OcMtmbn@Newstelter

Vo) ume [I, Number 2 February, 1979

The Oc.cU|tdt|on Newsletter Is published by the International Occultation Timing Association (I.O.T.A.) tdftor and Compositor: H. F. DdBoll, 6 N 106 white Oak Lane, St. Charles, Illinois 60174, U. S. A. Please senc1 editorial matters to the above, but send matters of circulation, address change, requests, back Issues, and all other IOTA business to IOTA, P. 0. Box 596, Tinley Park, Illinois 60477, U. S, A.

FROM THE PUBLISHER as. Some of this material, especially available. Since it won't be possible a list of the plans and addresses of even to begin the catalog work until For subscription purposes, this is the several IOTA members who are leading mid-March, the extended-coverage pre- fourth and final issue of 1978. path-edge expeditions for coordination dictions for 1979 likely will not be of observations in various areas, has distributed until April or even May. o.n.'s price is $1/issue, or $4/year been sent separately to to subscribers This means that we will miss the March (4 issues) including first class sur- who live in the western half of Canada 4th Hyades passage which is so favora- face mailing, and air mail to Mexico. and in the western and north-central ble for NOrth America, the March 13 Air mail is extra outside the U.S.A., U.S.A. If this information has not deep partial lunar eclipse in the Canada, and Mexico: $1.20/year in the been sent to you, and you are inter- Eastern Hemisphere, and the favorable Americas as far south as Colombia; ested in observing the eclipse frOm northern Milky Way passage in early $1.68/year elsewhere. Back issues also near the path edge, telephone me at April. Disappearances still can be are priced at $1/issue, Please see the 301, 585-0989. Two new addresses timed during these events without the masthead for ordering address. should be noted: Paul Asmus, 4655 S. aid of predictions, and postdictions Zang St., Morrison, CO 80465, phone can be computed to help with the iden- IOTA membership, subscription includ- 303, 978-0321; and Berton Stevens, tification of any non-X-catalog stars ed, is $7/year for residents of North 2112 E. Kingfisher, Rolling Meadows, whose occultations are timed. America (including Mexico) and $9/year TL 60008, phone 312, 259-2107. Pay- for others, to cover costs of overseas ments, change of address, and other There is a substantial amount of in- air mail. European (excluding Spain IOTA business should be sent to IOTA'S formation about new double stars from and Portugal) and U. K. observers post office box in Tinley Park, as various sources, but publication of it should join IOTA/ES, sending IN 10.-- given in the masthead. will have to wait for a future issue to Hans J. Bode, Bartold-knaust Str. of o.n., to be distributed in late 6, 3000 Hannover 91, German Federal The occultation by Melpomene, includ- March or Aprf1. An article on grazes Republic. Spanish, Potuguese, and ing the prediction phases. the data is long overdue, but it also will be Latin American occultation observers collection and organization, analysis, delayed. The 1977 total occultation may have free membership in 10TA/LAS. and continuing preparation of a jour- tally, and the index for o.n., volume including Occultation Newsletter en nal publication of the results, has i, probably will not be prepared until Espahol; contact Sr. Francisco Diego consumed a great deal of my time, dur- after April, after the more urgent Q., Ixpantenco 26-bis. Real dc Ids ing a period when the upcoming solar items mentioned above are handled. Reyes, Coyoacan, Mexico, D.F., Mexico. eclipse had already greatly overex- Some of the o.n. index material being tended my schedule. I hope to make the prepared by others still has not been IOTA NEWS most of IOTA'S contribution, past and received. If you are working on this, future, at a major conference about please try to send it in by early Ap- David Id. Dunham asteroids to be held in Tucson, AZ, in ril, or if this appears not to be pos- early March. Professional interest in sible, let me know as Soon as possible The total solar eclipse of February ?6 satellites of asteroids is increasing so that another volunteer can be found is currently the biggest item on rapidly. Consequently, I am making a for the task. IOTA'S agenda. Information about major effort to have the Melpomene re- IOTA's project for obtaining observa- sults, and asteroidal occultation pre- David Herald reports that the Southern tions of 2nd and 3rd contact timings, diction data for 1979, in as final a Astrographic Catalog project is virtu- and timings of other Baily's phenaqne- fom as possible by the end of this ally complete. The task of keypunching na, is given on p. 5 of the last is- month. This has completely disrupted the data is progressing satisfactori- sue; on pages 102 and 103 of the Jahu- most of my other IOTA-related work, ly, and Robert Clyde has been doing a dry issue of Sky and Telescope; and in especially that connected with lunar good job of proofreijding lists of the an article entitled "Eclipse Maps Off" occultations; overdue projects are be- keypunched data. Wayne Warren has re- on p. 5 of the 1978 December issue of ing postponed even further. This un- ceived the Algiers zone of the Astro- Astro-Oirectory News (Gall Publica- derscores the continuing vulnerability graphic Catalog on magnetic tape from tions, Toronto). Richard Lfnkletter of my occultation work, as long as it the Stellar Data Center in Strasbourg, has prepared much useful information has no official support and relatively France. As time permits, he and I will about the project arid has done much to little local help. work on the A.C. data, to eventually encourage and organize observations form a vast, comprehensive star cata- from Washington and Oregon. paul Asmus Hardest hit have been the extended- log suitable for asteroidal occulta- is providing IOTA'S service of supply- coverage total occultation predic- tfon searches, but work on the project ing copies of 1:250,000 maps showing tions. Most of the K-catalog stars are will be rather slow. due to the press the predicted path edges to those who included in USNO's X-cataloj, but as of other urgent duties. The large com- send him a self-addressed stamped en- has been