Baltic Astronomy, vol. Ί, 653-668, 1998.
BALDONE SCHMIDT TELESCOPE PLATE ARCHIVE AND CATALOGUE
A. Alksnis, A. Balklavs, I. Eglitis and 0. Paupers Institute of Astronomy, University of Latvia, Raina bulv. 19, Riga LV-1586, Latvia Received November 20, 1998.
Abstract. The article presents information on the archive and catalogue of the astrophotos taken with the Schmidt telescope of the Institute of Astronomy of the University of Latvia (until July 1, 1997 - Radioastrophysical Observatory of the Latvian Academy of Sciences) in the period 1967-1998. The archive and catalogue contain more than 22 000 direct and 2300 spectral photos of various sky regions. Information on the types of photo materials and color filters used as well as on most frequently photographed sky fields or objects is given. The catalogue is available in a computer readable form at the Institute of Astronomy of the University of Latvia and at the Astrophysical Observatory in Baldone (Riekstukalns, Baldone, LV-2125, Latvia), e-mail: [email protected].
Key words: catalogs: plate archive - telescopes: Baldone Schmidt - methods: observational
1. INTRODUCTION
One of the main tasks of astronomers is to obtain observational data on various objects of the Universe and preserve these data for their use in future. Initially the observational data in the direct or treated form were kept in paper records, later on as printed catalogs stored in libraries. For more than 100 years astronomers have gath- ered and stored in plate archives the information directly recorded on photographic emulsion layer of glass or film plates. 654 A. Alksnis, Α. Balklavs, I. Eglitis, O. Paupers
Table 1. The largest Schmidt telescopes.
Observatory The entrance Acting since Country aperture year (cm)
Palomar 122 1947 U.S.A. Bloemfontein 81 1950 South Africa Hamburg - Calar Alto 80 1955 Germany Tautenburg 134 1960 Germany Byurakan 100 1961 Armenia Kvistaberg 100 1964 Sweden Baldone 80 1967 Latvia La Silla 100 1969 ESO, Chile Siding Spring 124 1973 Australia Kiso 105 1974 Japan Merida 100 1976 Venezuela Calern 90 1976 France
For more than 30 years such an astronomical plate archive (or glass library) of photographic negatives, obtained with the Baldone Schmidt telescope is being collected at the Astrophysical Observa- tory of the Institute of Astronomy, University of Latvia (until July 1, 1997 - Radioastrophysical Observatory of the Latvian Academy of Sciences). The Baldone Schmidt telescope (80/120/240 cm) was put into operation in December 1966 on the Riekstukalns hill (Λ = +24° 24.0', b = 56° 47', altitude h = 75 m) near Baldone town. The telescope still resides among the 12 largest wide field Schmidt tele- scopes in the world (Table 1). The first astronomical photos were obtained in January 1967 (Alksnis 1976). They cover a field of 4° 46' in diameter, the size of photoplates is 24 χ 24 cm. The optical characteristics of the telescope are described by Paupers (1971) and Alksnis (1973b). The scientific interests of the Latvian astronomers in the field of stellar astronomy from the very beginning were directed mainly to carbon stars (see, for example, Alksne L· Ikaunieks 1981, Alksne, Alksnis & Dzërvïtis 1991 and references therein, and several review papers: Balklavs 1971, 1976, 1986, 1987). Therefore, the major- ity of plates, both direct and spectral, obtained with the Baldone Schmidt telescope plate archive 655
Schmidt telescope, cover the zone along the galactic equator, where the galactic carbon stars are concentrated (Figs. 1 and 2). According to the data of the IAU Commission 9 Working Group on Wide Field Imaging (now the Working Group on Sky Surveys) in the wide-field plate archives of the observatories all over the world in 1994 there were more than 1.7 million wide-field plates of which more than 380 000 have been obtained with Schmidt telescopes including more than 20 000 - with the Baldone Schmidt telescope (Tsvetkov et al. 1995). In the last 20 years the digitalization of astronomical informa- tion is progressing. At present the observational data and treated results are obtained in a computer readable form mainly online and stored in data bases. Nevertheless, the value of astronomical plate archives does not decrease: they contain information in the optical range of the former changes of cosmic objects, investigations of which have become especially important at present, when astronomers are gaining information in the whole range of electromagnetic spectrum from gamma to radio waves.
