OccdhtlM3Newstelter
Volume II, Number 10 january, 1981
Occultation Newsletter is published by the International Occultation Timing Association. Editor and Compositor: H. F. DaBo11; 6 N 106 White Oak Lane; St. Charles, IL 60174; U.S.A. Please send editorial matters to the above, but send address changes, requests, matters of circulation, and other IOTA business to IOTA; P.0. Box 596; Tinley Park; IL 60477; U.S.A.
NOTICE TO LUNAR OCCULTATION OBSERVERS paho1. by contacting Sr. Francisco Diego Q., Ixpan- tenco 26-bis, Real dc Ids Reyes, Coyoacdn, Mexico, L. V. Morrison D.F., Mexico. Currently, however, the Latin American Section is experiencing problems with funding, and On 1981 January 1 the international centre for the for the time being, it may be necessary for would-be receipt of timings of occultations of stars by the IOTA/LAS members to subscribe to the English-lan- Moon will be transferred from HM Nautical Almanac guage edition of o.n., or to join the parent IOTA. Office, Royal Greenwich Observatory, England to As- tronomical Division, Hydrographic Department, Japan IOTA NEWS
"' From that date observers should send their lunar oc- cultation reports and any correspondence connected David W. Dunham with lunar occultations to the following address: As of 1981 January 1, H. M. Nautical Almanac Office, Astronomical Division at the Royal Greenwich Observatory, England, will Hydrographic Department discontinue collecting observations of lunar occul- Tsukiji-5 tations. After that date, observers should send Chuo-ku, Tokyo their reports to the new International Occultation 104 JAPAN Centre in japan, as described in this issue's lead article. This poses a problem for 1980 reports, The layout of the report form may be changed a lit since most observers have been filling out their tie and observers should write to the Hydrographic HMNAO occu1tation report forms as they make their Department for new forms. During this change-over observations, and new report forms have been de- period it is important that observers should give signed by the I.O.C. Any reports sent to HMNAO will their full postal address, positions and descrip- simply be sent on to Japan. Since the I.O.C. report tions of their telescopes on the report forms, oth forms are rather similar to HMNAO'S, the I.O.C. erwise there may be considerable delay in reducing might accept reports, for 1980 only, on HMNAO's their observations. forms. I have written to the I.O.C. asking if this is all right, and hope to publish their reply in the Observations of occultations of stars by planets, next issue, which we hope to distribute early in satellites or minor planets should continue to be February. In the meantime, you might hold onto your sent to HM Nautical Almanac Office. 1980 data until we publish the decision. Also, the new I.O.C. report forms should be available by then, FROM THE PUBLISHER so that if you have not already filled out an HMNAO form, you could use the new forms instead. In any <~ For subscription purposes, this is the fourth and case, start using I.O.C. forms as soon as possible. final issue of 1980. Guillermo MallCn reports continued difficulties with O.n.'s price is $1/issue, or $4/year (4 issues) in high demand for use of the computer at the Universi- eluding first class surface mailing, and air mail "... dad Naciona1 Autonoma dc Mexico, so that graze pre- Mexico. Air mail is extra outside the U.S.A., Can."- dictions for Latin American section members are da, and Mexico: $1.20/year in the Americas as far still available only through membership in the main south as Colombia; $1.68/year elsewhere. Back is- I.O.T.A. Ma11Cn is applying for resumed support of sues also are priced at $1/issue. Please see the IOTA/LAS operations in Mexico City, hoping for com- masthead for the correct ordering address. puter access perhaps in April, hopefully in time to compute graze predictions for the second half of IOTA membership, subscription included, is $7/year 1981. If you need the total occultation predictions for residents of North America (including Mexico) for 1981 which were originally supplied by Mdllen, and $9/year for others, to cover costs of overseas write to me at P. 0. Box 488, Silver Spring, Mary- air mail. European (ordinarily excluding Spain and land 20907, U.S.A. If there is a large demand for Portugal) and U. K. observers should join IOTA/ES, such predictions, I will send magnetic tape data for sending DM 12.-- to Hans j. Bode, Bartold-knaust Latin America to Walter Morgan so that he can supply Str. 8, 3000 Hannover 91, German Federal Republic. them. Spanish, Portuguese, and Latin American occultation observers ordinarily may have free membership in The American Ephemeris and Nautical Almanac has been IOTA/LAS, including Occultation Newsletter en Es- substantially revised for 1981, and renamed The 174
Astronomical Almanac, published jointly by the Royal The inclusion of K-catalog stars in the regular USNO Greenwich and U. S. Naval Observatories. There is total occultation predictions for 1981 was mentioned an error in the 198] edition: The ephemerides given in the last issue. The calculation of J-catalog for the four main minor planets are 1abe11ed as predictions for 1981 will be delayed until February, "astrometric, 1950" when in fact they are apparent to allow time to create a new catalog with Praesepe- of date. Starting with the 1982 edition, these cluster stars, more southern stars from the Southern ephemerides actually will be astrometric, 1950. Astrographic Catalog project, and more northerly stars in the northern Milky Way from the Astrogra- The errors in USNO'S XZ catalog, described in o.n. 2 phic Catalog. These stars are not in the current J- (6) 58-60, have still not been corrected. Hence, catalog, but begin to be occulted during 1982 as the the magnitude of X05404 is still given as 5.8 in the Lunar node regresses. The delays in doing this work USNO total occultation predictions for 1981, al- have resulted from the usual new-year prediction though the star's magnitude is actually 11.3. Thom- crunch, greater this time due to the much larger as Van Flandern has recently programmed a method for number of planetary occultations during 1981, and my updating information about non-SAO stars in the XZ involvement with favorable but time-consuming aster- catalog. Sometime during the next few months, I oidal occultation observations late in 1980. plan to write a program to read my magnetic tape of K - XZ matched data and generate input data to cor- John Phelps produced and distributed the very useful rect the bad magnitudes and spectral types in the IOTA membership list of 1980 September. I found current version of the XZ. So if X05404 is occulted only a few errors, such as "Chris Aikhan" (should be during ]982, its magnitude should be listed correct- "Chris Aikman"). Dr. A. a. Nefedjev, who computed ly as ]1.3 in the USNO predictions for that year. graze predictions for Soviet observers, died a few years ago. Just after the list was produced, Our first publication on Solar variations from Richard Nolthenius moved to 1137 N. Clark, Apt. 5, eclipses, "Observations of a Probable Change in the still in West Hollywood, CA, and Derald Nye moved to Solar Radius Between 1715 and 1979," has appeared Route 7, Box 511, Tucson, AZ 85706. The geographic- in Science 210 (4475) 1243-1245, issue of 1980 De- al listing in Part II should be most useful for con- cember 12. We have not yet received reprints, but tacting other observers in your area. a large supply should be available soon, hopefiillt to be announced in the next issue of o.n. Copies Byron D. Groves, 601 N. Parkcenter Dr., Suite 10], will