mentioned previous y, a few puter runs which will be needed most velope and extra stamps for dupllca- hundred K stars are not in the X-cata- likely will have to wait until USNO tfon and handling. He is also working log. The prediction data for the j- obtains a new computer, which protmbly with Keith Strait and me to prepare a catalog for 1979 have errors which will occur in April. Another tdsk speck) mailing to 150 high schools, need to be corrected, and a new cata- which will require the new computer is 50 newspapers, and 43 te)evfsion'sta- log is needed to include the 1979 Sep- the integration of ephemerides for tfons in cities and towns very close tember 6 lunar eclipse star field and many more minor planets for which dC- to the path edges, in order to encour- Southern Astrographic Catalog project curate orbital elements have become age useful observations in these are- data for the -19° zone. which are now available during the past year. 12

JUNO LARGER THAN EXPECTED; the star's angular diameter would be the ldashington-Baltimore area. Stair- PROBABLE GRAZE BY DISTANT SATELLITE less than 0504 for a central occulta- step events in the photoelectric rec- tion. But for the secondary occulta- ords clearly reveal the star's duplic- David hi. Dunham and Yaron Sheffer tio: , Sheffer mted that disappearance ity. In additicn, a 5.8-second occul- and reappeamnce were not instantane- tation was recorded photoelectrically On July 13, William Penhallow made as- ous, estimated that e:ich lasted about at Ferntmnk Science Center, near At- trometric observations in an attempt OSI. This iinplies that the secondary lante, GA, over 600 km south of the to improve the prediction fOr the July occultation was nt'drjy grazing, so path for the main event. The Atlanta 19th occu)tdtion of Ll-mag. SAD 1440- that he observed a .3-km chord for an record also shows steps attributable 70 by (3) Juno, the path of which was object perhaps 10 km in diameter. to the stellar secondary, giving expected to cross northwest Africa and strong evidence that a large sate1)itE the eastern Mediterranean Sea, accord- Sheffer's secondary occultation occur- of Melpomene occulted the star there. ing to the Perth 70 star position and red four minutes before the occulta- Unfortunately, this and a few other the published ephemeris for Juno, both tion by Juno. indicating a separation reported secondary events have not of which are considered highly relia- of m, or about 3100 km in the plane been confirmed by observations at oth- ble (see o.n. i (14), 144). Conse- of the sky at Juno's distance. This is er stations; no other stations so far quently, Dunham was amazed that Pen- the largest distance of a satellite known, have been close enough to the hallow's data indicated a 2:'1 south from a minor planet observed during an tracks for the observers reporting the shift, moving the path down to Brazil 0ccu)tdtion, showing that these ob- secondary events to have a reasonable and central Africa. IOTA sent a tele- jects very well might be completely chance for an occultatfon by the same gram to Jorge Polman in Recife, asking separated from the primary via direct satellite. This underscores more than him to notify other observers in Bra- earth-based observation. The observa- ever the need for observations from zil, but he was oUt of town and did tion for this particular satellite pairs of stations a few kilometers not return and read the telegram until would be difficult, since its magni- apart. Nevertheless, the evidence from the day after the event. Later, cor- tude was probably about 17, while Ju- this occultation, as well as from Her- rection of a computer error, which af- no's magnitude was 9.4, but it would culina and the nwierous isolated ob- fected only southern declination cal- be reasonable to expect larger, servations from other occultations, culations, showed that the shift brighter satellites whose direct de- leaves little room to doubt the idea should have been ):'1 south. But the tection would be easier. The satellite that most minor planets have many sat- corrected value turned out to have is well beyond the point where the at- ellites. considerable error, since 6 days be- traction by Juno equals the attraction fore the event, Juno and the star were by the sun, about 1400 km or 1:'1 in Observations of the Occultation by near opposite edges of Penhallow's this case. Satellites noted during Melpomene. I was elated to join the plates; apparently, a separation of 1° previous asteroidal occultations have ranks of less than }00 observers in or less, as was obtained for Herculina been near, Or less than, this dis- the world who have seen a star occult- on June 5, is needed for accurate re- tance, although we can not be sure ed by an asteroid. It seemed a just sults. But cloudy skies prevented Pen- since the third dimension, distance reward for the hard work I had done to hallow from obtaining plates closer to from the observer, is unknown. The Ju- organize for the event locally and na- the time of the occultation. no satellite, like the earth's moon tionally, to publicize the occulta- and several other solar system satel- tion, and to verify that what I felt Gordon Taylor was more fortunate, ob- lites, shows that the true radius of to be the best prediction (indicating taining a plate at Royal Greenwich Ob- the sphere of influence is not deter- that the event probably would occur in servatory four nights before the mined by the ratio of the attracting the Washington area) was actually event, when Juno was 53' from the forces, which are inversely propor- best. The change in the combined star. His path showed a 0!'2 shift tional to the square of the distance, light, a drop of over a magnitude, was south of the nominal prediction, which but is determined by the ratio of the startling as seen with my 25-cm re- turned out to be very accurate, and tidal forces, which are inversely pro- flector. I was even more amazed to no- more in line with expected accuracies portional to the cube of the distance. tice a second small drop half a second for the Perth 70 star position and Ju- The true radius of the sphere of in- later; I remarked that the star was no ephemeris, although the time he fluence, as calculated from the theory