2. PLATE ARCHIVE
Each plate of the Baldone Schmidt telescope has been taken in order to study a definite cosmic object or group of objects, therefore only for these objects either brightness or coordinates on the plates have been measured. Usually about 95% to 99% of the information recorded on the emulsion layer of plate remain unused. However, in future this information might be very important for other investiga- tions. Therefore, these plates have to be stored at least until they will be scanned and transformed to a computer readable form. Unfortunately the Baldone Observatory has no special deposi- tory for the plate archive. The glass and film plates are stored ver- tically in the rooms of the Schmidt telescope dome, where they are less subjected to rapid temperature variations. The plates are placed in the original ORWO 24 x 24 cm size plate packing boxes, arranged on shelves in the chronological sequence. A small percentage of the archive plates are in use by people of various astronomical research institutions, mainly by those, who participated in the photographing process. Photos of the Baldone Schmidt telescope archive have been ob- tained mainly on the ORWO (East Germany) astronomical plates 656 A. Alksnis, Α. Balklavs, I. Eghtis, O. Paupers
Fig. 1. All-sky distribution of the 22 000 direct exposures, made with the Baldone Schmidt telescope, plotted in equatorial coordinates in equal-area projection.
12
— 90c
Fig. 2. All-sky distribution of the 2300 spectral exposures (as in Fig. 1). Schmidt telescope plate archive 657
1400 1200 1000 800 600 400 200 0 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97
Fig. 3. Distribution by time (years) of the number of photos (the lighter shaded columns) and of the sum of duration (in hours) of exposures (the darker shaded columns) obtained with the Baldone Schmidt telescope in the period 1967-1998.
(Astro Platten ZU1, ZU2, ZU21, ZP1, ZP3) of the 24 x 24 cm size and on the film plates (different versions of A500, A600, A700) of the Photographic Research Institute in Kazan (Russia), but a small quantity - on the Eastman Kodak plates (mainly IN). Since 1995, the plates NT-1AS (Mikhailov & Sheglov 1994), made in Pereyaslavl- Zalessky (Russia) and hypersensitized in hydrogen, have been used. For stellar photometry, the plates and light filters have been used to accomplish the passbands of standard photometric systems: the U, Β, V passbands, the Becker R passband and the Krön I passband (Alksnis 1973a, Alksnis, Alksne L· Daube 1973, Duncans 1979). In Table 2 the numbers η of direct photos taken with the most frequently used emulsion type and filter combinations are listed. The information on different types of photo emulsions used in astronomy is gathered in the recent book by Dokuchaeva (1995). Spectral plates have been obtained using 2° and 4° objective prisms of the 80 cm diameter, which provide the reciprocal dispersion of 1130 Â/mm, resp. 600 Â/ mm at the hydrogen H7 line (Alksne et al. 1989). Various combinations of filters and emulsion types have been used taking into consideration the necessary wavelength range. 658 A. Alksnis, Α. Balklavs, I. Eghtis, O. Paupers
Table 2. Combinations of the photo emulsions and filters most frequently used for the direct plates.
Emulsion Filter η Emulsion Filter η
- U
ZU21 — 262 ZU21 UG1 337
ZU1 - 119 ZU2 UG1 229
ZP3 - 21 ZU21 UFS3 87
A500N - 20 ZU1 UG1 62
Β V
ZU21 GG13 2703 A600N ZhS17 2101 ZU2 GG13 1691 A600 ZhS17 1799 NT-1AS GG13 207 A600U ZhS17 380 A500N GG13 204 A600RP ZhS17 219
R I
ZP1 RG1 7014 IN KS19 848 ZP1 KS13 1577 IN RG1+BG3 441 ZP3 RG1 739 1840 RG1 26 A700N KS13 240 IVN KS19 10
For the search of carbon stars, the orthochromatic Kazan A600 astro films and the Kodak IN infrared plates were mostly used (Table 3). In total more than 160 various combinations of filters and photo emulsions for direct photos and more than 110 combinations for spec- tral photos were used. Many of the sky regions have been photographed tens and some of them even hundreds of times, in order to investigate variability of stars. Most frequently photographed objects or regions are listed in Table 4 (for direct plates) and Table 5 (for spectral plates) with the total number of plates η of the object obtained in 1967-1998. Fig. 3 shows the distribution of the number of the Baldone Schmidt telescope photos by time in years (lighter shaded columns) and of the corresponding sum (hours) of exposure duration (darker shaded columns). During the first five years of the telescope Schmidt telescope plate archive 659
Table 3. Combinations of photo emulsions and filters mostly used for the spectral photos.
