22.33 1.73 118.02 23.29 1.61 198.01 24.26 1.34 278.01 25.48 1.05 42.05 ...... 22.38 1.76 122.02 23.33 1.57 202.01 24.33 1.34 282.01 25.61 0.95 46.04 ...... 22.44 1.79 126.02 23.35 1.60 206.01 24.37 1.36 286.01 25.62 1.18 50.04 ...... 22.52 1.77 130.01 23.39 1.54 210.01 24.50 1.29 290.01 25.63 1.06 54.04 ...... 22.56 1.79 134.01 23.39 1.57 214.01 24.59 1.24 294.01 25.90 1.00 58.03 ...... 22.61 1.75 138.01 23.40 1.55 218.01 24.66 1.24 298.01 26.15 0.88 62.03 ...... 22.66 1.73 142.01 23.38 1.57 222.01 24.70 1.27 302.01 26.25 0.78 66.03 ...... 22.67 1.74 146.01 23.41 1.50 226.01 24.75 1.18 ...... 70.03 ...... 22.73 1.75 150.01 23.42 1.51 230.01 24.85 1.17 ...... 74.03 ...... 22.77 1.80 154.01 23.37 1.57 234.01 24.83 1.27 ...... UGCA 92 0.00 ...... 23.07 1.73 42.05 23.20 1.51 86.02 24.15 1.65 130.01 25.03 1.70 2.83 ...... 23.02 1.78 46.04 23.27 1.52 90.02 24.24 1.56 134.01 25.22 1.53 6.32 ...... 22.95 1.64 50.04 23.33 1.55 94.02 24.27 1.59 138.01 25.54 1.42 10.20 ...... 22.94 1.68 54.04 23.43 1.53 98.02 24.39 1.65 142.01 25.65 1.50 14.14 ...... 22.99 1.56 58.03 23.51 1.62 102.02 24.46 1.68 146.01 25.74 1.60 18.11 ...... 23.03 1.50 62.03 23.61 1.62 106.02 24.52 1.56 150.01 25.88 1.54 22.09 ...... 23.02 1.50 66.03 23.72 1.59 110.02 24.56 1.59 154.01 26.03 1.70 26.08 ...... 23.07 1.48 70.03 23.80 1.70 114.02 24.64 1.65 158.01 26.48 1.35 30.07 ...... 23.08 1.49 74.03 23.89 1.67 118.02 24.64 1.71 ...... 34.06 ...... 23.09 1.50 78.03 23.97 1.68 122.02 24.82 1.53 ...... 38.05 ...... 23.12 1.52 82.02 24.03 1.69 126.02 24.88 1.73 ......

UGCA 105

0.00 ...... 20.95 1.22 74.03 22.53 1.12 150.01 23.48 1.05 226.01 24.38 0.95 2.83 ...... 21.00 1.28 78.03 22.60 1.11 154.01 23.50 1.06 230.01 24.45 1.04 6.32 ...... 21.07 1.26 82.02 22.67 1.09 158.01 23.52 1.08 234.01 24.50 1.01 10.20 ...... 21.15 1.24 86.02 22.72 1.10 162.01 23.57 1.07 238.01 24.58 0.98 14.14 ...... 21.23 1.21 90.02 22.79 1.10 166.01 23.60 1.10 242.01 24.66 0.91 18.11 ...... 21.30 1.20 94.02 22.85 1.08 170.01 23.63 1.07 246.01 24.74 0.89 22.09 ...... 21.40 1.22 98.02 22.90 1.06 174.01 23.68 1.04 250.01 24.76 0.89 26.08 ...... 21.50 1.22 102.02 22.93 1.07 178.01 23.70 1.07 254.01 24.82 0.86 30.07 ...... 21.61 1.22 106.02 22.98 1.08 182.01 23.72 1.09 258.01 24.92 0.83 34.06 ...... 21.74 1.23 110.02 23.03 1.08 186.01 23.76 1.09 262.01 24.98 0.84 38.05 ...... 21.85 1.21 114.02 23.11 1.05 190.01 23.82 1.07 266.01 25.02 1.00 42.05 ...... 21.96 1.24 118.02 23.15 1.08 194.01 23.92 1.01 270.01 25.11 0.98 46.04 ...... 22.04 1.22 122.02 23.20 1.08 198.01 23.97 1.03 274.01 25.15 0.99 IC 342/MAFFEI GROUP REVEALED 77

TABLE 7ÈContinued

[ [ [ [ a kI kV kI a kI kV kI a kI kV kI a kI kV kI 50.04 ...... 22.14 1.17 126.02 23.26 1.08 202.01 24.04 1.06 278.01 25.25 1.00 54.04 ...... 22.22 1.18 130.01 23.27 1.07 206.01 24.10 1.02 282.01 25.34 0.97 58.03 ...... 22.28 1.15 134.01 23.31 1.11 210.01 24.18 0.98 286.01 25.40 0.90 62.03 ...... 22.33 1.14 138.01 23.35 1.08 214.01 24.22 1.00 290.01 25.47 0.86 66.03 ...... 22.38 1.14 142.01 23.42 1.03 218.01 24.27 0.98 294.01 25.47 0.94 70.03 ...... 22.45 1.14 146.01 23.45 1.03 222.01 24.28 1.03 298.01 25.56 0.83

M81

0.00 ...... 14.38 1.80: 156.05 19.29 1.32 380.02 20.91 1.20 604.01 22.68 1.16 2.83 ...... 14.49 1.76: 164.05 19.37 1.31 388.02 20.99 1.19 612.01 22.72 1.10 6.32 ...... 14.99 1.47: 172.05 19.45 1.31 396.02 21.04 1.17 620.01 22.80 1.06 10.20 ...... 15.54 1.34 180.04 19.52 1.30 404.02 21.09 1.17 628.01 22.78 1.18 14.14 ...... 15.94 1.34 188.04 19.61 1.29 412.02 21.11 1.20 636.01 22.89 1.17 18.11 ...... 16.25 1.35 196.04 19.69 1.28 420.02 21.19 1.18 644.01 22.95 1.04 22.09 ...... 16.51 1.36 204.04 19.77 1.28 428.02 21.22 1.18 652.01 22.97 1.02 26.08 ...... 16.75 1.36 212.04 19.85 1.30 436.02 21.29 1.18 660.01 23.07 1.15 30.07 ...... 16.94 1.36 220.04 19.92 1.29 444.02 21.35 1.15 668.01 23.05 1.36 34.06 ...... 17.09 1.36 228.04 20.00 1.29 452.02 21.40 1.18 676.01 23.14 1.21 38.05 ...... 17.23 1.35 236.03 20.07 1.27 460.02 21.46 1.19 684.01 23.10 1.30 42.05 ...... 17.36 1.35 244.03 20.14 1.26 468.02 21.52 1.15 692.01 23.22 1.25 46.04 ...... 17.48 1.34 252.03 20.19 1.29 476.02 21.58 1.17 700.01 23.20 1.14 50.04 ...... 17.59 1.34 260.03 20.27 1.26 484.02 21.69 1.15 708.01 23.29 1.05 54.04 ...... 17.69 1.34 268.03 20.33 1.27 492.02 21.80 1.14 716.01 23.38 1.06 58.03 ...... 17.78 1.34 276.03 20.37 1.28 500.02 21.81 1.17 724.01 23.38 1.11 60.13 ...... 17.82 1.34 284.03 20.44 1.24 508.02 21.91 1.19 732.01 23.41 1.07 68.12 ...... 17.99 1.34 292.03 20.48 1.23 516.02 21.95 1.16 740.01 23.56 0.94 76.11 ...... 18.14 1.34 300.03 20.53 1.22 524.02 22.05 1.07 748.01 23.73 0.87 84.10 ...... 18.28 1.34 308.03 20.57 1.23 532.02 22.05 1.17 756.01 23.67 1.22 92.09 ...... 18.41 1.35 316.02 20.61 1.21 540.02 22.17 1.11 764.01 23.67 1.20 100.08 ...... 18.54 1.36 324.02 20.66 1.22 548.02 22.20 1.15 772.01 23.87 1.18 108.07 ...... 18.67 1.36 332.02 20.68 1.22 556.01 22.26 1.15 780.01 24.18 0.75 116.07 ...... 18.77 1.36 340.02 20.72 1.18 564.01 22.39 1.08 788.01 23.87 1.26 124.06 ...... 18.87 1.35 348.02 20.75 1.21 572.01 22.36 1.14 796.01 23.95 0.99 132.06 ...... 18.98 1.35 356.02 20.78 1.22 580.01 22.44 1.12 ...... 140.06 ...... 19.10 1.33 364.02 20.83 1.20 588.01 22.55 1.08 ...... 148.05 ...... 19.20 1.33 372.02 20.86 1.20 596.01 22.57 1.07 ......

a These proÐles were derived by Ðtting isophotes with ellipses with a Ðxed center, shape, and orientation. a is the length of the ~2 [ [ semimajor axis of the Ðtted isophote, in arcseconds.kI is the surface brightness of the isophote in I, in mag arcsec .kV kI is the V I color of the isophote. See Table 5 for the adopted axis ratio and orientation of the Ðtted ellipses. cant radial color gradients, with the central concentration derived by Krismer, Tully, & Gioia (1995) are 0.45 ^ 0.18 increasing with increasing e†ective wavelength. mag fainter than ours. Since our simulated aperture photo- [ [ The e†ective colors,(B V )e and(V I)e, are the inte- metry on these same galaxies agrees well with published grated colors within the e†ective aperture as deÐned in blue photoelectric photometry from other sources, the measure- light. Unlike total colors, these are derived by interpolation ments by Krismer, Tully, & Gioia must be regarded as too (as opposed to extrapolation), so generally have better pre- faint, possibly due to the limited Ðeld of view. For Dwin- cision (Buta et al. 1995). Measurements listed in Table 13 geloo 1, V and I magnitudes measured by Loan et al. (1996) will be used in a later paper as aids to estimating extinction. are 0.65 mag fainter than ours on average. Measurements in V and I for Cas 1 and UGCA 92 by Karachentsev et al. ^ 6.6. External Checks on the Total Magnitudes (1997) are systematically fainter than ours by 0.90 0.29 mag, but the V -band measurement of UGCA 92 by Kara- Total magnitudes in V and I have been measured pre- chentseva et al. (1996) is 0.32 mag brighter than our value. viously for several galaxies in our sample. It is worthwhile Except for M81, discrepancies are all much larger than our comparing the results with ours, especially to gauge how estimated uncertainties. Clearly, previous conclusions previous measurements have been a†ected by limitations on about the group as a whole may have been seriously Ðeld size and sensitivity and by contamination by fore- a†ected by errors in the photometry of its members. ground stars. Table 14 summarizes the observations to date. Although our results for M81 agree well with other sources (based on the proÐles shown in Fig. 24o), there are many 6.7. External Check on ProÐles disparities for the galaxies in the IC 342/Ma†ei Group. Kent (1987) Ðtted free ellipses to Thuan-Gunn r-band Ables (1972) photographically derived a B-band magnitude images of M81 to derive surface brightness proÐles along for IC 342 which is 0.27 mag brighter than ours. The I-band the major and minor axes of the galaxy. Although our pro- magnitudes of NGC 1560, NGC 1569, and UGCA 105 Ðles are not in this photometric system, V and I bracket the TABLE 8 B AND B[V PROFILES OF IC 342, MAFFEI 1, AND MAFFEI 2DERIVED BY FITTING FIXED ELLIPSESa