be sent to a]] observers who reported observe- Santa Ana, CA 92705, wrote to me in September asking tions, or otherwise were involved in the effort, again if I.O.T.A. would like to meet with the West- near the edges of the 1976 and 1979 total eclipse ern Amatetir Astronomers in Orange, CA, from 1981 paths. More recent analyses were mentioned on p. July 23 to 26, and assumed that we would not if he 102 of the last issue, but further more refined had no reply by Thanksgiving. I had hoped that this calculations have shown no significant variation issue would ha:ie been distributed before then, to between the total eclipses of )979 and 1980, but see if there was any interest in at least a regional perhaps a small expansion from 1976 to ]979. J.H. IOTA meeting. I did not reply, since the dates con- Parkinson, L.V. Morrison, and F.R. Stephenson haw flict with a possible trip to observe the 1981 July published an analysis of central eclipse timings 1· 31 Solar eclipse, and the distance is too great for a paper, "The Constancy of the Solar Diameter ovej the other IOTA officers. If there is some local in- the Last 250 Years," in a recent issue of Nature. terest, an at least informal regional IOTA session They found no significant variation, but their ob- might still be arranged. servational errors are greater than ours since their method does not have the advantage of the Last August 12th, Russ Genet, M. D. Overbeek, Wayne grazing geometry and is much more strongly affecttm Warren, Hark Trueblood, and I met in Silver Spring, by random and 1ibration-dependent systematic errot- MD, to discuss photometry of occultations. Russ in Watts' Lunar limb correction data. They point Genet, 1247 Folk Rd., Fairborn, Oh 45324, phone out that our result depends largely on the rather 513, 879-4583, is co-editor of the i.a.p.p.p.c. uncertain location of the observer at the northerr (International Amateur-Professional photoelectric limit of the 1715 eclipse. However, we have recer.'- photometry Communication), the 2nd issue (1980 1y found well-documented observations at both edg€ Sept.) of which contained a summary of their first of the path of the 1925 January 24th total eclipse. annual symposium held in Dayton and Fairborn just analysis of which reveals a Solar radius over 0:'6 before the 1980 Apollo Rendezvous in June, short larger than that derived from the recent eclipses, sketches of the backgrounds of the first 51 members and slightly larger than the value we derived for of I.A.P.P.P., and articles with titles such as 1715. The 1979 eclipse occurred three Saros cyck-. "A Solid State Photometer," "A photoelectric Data after the 1925 eclipse, so the geometry and 1ibra- Reduction Program in BASIC for Microcomputers," tions were similar. In 1979, two contacts and one and "High Speed Spectroscopy of Algol Systems." bead event were produced by three Lunar valleys which produced three of the four defining contacts The next issue will be published a few weeks after in 1925. An analysis of just these three 1979 this issue, and will contain mainly several reduc- events confirms our earlier analysis of a correc- tion profiles of grazing occultations, finder tion near zero to ±0:'2 accuracy, and we have a charts and maps for some of the early 1981 planet- similar less accurate result from three 1980 eclipse ary occultations, and probably less text than this bead timings. It appears that we have strong evi- issue. Articles on new double stars and on grazes dence for a substantial decrease of the Solar ra- reported to IOTA may be delayed until the following dius from 1925 to the present. The variations do issue #]2 scheduled for early April, with a mid- not seem to be secular, but rather may be irregular March deadline for receipt of material by DaBo11. or partly periodic, perhaps with time scales of tens Joseph Carroll, Minnetonka, MN, hopes to have dc- of years, perhaps related to the sunspot cycle. cu1tation tallies for two or more recent years ready for that issue. He notes that his tally work 115
" is considerably facilitated if observers put their and are named from meteorites with similar proper- HMNAO station/observer/telescope codes on their ties. Hence, specific mineralogies are implied, annual occultation count coupon. which may not be completely correct. But most as- teroids of a given type probably do have similar GRAZING OCCULTATIONS compositions. The six types are described below: C low albedo, carbonaceous David Id. Dunham S moderate albedo,_ silicate M moderate albedo, metallic Reports of observations of grazing occultations E high albedo, ensUtite achondrites should be sent to me at P. 0. Box 488, Silver R moderate to high albedo, red (iron silicates) Spring, Maryland 20907, U.S.A. If possible, a copy U .u.nusua7, not in the other"five categories of the report should be sent to the International Occultation Centre (I.O.C.), Astronomical Division, Composite types, such as "CMEU," only mean that the Hydrographic Department, Tsukiji-5, Chuo-ku, observations exclude the other types. Tokyo, 104 japan, and it should be stated on the re- port whether or not a copy was sent to the I.O.C. A complete description of the S-column in the second If no such indication is given, it will be assumed table (source of star's position) was given in o.n. that no copy was sent, and I will make and send a 2 (7) 62-63. copy to I.O.C. Graze reports should no longer be sent to H. M. Nautical Almanac Office at the Royal Most of the events in the table were found by Gordon Greenwich Observatory, England. I have quite a few Taylor at the Royal Greenwich Observatory and pub- reports of 1980 grazes which need to be sent to the lished in his Bulletin 20 of I.A.U. Comission 20'S I.O.C., and am looking for a volunteer to tran- Working Group on Predictions of Occultations by Sat- scribe these reports onto the new I.O.C. forms. ellites and Minor Planets. Derek Wa11entinsen, com- paring the SAD catalog manually with astrometr'ic In late October, the I.O.C. sent copies of their ephemerides supplied by me, found the events on the " proposed report forms to H.M.N.A.O. and to U.S.N.O. following 1981 dates and published predictions of asking for comments. I got a copy of USNO'S copy them in Contribution No. 2 of the James-Mims Obser- and wrote a letter to I.O.C. enclosing a copy of vatory (see p. ]04 of the last issue): jan. 23, IOTA'S form, and suggested several relatively minop March 6 (216 Kleopatra), March 19, June 26, July 2, modifications that could be made to include all of July 15, Nov. 28 (624 Hektor), and Dec. 14. He also the information now requested on IOTA'S form. independently found many of the events listed by Even if they do not change their form, a large are.: Taylor, and also found ten events which miss the is provided for comments, and part of this can be Earth by less than one arc second, so that, due to blocked into specific columns for any of the addi- star position or ephemeris error, an occultation may tional information which IOTA may want. In any be visible from the Earth's surface, most likely in case, IOTA will soon abandon its current forms for the polar regions. Taylor found two of his events, grazes and use the finally-adopted I.O.C. form, pe- those on Jan. 26 and on Sept. 19, after he had haps adding some columns in the comments section a issued Bulletin 20, so he sent predictions for those noted above. When the new forms become available, events to observers later. The occultation by Venus they will be distributed First to active graze ob- on Nov. 17 was first publicized by jean Meeus; Steve servers and later to all IOTA members. Albers found the occu1tation by Mercury.