Emulsion Filter η Emulsion Filter η
Blue spectrum Yellow spectrum
A600 GG13 98 A600 - 403
ZU2 - 68 A600N GG5 167
ZU21 - 33 A600N - 139 A600N GG13 31 A600 GG5 120
Red spectrum Infrared spectrum
103aF - 123 IN RG1 158
103aF RG1 45 IVN - 43
A700F - 41 IN - 37
A700N — 37 1840 — 32
operation (1967-1971) the number of photos obtained annually grad- ually reached a level of 800. From 1975 to 1988 it was still higher and varied about the average value of 1100. Continuous and fast decline is seen after 1988. In 1995 the annual number of photos was almost five times smaller. Similar is the distribution of the annual sum of exposures. The intensity of the use of the Baldone Schmidt telescope in the last 10 years has decreased because of the cut down of the as- tronomical research funding. Both the budget and the staff of the Radioastrophysical Observatory of the Latvian Academy of Sciences and the Institute of Astronomy of the University of Latvia have drastically decreased. Acquirement of the necessary photo materials has completely stopped. Therefore in the last four years the plate archive in the Baldone Observatory has increased only by about 300 photos annually. The time-expired and fogged ORWO plates are now almost completely exhausted. A small quantity of rather fresh NT-IAS plates made in Russia and supplied by the Sternberg As- tronomical Institute are used for the common work: the search and study of novae in the Andromeda galaxy. 660 A. Alksnis, Α. Balklavs, I. Eghtis, O. Paupers
Table 4. Most frequently photographed sky objects (direct photos).
Object η Object η Object η
CIT6 3078 Τ Dra 144 Ν Cyg 1975 73 M31 532 174,+7 139 U Cyg 73 Tr 2 461 94,+3.5 133 U Lyr 72 DY Per 393 94,0 133 NGC 659 72 BC 56 325 94,+7 129 82,+7 69 NGC 1245 319 IC 5146 127 CIT5+1245 69 NGC 1664 284 90,+3.5 126 82,+0 69 90,-3.5* 265 NGC 1893 124 NGC 7031 68 IRC+10216 263 90,0 124 82,+3.5 66 Stock 4 254 NGC 7092 123 CRL 3116 65 86,+7 253 86,+10.5 121 Dol 2 64 NGC 7063 247 90,-7 120 RU Vir 63 NGC 6871 236 94,+10.5 119 IC 1848 62 AFGL 2881 232 94,-7 113 Pluto 62 NGC 7128 230 174,-7 107 OW Aql 58 86,0 220 174,0 107 82,-3.5 58 94,-3.5 220 174,+3.5 106 NML Tau 56 86,-7.5 214 NGC 457 103 82,-7 56 86,-3.5 213 MQ Cyg 102 NGC 7654 55 178,-7 213 92,+6.5 100 Coma Berenices 54 178,+3.5 203 SS Vir 98 VCyg 54 178,0 203 90,+1.3 98 EU And 53 86,+3.5 201 CT Lac 97 CT Vul 52 CIT6+SA54 194 BM Gem 95 WX Cyg 51 178,-3.5 184 NGC 1817 91 Gal. I* 50 90,+7 178 174,-3.5 90 NGC 2129 49 NGC 7789 174 CIT5 90 82,+10.5 49 178,+7 173 NGC 1528 89 90,+10.5 46 Comet Η alley 171 NGC 2251 88 86,-10.5 46 NGC 7419 169 94,-10.5 88 Comet Austin 46 IRC+20370 169 NP Her 84 Comet Hale-Bopp 46 V CrB 164 T+X Cnc 84 Comet Crommelin 45 KL Cyg 161 Gal. II* 77 IRC+40070 44
Notes: 90,-3.5 - field with galactic coordinates of the center i = 90°, b = -3.5°; Gal. I - the galactic field at a = 12h05m, δ = +49°; Gal. II - the galactic field at a = 14hllm, δ - +55°38; Schmidt telescope plate archive 661
Table 5. Most frequently photographed sky objects (spectral photos).