[ [ [ [ a kB kB kV a kB kB kV a kB kB kV a kB kB kV IC 342

0.00 ...... 17.67 0.67 165.08 24.01 1.17 445.03 24.90 1.04 725.02 26.77 1.00 2.83 ...... 18.24 0.68 175.07 24.09 1.20 455.03 24.91 1.03 735.02 26.87 0.98 6.32 ...... 19.83 0.81 185.07 24.14 1.22 465.03 24.96 1.04 745.02 26.97 0.98 10.20 ...... 21.25 1.10 195.06 24.10 1.18 475.03 25.01 1.04 755.02 27.01 0.90 14.14 ...... 21.89 1.23 205.06 24.10 1.16 485.03 25.03 1.01 765.02 27.15 1.00 18.11 ...... 22.25 1.30 215.06 24.12 1.17 495.02 25.13 1.04 775.02 27.24 1.03 22.09 ...... 22.44 1.30 225.06 24.14 1.17 505.02 25.15 1.00 785.02 27.21 0.92 26.08 ...... 22.57 1.27 235.05 24.08 1.11 515.02 25.20 1.00 795.02 27.46 1.11 30.07 ...... 22.62 1.20 245.05 24.08 1.11 525.02 25.28 1.01 805.02 27.53 1.13 34.06 ...... 22.75 1.22 255.05 24.08 1.08 535.02 25.31 0.99 815.02 27.63 1.15 38.05 ...... 22.92 1.26 265.05 24.09 1.07 545.02 25.35 0.99 825.02 27.62 1.06 42.05 ...... 23.03 1.27 275.05 24.08 1.03 555.02 25.35 0.96 835.02 27.65 1.09 46.04 ...... 23.17 1.32 285.04 24.16 1.07 565.02 25.41 0.98 845.02 27.59 0.92 50.04 ...... 23.27 1.32 295.04 24.23 1.09 575.02 25.48 0.97 855.02 27.63 0.86 54.04 ...... 23.37 1.35 305.04 24.29 1.07 585.02 25.56 0.98 865.01 27.54 0.75 58.03 ...... 23.41 1.31 315.04 24.37 1.10 595.02 25.60 0.96 875.01 27.74 0.90 62.03 ...... 23.43 1.29 325.04 24.38 1.07 605.02 25.68 0.97 885.01 27.86 0.90 66.03 ...... 23.47 1.28 335.04 24.41 1.06 615.02 25.76 1.00 895.01 28.13 1.08 70.03 ...... 23.53 1.31 345.04 24.46 1.06 625.02 25.80 0.97 905.01 28.04 1.05 74.03 ...... 23.57 1.30 355.04 24.57 1.09 635.02 25.89 1.00 915.01 27.84 0.82 85.15 ...... 23.66 1.30 365.03 24.62 1.09 645.02 25.99 1.01 925.01 27.97 0.87 95.13 ...... 23.73 1.29 375.03 24.69 1.10 655.02 26.04 0.97 935.01 28.23 1.05 105.12 ...... 23.75 1.24 385.03 24.70 1.07 665.02 26.10 0.97 945.01 28.04 0.72 115.11 ...... 23.78 1.23 395.03 24.73 1.05 675.02 26.20 0.99 955.01 27.94 0.71 125.10 ...... 23.81 1.22 405.03 24.81 1.08 685.02 26.28 0.98 965.01 27.93 0.64 135.09 ...... 23.81 1.17 415.03 24.87 1.10 695.02 26.38 0.98 975.01 28.08 0.84 145.09 ...... 23.89 1.19 425.03 24.87 1.07 705.02 26.55 0.98 985.01 28.01 0.80 155.08 ...... 23.94 1.17 435.03 24.89 1.06 715.02 26.65 0.99 995.01 28.19 0.87 Maffei 1 0.00 ...... 22.68 2.83 50.04 25.65 2.34 102.02 26.91 2.49 154.01 27.58 2.48 2.83 ...... 22.82 2.68 54.04 25.61 2.18 106.02 26.91 2.46 158.01 27.34 2.18 6.32 ...... 23.28 2.53 58.03 25.82 2.26 110.02 26.87 2.37 162.01 27.49 2.28 10.20 ...... 23.82 2.45 62.03 26.03 2.35 114.02 27.00 2.44 166.01 27.71 2.44 14.14 ...... 24.29 2.50 66.03 26.14 2.35 118.02 27.10 2.47 170.01 27.83 2.51 18.11 ...... 24.57 2.45 70.03 26.30 2.40 122.02 27.15 2.47 174.01 27.52 2.17 22.09 ...... 24.79 2.42 74.03 26.39 2.42 126.02 27.15 2.40 178.01 27.89 2.49 26.08 ...... 24.85 2.30 78.03 26.44 2.40 130.01 27.20 2.43 182.01 27.94 2.45 30.07 ...... 25.10 2.38 82.02 26.57 2.46 134.01 27.19 2.36 186.01 28.33 2.77 34.06 ...... 25.35 2.46 86.02 26.59 2.43 138.01 27.03 2.16 190.01 28.01 2.38 38.05 ...... 25.37 2.35 90.02 26.50 2.28 142.01 27.32 2.38 194.01 27.79 2.13 42.05 ...... 25.44 2.31 94.02 26.61 2.34 146.01 27.37 2.38 198.01 28.15 2.40 46.04 ...... 25.55 2.34 98.02 26.79 2.43 150.01 27.73 2.68 ......

Maffei 2

0.00 ...... 24.22 2.33 100.08 27.20 2.43 212.04 28.66 2.74 324.02 29.81 2.95 2.83 ...... 24.63 2.51 108.07 27.34 2.50 220.04 28.73 2.72 332.02 29.52 2.54 5.66 ...... 24.97 2.54 116.07 27.51 2.58 228.04 28.10 2.08 340.02 28.43 1.35 12.65 ...... 25.61 2.47 124.06 27.92 2.89 236.03 28.33 2.27 348.02 29.23 2.12 20.40 ...... 26.06 2.56 132.06 27.66 2.54 244.03 28.39 2.26 356.02 29.34 2.09 28.28 ...... 26.22 2.56 140.06 27.65 2.49 252.03 28.26 2.12 364.02 29.85 2.50 36.22 ...... 26.50 2.65 148.05 27.99 2.73 260.03 28.75 2.46 372.02 30.13 2.77 44.18 ...... 26.53 2.55 156.05 27.84 2.54 268.03 28.61 2.21 380.02 30.27 2.97 52.15 ...... 26.52 2.40 164.05 27.78 2.37 276.03 28.34 1.92 388.02 29.41 2.16 60.13 ...... 26.69 2.41 172.05 27.43 1.95 284.03 29.10 2.48 396.02 30.95 3.59 68.12 ...... 26.85 2.43 180.04 27.66 2.09 292.03 29.02 2.37 404.02 30.50 3.14 76.11 ...... 26.75 2.26 188.04 27.61 1.93 300.03 29.48 2.77 412.02 30.18 2.78 84.10 ...... 27.07 2.47 196.04 27.84 2.14 308.03 28.53 1.71 420.02 28.72 1.42 92.09 ...... 27.13 2.44 204.04 27.92 2.09 316.02 28.53 1.75 ......

a These proÐles were derived by Ðtting isophotes with ellipses with a Ðxed center, shape, and orientation. a is the length of the semimajor ~2 [ [ axis of the Ðtted isophote, in arcseconds.kB is the surface brightness of the isophote in B, in mag arcsec .kB kV is the B V color of the isophote. See Table 5 for the adopted axis ratio and orientation of the Ðtted ellipses. IC 342/MAFFEI GROUP REVEALED 79

TABLE 9 I, V [I, B, AND B[V PROFILES OF MAFFEI 1DERIVED BY FITTING FREE ELLIPSESa A. I AND V [I PROFILES

a k Color a k Color a k Color a k Color

0.00 ...... 16.64 3.22 9.31 18.01 3.26 42.78 19.88 3.24 196.57 22.63 3.20 2.23 ...... 16.87 3.27 10.24 18.13 3.24 47.06 20.02 3.20 216.23 22.83 3.19 2.45 ...... 16.91 3.26 11.27 18.23 3.22 51.76 20.18 3.16 237.85 22.98 3.07 2.70 ...... 16.95 3.26 12.39 18.34 3.22 56.94 20.35 3.15 261.64 23.21 3.19 2.97 ...... 16.99 3.26 13.63 18.46 3.22 62.63 20.51 3.15 287.80 23.40 3.14 3.26 ...... 17.04 3.28 14.99 18.59 3.22 68.90 20.68 3.16 316.59 23.60 (3.12) 3.59 ...... 17.09 3.27 16.49 18.73 3.21 75.79 20.85 3.10 348.24 23.82 (3.12) 3.95 ...... 17.16 3.28 18.14 18.88 3.21 83.37 21.01 3.14 383.07 24.00 (3.12) 4.34 ...... 17.23 3.28 19.96 19.01 3.22 91.70 21.14 3.12 421.38 24.23 (3.12) 4.78 ...... 17.31 3.26 21.95 19.13 3.25 100.87 21.28 3.08 463.51 24.54 (3.12) 5.26 ...... 17.40 3.24 24.15 19.25 3.32 110.96 21.43 3.01 509.86 24.77 (3.12) 5.78 ...... 17.49 3.24 26.56 19.34 3.33 122.06 21.60 3.03 560.85 25.04 (3.12) 6.36 ...... 17.59 3.23 29.22 19.46 3.30 134.26 21.81 3.12 616.94 25.35 (3.12) 6.99 ...... 17.69 3.24 32.14 19.55 3.30 147.69 22.02 3.08 ...... 7.69 ...... 17.79 3.26 35.35 19.64 3.30 162.46 22.21 3.13 ...... 8.46 ...... 17.90 3.26 38.89 19.75 3.30 178.70 22.41 3.07 ......