The corrections to the USNO graze predictions des- About half of the asteroidal ephemerides I use are cribed on pages 95 and 96 of the last issue should computed from osculating orbital elements computed no longer be applied; they have been taken care of by Paul Herget at Cincinnati Observatory and pub- with changes to the ACLPPP profile printing prograz lished in the Minor planet Circulars in 1978 (P:os. sent to all computors for the 198] predictions. 4361-4390) and in 1979 (Nos. 4824-4825). Most of the others were calculated at the Leningrad Insti- PLANETARY OCCULTATION PREDICTIONS tute of Theoretical Astronomy (I.T.A.) and published K-" David bl. Dunham in the Epheinericies of Minor Planets (E.M.P.) for 1980 or 1981. For many events, elements from both sources are available, so that I can make two separ- Predictions of occultations of stars by major and ate predictions. For events on the following dates, minor planets, all but one during 1981, are given ii} the ephemerides differ by less than 0!'4 and less . two tables. They are like the tables described in than 2.5 minutes in time, smaller than the expected o.n. 2 (2) 16-18, except that in the second table, errors relative to the occulted stars: Jan. 23, the geocentric angular velocity of the object in dc- Feb. 1 (18 Melpomene), March 6 (54 Alexandra), grees/day is listed with the position angle of mo- March 19, April 2 (36 Atalante), April 4 (83 Bea- tion under the comnon heading "Motion," and the tax- trix), April 15, April 20, April 26 (13 Egeria), onomic type of asteroids is given in a new column April 29, May I], May 14, May 17, May 20, May 21, between the columns for the radius of sphere of in- May 26, May 30, Aug. 9 (354 Eleonora). Aug. 26 (70 fluence (RSOI) and motion. Panopaea), Sept. 6, Oct. 7, Nov. 2, Nov. 18, Nov. 28 (16 Psyche), and Dec. 14. Larger ephemeris differ- The taxonomic types are those given in the Tucson ences are given in Table 3, in the sense I.T.A. mi- Revised Index of Asteroid Data (TRIAD) as published nus Herget, except for one noted case. The value in the book Asteroids (see p. 104 of the last issue) in the shift column gives the path differences in and are described on pages 783-806 of that book. arc seconds measured perpendicular to the asteroid's Based on new comprehensive observations, the type of gEocentric motion; the letter following it tells (216) K1eopatra has been revised to "M." The types which direction the occultation path will be dis- are determined mainly from observations of albedo placed on the Earth's surface from the nominal (usu- (reflectance) and spectral characteristics (color), ally Herget) prediction. The value in the At column e+"5 E O "·m C-P " El M 0 0 N "·CD CD m= "S (D " UNIVERSAL P L A N E T S T A R OCCULTATION Cl n "S O ~ C» SUN El %Sn1 (JZ = CD COrPS m" DATE TIME NAME m, 8,Alj SAD No mv . & R.A.(1950)DCC. Am. Dur. df. E Possible Area " = = —h n In m c-p3 CD = :T Di!8?1 }Oh49" 106" Jupiter -i .8 5.66 138820 8.6 AO 12h27?8 -1"40'0.0 110m 22 2 North America 7 Qj C E 72°117" 15+ none 0 = O.Qi.c-PE :T C CD "· (D "· CD j:?815 10 42 Semele 13.3 2.17 109752 9 2 F8 112.1 3 31 4.1 6S16 28 s.e. Australia; New Zea1and?s M'a="= 93 104 1- none "S (D "· CD W CD "3 e+m {d U""5 108 130 4+ none 3 In =10 ~(0 jan 8 2 08-20 Nysa 10.4 1.59 119165 9.0 G0]1 58.4 2 09 1.7 7 27 34 s. Europe, Mideast m- = Al CP 36 103 87- all = D 3 G) C-FCD = jan 23 19 20 Daphne 12.1 2.80 160962 9.2 K5 17 56.4 -12 08 3.0 4 7 20 Aleutian Islands O m"·c0 jO) (D 114 134 67- el 25°ltd "5 4¢n < "S jan 26 7 05-14 Corduba 13.3 1.89 111635 8.9 K2 4 07.2 4 15 4.4 14 34 26 Hawaii, w. U.S.A. X P CD ~(j3 18 106 49- none TJ 6·. ~ :E '< (D Jan 28 7 43 Mercury -0.8 1.08 164713 5.1 FO 21 50.6 -]3 47 0.0 103 4 1 e. Siberia, Hokkaido ~:J 4CjCD C-P O 35 13 15- all A} 0 "J7 O CI Feb 1 3 01 Melpomene 11.3 3.14 161626 9.2 AO 18 31.9 -16 10 2.2 3s 8 31 Caspian Sea area; Mideast?s = '1 CJCD = (D 49 10 11- c140°E CD - c-r cp = Feb 1 17 40 l'leptune-R? 8.0 30.92 13.4 17 32.6 -21 59 .16 33m43 1 e. Australia c-f 'Tj v} v) :t(q c-f Feb 5 3 33 Minerva 12.5 3.07 187067 9.2 GO 18 34.8 -29 43 3.4 tjs 8 26 e. equatorial Africa 39 41 0+ all Cl) Hi O CD A) T 73 167 54+ none .> E °= ~ = t:. ;;' Feb 12 1 12 Metis 11.6 2.75 184474 9.0 KO 16 32.0 -20 02 2.7 7 13 24 S. Africa C3(D on Al O < 23 151 100+ all 'D&'D"3CDc+ Feb 18 12 31 julia 11.2 2.96 10.2 F8 23 12.9 4 29 1.4 3 7 26 e. Tibet 4· 7 LO "' ~h 71 51 75- all < CD = 3 Feb 24 5 35 Pandora 13.1 3.14 185534 9.1 K5 17 32.7 -28 55 4.1 7 13 25 southern S. America .