Object η Object η Object η CIT6 60 86,+3.5 14 178,0 9 NGC 6871 40 86,0 14 Stock 4 8 S Cep 34 86,-7 14 X Cnc 9 V CrB 29 VY UMa 13 UV Aur 9 U Cyg 29 UX Dra 13 NGC 1893 8 Τ Dra 26 VX Gem 13 90,+7 8 BD Vul 26 ZZ Gem 13 HD 201626 8 OW Aql 26 TX Lac 13 174,+3.5 8 Y CVn 25 ST Cam 12 Τ Lyn 8 SS Vir 24 HD 19557 12 94,+7 8 U Lyr 24 IQ Cyg 12 ρ UMa 8 Τ Lyr 23 AX Cyg 12 NGC 7419 8 WX Cyg 23 90,0 11 RU Vir 8 W Cas 23 HD 156074 11 RV Cyg 8 NGC 1664 22 94,+3.5 11 VCyg 8 WZ Cas 21 94,0 11 90,+3.5 7 RS Cyg 21 IC 5146 11 HD 76396 7 HD 59643 20 MQ Cyg 11 VX And 7 RY Dra 16 NP Her 11 DX Cas 7 Ζ Psc 15 EW And 11 82,0 7 UU Aur 16 174,0 10 Pulk. 98* 7 RR Her 16 174,-3.5 10 XSge 7 86,+7 16 94,-3.5 10 82,+3.5 7 86,-3.5 16 178,+3.5 10 HD 197604 7 Y Per 16 NGC 7789 10 BD 2 3336 7 RZ Peg 16 NGC 2251 10 NGC 7063 6 HD 76847 16 TV Lac 10 174,-7 6 NGC 1245 15 Pulk. 117* 9 RV Mon 6 90,-3.5 15 90,-7 9 HD 79319 6 BD 38°955 15 174,+7 9 178,-7 6 Tau 15 BL Ori 9 178,-3.5 6 TT Cyg 15 178,+7 9 FU Aur 6 NGC 7128 14 94,-7 9 NGC 6811 6
Note: Pulk. 98 and Pulk. 117 - fields of the Pulkovo Observatory plan for the reference system connected to galaxies. 662 A. Alksnis, Α. Balklavs, I. Eglitis, O. Paupers
3. THE COMPUTER-READABLE CATALOGUE OF THE BALDONE SCHMIDT TELESCOPE PHOTOS
The data of photos obtained with the Baldone Schmidt telescope are now arranged in a computer readable catalogue. Each entry con- tains information on one exposure registered and numbered in the record book of the Schmidt telescope. The entries follow in chrono- logical sequence and contain the following information in Columns 1-12 (see the examples in Tables 6 and 7). Column 1. The registration number of the glass or film plate according to the record book. This number in some cases is repeated when on one plate two or more exposures are made. Column 2. The date before midnight of the night of observation (the last two digits of the year, the month and the day). Column 3. The name of the object or the designation of the sky region observed. Columns 4 and 5. The equatorial coordinates of the center of the field of view - right ascension (hours, minutes, seconds) and declination (degrees and arcminutes) approximately for the equinox of the year of observation. Column 6. The moment of the beginning of exposure - hours, minutes and (usually) seconds according to the third time zone Τ 3 = UT + 3 h. Column 7. Duration of exposure in minutes. Column 8. The type of the photo emulsion used. Column 9. The light filter used. Column 10. The photometric system or the spectral region of the passband. Column 11. The exposures which were interrupted by clouds are marked by * sign, the multiple shifted exposures are marked by + sign. Column 12. Information about masks and prisms is given. The letter m means the half-field mask used to expose the eastern (ml), western (m2), southern (m3) or northern (m4) half of the field of view; ρ means that the 11 cm diameter auxiliary prism (Racine wedge) was used to extend the photometric sequence to fainter mag- nitudes; wl to wl7 are one-square-degree field photos; approximate coordinates of their centers can be determined by adding the correc- tions Δα and Δ<$ to the coordinates of the field center of the telescope R.A. and Dec., given in columns 4 and 5 of the catalogue. Sp2 and Sp4 mean that 2° or 4° objective prisms were used for the spectral Schmidt telescope plate archive 663 plates. Sp90 and Sp270 indicate that the prism has been turned by 90° with respect to the normal state, wl 4 to wl7 4 mean that the 4° objective prism was used for spectral photos and they were taken through one-square-degree masks No.l to No.17. The coordinates of the center for these photos can be determined with the corrections Δα and Δ<5, as in the case of direct plates. The corrections depend on the mask number used as follows: for right ascension: wl3, wl7 Δα = -3a wll, wl2, wl5, wl6 Δα = -a wl, w2, w5, w6 Δα = +a w3, w7 Δα = +3a for declination: w2, wl2 Δδ = -1°48' wl, w3, wll, wl2 Δδ = -36' w5, w7, wl5, wl7 Δδ - +36' w6, wl6 Δδ = +1°48' where a = 2.4/cos¿> (in arcmin). In those rare cases, when the telescope during the exposure was in the inverse position, the sign of the corrections Δα, Δδ has to be changed. In this case the field mask order should be also inter- changed: ml to m2 and m3 to m4 and vice versa.