B. B AND B[V PROFILES a k Color a k Color a k Color a k Color 0.00 ...... 22.68 2.83 5.23 23.17 2.56 13.57 24.04 2.39 35.21 25.68 2.75 2.22 ...... 22.79 2.67 5.76 23.24 2.53 14.93 24.16 2.39 38.73 25.45 2.43 2.44 ...... 22.82 2.66 6.33 23.31 2.52 16.42 24.33 2.41 42.60 25.59 2.50 2.68 ...... 22.84 2.65 6.97 23.42 2.52 18.07 24.49 2.43 46.86 25.86 2.65 2.95 ...... 22.88 2.65 7.66 23.55 2.53 19.87 24.57 2.38 51.55 25.97 2.64 3.25 ...... 22.91 2.61 8.43 23.65 2.51 21.86 24.73 2.39 56.70 25.95 2.48 3.57 ...... 22.99 2.64 9.27 23.75 2.50 24.05 24.81 2.29 62.37 26.11 2.48 3.93 ...... 23.03 2.61 10.20 23.82 2.48 26.45 24.77 2.16 68.61 26.24 2.42 4.32 ...... 23.07 2.59 11.22 23.89 2.46 29.10 24.95 2.24 75.47 26.43 2.49 4.76 ...... 23.13 2.58 12.34 23.95 2.42 32.01 25.31 2.49 ......

a These proÐles were derived by Ðtting isophotes with ellipses whose centers, shapes, and orientations were permitted to change with radius. a is the length of the semimajor axis of the Ðtted isophote, in arcseconds. k is the surface brightness of the isophote in the speciÐed bandpass (I or B), in mag arcsec~2. ““ Color ÏÏ is the corresponding color of the isophote (V [I or B[V ). e†ective wavelength of KentÏs Ðlter. It is particularly valu- interpolated them at the radii of KentÏs proÐles. Major axis able to compare our results with KentÏs to check the integ- proÐles were converted to minor axis proÐles by multi- rity of the relative calibration of our proÐles over a wide plying the major axis radii by the Ðtted axis ratios. To try range of surface brightness. and approximately match the e†ective wavelength of r,an For the comparison, it is best to use surface brightness average of the proÐles in V and I was computed along each proÐles derived by Ðtting free ellipses, speciÐcally via the axis. The results are compared with KentÏs in Figure 37a, GALPHOT routine SPHOT (these are not illustrated in where di†erences in surface brightness are plotted against this paper). Thus, we transformed our SPHOT proÐles of distance from the nucleus along both the minor and major M81 to the standard V and I systems, and then linearly axes.

TABLE 10 PARAMETERS FROM r1@4 LAW FITS TO MAFFEI 1 AND NGC 1569

Radius Range ke ae or be p(Ðt) Object Filter ProÐle (arcsec) (mag arcsec~2) (arcsec) (mag arcsec~2) (1) (2) (3) (4) (5) (6) (7)

Maffei 1 ...... B Fixed-ellipse Ðt 6È200 28.42 240.8 0.132 Maffei 1 ...... V Fixed-ellipse Ðt 10È560 26.03 233.0 0.109 Maffei 1 ...... I Fixed-ellipse Ðt 14È730 22.77 213.6 0.054 Maffei 1 ...... V Free-ellipse Ðt 16È288 26.04 233.4 0.086 Maffei 1 ...... I Free-ellipse Ðt 16È617 22.64 203.6 0.039 NGC 1569 ...... I Minor axis 8È93 19.85 15.1 0.034

NOTES.ÈCol. (1): Name of galaxy. Col. (2): Name of Ðlter. Col. (3): Origin of surface brightnesses. Col. (4): Range of radius over which r1@4 law was Ðtted, in arcseconds. Col. (5): Surface brightness of the e†ective isophote, i.e., the isophote of the spheroid encompassing half of the total light of the r1@4 law, in mag arcsec~2. Col. (6): Length of the semimajor axis (Ma†ei 1) or semiminor axis (NGC 1569) of the e†ective isophote, in arcseconds. Col. (7): Standard deviation of surface brightnesses about the Ðtted proÐle, in mag arcsec~2. 22

22 Cassiopeia 1 Dwingeloo 2

24 .·.·· f' 24 f' NE ... .. 511' ., ·. .. " ""' .,...... ""'... ".,...... 26 ..., .. .. s 26 .. .. NW SE i 1: "' "'• 2B 2B

-150 -100 -50 0 50 100 150 -100 -50 0 50 100 r(arcseconds) r{arcseconds)

FIG. 25.ÈUnfolded major axis (/ \ 94¡) and minor axis (/ \ 4¡) FIG. 27.ÈUnfolded major axis (/ \ 72¡) and minor axis (/ \ 162¡) I-band surface brightness proÐles of Cas 1. The solid lines show the model I-band surface brightness proÐles of Dwingeloo 2. The solid lines show the given in Table 12. Di†erent sections are labeled (E, east; W, west; N, north; model given in Table 12. Di†erent sections are labeled as in Fig. 25. The S, south). The minor axis proÐle has been shifted by ]2.0 mag for clarity. minor axis proÐle has been shifted by ]2.0 mag for clarity.

22 IC 342 ,~ 20 " 24 f' " NW " ".,"'... ~ "~ ..., "'- ..., 5 26 5 25 :3: :3: ... 2B

-400 -300 -200 -100 0 100 200 300 400 -1000 -500 0 500 1000 r(arcseconds) r(a.rcseconds)

FIG. 26.ÈUnfolded major axis (/ \ 111¡) and minor axis (/ \ 21¡) FIG. 28.ÈUnfolded major axis (/ \ 87¡) and minor axis (/ \ 177¡) I-band surface brightness proÐles of Dwingeloo 1. The solid lines show the I-band surface brightness proÐles of IC 342. The solid lines show the combined spheroid/disk model given in Table 11. Di†erent sections are combined spheroid/disk model given in Table 11. Di†erent sections are labeled as in Fig. 25. The minor axis proÐle has been displaced by ]1.0 labeled as in Fig. 25. The minor axis proÐle has been displaced by ]2.0 mag for clarity. mag for clarity.

Maffei 1 18 Major Axis rj1=84° 18

20 20 ,r .rI ti ti Ol Ol Ill Ill ..ti ..ti OS OS bll bll OS 22 OS 22 8 8 1: 1:

24 24

26 26

5 5 2,;. 3 111 2 1/4 3 r (arcseconds ) r (arcseconds 111)

FIG. 29.ÈFolded major and minor axis I-band surface brightness proÐles of Ma†ei 1. The solid lines show the model resulting from the Ðt to the elliptically averaged (Ðxed-ellipse) proÐle in I (see Table 10). 80 22

MB 1 20 Maffei 2

24 '! 'r~ .. 0 22 0 .... w w SE w w 0 0 ...., " " - " "Oil "' 24 26 .. . " "s .. . .. 1 1: ~· 26

28 NE 511

-400 -200 0 200 400 600 r(arcseconds) -150 -100 -50 0 50 100 150 r(arcseconds) FIG. 30.ÈUnfolded major axis (/ \ 23¡) and minor axis (/ \ 113¡) FIG. 31.ÈUnfolded major axis (/ \ 107¡) and minor axis (/ \ 17¡) I-band surface brightness proÐles of Ma†ei 2. The solid lines are based on I-band surface brightness proÐles of MB 1. The solid lines show the model the combined spheroid/disk model given in Table 11. Di†erent sections are given in Table 12. Di†erent sections are labeled as in Fig. 25. The minor labeled as in Fig. 25. axis proÐle has been shifted by ]2.0 mag for clarity.

20

22

0 ' w "0 24 " "Oil "a 1: 26

NW SE

28

-400 -200 0 200 400 r(arcseconds)

FIG. 32.ÈUnfolded major axis (/ \ 21¡) and minor axis (/ \ 111¡) I-band surface brightness proÐles of NGC 1560. The solid lines show the various Ðts given in Table 12. Di†erent sections are labeled as in Fig. 25.

NGC 1569 NGC 1569 18 18 .... Major Axis !/>=119° Minor Axis !/>=29° \, ""'I. 20 20 ..--. ··~ .r I u . I u Ql Ql Ill Ill u u I-< I-< OS OS bl] 22 blJ 22 OS OS 8 8 ~ ~

24 24

26 26 'I<

4 1.5 1/f 2 2.5 1/f 3 r (arcseconds )

FIG. 33.ÈFolded major and minor axis I-band surface brightness proÐles of NGC 1569. The solid lines show the model given in Table 10. 81 82 BUTA & MCCALL Vol. 124

important are the residuals with respect to the o†set (which 22 is marked with a solid horizontal line in each panel of Fig. 37a). Along the major axis, the proÐle shapes agree to within 0.04 mag all the way from the center to the limiting

24 radius at which SPHOT was able to Ðt ellipses (about 550A). Along the minor axis the agreement is comparable, except at radii within 20A of the nucleus, where KentÏs surface brightnesses are systematically fainter than ours. Given that the major axis proÐles agree so well, the discrepancy along the minor axis may be associated with di†erences in derived axis ratios. Note that our V -band image of M81 su†ered 28 from a slight focus error (as did the calibration for its night), •""'" and this may contribute to some disagreement at small -300 -200 -100 o 100 200 300 r(arcseconds) radii. Isophotes beyond a radius of 500A are largely outside the IG \ \ F . 34.ÈUnfolded major axis (/ 27¡) and minor axis (/ 117¡) spiral structure and have a similar shape and orientation. I-band surface brightness proÐles of UGCA 86. The solid lines show the model given in Table 12. Di†erent sections are labeled as in Fig. 25. The Thus, it is possible to extend our comparison with KentÏs minor axis proÐle has been shifted by ]2.0 mag for clarity. data to 800A by making use of the V and I proÐles we derived by Ðtting Ðxed ellipses. The comparison is shown in 22 Figure 37b. In the Ðgure, the average of our V and I proÐles along the major axis (crosses) is superimposed upon KentÏs UGCA 92 r-band proÐle corrected for the 0.47 mag o†set arising from the di†erence in photometric systems (solid curve). Between ,~ 24 500A and 800A, the slopes of the proÐles agree extremely E " ... " well. Di†erences in shape inside 500A are due to the di†er- ""' ,;,.,/' "'.,..,.'"""· " ence in Ðtting technique (Ðxed vs. free ellipses). ".,'" . , .,Oil 26 ~,,,: ANALYSIS AND DISCUSSION OF KNOWN s ... ~ 7. N . 1: .. .. AND SUSPECTED MEMBERS OF THE , , . • 11,.. IC 342/MAFFEI GROUP 28 7.1. Camelopardalis A I. Karachentsev noticed this object in 1991 while search- -150 -100 -50 o 50 100 150 r(arcseconds) ing for nearby galaxy candidates on the Palomar Sky Survey (Karachentsev 1994). We did not take any images of FIG. 35.ÈUnfolded major axis (/ \ 74¡) and minor axis (/ \ 164¡) it, because we were unaware of its existence at the time of I-band surface brightness proÐles of UGCA 92. The solid lines show the our observations. Cam A appears as a barely perceptible model given in Table 12. Di†erent sections are labeled as in Fig. 25. The minor axis proÐle has been shifted by ]2.0 mag for clarity. smudge on the POSS II near NGC 1560. CCD images taken by Karachentseva et al. (1996) at LÏObservatoire de Haute-Provence show bright knots near the center. Also, the galaxy appears partly resolved on photographs taken 22 with the Russian 6 m (Karachentseva et al. 1996). Using their CCD images, Karachentseva et al. (1996) per- formed surface photometry, Ðnding an exponential proÐle '1 24 with no color gradient. The total B[V color was measured "~ .."'" to be 0.83, implying that the intrinsic color is 0.66 after .. correction for foreground reddening (Burstein & Heiles _g.. 26 ~ 1978; see also the NASA Extragalactic Database). The :l: intrinsic color is typical of dwarf spheroidals, but might also be indicative of a dwarf irregular which has stopped 28 forming stars. Certainly, the color is much redder than would be expected for a typical reÑection nebula in the -300 -200 -100 o 100 200 300 Milky Way. No 21 cm emission has been detected between r(arcseconds) [600 km s~1 and 1600 km s~1 down to an rms level of 2.1 FIG. 36.ÈUnfolded major axis (/ \ 179¡) and minor axis (/ \ 89¡) mJy, although it is possible that it is confused with a high- I-band surface brightness proÐles of UGCA 105. The solid lines show the velocity cloud at [132 km s~1 (Karachentseva et al. 1996). model given in Table 12. Di†erent sections are labeled as in Fig. 25. The Cam A was classiÐed as ““ dSph/dIr ÏÏ by Karachentseva et minor axis proÐle has been shifted by ]2.0 mag for clarity. al. (1996), but Karachentseva & Karachentsev (1998) updated this to ““ Sph? ÏÏ. On average, the absolute levels of KentÏs major and Cam A has all the markings of a real disk galaxy, prob- minor axis proÐles are 0.47 mag and 0.46 mag fainter, ably gas deÐcient, although probably not a pure dwarf respectively, than ours. The o†sets, which are identical spheroidal. Despite the lack of a velocity, its location on the within errors, simply reÑect the fact that the average of V sky and its apparent proximity suggest that it is a likely and I is an inexact approximation to r. What are more member of the IC 342/Ma†ei Group. No. 1, 1999 IC 342/MAFFEI GROUP REVEALED 83