probably double. The duration for the predicted was just over two minutes of motion of three bodies, is actually primary's occultation was 1255 at my too late. His path crossed Israel, so 94,000 km or 71", far beyond the ob- site near Phoenix, MD, about 25 km he telexed data to the Wise Observa- ject seen by Sheffer, for juno. The north of Baltimore and on the 0'.'20 tory there. They could not spare their radius of the sphere of influence north shift line on the map on p. 8 of own telescope for it but they were go- changes as the distanc. from the sun the last issue. Joan Dunham and Fred ing to inform local amateurs. Unfortu- varies, but is never less than 60,000 Espenak saw an occultation lasting nately, no observations are known to km, probably much greater than the just over 145 seconds near Columbia, have resulted from this effort. distance of Sheffer's satellite. Fu- MD, at 0!'16 north. IOTA member David ture asteroidal occultations perhaps Skillman, using digital equipment Yaron Sheffer, at Kfar-Saba, Israel, could be observed profitably from the which he designed and assembled after alerted to the event by Dunham's arti- entire nighttime area of the earth regular working hours, recorded a cle on occultations in the 1978 Janu- facing the star, at least for very fa- 15.96-second occultatfon with a 31-cm ary issue of Sky and Telescope, made vorable events. reflector at Goddard Space Flight Cen- the only known observation of the oc- ter's Optical Facijity, near Belts- cultation. Observing under excellent Marco Cavagna, near Milan, Italy, also ville, MD, at 0'.'144 north. Unfortun- conditions with a 6-cm refractor, he watched SAD 144070, but he was far ately, the 92-an telescope there was timed a )957 occultation starting at north of the occultation path and saw oUt of order. Mfchae1 A'Hearn record- 23hOlm20S5 UTC. This gives a chord no fading of the star. Hans-joachim ed the event photoe1ectrically with a length of 256 km, several kilometers Bode distributed information about the SI-cm telescope at the University of larger than the diameter expected from event to many European observers, most Maryland's observatory In College infrared radiometry and polarimetry, of whom apparently had cloudy skies; Park, MD, at 0!'139 north; this was the so that the occultation was apparently no observations of secondary occulta- third occultatlon of a star by a minor nearly central at Kfar-Saba. Four min- tions or fadings have been received planet which he recorded during 1978! utes before the main 0ccu)tation, the from them. Thomas Van Flandern and Richard star disappeared for a quarter of a Schmidt recorded the occultation pho- second. Sheffer is confident that it DUPLICITY OF BOTH (IB) MELPOMENE toelectrically at the U. S. Naval Ob- was not an atmospheric effect; during AND SAD ))4159 DISCOVLRED DURING servatory at 0!'127 north. Bob Bolster the 20-minute observation period, the OCCULTATION recorded the southernmost chord visu- star's )ight remained very stable, ex- ally at ISSI from Alexandria, VA, at cept for the two 0ccu)tations. [mer- David Id. Dunham 0!'11 north: The next known observer sion and emersion for the occultation north of Phoenix, MD, was Emil Vol- of Juno appeared sharp, as would be The occultation of SAD 114159 by (IB) check at West Chester, PA, at 0!'26 expected for visual observations. The Melpomene on December 11 was success- north; he had no occultation. Similar- time expected for a noticeable fade fully timed by four visual observers ly, Larry Dunke1man saw no occultation due to Fresnel diffraction enhanced by and three photoelectric stations In by Melpomene at his site near Lady- 13 smith, VA, at OUR north, the next Om of 0.3 (the asteroid would be three curve near the center of the event, as successful observer south of Alexan- times as bright as the secondary). I if the secondary rea??eared briefly, dria. was able to see this change visually but it could be noise. Such a "flash" due jj t"2 gocj seeing and the fact would be possible if the satellite The Size and shape of Melpomene. The that it occurred soon after the pri- were a coalesced pMr of objects, each maximum observed chord was }32 km at mary disappeared. In general, I prob- nearly ?5 km in diameter. The primary the Goddard site. The mean diameter is ably would not notice such d small star t;,uu1a then be occulted by nearly probably near 135 km, about 10% smal- change. The secondary probably reap- the long axis of the two objects, ler than expected. Departures from a peared at my site while the primary while the secondary star would cut a spherical or elliptical shape, accord- still was occulted, but I did not no- northern path, reappearing briefly in ing to the photoelectric records, are tice such an event. In the USNO and the gap between the two objects; see at least a few kilometers, although University of Maryland records, the the diagram below (a noisy secondary the three photoelectric chords are secondary had about one fourth the in- occultation in Reitsema's photoelec- rather closely spaced. If al] of the tensity of the primary. The color re- tric record of the May 29th occulta- observations except thoSe near. Colum- sponse for the photometers used there tion by Pa11as may have a similar ex- bia are considered, the outline is is not yet known, so the difference planation; note also the quick double roughly circular with irregularities frOm Goddard could be due to a differ- events described by Poss and Noltheni- of nearly ten kilometers. Since the ence in the colors of the stellar com- us below). The sky was about 75% cov- motion was 8 km/sec., the visual tim- ponents, which probably are of differ- ered with thick cirrus at the time; ings should be accurate to 3 km or ent spectral types. One fourth inten- Williamon was fortunate to have a better. The observations at Columbia, sity corresponds to Dm = 1.5 or com- break in the clouds for several min- when compared to the others, imply a ponent mags. of 8.6 and 10.1. In this utes around the time of the event. But very irregular shape, with a 20-km- case, an occultation event of the sec- other observers in the Atlanta area deep valley on the advancing edge of ondary would produce a ijm of 0.4, if and in northern Georgia were not so Melpomene and a