4. LIST OF THE OBJECTS OBSERVED
Two lists of the objects observed have been made for more con- venient use of the catalogue. The lists are separate for direct photos and for spectral plates. The first list includes information on more than 1300 objects, the second - on more than 600 objects. Examples of the entries of these lists are given in Tables 8 and 9 which contain the following information. Column 1. Sequential number of the object in the list. Column 2. Name of the object or sky region used in the cata- logue. Columns 3 and 4. Right ascension (in hours, minutes and sec- onds) and declination (in degrees and arcminutes) of the center. Column 5. The number of the first photograph of the object in the catalogue. Column 6. The date of the first photo of the object (the last two digits of the year, the month, the day). Column 7. Total number of photos of the corresponding object or sky region. A. Alksnis, Α. Balklavs, I. Eglîtis, O. Paupers
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Τ}, o ¡3 co σ t- h- co < υ o « .ü E ν o u ^ Λ β (O i 3 o O Η Η Q j? O -Ο Ν Η O o > X £ Oh Ο £ ü ζ ζ O ü « Í3 ? Q O >« 00 • Table 8. Examples of entries in the list of objects (direct photos). No. in Object R.A. Dec. Plate Date η the list h m s ο ι No. y m d 1 2 3 4 5 6 7 125 174,0 05 28 35 33 59 1884 711219 107 313 AF Aur 05 41 24 44 53 10055 811116 13 385 BD 47 3468 21 36 50 48 49 8166 791020 8 412 BN Gem 07 26 12 27 39 12252 840215 1 613 HD 13332 14 58 01 10 11451 830227 1 773 M 92 17 16 12 42 42 15604 870311 8 891 NGC 4151 12 13 30 38 13 11536 830416 2 937 NGC 6946 20 34 61 15 16662 880409 13 1328 U Cam 03 50 62 25 9480 810327 24 1333 U Hya 10 32 30 13 16 9483 810327 6 1353 V1128 Cyg 19 30 45 28 39.5 17980 891205 1 Table 9. Examples of entries in the list of objects (spectral photos). No in Object R.A. Dec. Plate Date η the list h m s o / No. y m d 1 2 3 4 5 6 7 23 102,-7 22 35 28 50 10.7 742 740914 1 63 158,0 04 38 02 48 43 1748 911008 3 103 178,-7 05 12 19 26 43 622 740220 6 215 BD 71 600 12 00 00 70 22 636 740222 1 510 TT Cyg 19 41 06 31 20 1383 830818 15 297 HD 166097 18 05 19 12 07 1183 790728 3 323 HD 235661 21 54 18 54 23 1184 790729 2 363 IQ Cyg 19 43 28 33 46 1207 790818 1 458 R Gem 07 14 45 23 35 1 930123 2 581 WS 470 20 48 17 53 24.0 1221 790916 1 586 WS 657 21 49 42 46 42 1220 790915 2 Schmidt telescope plate archive 667 5. ELECTRONIC FORMAT OF THE CATALOGUE Table 10 describes the electronic format of the computer- readable catalogue. For more information on the Baldone Schmidt telescope plate archive contact by e-mail: [email protected]. Table 10. The format of the catalogue. Col. Bytes Format Content Col. Bytes Format Content 1. 1-5 15 Plate No. 6. 43-48 A6 Begin. Texp (hms) 6 XI 49 XI 2. 7-8 12 Year 7. 50-52 13 Duration texp (min) 9-10 12 Month 53 XI 11-12 12 Day 8. 54-60 A6 Emulsion 13 XI 9. 61-66 A6 Filter 3. 14-24 All Object 67 XI 4. 25-26 12 R.A. (h) 10. 68 Al System (Sp. region) 27 XI 69 XI 28-29 12 R.A. (m) 11. 70 Al Notes 30 XI 71 XI 31-32 12 R.A. (s) 12. 72-78 A6 Notes 33 XI 5. 