> A) A) A' D (D 92 171 56- e162°W m3 c-Fer ""S Feb 26 10 50 Arethusa 12.8 2.56 94045 8.3 K2 4 35.5 15 25 4.5 10 20 22 e.China, s.japan, Hawaii (low) Dj A, "· = O Mar 6 i 37-76 Alexandra 13.0 2.65 79033 8.7 KO 7 01.2 26 14 4.3 40 73 22 n.w.Africa, c.Brazi1, Iberia?n 119 123 0- none Mar 6 8 18 Kleopatra 11.5 2.62 110447 8.8 GO 2 14.2 9 33 2.8 3 8 29 New Zealand (North Island) 49 50 O-f none kq§2aEF Mar 9 1 56 Hesperia 13.4 3.82 162369 9.4 F5 19 12.5 -14 38 4.0 4 13 51 S. Africa?n 6] 97 10+ none Mar 13 14 14 Parthenope 11.4 2.44 161895 9.4 B9 18 47.7 -19 43 2.2 5 11 23 New Zealand (South Island) UE¶iijs 71 168 56+ none A) 0 ~ W —h In = ~· -S D v) rr Mar 19 11 41 Doris 11.4 2.10118832 9.0 K211 21.9 2 12 2.5 12 22 20 n. central U.S.A., w. Canada 172 7 99+ all a J· (A j = H· = = Ch · C-F A' Mar 25 21 21 Laetitia 10.9 2.17 139976 8.1 KO 14 28.1 -2 53 2.9 15 28 20 S. Africa 147 27 77- e 6°E ~ (D D "nO com a. = < I Apr 2 0 39-47 Winchester 13.2 2.83 100625 7.4 KO 13 31.9 14 22 5.8 12 19 20 cen.USSR;eEurope,Scandinavia?s 158 134 11- e 55 E = A) In U7 (D Apr 2 19 42-56 Atalante 13.9 2.74 205907 9.3 F8 14 42.4 -32 36 4.6 9 24 32 n. Australia, S. Africa 141 114 6- e125 E ' 7 S 2 " Apr 4 10 03-10 Aegina 12.9 1.84 158864 8.6 F8 14 49.3 -17 37 4.3 12 31 25 n. U.S.A. and s. Canada 149 743 0- none (D Apr 4 18 14 Beatrix 13.8 3.48 92925 9.0 F8 2 21.8 15 28 4.8 3 8 43 s. central Europe 24 26 0+ none 47 22 12+ all g q.qj —lcr:rm Apr 7 16 20 Pa11as 9.1 2.82 130921 8.8 KO 4 02.2 -6 54 0.9 13 8 8 cen. U.S.S.R.?s c-r Jo< ='< (D O Apr 8 18 50 Semele 13.9 3.26 93474 8.4 K2 3 28.6 17 39 5.5 3 8 42 n. Africa, Mediterranean 36 20 22+ all (D cn Q} CD "3 7 66 23 47+ all V Al "· —lea Apr 11 3 33 Aurora 13.2 3.26 58389 8.1 GS 5 41.5 30 36 5.1 7 12 25 s.e. Pacific (Cl "n W (D 60 73 84+ all =¶ A) 0^< ¢·1·.> Apr 15 1 44 Psyche 11.5 3.20 77370 9.1 AS 5 37.2 21 19 2.5 8 11 19 n.w. South America O CD D" 3 ) - O TJ CD ~m O Uj CD Apr 20 3 09-15 Atalante 13.7 2.63 205617 8.7 K2 14 27.1 -32 57 5.1 8 19 31 Iberia?s; maritime Canada(1ow) 157 23 99- all CD {D G "S 81 119 96- e165°W ~ E C-F O Apr 21 6 48-52 Ceres 8.5 2.52 60300 8.8 GS 7 40.2 30 25 0.6 48S15 4 w. central Pacific; Hawaii?n CD "p~CD -h7 > 158 60 56- e 55 E In C-P · Cl. O = con Apr 26 19 45-55 Uranus 5.4 17.88 10.2 15 45.5 -19 37 .17 42m41 1 Australia, Asia, Africa V) = —I "3 j·m ~ · m c-r R' Apr 26 22 30 Egeria 11.2 1.96 209308 8.9 B9 17 46.1 -34 05 2.4 30S34 12 China, India 128 35 55- e 20 W '< C+>O = In = · (n )· C> "· Apr 29 20 01 Vibilia 13.3 3.04 79051 8.3 K2 7 03.0 25 54 4.9 5 12 33 n. Africa; Mediterranean?n 65 125 25- none Jp (D ". cn < A) = O e-r CD a May 4 23 19 Mi nerva 12.0 2.15 190234 9.4 GS 21 16.7 -25 28 2.6 9 15 18 e. equatorial Africa 90 101 1+ none A) O 7 "· CI 7 0.U"CTO Q C-P May 9 8 12 Melete 14.0 3.13 97880 8.9 FO 8 28.7 12 55 5.1 7S18 32 Pacific Ocean; Hawaii?n 78 9 33+ all CD U7 "·= = r+=" 145 129 46+ w170°E = cd c-pen In =(0 May 10 12 18-27 Neptune 7.9 29.44 13.9 17 33.8 -21 57 .49 45m58 1 Pacific Ocean, Australia m u In {D (D A) < -b.Cj O May 10 22 39 Pa11as 9.0 2.94 131847 6.2 GS 5 08.4 -2 19 2.8 11' 7 8 Brazil; n.Chile, n.1\rgentina?s 36 67 50+ all C-F m O m P—I U" (D m·=w CD · cn May 11 18 15 Daphne 12.2 2.02 10.6 F5 20 56.8 0 18 1.8 ]4 19 14 s.e. Austra1ia?n; New Zealand 94 157 59+ none J CD = m (D —hO "5rp· ""S May 13 7 08 Arethusa 13.4 3.56 95447 5.3 B9 6 12.5 16 10 8.1 4 9 31 central Pacific; Hawaii?n(1ow) 42 77 73+ al] O =CQ .>~>< W V) CD ~ '< · R' May 14 7 51 Alexandra 13.6 3.60 11.3 K5 7 42.9 22 02 2.5 6 13 29 Alaska, n.w. Canada?n 61 68 81' all C+ m C-P Qj u "· O "· May 17 11 02 Be11ona 12.9 3.30 146428 8.9 A2 22 56.9 -6 53 4.1 5 15 44 s.e. Pacific; s. Chi1e?s 73 124 98+ W 85°W In '< a. = -5 D 70 120 99- all r+ Jp = n a" » May 20 0 20 Patientia 12. 5 3. 20 10.3 A2 8 55.6 29 58 2.3 11 13 17 Newfoundland; Canary Is1ands?n CD O a- a ? 3' " May 21 7 38 Be11ona ]2.9 3.25 146472 9.2 KO 23 00.4 -6 38 3.7 5 16 43 n. South America 76 79 95- all 2:5= :E 7w G) "· 7 O "· CD ~ May 22 1 5 33 Irene 11 .8 2.86 165440 7.4 KO 22 58.8 -14 32 4.4 8M6 27 Papua,Queens1and?s ;s.w.Pacific 81 60 88- ail m. c·r(0 n :E (D 159 39 75- e115°W O C-F = A) May 24 8 17-23 Neptune-R? 7.9 29.33 14.8 17 32.4 -21 55 .09 38m49 1 Yjestern Hemisphere O = Cl G "· 7 n CD O C^T3 I) " May 26 0 32-41 Hesperia 12.7 2.79 163084 8.9 F5 19 50.8 -70 14 3.8 23S71 37 south,ern Africa 126 29 59- e 15 hi n a ~· W ='< C SJPTJ :3 (D May 29 12 48-56 Parthenope 10.2 1.50 163352 8.6 KO 20 10.4 -17 2 1.9 65 101 14 s. Pacific 126 71 22- e145 Id ~-5 eccl onE -h a: CI c-p "· Ai Aj May 30 20 07-25 Hestia 11 .7 1.58 159945 9.0 AO 16 26.8 -18 08 2.8 12 22 17 Indonesia, equatorial Africa 176 144 10- (d Ere") (n < c-F a O C-F O Jun 5 3 02-22 Antigone 10.2 1.39 142674 6.7 NB 18 47.6 -7 58 3.6 20 41 18 U.k.?s;s.e.Canada;s.e.U.S.A.?s 148 164 10+ W 80 Id ~0 "· O c-r "· = 7 60 22 16+ 3 35 W ej 3 = =0 in Jun 5 23 43 Patroclus 16.5 6.29 61509 9.3 KO g 25.6 36 29 7.2 6 17 57 Chile; n. South America?n = ' :2 ? & jun 7 5 48 Ate 12.8 2.67 98622 8.9 KO 9 28.4 12 05 3.9 5 10 25 south central Pacific Ocean 65 4 28" all
( .I G ( (