similarly high moun- the primary is behind the asteroid. lucky and, due to the clouds, obtained tain on the other side. Although it no observations which might have con- can not be completely ruled out that The reappearance of the secondary oc- firmed the satellite. Unlike "cloud" the observers may have been 2 to 3 curred 2.5 seconds before that of the events, the level changes for the seconds late in their timings (neither primary at Goddard, but this interval Fernbank secondary occultation are saw both events), the trend of the was only one second at USNO, only 13 sharp. The analysis about the satel- other data does favor a large mountain km away. The difference in time corre- lite given on I.A.U. Circular No. 3315 on the reappearance side. sponds to a similar linear distance. (1978 December 14), where it is desig- Since the secondary was north of the nated 1978 (IB) }, is wrong because The center of the path apparently was primary, it followed a more northerly the stellar components were incorrect- near 0!'15 north, with the central time track behind the asteroid for each ly assumed to be "roughly equal in 4.7 minutes before the nominal times station. Hence, the short chord for brightness." the secondary seen at Goddard is prob- shown on the map on p. 8 of the last SECONDARY issue (hereafter called simply "the ably close to the chord for the pri- map"). The northern limit was probably mary seen visually near Columbia, --- pRIMARY near 0!'23 north and the southern limit strengthening the idea of a large probably near 0!'06 north. If there is dent, or other topographic feature, on any observer who observed either an Melpomene discussed above. occultation Or a miss near this path, who has not yet sent me a report of Skillman notes another small level Atlanta was at about 0!'56 south and his observation, please do so as soon change about 1.8 seconds before the the event was 5.5 minutes before the as possible. According to the National reappearance of the secondary. It is nominal time of closest approach by weather Service and some observers, only about 920 of the drop due to the Melpomene. The star-asteroid separa- clouds prevented observation from the primary. If it is due to the reappear- tion in the plane of the sky was 0?95, path in the Midwest and Pacific North- ance of a third star, it would be 750 km, or 5.5 Melpomene diameters. If west. It may have been clear in Wyo- about mag. 11.8. Van Flandern notes the satellite were a 45-km spherical ming, but as far as I know, nobody at- that a third star may be present in object, it would be about 24 mag. tempted observations there. the USNO record, but noise makes it fainter than Melpomene. This is favor- hard to tell. Due to the unreliable able enough that James Christy (dis- The Stellar Duplicity. There is no drive on the telescope, a 3' diaphragm coverer of Charon) and others at USNO previous record of duplicity for this was used, so perhaps ;:.e level change are attempting direct double star ob- spectral type KO star. In the three was due to a faint, unrelated star servations (One night in late Decem- photoelectric records, the close sec- which passed out of the field. Arnold ber, when the seeing was good and the ondary both disappeared and reappeared Klemola notes that on one of his two Mtitude was about ?0°, well short of before the primary. My disappearance plates, there is evidence for a star cilmination, they visually noticed an observation is the only known visual of perhaps 12th mag. about 2" east of elongated image. They waited for cul- timing of an event involving the sec- SAD 114159, but thinks it may be a mination to try to photograph it, but the seeing had deteriorated by then). ondary star. I was wei) north of the plate defect. Such a star would have Washington area, so the event position been occulted about 3 minutes before The satellite could offset the center angles were very different at my site the primary. With the primary in view, of light from MelWmene by several from those at the photoelectric sta- such an occultation would be lost in hundredths of a second of arc. But if the satellite is a smaller coalesced tions. the noise of even a good photoelectric record. double object, It will be fainter, and A very preliminary analysis of the ob- difficult to detect. servations gives an approximate sepa- Occultations by Secondary objects. ration of the secondary from the pri- Richard ldilliamon obtained the most If there were any observations made mary of 0'.'04 in a position angle about striking photoelectric record of a between O':S south and 0% south on the 30". secondary occultatlon, using d 91-cm map which have not yet been reported, reflector, at Fernbank Observatory, please send them to me, whether posi- According to Skillman's photoelectric Atlanta, GA. The duration for the oc- tive or negative. The south suburbs of data, the primary was seven times as cultation of the primary corresponds Memphis, TN, and the north suburbs of bright as the secondary, giving Am = to a chord length of 48 km, on the Sacramento, CA, are especially well- 2.]. Skillman used an unfiltered IP21 likely assumption that it was caused situated near the path. Larry Wasser- photometer. If the star's total magni- by a satellite of Melpomene. There is man reports the closest currently tude is 8.35, the V-mag. determined by a further drop of about \ the main known observation, negative, from the Rick Binzel, the component magnitudes drop about one second after the disap- University of Oklahoma's observatory, would be 8.5 and 10.6. If the asteroid pearance to about one second before near Norman, OK, 30 km south of the was at minimum, its V-mag. was 9.4, the reappearance, in good agreement Fernbank track, at about 0:'59 south. according to Binze)'$ data. If the with the stellar secondary events in The closest observation I know north primary is occulted, an occultation the USNO and University of Maryland of the path was made by Paul McBrlde, event of the secondary would produce a records. There is a spike in the light Green Forest, AR, at 0':44 south, but )4