TABLE 11 PARAMETERS FROM PHOTOMETRIC DECOMPOSITION OF SEVERAL GROUP MEMBERS

sph sph disk disk ke ae ke ae Object Filter (mag arcsec~2) (arcsec) qsph (mag arcsec~2) (arcsec) qdisk (1) (2) (3) (4) (5) (6) (7) (8)

Dwingeloo 1 ...... I 25.61: 63.4: 1.00: 24.96: 299.7: 0.70 IC342...... B 23.31 25.3 0.87 25.05 351.2 0.87 IC342...... V 22.53 32.2 0.87 23.79 327.2 0.87 IC342...... I 21.46 54.6 0.87 22.11 318.6 0.87 Maffei 2 ...... I 23.64 78.7 0.85 22.56 188.5 0.42

NOTES.ÈCol. (1): Name of galaxy. Col. (2): Name of Ðlter. Col. (3): Surface brightness of the e†ective isophote of the spheroid, i.e., the isophote of the spheroid encompassing half of the total light of the r1@4 law, in mag arcsec~2. Col. (4): Length of the semimajor axis of the e†ective isophote of the spheroid, in arcseconds. Col. (5): Axis ratio of the spheroid (minor relative to major). Col. (6): Surface brightness of the e†ective isophote of the disk, i.e., the isophote of the disk encompassing half of the total light of the exponential law, in mag arcsec~2. Col. (7): Length of the semimajor axis of the e†ective isophote of the disk, in arcseconds. Col. (8): Axis ratio of the disk (minor relative to major).

7.2. Camelopardalis B beyond the Local Group. However, by measuring the spec- II This object was noted Ðrst as a faint smudge on the POSS trum of an H region in the galaxy, Weinberger & Saurer II, and then proved to be a nearby dwarf irregular galaxy in (1998) revealed that Cas 1 is signiÐcantly less extinguished the IC 342/Ma†ei Group via 21 cm observations than suspected by both Tikhonov (1996) and Karachentsev (Huchtmeier, Karachentsev, & Karachentseva 1997). We et al. (1997) and that it is most likely a dwarf member of the did not take images of it because it had not yet been dis- IC 342/Ma†ei Group. covered at the time of our 1995 observing run. Besides the Our images (Fig. 6) reveal a broad barlike zone and an H I properties, little is known about it. asymmetric appearance similar to the Small Magellanic Cloud. A map of the V [I color index (not shown) reveals 7.3. Cassiopeia 1 that the barlike zone has bluer colors than the surrounding This object was noticed Ðrst by Blitz, Fich, & Stark disk, indicating concentrated star formation in that region. (1982), who suspected it to be an H II region. It was redis- The elliptically averaged surface brightness proÐles (Fig. covered by Weinberger (1995), who argued instead that it 24a) are Ñat inside r \ 50@@, and decline exponentially was a highly reddened dwarf irregular galaxy. Via 21 cm beyond this radius in both V and I. The color proÐle dis- observations, Huchtmeier et al. (1995) conÐrmed that it was plays the di†erence between the inner and outer regions. In a galaxy, revealing it to have a radial velocity consistent both V and I, total magnitudes were obtained by extrapo- with membership in the IC 342/Ma†ei Group. They assign- lating to inÐnity an exponential Ðtted to the zone between ed the name Cassiopeia 1. After analyzing a color- 90A and 162A. magnitude diagram of the brightest stars, Tikhonov (1996) Major and minor axis proÐles are shown in Figure 25. suggested that the galaxy is in fact a member of the Local The solid lines which are superimposed were derived from Group. On the other hand, similar work by Karachentsev et the exponential Ðt to the outer parts of the elliptically aver- al. (1997), but with di†erent data, pointed to a distance aged proÐle (which was derived using an axis ratio of

TABLE 12 PARAMETERS FROM EXPONENTIAL DISK FITS

Radius Range ke ae or be p(Ðt) Object Filter ProÐle (arcsec) (mag arcsec~2) (arcsec) (mag arcsec~2) (1) (2) (3) (4) (5) (6) (7)

Cassiopeia 1 ...... V Fixed-ellipse Ðt 90È162 24.79 53.9 0.089 Cassiopeia 1 ...... I Fixed-ellipse Ðt 90È162 22.81 56.8 0.060 Dwingeloo 2 ...... I Fixed-ellipse Ðt 50È118 23.79 49.2 0.111 MB1...... I Fixed-ellipse Ðt 0È160 24.28 81.3 0.072 MB2...... I Fixed-ellipse Ðt 46È62 20.20 13.2 0.073 MB3...... I Fixed-ellipse Ðt 0È46 24.43 51.3 0.068 MB3...... I Fixed-ellipse Ðt 50È78 23.34 30.6 0.079 NGC 1560 ...... I Mean minor axis 8È80 21.92 30.5 0.038 NGC 1560 ...... I Mean major axis 375È450 15.59 65.7 0.116 NGC 1560 ...... I NE major axis 100È300 22.56 185.8 0.064 UGCA 86...... I Fixed-ellipse Ðt 6È290 23.64 139.1 0.040 UGCA 92...... I Fixed-ellipse Ðt 38È102 24.11 85.0 0.017 UGCA 105 ...... I Fixed-ellipse Ðt 186È294 22.60 113.7 0.026

NOTES.ÈCol. (1): Name of galaxy. Col. (2): Name of Ðlter. Col. (3): Origin of surface brightnesses. Col. (4): Range of radius over which exponential law was Ðtted, in arcseconds. Col. (5): Surface brightness of the e†ective isophote of the disk, i.e., the isophote of the disk encompassing half of the total light of the exponential, in mag arcsec~2. Col. (6): Length of the semimajor axis (all galaxies) or semiminor axis (““ mean minor axis ÏÏ of NGC 1560) of the e†ective isophote, in arcseconds. Col. (7): Standard deviation of surface brightnesses about the Ðtted proÐle, in mag arcsec~2. 84 BUTA & MCCALL Vol. 124

TABLE 13 the astronomical community as a result of the earlier STANDARD ISOPHOTAL AND EFFECTIVE PARAMETERS FOR announcement by Kraan-Korteweg et al. (1994). It appears THREE GALAXIES to be the fourth brightest member of the IC 342/Ma†ei Group, although it is substantially less luminous then the Parameter IC 342 Maffei 1 Maffei 2 three brightest galaxies. log D (B)(0.1)@ ...... 2.19: 1.00 0.26 Dwingeloo 1 has been the subject of a detailed photo- 25 I log R25(B) ...... 0.02: 0.11 0.12 metric investigation by Loan et al. (1996), and the H has /25(B) (1950) (deg) ...... 44: 96 67 been mapped by Burton et al. (1996). CO observations have log Ae(B)(0.1)...... @ 2.052 1.870 1.646 been reported by Kuno,Vila-Vilaro , & Nishiyama (1996), log Ae(V )([email protected])...... 2.031 1.816 1.636 Li et al. (1996), and Tilanus & Burton (1997). log Ae(I)([email protected]) ...... 2.011 1.786 1.616 Kraan-Korteweg et al. (1994) suggested that Dwingeloo 1 log De(B)(0.1)...... @ 2.084 1.932 1.823 is a barred spiral, possibly of Hubble type SBb. On the basis log D (V )([email protected])...... 2.062 1.880 1.808 e of our images (Fig. 7), we suggest a type of SB(s)cd. Its type log De(I)([email protected]) ...... 2.042 1.850 1.782 [ and luminosity make it comparable to M33. The galaxy has (B V )e ...... 1.13 2.42 2.41 [ two bright inner arms within an extended disk, but only a (V I)e ...... 1.68 3.12 3.17 small core region. In a V [I color index map (not shown), NOTES.ÈThe standard isophote has a surface brightness in B ~2 the inner arms are notably blue compared to the disk light. of 25 mag arcsec .D25, the isophotal diameter, is the length of the major axis of the standard isophote, in tenths of arcminutes. Orientation parameters derived from Ðts of free ellipses R , the axis ratio, is the ratio of the length of the major axis are consistent with kinematic values stemming from a Ðt to 25 I relative to the minor axis for the standard isophote./25 is the the velocity Ðeld deÐned by H (see Table 6). Figure 24b position angle of the major axis of the standard isophote, mea- shows the elliptically averaged proÐles in V , I, and V [I. sured eastward from north, for epoch 1950.Ae(Ðlter), the e†ec- Our proÐle in I agrees well with that published by Loan et tive aperture, is the diameter of the circular aperture encompassing half of the total light of the galaxy in the speciÐed al. (1996), but our V -band proÐle becomes systematically Ðlter, in tenths of arcminutes.De(Ðlter), the e†ective diameter, is brighter than theirs with increasing radius. This partly the length of the major axis of the isophote encompassing half of explains why our total magnitude in V is so much brighter the total light of the galaxy in the speciÐed Ðlter, in tenths of [ [ than their estimate (see Table 14). Loan et al. also found arcminutes.(B V )e and(V I)e, the e†ective colors, are the [ [ integrated B[V and V [I colors, respectively, within A (B). that both V R and V I declined steeply with radius, but e our V [I proÐle is relatively Ñat. There is a drop in the color index connected with the spiral arms, and a slight 0.760Èsee Table 5). Along both axes, they describe the increase in the outer disk. The bar region appears to be slope of the light distribution outside of the core reasonably slightly bluer than its immediate surroundings. Phillipps & well. Davies (1997) have shown using surface brightness argu- ments that the photometry of Loan et al. (1996) leads to an 7.4. Dwingeloo 1 unrealistically high estimate of the foreground extinction In 1994, interest in the region of the Ma†ei galaxies toward the galaxy. received fresh impetus with the discovery of Dwingeloo 1 at From the I-band image, it is clear that the spheroid is 21 cm (Kraan-Korteweg et al. 1994; Huchtmeier et al. very small in Dwingeloo 1. The positioning of a bright fore- 1995). Note that Huchtmeier et al. (1995) called this object ground star near the center gives the false impression of a Cassiopeia 2, but the name Dwingeloo 1 was adopted by larger spheroid. The surface brightness proÐle along the