p vi ~C-FU) =VJ MINOR PLANET MOTION S T A R STELLAR DIAMETER COMPARISON DATA APPARENT g "S ~·'< ='e O CD DATE Nq, Name km-diam.-" RSOI Type °/Day !!A SAD No DM No. D M.': I! Time .Bf. S AGK3 No 'Shift Time RA. Dec. : &Ec.9 ms S; "· Rj C CD Gu Ci 1980 ~0 Cl c-rm w s) ~ = CT "· "· T (D CD Dec 11 Jupiter 140904 34.79 0.125 112°138820 -01 °2677 0.07 294 14 0.6 X S 1°1673 -0!'37 A'4 12h29'!'3 -1°50' = (n O C-F" p (n
an early I.T.A. orbit. Improved orbits = CD "· W W 1981 E 7 CD =0 "· CD "S "P u In jan 5 86 Semele 113 0.07 377 C 0.273 59 109752 +03 174 0:11 173 10 0.6 P N 3 143 0.28 -0.1 1 13.7 3 41 ) X Al cn m O ) "· = ~ U" jan 8 44 Nysa 68 0.06 152 E 0.]91 102 119165 +02 2505 0.15 169 18 0.7 X N 2 1540 -0.23 0.5 12 00.0 I 59 U7 CL · P ) e+ O c-r —4 7 '< = jan 23 41 Daphne 204 0.10 783 C 0.551 86 160962 -12 4884 0.50 1017 22 3.1 S 17 58.1 -12 08 G) In Gn · (D W CI Ap J>CJ.:E c-r Jan 26 365 Corduba 107 0.08 350 C 0.139 42 11)635 +04 644 0.35 484 61 1.8 S N 4 422 -0.35 -0.6 4 08.9 4 20 E Q" e ' d' 2 -A Jan 28 Mercury 4880 6.20 4308 1.440 63 164713 -]4 6149 0.55 434 9 2.1 P 21 52.2 -13 39 "" 3?S."U Feb 1 18 Melpomene 148 0.06 556 S 0.463 87 ]61626 -16 4936 0.05 106 2 0.3 S 18 33.7 -16 09 !£=e 7? 3g Feb 1 Neptune 50184 2.24 0.027 92 KMN 27 0.12 2777 108 2.5 H 17 34.5 -22 00 = LO CD C-F C-F "S Feb 5 93 Minerva 170 0.08 680 C 0.474 89 187067 -2915159 0.12 258 6 0.7 X 18 36.7 -29 41 " '~·" CD In = in Cid E CD Feb 12 9 Metis 168 0.08 742 S 0.296 101 184474 -19 4382 0.26 522 21 1.6 X 16 33.8 -20 05 m"mn =n (d mw O CD O < < Feb 18 89 julia 168 0.08 586 S 0.554 63 +03 4842 0.07 144 3 0.4 A N 4 3129 23 14.5 4 39 =CD 3 "S = "MD Feb 24 55 Pandora 185 0.08 962 CMEU 0.281 100 185534 -2813325 0.53 1213 46 3.5 X 17 34 .6 -28 56 "BE " =:: O "S c-FTj V) = Feb 26 95 Arethusa 168 0.09 780 C 0.207 85 94045 +15 663 0.46 854 53 2.7 X N15 394 0.15 -0.2 4 37.2 15 29 = "· (D (D r'r ~ "· m a.w CD CD = Mar 6 54 Alexandra 177 0.09 985 C 0.055 197 79033 +26 1447 0.38 725 165 2.3 X N26 759 0.03 5.1 7 03.1 26 12 C_d ¶0 er = < m · m c-r -hO Mar 6 216 Kleopatra 130 0.07 404 M 0.513 76 110447 +09 296 0.16 307 8 1.0 Z N 9 218 -0.45 -0.0 2 15.8 9 42 = E "S "S ~ · =' U":E O < Mar 9 69 Hesperia 108 0.04 498 M 0.254 77 162369 -14 5349 0.09 252 9 0.7 S 19 14.3 -14 35 "i :> m "· S j. ) Cl C-P c-r = Mar 13 11 Parthenope 155 0.09 577 S 0.393 85 161895 -19 5192 0.04 72 2 0.2 X 18 49.6 -]9 41 CO =' U7 "·= C-FCO " "· D =" Mar 19 48 Doris 149 0.10 724 U 0.203 302 118832 +02 2420 A 0.33 505 39 1.8 X N 2 1488 0.15 0.3 11 23.5 2 01 8Ezu:a Mar 25 39 Laetitia 158 0.10 782 S 0.159 314 139976 -02 3855 0. 51 796 77 2.7 P 0.15 -1.3 14 29.7 -3 02 = ~ A) O" Al E Apr 2 747 Winchester 208 0.10 1457 C 0.200 301 100625 +14 2636 0.69 1419 83 4.3 S N14 1386 -0.83 0.2 13 33.4 14 12 cn O m<< m W + + ""S In CP CO Apr 2 36 Atalante 124 0.06 636 C 0.163 255 205907 -3210347 0.10 207 15 0.6 S 14 44.3 -32 44 cn O "0 = c-r = = - O Apr 4 91 Aegina 106 0.08 386 C 0.154 281 158864 -17 4202 0.15 195 23 0.7 X 14 51.1 -17 45 C I CO Ch = Apr 4 83 Beatrix 178 0.05 429 C 0.423 69 92925 +15 335 0.12 305 7 0.8 X N15 207 -0.01 0.6 2 23.5 15 36
Apr 7 2 Pa11as 538 0.26 3620 U 0.492 71 130921 -07 734 0.36 743 18 2.2 S 4 03.7 -6 49 Taylor and by me, gives residuals in declination of In 3 O =m
Apr 8 86 Semele 113 0.05 N17 305 0.51 -0.0 3 30.3 17 45 1977 observations; the earlier I.T.A. orbit, used by "P "· U" [D m 390 C 0.447 73 93474 +17 565 0.43 1029 23 2.9 X e-tun In "S o"
Apr 11 94 Aurora 191 0.08 1017 C 0.297 94 58389 +30 994 0.59 1400 48 3.9 S N30 582 -0.35 0.5 5 43.5 30 37 orbits by Herget and two I.T.A. all satisfy late F In COCO " "S CD "· Apr 15 16 Psyche 249 0.11 N21 548 0.78 0.3 C'FC+< c-r U7 1438 M 0.331 85 77370 +21 922 0.07 153 5 0.4 X 5 39.0 21 20 "· = A] W = Apr 20 36 Atalante 124 0.06 ]4 29.0 -33 06 O (D C-P m 637 C 0.207 271 205617 -3210154 0.39 752 46 2.3 S = "P m Cl Apr 21 1 Ceres 1025 0.56 10832 C 0.283 103 60300 "30 1557 0.22 398 18 1.3 S N30 836 -0.06 0.1 7 42.2 30 20 Apr 26 Uranus 50300 3.88 0.037 283 -19 4222 0.21 2693 134 3.2 H 15 47.3 -}9 43 o"USS W rt· 7k" Apr 26 13 Egeria 245 0.17 1335 C 0.136 197 209308 -3412108 0.05 73 9 0.3 S 17 48.2 -34 05 =" A) CD m " = · Apr 29 144 Vibilia 132 0.06 543 C 0.319 97 79051 +26 1453 0.82 7802 61 5. 