one of the portable photoelectric sta- DC area. Seeing variations can't yet plate; to obtain this configuration, tions in Utah or Colorado was probably be ruled out, but the post-emersion no guide star was available. closer to the Fernbank track. McBride "noise" may have been due to a cloud 5. 0!'39 south. A result obtained by timed some short (about 055 duration) of small objects (IQ meters or less) making a straight average of all the blinks, some of which he felt were near Melpomene, which passed over the Flagstaff 33-cm results. Wasserman probably not atmospheric, and one of star (which subtended d few hundred said that a couple of the data points which corre',ponded to the time of the meters at the asteroid's distance). were not in agreement with the linear Atlanta satdilte. However, sInce he This hypothesis might be tested during trend noted above, and felt that a was 95 km north of the Atlanta path, a future occultation by a pair of pho- straight average might be ,ipp1icable. it is very unlikely that the event toelectric stations in line, separated Wd4 part of the Atlanta satellite, but by several hundred meters. They should All dstrometry, including Taylor's it could be an occultation by d small record similar noise structure, sepa- early result, correctly predicted that satellite of the Atlanta satellite. No rated a small amount in time corre- the event would occur from 4 to 5 min- events were noted at the observatory sponding to the motion of the asteroid utes earlier than the nominal predic- of the University of the South, Sewan- occultation shadow, if the hypothesis tion. Bad weather in England prevented ee, TN, which, at 0!'43 south, was Is true. Taylor from getting any "last-minute" close to McBride's path. astrometry for the event. Astrometry. As noted on p. 8 of the A possible two-second secondary qc- last issue, Gordon Taylor issued a I felt that predictions 2 and 3 were cu)tatfon is evident in Howard Poss' prediction based on early astrometry, most likely correct, canceled our ex- photoelectric trace obtained at Am- indicating a 0:'2 south path. The big- pedition to South Carolina, and en- bler, PA, about 0:'29 north and 4.5 gest astrometric effort by far was couraged observation from the DC area. minutes earlier than the nominal time. made by Larry Wasserman and co-workers Klemola's astrometric equipment and Emil Volcheck was the next observer at Lowell Observatory, Flagstaff, AZ. measurements are of the highest quali- south, at 0:'26 north, while Leith Hol- Besides some prelimfnary astrometry, ty; the prediction of the )977 March loway and john Church also saw no oc- over 15 plates were obtained, taken occultation by Uranus using his re- cultation near Princeton, NJ, at om every clear night starting November sults was the most accurate. An aver- north. This is not surprising, since 28th. By December 5, their results, age of the less certain predictions I the path for the Ambler object might obtained with a small-field 33-cm and 4 also strengthened the idea of be only about 15 km lo':oa wide. The telescope and using a secondary net- predictions 2 and 3 being correct. path is perhaps smaller, since the work of faint reference stars tied to Prediction 1 was the latest result, record has three dips during the two SAD positions, seemed conclusive. with the objects closest together; seconds, perhaps caused by two or Their predicted path, at 0:'49 south, past occultations have shown that the three close small objects. was published on I.A.U. Circular 3312, latest results are usually the best. with the statement (audacious and too Consequently, I encouraged observers Richard Nolthenius, Mountainview, CA, optimistic, in retrospect) that "The in the New York City area and New Jer- 0:'76 south) reported two k-second qc- formal standard error in the north- sey to observe (by then, it was appar- cultations, separated by one second, south direction is less than half the ent that clouds probably would prevent Which he observed visually under good track width of about 180 km." I start- observation farther west). But Wasser- conditions, 6.8 minutes earlier than ed to make plans for an expedition to man and I realized it was a new, un- the nominal time for his location. South Carolina. Five observers from tested technique; a small error in Perhaps the events were caused by a the DC area were willing to undertake measuring the star trail could produce coalesced pair of lO-km objects. James the long trip. Dr. John Safko at the a sUbstantial error. Penhallow remark- Van Nuland, observing from a site in University of South Carolina, Colin- ed that his plates were not of the San jose, CA, many km to the south, bid, SC, established a message center, highest quality; we suspected that 1° saw a 052 blink, but three minutes and observers in South Carolina, separation was too much for an accu- after Nolthenius' pair of events. Rick northern Georgia, and westward along rate result (for his good astrometry Baldridge, observing with a a-cm re- the track were mobilized. for Herculina, the objects were r flector at Foothill College Observa- apart). Bad weather prevented observa- tory, 3 km south of Nolthenius' path, On Friday, December 8, the picture be- tion when the objects were closer. reported no occultation, but nobody gan to change. Wasserman telephoned, was that close north of Nolthenius. saying that their most recent astrom- Wasserman and others at Flagstaff de- There are several other visual "blink" etry, when combined with their earlier cided to cover prediction 5. Seven observations, and a few reports of results, indicated a linear northward portable photoelectric stations (2 sudden brightenings where a corre- shift which, extrapolated to Dec. I], from Lowell Observatory, 3 from the sponding dinning was missed. Many of indicated that the path might be in University of Arizona, Tucson, led by these are probably atmospheric seeing the Washington, DC area. Late that William Hubbard; 1 from Cornell Uni- variations, but some could be caused afternoon, Arnold Klemola telephoned versity, Ithaca, NY; and 1 from New by I- to 2-km-sized objects. his data obtained on Dec. 6 at Lick Mexico) were deployed across west-cen- Observatory, CA. My calculations using tral Utah and southern Colorado. Pre- One spike event in USNO'S trace goes his data also put the path in the DC diction 5 was selected partly for ex- down to the asteroid light level, not area. Fifteen