TABLE 14 COMPARISON OF TOTAL MAGNITUDES

Our Published Object Filter Magnitude Magnitude Published [ Ours Reference

Cas1...... V 13.97 14.62 0.65 1 Cas1...... V 13.97 14.71 0.74 2 Cas1...... I 11.98 12.62 0.64 2 Dwingeloo 1 ...... V 13.08 14.0 ^ 0.5 0.92 3 Dwingeloo 1 ...... I 10.33 10.7 ^ 0.2 0.37 3 IC342...... B 9.37 9.10 [0.27 4 NGC 1560 ...... V 11.27 11.44 0.17 5 NGC 1560 ...... I 10.26 10.70 0.44 6 NGC 1569 ...... V 11.06 11.03 [0.03 5 NGC 1569 ...... I 9.84 9.98 0.14 6 UGCA 92...... V 14.20 13.88 [0.32 7 UGCA 92...... V 14.20 15.42 1.22 2 UGCA 92...... V 14.20 14.89 0.69 2 UGCA 92...... I 12.62 13.84 1.22 2 UGCA 105 ...... I 10.41 11.18 0.77 6 M81...... V 6.92 6.94 0.02 5 M81...... I 5.65 5.70 0.05 8

REFERENCES.È(1) Tikhonov 1996; (2) Karachentsev et al. 1997; (3) Loan et al. 1996; (4) Ables 1972; (5) de Vaucouleurs et al. 1991; (6) Krismer et al. 1995; (7) Karachentseva et al. 1996; (8) Pierce & Tully 1992. No. 1, 1999 IC 342/MAFFEI GROUP REVEALED 85

1

.8 16 M81 - µ,.(Kent)-0.47 .6 x <µ> (Ours) ,...... _ ~ .4 ,...... _ 18 ;:1 .. I 0 CJ '-' QJ I\ .2 Vl ::t CJ V 0 ""'al 20 I tl(J ,...... _ al ~ .8 8 Q) "-" ::,::: ::t 1 ·6 22 .4

.2 24 (b)

100 200 300 400 500 0 200 400 600 800 r( arcseconds) r( arcseconds)

FIG. 37.È(a) Comparison between major and minor axis proÐles of M81 derived by Kent (1987) and by us by Ðtting free ellipses, with the di†erence in surface brightness plotted as a function of radius. KentÏs proÐles are for the Thuan-Gunn r band, while ours are the average of V and I. The horizontal line in each panel shows the o†set due to the Ðlter mismatch. There is good agreement between the shapes of the proÐles. (b) Comparison between the major axis proÐle of M81 derived by Kent (1987) by Ðtting free ellipses and by us by Ðtting Ðxed ellipses. Surface brightnesses are plotted as a function of radius. Our proÐle is the mean of V and I. KentÏs r-band proÐle has been corrected for the zero-point o†set by subtracting 0.47 mag. The graph displays the good agreement in the shape of the proÐles beyond 500A radius. Disagreements for radii less than 500A are due to the di†erence in the Ðtting procedure. major axis, which is nearly parallel to the bar, is illustrated the uncleaned image, there is a hint of elongation from in Figure 26. It decays exponentially in the bar region, southwest to northeast; this was also seen in a K-band consistent with a late-type barred spiral (Elmegreen & image published by Burton et al. (1996). Elmegreen 1985). Unfortunately, two bright stars overlap the galaxy, so the We attempted a decomposition of the spheroid and disk morphology is difficult to assess and surface photometry is components of Dwingeloo 1 using the northeast half of the complicated. In our images, the brighter of the two overlap- minor axis. This is the near side of the minor axis according ping stars was saturated in both V and I. To remove it, we to Burton et al. (1996). The far side of the minor axis could Ðrst identiÐed across the whole image several stars of not be used because it is a†ected by the bright foreground similar brightness. Then we computed a psf from the star near the center and it was not possible to remove that sample. To cover all of the detected light, it was necessary to star very accurately. The Ðt was restricted to r ¹ 58@@ and use a psf radius of 16 pixels, twice what was used in normal 160@@ ¹ r ¹ 280@@. Weights were set according to the sta- runs of KILLALL. Then, the DAOPHOT task SUBSTAR tistical error of each point. Solutions for the free parameters was applied to remove the star superimposed upon are summarized in Table 11, and the Ðt is shown as a solid Dwingeloo 2. The right panel in Figure 8 shows the Ðnal curve in Figure 26. The solid curve superimposed on the result. Although the wings of the bright star were fairly well major axis proÐle is the Ðt to the minor axis proÐle cor- removed by SUBSTAR, the obvious hump on the northern rected for foreshortening (using the axis ratios given in side of the galaxy may be partly an artifact. Any nucleus Table 11). The model describes the surface brightness of the would not have been recovered. On the basis of the cleaned disk at intermediate radii fairly well, but appears to over- image, we suggest that Dwingeloo 2 is a Magellanic dwarf estimate the surface brightness at large radii. The enhance- of type Im. ment of the major axis proÐle over the bulge model is due to Orientation parameters derived from Ðts of free ellipses the bar. Based upon the Ðt, the spheroid contributes 7% of are compared with kinematic values in Table 6. Burton et the total light in I. According to Simien & de Vaucouleurs al. (1996) found a kinematic position angle decreasing from (1986), this is consistent with a type of Scd if the spheroid is 117¡ at0.3@ to 91¡ at 2.3,@ as compared with 72¡ from our less prominent in B. images. The position angle of the H I distribution is in better agreement with the I-band position angle, as shown by 7.5. Dwingeloo 2 Figure 8 of Burton et al. (1996). The o†set of the center of This galaxy was discovered at Westerbork while mapping the H I distribution from the photometric center has been Dwingeloo 1 at 21 cm (Verheijen, Burton, & Kraan- discussed by McCall & Buta (1997). We note that our axis Korteweg 1995; Burton et al. 1996). It is likely that it is a ratio for Dwingeloo 2 may be a†ected somewhat by incom- physical companion of Dwingeloo 1 because of its similar plete removal of the brightest superimposed foreground star. radial velocity and close proximity (only 21@ to the west- Because the removal of the superimposed bright stars northwest). Our I-band images are shown in Figure 8. In was imperfect, the elliptically averaged proÐles (Fig. 24c) are 86 BUTA & MCCALL Vol. 124 uncertain. At least the V and I proÐles are similar in shape. and M101. Newton (1980a) suggested that an active ellip- Within the uncertainties, the integrated color is similar to tical galaxy, UGC 2826, might be the perturber, but a those of Dwingeloo 1 and MB 3, which su†er a comparable recently measured radial velocity (Strauss et al. 1992) rules level of reddening. As usual, the total magnitude in I given this out. in Table 5 was derived via integral photometry, with Our analysis of the total magnitudes and colors of IC 342 extrapolation accomplished using an exponential Ðt to the was based upon the photometric orientation parameters, region from 50A to 118A (see Table 12). However, because since these necessarily deÐne the light distribution. Inter- \ the V -band proÐle is noisy, the total V magnitude was estingly, a Ðt of an ellipse to the standard isophote (kB obtained by forcing the slope in the radius range 50A to 118A 25.00 mag arcsec~2, semimajor axis 8@) gives a photometric to be the same as in I, and then solving for the zero point. position angle of 44¡ and an inclination closer to 20¡. The major and minor axis proÐles in I are shown in Although the position angle agrees better with the kine- Figure 27. Displayed solid lines are derived from the expo- matic line of nodes, the standard isophote is strongly nential Ðt to the elliptically averaged proÐle. Although the a†ected by spiral structure. Note that the distribution of H I signal-to-noise ratio in the proÐles is very low, the Ðt is symmetrical within 20@ (Newton 1980a). describes the surface brightness distribution at the periph- The elliptically averaged proÐles are shown in Figure 24d. ery of the galaxy reasonably well. The bright spiral structure causes large, broad humps in the BV I proÐles at radii from 200A to 750A. Extrapolations used 7.6. IC 342 to derive total magnitudes were based upon exponential Ðts Interest in IC 342 has been motivated primarily because to the data beyond 755A. of its status as a nearby, large, late-type spiral with a low Figure 28 shows the major and minor axis proÐles. There inclination. This fact stimulated early e†orts at surface pho- is so much structure and asymmetry that these are simply tometry (Ables 1972) and interferometric mapping (Newton too complicated to use to decompose the galaxy into its 1980a, 1980b). It also led McCall, Rybski, & Shields (1985) spheroid and disk components. Instead, we have used the to include the galaxy in a spectroscopic survey of giant elliptically averaged proÐles for this purpose. This is feasible extragalactic H II regions, which ended up triggering a great because the galaxy is nearly face-on. The Ðts were made to deal of research into the IC 342/Ma†ei Group, including each Ðlter independently. In I, they were conÐned to the that leading to this paper. The galaxy has attracted the radius ranges 14@@ ¹ a ¹ 195@@ and 755@@ ¹ a ¹ 995@@.InB attention of microwave astronomers because its nucleus dis- and V , the same inner zone was Ðtted. However, the outer plays strong molecular emission (e.g., Henkel, Mauersber- zone was limited to 755@@ ¹ a ¹ 955@@ in B and to ger, & Schilke 1988; Irwin & Avery 1992), much of which 755@@ ¹ a ¹ 965@@ in V . The restriction to a º 14@@ was neces- appears to be concentrated in a small ring of molecular sary to avoid the blue nucleus. The results of the nonlinear hydrogen which is vigorously forming stars (BoŽ ker, FoŽ rster- least squares Ðts, which gave equal weight to all points in Schreiber, & Genzel 1997; Lo et al. 1984; Becklin et al. the above ranges, are listed in Table 11. The Ðt for the 1980). The ring is suspected to be a manifestation of the I-band is depicted by the solid curves in Figure 28. The Inner Lindblad Resonance(BoŽ ker et al. 1997). curve for the minor axis was computed by assuming axis Our I-band images of IC 342 are shown in Figure 9. The ratios of 0.87 for both the spheroid and the disk. cleaned image does a good job of illustrating the large-scale In I, the Ðt to the elliptically average proÐle provides a structure of the galaxy. A deeper negative print of the good representation of the lower envelope of the surface cleaned I-band image (Fig. 10, left) reveals unusually shaped brightness proÐles along the major and minor axes. The outer isophotes and a possible faint extension to the spheroid contributes 3.4% of the total light in B, consistent southwest of center. A large wedge-shaped reÑection nebula with the mean for Scd galaxies (Simien & de Vaucouleurs can be seen to the east of IC 342, giving the impression that 1986). the galaxy is viewed through a window in the dust distribu- The right panel of Figure 10 shows a V [I color index tion. The foreground material prevented us from doing map of the inner disk of IC 342. In this map, bluer features surface photometry to radii beyond 1000A. are dark while redder features are light. The map shows that Rots (1979) and Newton (1980a) discovered a large-scale the spiral arms are bluer than the interarm regions. A beau- asymmetry, too, in the distribution of H I. To the east of the tiful pattern of spiral dust lanes can be seen in the inner center, there is a steep gradient in H I, whereas to the north- regions. There is a sharp drop in the color index within a west there is an extension of low surface brightness visible radius of 10A, which is especially apparent in the elliptically out to 43@ from the nucleus. Also, the velocity Ðeld shows averaged V [I proÐle in Figure 24d. This is the site of the evidence for a warp (Newton 1980a). starburst. Orientation parameters from free ellipse Ðts are com- pared with kinematic values in Table 6. The photometric major axis at large radii is at a position angle of 87¡, grossly 7.7. Ma†ei 1 discrepant with the kinematic line of nodes, which is at 39¡. As stated earlier, this is a giant elliptical galaxy which is The major axis of the distribution of H I is closer to the certainly one of the most luminous galaxies in the IC 342/ photometric major axis, though, being at a position angle of Ma†ei Group, and which may well be the most massive. 115¡ (Rots 1979; Newton 1980a). In I and at 21 cm, the Indirect conÐrmation of the morphology comes from the outer isophotes are not centered on the nucleus. Thus, the recent ASCA discovery of an extended distribution of hard distributions of both stars and gas are distorted, indicating X-ray emission centered on the nucleus, which points to the that IC 342 has been subjected to an interaction. existence of a widespread population of X-ray binaries Rots (1979) suggested that UGCA 86, located only 94@ to (Reynolds et al. 1997). the southeast, is tidally interacting with IC 342. In particu- Our images of Ma†ei 1 are displayed in Figure 11, Figure lar, he noted similarities to the conÐguration of NGC 5474 12, and the top two panels of Figure 14. They reveal, on one No. 1, 1999 IC 342/MAFFEI GROUP REVEALED 87 \ hand, the large angular extent of Ma†ei 1 at 0.8 km, and, on tion must beAB 6.4 mag. Thus,AV + 5.0 mag, which is the other hand, the presence of dust in the inner regions. consistent with Spinrad et al. (1971) and Buta & McCall Figure 14 dramatically illustrates the e†ects of Galactic (1983). A comprehensive discussion of the extinction of extinction on the apparent size of the galaxy by showing B- Ma†ei 1 and the other galaxies in the IC 342/Ma†ei Group and I-band images side by side. In the B-band image, Ma†ei will be presented in a separate paper. 1 appears 1@ to 2@ across, whereas in the I-band image, the galaxy can be traced to a diameter of about 23@, exceeding 7.8. Ma†ei 2 by about 50% the size estimated by Buta & McCall (1983) As noted by Spinrad et al. (1973), Ma†ei 2 may be more from aperture photometry. The type appears to be E3. extinguished than Ma†ei 1 by about a magnitude in V . Comparison of Figure 14 with Figure 11 suggests the Thus, its morphology has been difficult to study at optical presence of isophotal twisting, although we caution that we wavelengths. Hurt et al. (1993a) presented an image of do not know how much of this twisting is real or due to Ma†ei 2 at 2.2 km(K) that revealed a clear bar and spiral problems with glowing foreground material. The isophotes arms, but it was not deep enough to reveal accurately the not only twist from the inner to the outer regions, but true extent of the galaxy. The image suggested that Ma†ei 2 become increasingly miscentered to the northeast, the has an intrinsic asymmetry. Similar asymmetries also general direction of foreground complexes. appear in the radio continuum and at 21 cm (Hurt, Turner, Comparison of the cleaned image with the uncleaned & Ho 1996). These Ðndings were conÐrmed by the excellent image in Figure 11 reveals a large patch of dust due north of image of Ma†ei 2 obtained in the 2 Micron All-Sky Survey the nucleus. Closer to the center is a narrow dust lane that (Huchra et al. 1994). Hurt et al. (1993a) and Hurt et al. was Ðrst noted by Ford & Jenner (1971). This feature also is (1996) attribute the asymmetry to be a consequence of a visible on the second Palomar Sky Survey. To illustrate the disturbance by a small companion close to the northwest dust better, a model based on Ðts of free ellipses to the end of the bar. cleaned image (see ° 6.2) was subtracted from both the Soon after its discovery, Ma†ei 2 was recognized to have cleaned and uncleaned images. The di†erence images are warm and dense molecular gas in its central regions shown in Figure 12. Although we are uncertain about the (Rickard, Turner, & Palmer 1977) and was subjected to location (Galactic or extragalactic) of the dust, the complex many microwave studies. Aperture synthesis observations structure apparent in the di†erence images suggests that of CO by Ishiguro et al. (1989) revealed a small bar of Ma†ei 1 is a dust-lane elliptical. This would not be unusual, molecular gas and a ringlike feature centered on the nucleus because some 40% of ellipticals are of this type (Sadler & (see also Hurt et al. 1993b). The nucleus appears to have Gerhard 1985; Goudfrooij 1995). undergone a starburst, perhaps fed by the bar, which has led The elliptically averaged proÐles in Figure 24e show to an outÑow of molecular gas akin to that in NGC 1068 clearly that Ma†ei 1 follows a de Vaucouleurs r1@4 law over (Ishiguro et al. 1989). The large-scale distribution of H I in most of its extent. Formal Ðts of the law were made inde- Ma†ei 2 has been mapped by Hurt et al. (1996), who pendently to the proÐles in B, V , and I. These are shown as detected emission across 15@. solid lines in Figure 24e.InI, the r1@4 law matches the Our new I-band images of Ma†ei 2 are shown in Figures observations over a range of 7 mag from 14A to at least 730A. 13 and 14. The cleaned image reveals a spectacular spiral of Thus, there is no question about the identiÐcation of Ma†ei Hubble type Sbc. The bar is weak at 0.8 km, so we favor the 1 as a pure elliptical galaxy. At radii less than 14A, the classiÐcation SABbc. Although Ma†ei 2 appears asym- elliptically averaged proÐles show excess light relative to the metric in Figure 13, the deep image displayed in the lower r1@4 Ðt. The excess seems to decrease from I to B. Table 10 right panel of Figure 14 shows that it becomes more sym- lists the results for the free parameters. Derived e†ective metric at very low light levels. The faintest isophote seen in radii range from 214A in I to 241A in B. The result in I is this image is about 17@ in angular diameter, the greatest 35% larger than the value of 157A derived by Luppino & optical extent ever noted for the galaxy. The lower left panel Tonry (1993) from a Ðt to a K@-band proÐle extending out to of Figure 14 shows our B-band image of Ma†ei 2, dramat- about 90A. ically illustrating the e†ects of Galactic extinction on its The Ðt to the I band is compared with the folded major apparent angular size. and minor axis proÐles in Figure 29. The solid line superim- Hurt et al. (1993a) detected a fuzzy feature 3@ to the north- posed upon the minor axis proÐle was derived assuming an east of Ma†ei 2. They concluded that it was a small com- axis ratio of 0.729 (Table 5). The Ðt describes the major and panion, and suggested that it might be responsible for the minor axis proÐles quite well. The departures in the inner asymmetry. Our deep image reveals that the feature noted region, especially along the minor axis, reÑect a somewhat by Hurt et al. is most likely part of a spiral arm. There is greater ellipticity than average (see Fig. 23e, as well as Fig. 4 even a counterpart on the opposite side (motivating the of Luppino & Tonry 1993). classiÐcation of the variety as rs).- Also listed in Table 10 are the mean e†ective surface The orientation parameters from free ellipse Ðts are con- brightness and radius of Ma†ei 1 in V and I derived from sistent with kinematic values (see Table 6). The elliptically Ðts to the free-ellipse proÐles given in Table 9. Even though averaged proÐles which follow from these parameters are the center, axis ratio, and position angle were allowed to shown in Figure 24f.InV [I, there is a color gradient vary with radius, the e†ective parameters are very similar to where the spheroid predominates. The gradient is less those derived from the elliptically averaged proÐles. evident in the fairly noisy B[V proÐle. In all three Ðlters, The e†ective surface brightness of Ma†ei 1 in B can be the average surface brightness declines exponentially with a compared with a mean value for ellipticals computed by roughly uniform color beyond a radius of 50A. Since Ma†ei Simien & de Vaucouleurs (1986). For an average unob- 2 is a late-type spiral, the integrated V [I color index of \ ~2 scured E3 galaxy, SkeT 22.0 mag arcsec in B. If Ma†ei 3.12 suggests that it is reddened more than any other galaxy 1 has the same intrinsic surface brightness, then the extinc- in our sample. 88 BUTA & MCCALL Vol. 124