34-36 13 Dec. (o) 37 XI 38-41 F4.1 Dec. (/) 40 XI ACKNOWLEDGMENTS. The Baldone Schmidt telescope plate archive could not be made without efforts of numerous staff mem- bers of the Radioastrophysical Observatory: astronomers-observers, who during the over the 30 last years for longer or shorter time ob- served with the Schmidt telescope (I. Daube, L. Duncans, I. Jurgltis, I. Platais, I. Pundure, A. Rudzinskis, P. Simanskis, J.-I. Straume and others), laboratory assistants (I. Jurgltis, A. Birzvalks), who in the dark-room processed the exposed plates, assistants (Z. Jumil^e, M. Egllte, V. Ozoliija, D. Zaime), who copied the record book and made description on plates, and the technical staff (A. Avotiijs, J.Breijlps, V. Jumiljis, J.Kizla, G. Spulgis), who provided the func- tioning of the telescope. A special acknowledgement is due to the 668 A. Alksnis, Α. Balklavs, I. Eglitis, O. Paupers women-astronomers liga Daube and Irena Pundure. Their selfless and hard work even during cold and long winter nights, their for- bearance and unflagging enthusiasm should be acknowledged. REFERENCES Alksne Z.K., Ikaunieks J.J. 1981. Carbon Stars. Ed. by J.H.Baumert, Pachart Pubi. House, Tucson, Arizona Alksne Z., Alksnis Α., Ozoliça V, Platais I. 1989, Investigations of the Sun and Red Stars, Riga, No. 30, 40 (in Russian) Alksne Z.K., Alksnis A.K., DzërvTtis U.K. 1991, Properties of Galactic Carbon Stars, Orbit Book Company, Malabar, Florida Alksnis A. 1973a, in Photometric Investigations of Red Stars, ed. A. Balklavs, Zinätne Publishing House, Riga, p. 149 (in Russian) Alksnis A. 1973b, in Photometric Investigations of Red Stars, ed. A. Balklavs, Zinätne Publishing House, Riga, p. 165 (in Russian) Alksnis A. 1976, Zvaigzçotâ Debess, Ziema 1976/77, p. 1 (in Latvian) Alksnis Α., Alksne Z., Daube I. 1973, in Photometric Investigations of Red Stars, ed. A. Balklavs, Zinätne Publishing House, Riga, p. 7 (in Russian) Alksnis Α., Platais I. 1997, Baltic Astronomy, 6, 471 Balklavs A. 1971, Proceedings of the Acad. Sc. of the Latvian SSR, No. 3 (284), 69 (in Russian) Balklavs A. 1976, Proceedings of the Acad. Sc. of the Latvian SSR, No. 7 (348), 3 (in Russian) Balklavs A. 1986, in The Academy of Sciences of the Latvian SSR, 1946- 1988, Zinätne Publishing House, Riga, p. 149 (in Russian) Balklavs A. 1987, Proceedings of the Acad. Sc. of the Latvian SSR, No. 1 (484), 68 (in Russian) Dokuchaeva 0. 1995, The Astronomical Photography. Materials and Methods, "Fiziko-matematicheskaya literatura" Publishing House, Moscow (in Russian) Duncäns L. 1979, Investigations of the Sun and Red Stars, No. 10, 13 (in Russian) Mikhailov D. K., Sheglov P. V. 1994, in Astronomy from Wide-Field Imag- ing, eds. Η. T. McGillivray et al., Kluwer Academic Publishers, p. 157 Paupers 0. 1971, university project work (in Latvian, unpublished) Ts vet ko ν M., Stavrev Κ., Tsvetkova Κ, Mutafov Α., Mikhailov M.-E. 1995, in The Future Utilization of Schmidt Telescopes, eds. J. A. Chapman, R.D.Cannon, S.J.Harrison L· B.Hidayat, PASP Conference Series, Vol. 84, p.148