hours before the occul- pediency, to minimize travel distance. to the bottom, as would be expected tation, however, the following five The weather also dictated southern lo- fOr an instrumental glitch. A few sim- predictions were available: cations, since overcast skies were ilar spikes, possibly caused by very I. o:'y north. Based on plates taken predicted for central Idaho, and pros- small objects, occur in other traces with the 155-cm small-field USNO tele- pects were not encojmging for more made as far away as Tucson, AZ (t'24 scope at Flagstaff, AZ, on Dec. 9 and distant Wyoming. Also, they realized south). For a period after the reap- 10, U.T. The field was too small to that the northern predictions would be pearance, USNO'S photoelectric record show any reference stars other than covered by established observatories; was about three times noisier than SAD 114159, so only differential mea- the locations they selected filled d usual for several seconds. Tom Van surements were made between it and gap in photoelectric coverage. Flandern noticed the star flfckering Melpomene, using a trailed image of as he observed through the guide the star to determine orientation and The prediction using K1emo)a'$ data scope. Charles Worley, observing with the motion of Melpomene between the (2) turned out to be the best, appar- the 66-cm refractor about 100 meters two nights for the plate scale. ently accurate to within 0:'02! The away, remarked to Tom when they met 2. 0:'16 north. Klemola's result using time also was good to 0.1 minute. The after the event, "Too bad the seeing 10 AGK3 reference stars on a 4"x6" Flagstaff extrapolated prediction (3) went to pot at the reappearance." I plate. was also very good. The data are being also noticed some flickering after the 3. om north. Flagstaff 33-cm extra- reanalyzed with AGK3 reference star reappearance at my site, causing me to polated result. data to see if that could eliminate call out some false (stellar) second- 4. 0!'16 south. Based on two 2-minute the linear trend and give a consist- ary reappearance times (knowing that unguided exposures by Penhallow at ently accurate postdiction. The very the star was double at disappearance). Quonochontaug Observatory, RI, on [kc. last astrometric observations, double Similar phenomena may be present in 7. The objects were separated by about star observations (visual and photo- the other photoelectric records in the r, so that both barely fit on one graphic) by Charles kkjrley, the night 15 of the event at USNO, Washington, DC, day morning, most DC-area observers whom I talked by telephone, and the should also be noted. As the night were unwilling to attmpt observations minus 4.5-minute ;7rrection was pub- progressed, kbrley kept remarking to front other i:kan their home locations. lished in the lest issue and in other Van Flandern, "The POSitiOn angle is The good photuc;cctric coverage in the updates which I distributed, but a few not changing!" area made visual obszrvations there still we'it by the time inferred from almost redundant. The iizshington-area the m'p). The need to practice locat- other Observations. Besides the obser- observations covered 35 km, or about ing the star beforehand can not be vations reported above, reports have 26% of the diameter of Melpomene. overemphasized. Variable star and as- been received from many other observ- The observers who traveled north to teroid observers are mom skilled at ers reporting no occultations. These the Baltimore area extended the cover- finding objects in odd parts of the define a large region of space around age to 76 km or 562 of the diameter, sky than are most lunar occultation Melpomene devoid of satellites, at which substantially strengthens the observers. A good finder, and a very least to the kilometer level. The analysis fOr Melpomene's size and low-power (wide-field) eyepiece for "miss" reports which have been re- shape, making it perhaps the best de- the main telescope, help in locating ceived so far are tabulated below: termined for any asteroid, although the star. Know the angular diameter of there are probably more than 70 larger the field of view of your finder and Observer, Locatign Shift Value on Map minor planets. Fortunately, seven of main telescope when various eyepieces the more experienced occultation ob- are used (the moon's approximate T W. Lil)er, Harvard, MAb 0:'59 N servers were willing to travel oUtside diameter can be used for calibration). A. McRobert, Newton, MA 0.58 N the area, so that one station was set Some complained, "they all look the T. Hayward, Oteqo, NY 0.52 N up about 100 km south of Washington, same," or, "the star was in a crowded J. B0rt)e, Stormville, NY 0.46 N and three pairs of stations were es- Milky Way field." But a dense field R. Tuthi11, Mountainside, NJ 0.37 N tablished at the following approximate provides many signposts which should Id. Nissen, Quantico, VA" 0.08 N road distances from Washington: 50 km help identification. Form simple tri- J. Prideaux, Richmond, VA'J 0.03 S south; 50 km north; and 100 km north. angular or quadrilateral patterns to J. Brooks, Chatham, VA 0.14 S Three of the stations failed to obtain move from bright, familiar stars to D. Nye, Longmont, CO 0.21 S data for various reasons (including the star to be occulted. If you have P. Asmus, Denver, CO b f 0.25 S both at 50 km south), and a miss oc- any doubts about locating the star, G. Erickson, Davis, CA ' 0.62 S curred at the southernmost station. He take your telescope to a more experi- R. Bryant, Orinda, CA 0.70 S expected observers at Charlottesville enced observer a few nights before the ?, Chabot Obs., Oakland. CA" 0.72 S and Richmond, VA, to provide coverage event so that he can help you locate D. Wa11entinsen, d to the south, and observers in the the star. Remember that the presence Albuquerque, NM 0.75 S Philadelphia area and Delaware to give of the asteroid may affect the appear- G. Rattley, San Jose, CA" 0.76 S northern coverage (unfortunately, ance of the field (on future finder P. Newman & Rj Pricc» h those in Delaware, near the northern charts, we should indicate the aster- 1arland. TX 0.9 S limit, failed). in any case, Melpomene oid's position 24 hours before the showed that observers with