Because of the large tilt, it was not possible to use the of low surface brightness. However, despite a sensitive elliptically averaged proÐles to decompose the spheroid and search, no H I emission has been detected (McCall, Buta, & disk components. Instead, we used the proÐle along the Huchtmeier 1995; Huchtmeier & van Driel 1996), although southeast side of the minor axis for this purpose. As judged confusion with Galactic H I cannot be ruled out. Our new from the dust distribution, this corresponds to the far side of images (Fig. 16) show an object with an unusual morphol- the galaxy (see de Vaucouleurs 1958). Points were weighted ogy, almost ringlike in V . The object could be a one-armed according to the statistical error in the surface brightness. SB(s)m spiral. However, failure to detect the object at 21 cm Also, account was taken of the seeing by using a deconvolu- motivates consideration of the possibility that MB 2 is a tion table for the r1@4 law prepared by M. Capaccioli (see Galactic nebulosity of some sort. Capaccioli & de Vaucouleurs 1983). Solutions for the free The elliptically averaged proÐles (Fig. 24h) are relatively parameters are summarized in Table 11. Note that the e†ec- Ñat out to about 40A, but then fall exponentially with radius. tive radii tabulated refer to the major axis; these were com- It is this behavior which makes MB 2 appear to have a puted from the Ðtted values using the axis ratios given in sharp edge. Parameters describing the exponential decline Table 11 (estimated from the free ellipse ÐtsÈsee Fig. 23f in I are listed in Table 12. In V , a slight rise in surface and Table 5). brightness at a radius of 25A gives the impression of a ring. The model is illustrated by the solid curves in Figure 30. No Ha emission was detected. The Ðt to both sides of the minor axis is excellent. Along the Although the V [I color of MB 2 is very red major axis outside of the spheroid, there are signiÐcant (V [I \ 1.85), it is nevertheless 1.23 mag bluer than Ma†ei deviations about the Ðt, but the overall slope of the disk is 1 and 0.47 mag bluer than MB 2 (see Table 5). The color is reasonably well represented. almost a magnitude redder than that of the reÑection The spheroid contributes 22% of the total light in I (as nebula Object B located only 28@ to the north, which is given in Table 5). This is consistent with a classiÐcation of illuminated by a B3 V star (see ° 8). If MB 2 were a reÑection Sbc, since the contribution is likely to be even less in B nebula, the illuminating star would have to be quite red. At (Simien & de Vaucouleurs 1986). most, the reddening could be as high as that of Ma†ei 1, so E(V [I) \ 1.90 and (V [I)0 [ [0.05 (Buta & McCall 7.9. MB 1 1983; this paper; Laney & Stobie 1993; Taylor, Joner, & This is a small galaxy located 18@ southwest of Ma†ei 1. It Johnson 1989). If the reddening were the same as for Object was Ðrst noted by McCall & Buta (1995), who suggested it B, then E(V [I) \ 1.32 and (V [I)0\0.53 (see ° 8). Yet, for may be a physical companion to Ma†ei 1. It was conÐrmed the nebulosity of Object B, (V [I)0\[0.41. One would to be a galaxy by W. Huchtmeier (see McCall et al. 1995 expect the illuminating star of a reÑection nebula, especially and Huchtmeier & van Driel 1996), having a radial velocity if it is red, to be readily identiÐable in our I-band exposures, consistent with membership in the IC 342/Ma†ei Group. but all stars superimposed on MB 2 are very faint. On the basis of the uncleaned I-band image acquired in There is an IRAS point source at the position of MB 2 1992 (the discovery image), McCall & Buta (1995) suggested (IRAS 02332]5901). If it is actually associated with the a type of SAB(s)d?. However, the cleaned image of 1995 nebulosity, it might be a sign that there is a heavily extin- November 11 (Fig. 15) reveals a galaxy with a morphology guished star, perhaps a young stellar object, heating a sur- closer to IBm, although moonlight makes this image some- rounding cloud of gas and dust (see Yun et al. 1993). In this what less deep than that of 1992 (on the image of 1995 case, the nebulosity might be extended red emission from November 15, a streak of scattered moonlight passed right the photoluminescence of silicon nanoparticles (Witt, through the galaxy). For its size, the galaxy is deÐcient in H I Gordon, & Furton 1998). Unfortunately, the Ðeld is so (McCall et al. 1995; Haynes & Giovanelli 1984), suggesting badly contaminated with foreground stars that one has to that it has been a†ected by its proximity to Ma†ei 1. leave open the possibility that the IRAS source is not Elliptically averaged proÐles (Fig. 24g) were constructed associated (MB 1, which is known to be extragalactic, also from the mean of the images acquired in 1995. They are has an IRAS point source superimposed). We are currently exponential within the uncertainties, and there is little uncertain about the exact nature of MB 2, but we believe change in color with increasing radius. Total magnitudes that there is still the possibility that it is a dwarf galaxy. A were obtained by extrapolating an exponential Ðtted to the deep optical spectrum will be required to advance further. data between 0A and 158A. The parameters of the Ðt in I are listed in Table 12. 7.11. MB 3 The major and minor axis proÐles of MB 1 are shown in This object was identiÐed by McCall & Buta (1997) as a Figure 31. The exponential disk Ðt from Table 12 is marked second likely physical companion of Dwingeloo 1. It is by solid lines. The Ðt is reasonably good on all sides but the located only 9@ to the southwest of the larger galaxy (but it is northwest. not within the Ðeld of Fig. 7). Figure 17 shows our cleaned Though located only 18@ from Ma†ei 1, the total V [I and uncleaned I-band images. The galaxy appears to be a color of MB 1 is 0.76 mag bluer than that of Ma†ei 1, more dwarf spheroidal (dSph) rather than a dwarf elliptical, than might be expected if the object is simply an irregular because the surface brightness does not rise sharply toward galaxy su†ering 5.1 mag of visual extinction (Buta & Wil- the center, as it does for true ellipticals obeying an r1@4 law liams 1995). This suggests that the extinction in the direc- (see Kormendy 1985). However, in the system of Binggeli, tion of Ma†ei 1 may be patchy on rather small scales. Sandage, & Tammann (1985), where no such distinction is made, it would be classiÐed as dE6. 7.10. MB 2 The elliptically averaged proÐles of this small galaxy (Fig. This is the second di†use object found by McCall & Buta 24i) clearly rule it out as a background source. The central (1995). It is located 25@ to the south of Ma†ei 1. On their surface brightness is very low, and the proÐles show a images, the object appeared to be a dwarf irregular galaxy double exponential character, conÐrming its identiÐcation No. 1, 1999 IC 342/MAFFEI GROUP REVEALED 89 as a dwarf spheroidal galaxy (as against a dwarf elliptical) lagher, & Hunter (1994) and Greggio et al. (1998). Neutral and its linkage to Dwingeloo 1. The total magnitude in I is hydrogen has been mapped by Reakes (1980) and Stil & based on an exponential Ðt to the section from 50A to 78A. Israel (1998). Stil & Israel (1998) identiÐed an H I cloud only Parameters of the Ðt to this zone and to the zone from 0A to 8@ to the east, which they suggested might be a companion 46A are given in Table 12. The total magnitude in V was galaxy. However, there is no evidence for any stellar com- obtained by forcing the slope of the few points from 50A to ponent in our images. A high-resolution image of the whole 62A to be the same as in I, and then solving for the zero galaxy in B is displayed by Krismer et al. (1995). point. The color of the galaxy appears to be uniform out to Although active star formation is ongoing in super star 60A. clusters, Greggio et al. (1998) consider NGC 1569 to be a poststarburst galaxy, given that a global burst of star for- 7.12. NGC 1560 mation ended only 5È10 Myr ago. Devost et al. (1997) This is a large dwarf galaxy viewed almost edge-on. An suggest that the current episode of star formation, which excellent CCD image of NGC 1560 in B at high resolution began 2È4 Myr ago, was triggered by the burst. Greggio et is provided by Krismer et al. (1995). The mass distribution al. (1998) argue that the distance must be signiÐcantly less has been studied comprehensively by Broeils (1992), who than 4 Mpc, which would make NGC 1569 the nearest also showed that the H I disk is warped. The stellar content galaxy of its kind. has been examined in detail by Lee & Madore (1993). Our images are shown in Figure 19. The galaxy appears Our images in I are shown in Figure 18. The object is to be amorphous (Sandage & Brucato 1979). In the revised probably a spiral of type Sd or later. Some asymmetry is Hubble system, it would be classiÐed as I0 (de Vaucouleurs seen in the outer regions of the disk. et al. 1991). It is much more regular-looking in our deep The orientation parameters from free ellipse Ðts are con- I-band image than it is in the B-band image provided by sistent with kinematic values (see Table 6). The elliptically Krismer et al. (1995). The bright star to the north of the averaged proÐles which follow (Fig. 24j) show a hump at a center was originally masked for ellipse Ðtting but subse- radius of 350A, and there is little change in average color quently interpolated over in the process of creating the index with increasing radius. The total magnitudes were clean image displayed. The contaminated area is still visible. derived by exponentially extrapolating the sections beyond Figure 24k shows that the V [I color reddens outward r \ 350@@. across the galaxy. This inverse gradient (compared to The major and minor axis proÐles are shown in Figure normal galaxies) is caused by strong star formation in the 32. The major axis proÐle resembles that of the disks inner regions. Total magnitudes were obtained by exponen- studied by van der Kruit & Searle (1982a, 1982b), in that a tially extrapolating Ðts to the elliptically averaged surface clear cuto† is seen between 300A and 400A radius. This brightness proÐles at radii beyond 178A. Even though an region causes the hump to appear in the elliptically aver- r1@4 law seems to Ðt the major and minor axis proÐles over a aged proÐles. The galaxy is slightly asymmetric, because the fairly large range of radius, an exponential was chosen for gradient in surface brightness steepens at around 300A on extrapolation of integral photometry because of evidence the southwest side, and at around 375A on the northeast for a change in slope around 180A, beyond which the r1@4 side. Along the minor axis and on the northeast side of the law overestimates the surface brightness in both V and I major axis from 100A to 300A, the surface brightness declines (see Figs. 24k and 33). exponentially with radius. Folded major and minor axis proÐles in I are displayed in Table 12 summarizes the results of Ðts of exponentials to Figure 33. Along the minor axis, the light distribution obeys the mean minor axis proÐle, the mean major axis proÐle an r1@4 law from 8A to 92A. The solid lines in Figure 33 show beyond 375A, and the intermediate region on the northeast the best Ðt to these points, with the projection onto the side of the major axis. Note that some uncertainty in the major axis accomplished by adopting an axis ratio of 0.503 Ðtted parameters arises because the exact location of the (Table 5). Parameters of the Ðt are summarized in Table 10. center of NGC 1560 is not well deÐned. The solid lines in Note that weights were set by the statistical errors of the Figure 32 show the Ðts. At the extremities of the major axis, measurements. Along the major axis, the model predicts too the lines do not follow the points because they are derived much light within r \ 10@@ and beyond r \ 200@@. The large from the mean of the two halves; the displacements illus- hump along the major axis at intermediate radii is probably trate the asymmetry. Nevertheless, the slope of the Ðt caused by excessive star formation. beyond 375A agrees well with the observed slope. The line drawn between 100A and 300A on the southwest side of the 7.14. UGCA 86 major axis comes from the Ðt to the northeast side; clearly, This dwarf galaxy, shown in Figure 20, has a faint nucleus there is some asymmetry in this zone. The proÐle along the and an unusual detached, cometary component on the minor axis follows an exponential all the way into the mid- south side. On the sky, it is only 94@ southeast of IC 342. It plane, i.e., to values of z much less than the scale height of was discovered independently of Nilson (1974) by Rots the disk (which is 30A). The lack of curvature near the mid- (1979) and by R. B. Tully (1979, private communication to plane suggests that the disk is not isothermal, at least at Rots) during 21 cm surveys of the IC 342 area. The com- small z (van der Kruit & Searle 1982a, 1982b). etary component is also cataloged as VII Zw 009. Rots proved that it was a rotating dwarf irregular galaxy, pos- 7.13. NGC 1569 sibly interacting tidally with IC 342. This galaxy has been the subject of many previous inves- Saha & Hoessel (1991) observed a strongly resolved tigations concerned with starbursts (e.g., Waller 1991; population throughout the cometary component (the clump Heckman et al. 1995; Devost, Roy, & Drissen 1997). The at its ““ head ÏÏ is not resolved in our images). They suggested stellar content has been studied on the ground by Kara- that it could be a separate disturbed galaxy which, judging chentsev et al. (1997) and with HST by OÏConnell, Gal- from a color magnitude diagram, could be a member of the 90 BUTA & MCCALL Vol. 124