2 Z N25 808 0.23 0.9 7 04.9 25 51 OO'bU) >rt· X ~ = · May 4 93 Minerva 170 0.11 679 C 0.291 80 190234 -2515360 0.17 259 14 0.9 S 21 18.5 -25 20 "4(n V) CD "O — G =' · X N12 1043 0.43 -0.0 7 O (D May 9 56 Melete 142 0.06 674 C 0.208 92 97880 +13 1935 0.10 218 11 0.6 8 30.4 12 49 W-hE A) -h May 10 Neptune 50184 2.35 0.021 273 KMN 28 0.29 6291 339 5.9 H 17 35.7 -21 58 A) A) "S CJ May ]0 2 Pa11as 538 0.25 A S 2 1]8 -1.24 -0.5 5 10.0 -2 17 ';g 9<" 3536 U 0.535 78 131847 -02 1161 0.92 1958 41 5.8 O » ~ May 11 41 Daphne 204 0.14 870 C 0.245 59 -00 4138 0.05 75 5 0.3 A N 0 2613 20 58.4 0 25 LLC"? & May 13 95 Arethusa 168 0.07 809 C 0.368 93 95447 +16 1060 0.21 538 14 1.4 P N]6 586 1.19 0.2 6 14.3 16 09 = C-F O" ~ In ~ = "· May 14 54 Alexandra 177 0.07 979 C 0.258 107 +22 1766 0.18 464 17 ].2 X N22 920 0.01 0.0 7 44.7 21 57 MD C-F Q) ~P · = May 17 28 Be11ona 109 0.05 22 58.5 -6 43 V) O C.. Q. 464 S 0.239 74 146428 -07 5902 0.06 149 6 0.4 P -0.07 -0.2 7 m Aj May 20 45] Patientia 281 0.12 A N29 1008 8 57.4 29 51 = » CO A) 1827 C 0.273 Ill +30 1798 0.03 75 3 0.2 O ~ · "S ~ May 21 28 Be11ona 709 0.05 463 S 0.229 74 146472 -07 5918 0.24 563 25 1.6 X 23 02.0 -6 28 c-f U'i (D in · ~ (D O May 22 23 00.4 -14 22 cn m Co 14 Irene 155 0.07 715 S 0.235 80 165440 -15 6325 0.70 )448 71 4.3 S O m E m ¢= V) "P m May 24 Neptune 50184 2.36 0.025 273 KMN 29 0.62 13146 601 12.3 H 17 34.3 -21 57 G) = C-P u' May 26 69 Hesperia 108 0.05 503 M 0.055 306 163084 -10 5210 0.12 233 50 0.7 S 19 52.5 -10 09 =5&=m May 29 11 Parthenope 155 0.14 20 12.2 -]6 56 Al · O "S U? 560 S 0.053 93 163352 -17 5901 0.40 433 181 1.8 X W E CD = · CI CD May 30 46 Hestia 133 0.12 512 C 0.239 281 159945 -17 4585 0.05 59 5 0.2 P 0.12 0.5 16 28.6 -18 12 —IE CD m. Jun 5 129 Antigone 113 0.11 358 U 0.134 257 142674 -08 4726 19.36 19496 3476 83. 9 P -0.65 0.9 18 49.3 -7 56 U) = —b = S {D m rF U ~ Jun 5 617 Patroclus 159 0.03 1508 U 0.150 127 61509 +36 1964 0.23 1040 36 2.1 S N36 923 -0.35 0.2 9 27.5 36 21 n " Jun 7 111 Ate 156 0.08 606 C 0.386 709 98622 +12 2049 X 0.35 668 21 2.7 X N12 1148 0.17 0.6 9 30.1 11 56 (D ~1 118
0!'4, five times smaller than those given by the ne's orbits become apparent only when the asteroid other orbits, which say that the June 5th shadow of is closest to the earth near opposition in mid-1981. Patroclus will miss the earth's surface by 4!'5 or 21,000 km. Some recent astrometry is needed to The occultations by Uranus and by Neptune were found clarify the situation for Patroclus, as well as for by Arnold Klemola, Doug Mink, and jim Elliot by Tablesome of3 the(p. other120). largeThe differencesephemeris disain ?18)reementsMelpome-in scanning Lick Observatory plates. Their results for events for 1981 through 1984 will appear soon in the Astronomical jour- nal; I thank the au- thors for providing me with preprints. The central dura- tions for these e- vents usually are given in minutes ra- ther than seconds, ~cqo
Scandinavia?s; s.e. Canada ¢T3m cUM Q) CJ CI Cl. qj co m O -Q qj tv · CU = 24, also marked with ' "R?," is in the same category. The May 10 Neptune event is very favorable, and the one by Uranus on April 26 is the sec- ond best by that planet during the four-year interval covered by Klemola, Mink, and Elliot. A map showing my predicted paths of asteroidal occulta- tions during 1981 in the U.S.A., southern Canada, and northern Mexico will be pub- lished in the 1981 january issue of Sky 119 and Telescope [Ed: Actually, it does not appear in are being computed by joseph E. Carroll, 4216 that issue]. A similar map of the U.S.S.R. has been Queen's Way, Minnetonka, MN 55343, telephone 612, prepared and sutmitted for publication in a Soviet 938-4028. I recently supplied him with input data journal. Maps and finder charts for the early 1981 for the 1981 events, and we plan to compute and dis- events will be published in the next issue of o.n. tribute these predictions to everyone on the IOTA mailing list. If you want predictions for a differ- As noted in the last issue, local circumstances of ent station(s), send coordinates to joe Carroll. asteroidal and planetary occultations and appulses The local predictions are planned to supplement the data given in the I— - tables in this arti- = , #¢m'o i— g)~ r^rjr·.=Lc^cjLcjm~jm-~Gm=mw^m-Lnm¢ncn^mmmmonj~_mc'joc\jc")oc"^c)om~om·cno~~ b marker. The tape can be developed and measured to crucial step towards making a successful observa- obtain ofoi accuracy. Those using digital recording tion. A good, well-aligned finder scope consider- systems, if not otherwise synchronized to a clock ably facilitates this job, but the process of star accurately calibrated with time signals, can do the hopping can still take a considerable amount of same if a tone generator can be added to the circuit time if there is no bright star nearby. Those whose to beep when the digital data collection is started telescopes have setting circles can usually save and stopped. Records of the star and asteroid time by using them after lining the polar axis with brightness should be made before the objects merge the celestial pole to within a fraction of the dia- so that any drops after they merge can be checked meter of the field of view of the finder. The ap- for proper level. parent (of date) coordinates of the star are given in the 2nd table for this purpose. The telescope Table 3. Large Ephemeris Differences for 1981. then only needs to be pointed to a bright star in the approximate part of the sky where the asteroid Aster- is located, to set the right ascension dial (or to Date oid# Shift At