portable event). Some observers easily located I expect that the above list is rather equipment willing to travel to fill in the star around 10 PM local time, but incomplete. In particular, the posi- gaps can make an extremely valuable had difficulty in re-locating it just tions of the portable photoelectric contribution. before the event 6 hours later, when stations are not yet available. I plan the orientation was different; try lo- to publish a diagram, like the one for Unfortunately, most visual observers cating the star at the same time a the Qccultation by Herculina on p. 2 in our area (about 15 others who previous night [Ed: or if you can of the last issue, in a future issue. tried) failed to get observations. The avoid rotating the tube of your New- most experienced occultation observers tonian in its cradle, until after the Lessons Learned Concerning Observing were, in general, the most successful, star has been re-located, the re-ori- Strategies and Techniques. Perhaps the although a few of them also failed. I entation problem will be minimized]. biggest lesson learned is that already notified many observers who live more If you use a refractor, or short fold- mentioned, the need for observations than 25 km and less than 100 km from ed telescope design (e.g., a Schmidt- from pairs of stations to confirm qc- Washington, but all of them failed. Cassegrain), with a diagonal, you will cuitations by small satellites. Ob- Cirrus clouds prevented observation at see a mirror image of the field (one servers need to coordinate more with Fredericksburg, VA. One observer with direction reversed). Such observers others in their areas to arrange this, portable equiµnent was at a critical will find it useful to redraw the im- and to be willing to travel to other location near the snutp'orn limit. The portant parts of the star field on locations to give better coverage for site was near the PoLumac River, whose tracing (or other translucent) paper, the main event. Due to the unseasona- waters were much warmer than the air. and use the back side by shining a ble cold (about -8° C, necessitating Convective air currents from the river flashlight through it. Stockbauer's the wearing of tape recorders under produced such poor seeing that the ob- detailed chart was helpful in zeroing jackets, as successfully done during server was unable to obtain data. in on the star, but some noted that winter grazes) and the fact that the Large bodies of water should be avoid- some of the plotted stars were some- event occurred at 4 AM 1oc?i time Mon- ed during cold weather, unless a sub- what off position. This is because the (Continued in next column) stantial layer of ice prevents convec- charts were freehand sketches made at tion. Short-wave time signal radio re- the telescope. Better detailed charts "Began observing 4.0 min. before nomi- ception was poor that night due to so- might be prepared'from a plate taken nal time. A short occultation by Mel- lar activity; I obtained a good re- for early astrometry of the star, but pomene probably occurred at this site cording by holding the tape recorder since most plates are blue sensitive, 0.7 minute earlier. microphone next to the speahr of my such charts should be checked to gauge bPhotoelectric. Timekube played at full volume. One the visual brightness of the stars. "'A blink was observed, but no timing observer saw the occultation and tried Most detailed photographic atlases do preserved. The event was attributed to record local telephone time signals not have a large enough scale for our to seeing at the time. which I calibrated against ldhlV. When purposes, but might be of use in pre- 'JA dimming of the star for a few sec- he played back his tape, there was a paring detailed charts. We have a con- onds was attributed to watering eyes dial tone, since the telephone company tinuing need for volunteers with ac- caused by a cold wind. Details have installed equiµnent which automatical- cess to detailed star atlases, to help been requested to check for possible ly terminates a call to the time num- with the preparation of good-quallty coincidence with Nolthenius' pair of ber after one minute. One observer saw finder charts. blinks. the occultation from a site about 2 km :"Numerous seeing events." southeast of the Goddard site, but his I feel that a larger aperture is ad- Some gradual dips in the record are " timings were late due to interference vantageous for seeing an asteroidal attributed to cirrus. from headlights of a passing auto. occultation event since the change in qgegan observing late, 4.4 minutes be- light received by the eye Is propor- p,f0re nominal time. By far the most connon reason for no tional to the light-gathering power of Some relatively gradual brightenings observations was failure to locate the the telescope. I think this is more and fadings were recorded photoelec- correct star, or to find it too late important than the threshold argwnent trically and seen visually. (I noted the time to most of those to for using a small telescope, especial- 1 (, ill f'jr relatively faint stars, when The portable photoelectric stations fOr an airless planet.), and P is the seeing variations may also drop the from the University of Arizona were inverse of the Probability that an oc- Star's light below the threshold. Note set up in Utah, while those from Low- cultation will occur in the possible that, using a 25-cm telescope, I was ell Observatory and Cornell were in area, assuming a combined stellar - the only visual observer to see an Colorado, according to the table; all ephemeris positional error of l:'O event involving the close stellar sec- recorded no events: (That is, P is essentially the ratio ondary. Some observers using smaller of the width Gf the possible area of telescopes. who watched Melpomene and 0bser.y.¢_r., . ,Loca_t_i,o!! ,S.!!i .ft Va,1 I!'