Local Group. However, they could not exclude a distance Because the galaxy has no central concentration of light, as high as 3 Mpc. Karachentsev & Tikhonov (1993) sug- the center for constructing the elliptically averaged proÐles gested that the cometary component and the main body are (Fig. 24m) was chosen to be the average of the centers of free parts of the same galaxy, the morphology being much like ellipses Ðtted to the outermost isophotes. Beyond 50A, the what is seen in IC 2574 and NGC 2366 (Sandage 1961). proÐles appear roughly exponential. There is little change in Hodge & Miller (1995) found H II regions between the two color with increasing radius. Total magnitudes were parts, conÐrming the linkage. Based upon photometry of obtained by exponentially extrapolating the part of the the brightest stars, Karachentsev & Tikhonov (1993) and I-band proÐle between 118A and 154A and the part of the Karachentsev et al. (1997) suggested that UGCA 86 is not a V -band proÐle between 118A and 158A. Table 5 lists the member of the Local Group but instead is a companion of average of the total V magnitudes derived from two IC 342. Further work on the luminosity function of the H II separate images created from two successive sequences of regions has been done by Kingsburgh & McCall (1998). six frames. Our cleaned image of UGCA 86, displayed in the right The properties of the disk at intermediate radii were panel of Figure 20, clearly shows that the galaxy is a Magel- derived by Ðtting the points in the elliptically averaged lanic spiral akin to the LMC (with the cometary component proÐle between 38A and 102A. The parameters of the Ðt are being its 30 Dor). Faint Ðlaments near the southwest side of included in Table 12. Adopting an axis ratio of 0.554 (Table the galaxy are likely to be foreground reÑection nebu- 5), the Ðt is compared with the major and minor axis pro- losities, because a larger Ðeld shows a general irregular Ðles in Figure 35. Outside of the central region, the Ðt background. One of these may contribute to the impression describes the light distribution across the galaxy reasonably of a spiral arm. well. The elliptically averaged proÐle (Fig. 24l) is complicated by the unusual structure of the galaxy. The hump at 150A is 7.16. UGCA 105 caused entirely by the cometary star forming region on the This dwarf galaxy shows a small bar and very weak spiral south side. The color proÐle shows a large gradient, but it is structure (see Fig. 22), motivating us to classify UGCA 105 partly caused by inadequate removal of three superimposed as a late-type spiral rather than an irregular. Based upon bright bluish stars from the V -band image of the galaxy. photometry of the brightest stars (Karachentsev et al. 1997), Thus, the magnitude in V must be considered to be more the galaxy appears to be located on the far side of the IC uncertain than average for the other galaxies in our sample 342/Ma†ei Group. The inner 4@ is littered with H II regions (consequently, we have placed a colon next to the magni- (Kingsburgh & McCall 1998). tude and color listed in Table 5). An excellent image in B at higher resolution than ours is On either side of the hump, the elliptically averaged shown by Krismer et al. (1995). Their image displays some proÐle appears to decay exponentially with a single scale features clearly associated with the galaxy which were length. Consequently, we Ðtted an exponential over the removed by our cleaning process. Our image shows that range 6@@ ¹ a ¹ 94@@ and 218@@ ¹ a ¹ 290@@. Parameters of the UGCA 105 nearly Ðlled the entire CCD Ðeld available to Ðt are compiled in Table 12. Adopting a mean axis ratio of Krismer et al. (1995). 0.800 (Table 5), the Ðt has been superimposed upon the In our full images, there is a complex of nebulosity to the major and minor axis proÐles in Figure 34. The Ðt models northeast of UGCA 105. This is likely to be a reÑection the surface brightness proÐles along the major and minor nebula connected with a bright embedded star. The nebu- axes very well. losity is larger and more complex in V than in I. The elliptically averaged proÐles of UGCA 105 (Fig. 24n) 7.15. UGCA 92 are reminiscent of the proÐle of a type II Freeman exponen- Independent of Nilson (1974), Ellis, Grayson, & Bond tial disk. There is only a small change in color index with (1984) noticed this object, shown in Figure 21, during a increasing radius. Total magnitudes were obtained by expo- search for planetary nebulae. Based upon its morphology, nentially extrapolating the parts of the proÐles between they tagged it as a dwarf galaxy candidate. Hoessel, Saha, & 186A and 294A. Danielson (1988) proved that the object was a dwarf irregu- The major axis proÐle shown in Figure 36 reveals a lar galaxy by resolving it into stars. The color-magnitude serious asymmetry: the light distribution has a sharp edge diagram suggested that the distance might be near enough on the south side. The solid lines in Figure 36 are based to justify membership in the Local Group, but signiÐcantly upon the exponential Ðt to the elliptically averaged I-band larger distances could not be excluded. Karachentsev, Tik- proÐle between 186A and 294A. The parameters of the Ðt are honov, & Sazonova (1994) suggested that it forms a physi- listed in Table 12. At large radii, the Ðt models fairly well the cal pair with NGC 1569, which is 74@ away. The most recent slope of the light distribution on the north side of the major photometry of the brightest stars appears to conÐrm mem- axis and on both sides of the minor axis. bership in the IC 342/Ma†ei Group (Karachentsev et al. 8. NEBULOUS OBJECTS NEAR MAFFEI 1 AND OTHER 1997). GROUP MEMBERS The galaxy has no nucleus, but there is a barlike zone just to the south of the center deÐned by the outer isophotes. Ha Van den Bergh (1971) identiÐed three nebulous objects images obtained by Hodge & Miller (1995) and Kingsburgh within 8@ of Ma†ei 1 on a photograph taken with an experi- & McCall (1998) show that H II regions are concentrated mental red-sensitive photographic emulsion (Kodak 098) along the bar. There is a particularly bright one at the east on the Palomar 200 inch telescope. All three of these objects end, from which continuum emission is faintly visible in the are visible in Figure 11. The two nebulous stars 6@ to the left panel of Figure 21. The object was removed by the northeast of the center of Ma†ei 1 correspond to van den cleaning process, so it does not appear in the right panel of BerghÏs objects B and C. Buta, McCall, & Uomoto (1980) the Ðgure. observed the brighter of these two objects (B) and con- No. 1, 1999 IC 342/MAFFEI GROUP REVEALED 91