Notes use the difference of the right ascensions of the bright star and the one to be occulted) and to check Feb. 5 93 0':50N -0'!13 the declination. The coordinates of some bright Mar. 13 11 0.705 -].6 stars for this purpose can be obtained from the nat- May 4 93 1.02N -1.0 ional almanacs or from sources such as the yearly May 9 56 0.015 "4.3 Handbook of the Royal Astronomical Society of Cana- May 22 14 0.54N -1.3 da. To make it unneccesary for o.n. subscribers to May 29 11 0.26N -26.9 Motion very slow go to these other sources, a list of the 1981.0 pos- June 5 617 6.44N "7.4 Herget - ITA, see above itions of several bright stars are given in conveni- june 13 88 0.495 "0.4 ent form in Table 4. Most of the stars are first July 2 31 0.495 "13.] magnitude, but a few far from the ecliptic have not Aug. 7 18 1.40N -2.3 E.M.P. 1980 been included, and a few fainter zodiacal stars are Aug. 7 18 2.025 "3.9 Earlier I.T.A. included in parts of the Zodiac devoid of first- Aug. 20 409 3.985 -68.6 See discussion above magnitude stars. Since annual precession amounts to Aug. 27 105 1.47W -].7 E.M.P. ]980 50", the table can be used for a few years to an Aug. 27 105 0.98E +0.0 Earlier I.T.A. accuracy of a few minutes of arc. Sep. 4 18 ].50N -2.1 E.M.P. 1980 Sep. 4 18 2.125 "3.4 Earlier I.T.A. Table 4. Positions of Some Bright Stars for 1981.0 Sep. 20 14 0.50N "2.4 oct. 5 105 1.54W +0.7 E.M.P. 1980 Star R.A. Dec1. Oct. 5 ]05 0.25E -1.0 Earlier I.T.A. . Nov. I 471 2.03E -1.7 E.M.P. 1980 - early 11- B Ceti Oh 42'!'6 -18° 05' Nov. 28 624 0.125 "27.8 Hamal 2 06.1 +23 22 Nov. 30 471 4.03N "6.5 E.M.P. 1980 - early IK Aldebaran 4 34.8 +16 28 Dec. 5 40 0.075 -3.3 Rigel 5 13.6 -8 13 Capella 5 ]5.3 "45 59 Paul Maley describes effective methods for visual Betelgeuse 5 54.1 +7 24 observations in his article on p. 396 of the 1980 Canopus 6 23.5 -52 41 November issue of Sky and Telescope. Most import- Sirius 6 44.3 -16 41 ant is learning to find the star several hours, or Castor 7 33.4 +31 56 days, before the event. The records of this year' Procyon 7 38.3 "5 16 events emphasized the importance of quick reflexes Pollux 7 44.2 "28 04 Reaction times estimated by those who had timed fe» Regulus 10 07.4 +12 03 or no previous occultations were invariably short, Spica 13 24.2 -11 04 by over a second in some cases. Valuable experi- Arcturus 14 14.8 +19 17 ence can be gained by timing some Lunar events. cl Centauri 14 38.3 -60 45 " Antares 16 28.2 -26 23 We have stressed previously that observations shou"·i Vega 18 36.3 "38 46 be made from closely-separated pairs of stations t. Nunki 18 54.1 -26 ]9 obtain independently-confirmed timings of secondar, Altair 19 49.9 +8 49 occultations. Such observations would be strength- 0 Capricorni 21 46.0 -16 13 cried if the observers in a pair are separated by e- Fomalhaut 22 56.6 -29 43 nough distance :·ic·rCr the direction of motion of the shadow on the ground"to produce a time difference Of" Notes about Tndividua1 Occultations. two or more seconds. The motion of the occulting object can then be approximately determined to see 1980 Dec 11: This event will occur before subscrib- if it matches that of the asteroid. The direction ers receive this issue, but is included here since, parallel to the predicted asteroid's shadow path can as far as I know, it hasn't been published else- be estimated from the regional maps, while the mini- where. A preprint of this information is being sent mum desired distance, generally varying from about 5 to potential photoelectric observers, who have per- to 30 or more km, can be calculated from the separa- haps the only hope for obtaining useful data. In- tion of the equal time lines on the maps. For some formation about this occultation has also been dis- events with rapid motion, this becomes impractical; tributed by the Asteroid Intercept Radio Net. The stationing observers within 1 or 2 km of the same occultation of the star by Jupiter, which is nearly path becomes difficult for distances of about 50 km central, will not be observable due to the faint- or more along-track. ness of the star, but those in North America might see the star's light fluctuate when Jupiter's ring Locating the proper star to be occulted is the most passes in front of it sometime within the 45 minutes 121 preceding the disappearance (the tm j 26 (=) SAD 11 1633 star will be well south of the DIAFETER 107 m = C[Cl8 ring at emersion). Since material seems to be concentrated towards 35.ci I ·CO the outer edge of the ring, the O:B - G U star's light should be dinned rap- % idly when it first reaches the . h , e ring, then slowiY brighten as it °" .~"u_ o Z passes to the thinner inner por- jyt\" tions. Variations in the star's p light may reveal fine structure , within the ring. The star will L as Cl ,; ' (. 7, SAD shift) is assumed. The Dc? . 0,· , 4 e ring disappearance will occur "s" 'Q Oy 0 1·?. · ·' earlier at more southerly loca- , " Y r " " d , 0 , tions. M. I.T. astronomers plan " %d ° :Et "" - " P ," · m 0 9 · ' to monitor the event with the " ° o " (f)uo " ." 0 Kui per Al rborne Observatory "5 - " E 0° , " g " + , taurus . 0 near Panama. Doug Mink called ·1' % a , " o el) ° 0 ": ¶ 0' the event to my attention, but G O q · · d ' said he did not find it him " iiic35N J ° " · " . " + . self, and did not know when I '4 _ b " " C " , !'0 " " · asked how they learned of it " " , , 3 d · " " ' + " . C + ' e e " 1981 Jan 28: The star is µ . S cl . + 0 · Capricorni. Mercury' s 6:'2-di - ".' - , c " ° " S " " «"V " ameter disk will be 72% sunlit: 2 I? , (S " : . : ·'5 40, the dark-limb disappearance " r " " ' 0 P would be easy to observe except , , D for the small elongation from '2' ' "- " ", " c.::-' " '"", ""=". ' : " . ;q'" u it: 'S S < 3_ .4k L" /"·a" . j ' <. the sun. The reappearance " " _ , , . might also be observable since '981 jm 26 (365) cordubr sad 111635 0 . " Mercury' s surface brightness is less than the moon's; its light does ncit appear con- elongation less than 70°, useful last-minute astrom- centrated in a point like an asteroid's. My pre- etry to make a good prediction is impossible. How- dieted southern limit is just south of Hokkaido, ever, since (2) Pa11as is suspected of having a big where the occultation will occur only a few minutes sate11 ite from speckle interferometer observations , after sunset. some attempt to record a possible occultation might be made. Mar 19: SAD 118832 is the visual double star A.D.S. 8150. The 12th-magnitude companion, 1!'8 away in po- May 10, (2) Pa]1as: Although the solar elongation sition angle 75", may be occulted by (48) Doris in is small and the path location quite uncertain due Hawaii. But the nearly full moon only 7" away will to differences in the star's position, a large ef- hinder observation of even the primary star. fort may be worthwhile since the star is bright and since Pa11as may have a large satellite. Apr 7: A 1'.'0 south shift is needed to bring the path for this down to a region northwest of the Cas- May 13: SAD 95447 is 72 Orionis. pian Sea, but even there the combination of twilight and low altitude will make observation very diffi- June 5, (129) Antigone: This probably is the most cult. In case of a smaller south shift, putting the interesting asteroidal occultation of 1981 since SAD path farther north, the twilight-altitude situation 142674 is the irregular red variable star S Scuti. would be worse. For events like this with the solar It could be as faint as 8th mag., still bright e- 122 q I t -- nough for relatively easy observa- W tion. The star's anqqular diameter may be nearly 0'.'02, /6 that of j ,1 : " K?K 7'}5- Antigone, so even a central disap- 4" ' !l " ' f rj pearance will be gradual, lasting Q / , ¢ , over 3s. At the path edges, there L - , ¢ f. F . " f. F ) will be partial occultation zones I? perhaps 35 km wide. Visual ob- "j ' I"I-' " 1 servers should note start and end t · : of gradual events; photoelectric '"' t , ,,l,,j' observations are encouraged to I provide quantitative measurements. ^""' ? , , m Nov 17: The star is Nunki ((j Sag- \"\. \ 'T \ " t- :' "" / /(1" ittarii). Venus will not occult T another star this bright until it covers Regulus in 2044. This oc- SAD 1]1635 by Corduba 1981 jan 26 SAD 164713 by Mercury 1981 Jan 28 cultation of Nunki will occur aft- er sunset in eastern Africa, southwestern Asia, and eastern Eu- ? T """ 3" e rope. Venus' 27"-diameter disk will be 46% sunlit. Observers at the center of the occultation path will be able to see a spectacular -"¶i', ,., central flash in the middle of the )-:/'1 ""|:""Lj> occultation. Venus' spherical up- [,, ":, "2 d ___,~, ~' -" per aunosphere will focus Nunki's light so that it will appear as a '' X \[a"':\,-A" 2>: ' ring of light around the planet, , , .' .' "7"- . % ' 't L— ' -" "" ' " 'tb'- " ' "" V ' visible on the dark side. This ' "L '·., i- L a , P ."' i-R!Lj"":x,:' phenomenon was first observCd by \\ '", ' ". —Sc- -:- , " FZ'"""' ' r'j "^:" '' .'p ","7""µ-j" ·' / / ,·" the Kuiper Airborne Observatory during the occultation of e Genii- ' '-'""= 4zz?g'"'" 'jji::g(>"'""-"· "~:A %-'L>//_==" norum by Mars in 1976; it should be quite pronounced at this event ';.a'j 16]626 by Melpomene 1981 Feb KMN 27 by Neptune 1981 Feb 1 due to the negligible departure ot Venus' shape from a sphere. The central occultation line is ex- . . ,- =E" 1"^ J\jj;;,, pected to cross Ethiopia and So- --— , :p .L.' malia; farther west, for example .,..."E'7i ->"" ""¢= · . in northern Brazil and western e- · .' --"--"""$";f " "4- *"-', .:_" quatorial Africa, daylight may ·"'""iP""·'"" r ^'" - -K·-- -'-Aa -, , (to be continued, next issue) DM +03 4842 by julia 1981 Feb 18 SAD 185534 by Pandora 1981 Feb 24