TABLE 15 PARAMETERS FOR NEBULOUS OBJECTS NEAR MAFFEI 1 AND UGCA 105

Aperture Object R.A. (1950) Decl. (1950) (arcsec) VB[VV[I (1) (2) (3) (4) (5) (6) (7)

van den Bergh A ...... 0233 20.8 ]59 23 22 14 17.95 2.34: 2.89 van den Bergh A ...... 0233 20.8 ]59 23 22 20 17.91 2.45: 2.94 van den Bergh B (star) ...... 0233 26.2 ]59 29 33 14 13.87 0.83 1.09 van den Bergh B (nebula) ...... 0233 26.2 ]59 29 33 85 14.80 0.64 0.91 van den Bergh C (star) ...... 0233 20.8 ]59 30 44 14 16.79 1.13 1.63 van den Bergh C (nebula) ...... 0233 20.8 ]59 30 44 49 16.80 0.95 1.03 Dust patch north of Maffei 1 ...... 0232 51.5 ]59 41 57 63 ] 38 18.02 . . . 3.01 Nebula to northeast of UGCA 105 ...... 0511 24.4 ]62 40 14 300 13.60 . . . 0.73

NOTES.ÈCol. (1): Name of object. Col. (2): Right ascension, epoch 1950, in units of hours, minutes, and seconds. Col. (3): Declination, epoch 1950, in units of degrees, arcminutes, and arcseconds. Col. (4): Diameter of circular aperture encompassing object (within which photometry was done), in arcseconds. Col. (5): Magnitude in V within aperture. Col. (6): B[V color within aperture. Col. (7): V [I color within aperture. cluded that it is a B3 V star surrounded by a blue reÑection mag), which is much brighter than a typical globular cluster. nebula. Application of the Q-method to UBV photometry By way of comparison, the brightest globular cluster in [ of the star indicated that this object is 3 kpc distant, with NGC 5128 only hasMV B 11, assuming that the distance [ \ \ E(B V ) 1.04 mag andAV 3.33 mag. Van den Bergh is 3.9 Mpc (Hesser et al. 1984; Hui et al. 1993; Gilmozzi & suggested that Object C may be of the same nature, but that Panagia 1999). Spectroscopic observations are needed to object A may be a small compact galaxy or globular cluster. clarify the true nature of Object A. We have performed astrometry and photometry on the Further north of Ma†ei 1 is a complex of nebulosities three objects in our images to evaluate these interpretations. prominent in I that seem to be connected with dust. One of Table 15 summarizes the results. The positions are based on the brightest isolated patches in this complex is also listed in bright stars from the Space Telescope Science Institute Table 15. It is bright in I, barely visible in V , and invisible in Guide Star Catalog. The magnitudes and colors of the stars B. It is also prominent as a dust patch in our Ha image of in Objects B and C were determined using a 14A aperture, the Ðeld of Ma†ei 1, as is most of the rest of the complex. with the sky sampled from the surrounding nebulosities The object is extremely red, as red in fact as Ma†ei 1 itself. using an annulus 16A wide around this aperture. Thus, the object cannot be a typical reÑection nebula. Based upon E(B[V ), the reddening-free V [I color Our deep images of UGCA 92 reveal a very interesting index of the star in Object B is [0.23 ^ 0.05 (Laney & extended source 13@ to the northwest of the galaxy. It looks Stobie 1993; Taylor, Joner, & Johnson 1989), conÐrming its like two interacting galaxies, but it is centered on an IRAS identiÐcation as an early-type B star on the main sequence source which has been revealed to be a pair of T Tauri stars (Winkler 1997). The reÑection nebula surrounding the star (Strauss et al. 1992; M. Strauss 1996, private communi- is symmetric and slightly oval with a diameter of about 85A cation; J. Huchra 1996, private communication). No H I in I. emission is detectable (W. Huchtmeier 1997, private Object B provides an independent check on our B and V communication). We presently believe that the object is calibrations. The formal uncertainties in our photometry actually in the Milky Way, although its origin remains are ^0.03 mag in V , ^0.04 mag in I, and ^0.05 mag in unknown. A comprehensive discussion will be given in a B[V (from Table 3). Allowing for these uncertainties, the separate paper. There is also faint nebulosity due north of V -band magnitude of 13.87 agrees well with the photoelec- UGCA 92, almost certainly located in the foreground. tric value of 13.91 ^ 0.02 obtained by Buta et al. (1980). The Also listed in Table 15 are the magnitude and color of a B[V color is in exact agreement with that measured by large Galactic nebulosity near UGCA 105. The parameters Buta et al. (1980). refer only to the brighter section of a larger complex. The Object C appears to be a reÑection nebulosity similar to object is signiÐcantly bluer than UGCA 105, so it may be a that of Object B, but extended somewhat to the north. reÑection nebula. Being fainter and redder, it may be a more distant, more SUMMARY extinguished version of Object B. If the intrinsic B[V color 9. of the illuminating star is assumed to be the same as for that We have presented an extensive amount of photometric illuminating Object B, then the intrinsic V [I color of the information for 14 of the 16 currently known or suspected star must be [0.08, requiring that it be evolved (Winkler members of the IC 342/Ma†ei Group. The research has 1997). revealed a great deal about the structure of these galaxies Object A is more mysterious. It is deÐnitely extended on and provides a framework for improving estimates of our I-band image. The FWHM on this image is4A.8, versus extinction, distances, and masses. In successive papers we 3A.6 for Ðeld stars. The colors listed in Table 15 are nearly as will use the information to further elucidate the nature and red as those of Ma†ei 1, indicating that the object may be signiÐcance of the group. extragalactic. The V [I color is consistent with a globular cluster viewed through 5 mag of visual extinction (Forbes et We thank Lindsey Davis for making critical changes to al. 1996). However, if the object is associated with Ma†ei 1 the DAOPHOT package in IRAF that allowed us ultima- [ at a distance of 3 Mpc, thenMV B 14 (assuming AV B 5 tely to successfully remove the thousands of foreground 92 BUTA & MCCALL Vol. 124 stars a†ecting our images. We are also grateful to the Tele- the group. R. B. would like to thank York University for scope Assignment Committees of Kitt Peak National providing funds to enable him to work on this project Observatory for their generous allotment of telescope time during the summer of 1996. M. L. M. gratefully acknow- to this project. We thank H. G. Corwin, Jr., for providing ledges the continuing support of the Natural Sciences and some historical information on the NGC and IC galaxies in Engineering Research Council of Canada.

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Note added in proof.ÈAs this paper was going to press, W. Huchtmeier reported that three additional members of the IC 342/Ma†ei Group have been discovered (W. Huchtmeier, private communication [1999]). The Ðnds came from a H I survey of di†use sources identiÐed on the POSS II by V. E. Karachentseva and I. D. Karachentsev.