..S!!LN,8P visibility to the width of the expect- the star the previous night, felt that ed occultation path.). The combined observation might be difficult, since E. Bowell, Hugo. CO mo S area can be considerably reduced with the objects seemed of "similar bright- N. White. Eads, CO 0.36 S modern astrometric observations, and ness," but the star appeared substan- D. Godia, Price, UT 0.38 S the width 0' the possible area nar- tia11y brighter with my telescope. One R. Millis, Lamar, CO 0.41 S rowed to substantially reduce P, but last remark: As for lunar grazing oc- B. Zellner, Moab, UT 0.45 S as explained before, this can be ac- cultations, be sure to record exactly D. Walker, Monticello, UT 0.53 S complished best when the Manet and when you began and ended observation, star can be photographed on the same and note the start and stop times of Monticello was 42 km north of the At- plate, perhaps only 2 to 3 days before all intervals when observation was in- lanta path, so if the object occulted the event. Under PGssible A.r,eq, the terrupted for any reason, such as a the secondary star at Atlanta, nearly regions from which""the"'e\le"ntS"may oc- Cloud, telescope adjustment, Or check- corresponding events involving the cur with the sun below the horizon are ing a comparison star in a distant primary star should have occurred at listed in the chronological order in part of the field. Monticello. Unfortunately, due to tem- which the 0ccu}tation shadow will peratures below -20" C, the observers sweep over them. A "?" indicates that In sumary, much interesting data has at Monticello had much trouble with an occultation will occur in the area been collected during this occulta- guiding, and it's possible that the just mentioned only if the actua) path tion. hie learned a great deal, and star drifted out of the field of the shifts n(orth) or s(oUth) (tbe direc- should be able to do much better with photometer within seconds of an Occul- tion indicated by the letter following future events. Unfortunately, there tation. Moab was within a km or so of the "?") of the predicted path, usual- are no asteroidal 0ccu]tations as fa- the path for any objects which might ly by at least a few tenths of an arc vorable for North America during 1979. have occulted the star at Green For- second in the sky. The elongation or est, AR. None of the possible brief the sun from the planet is given under MORE ON MELPOMENE visual fadings noted at Green Forest El S,u,n.. Under MOON, the elongation are confirmed in the Moab photoelec- fr"oiiTthe planet is given under FI, the David KL Dunham tric record, where no guiding problems percent sunlit ("+" for waxing a"nd "-" were experienced. for waning phases) is given under Bob Bolster also observed the occulta- %.S.n1, and the approximate longitudes tion of the secondary star visually, PLANETARY OCCULTATIONS DURING 1979 fr0&""which the moon will be above the timing its reappearance only 053 be- horizon in the possible area are spec- fore the emersion of the primary. This David hi. Dunham ified under Up. For the latter, the establishes the primary-Secondary sep- moonrise or moonset terminator is aration as O:'OS in PA. 30°, accurate The first table below gives informa- E(ast)specifiedor hl(e$:fin d recsof Greenwich,of longitudepreced- to 5 km or so at Melpomene's distance, tion about planetary occultations dur- and confirming a large (over 10 km) ing 1979 in a form similar to the ta- ed by a letter w(est) or e(ast) to "mountain" at emersion, according to bles for 1978 events published in ear- specify the direction in which the Espenak's timing. D. Ski11man calcu- lier issues. All but one of the occul- moon will be above the horizon. "All" lates that the secondary star had 1/5 tations by minor planets were found by or "none" is used to specify whether the light of the primary star from his Gordon Taylor, Royal Greenwich Observ- or not the moon is up in the entire data, more than the J/7 value I esti- atory (he made ccxnputer comparisons of possible area if it is not crossed by mated, and in better agreement with accurate astrometric ephemerides of 49 the moonrise or moonset terminator, the results from the other photoelec- asteroids with the SAD and AGK3 star tric records. E. Bowell notes that the catalogs). The occultation by Euterpe One of the most important columns in occultation diameter is in good agree- on December 8th was published in the the table is Am, since it specifies ment with a recent polarimetric re- Swiss almanac. Der Sternenhinunel 1979; the observability of the event. A val- sult. A. Harris, who observed at Table Euterpe is not one of the objects con- ue less than 1.0 in general means that Mountain Observatory, Wrightwood, CA sidered by Taylor. Jean Meeus first the event can only be reliably ob- (1'.'04 soUth) had no occultation, but pointed out the occultation by Mars. A served photoelectrically. In case of recorded Melpomene's light curve. The second table gives further information exceptionally good atmospheric seeing, magnitude range was 0.3, with the oc- about the occultations. smaller magnitude drops might be de- cultation occurring near minimum tected visually. Consequently, the oc- light. According to his data, the as- Notes about Information in the First cultations of Oct. 6, and by Juno on teroid was 0.71 mag. fainter than the Table. The ranges of Universal Time Dec. 11 likely will not be noticed star (mag. 9.06 if the star was 8.35), are given in increasing order; if the visually. so that the total occultation L\m was occultation shadow will sweep across 1.16 (1.01 for the primary star and land areas during nighttime in two Notes about Information in the Second 0.35 for the secondary, assuming that minutes or less, only one time is giv- Table. The date, asteroid or planet the other component was occulted). en. Under PLANET, my is the visual name, and the star's SAD number are magnitude (usually photoelectric V- repeated for identiVication. The minor The 0'.'05 (42 km at Melpomene's dis- mag.), and 1\ is the geocentric dis- planet's number, and the expected di- tance) separation of the stellar com- tance in astronomical units at the ameter in kilometers, and the apparent PonentS poses problems with the inter- time of the occultation. Under STAR, angular diameter in arc seconds, are pretation of the light curve for the my is the visual magnitude (converted ?iven. The diameters for (2) puns, occultations by secondary objects. The to d photoelectric V-mag. scale using 3) Juno, (6) Hebe, (IB) MeWmene, model I proposed for the Fernbank oc- data from the skmp Catalog described and (53?) Hercu)im were determined cultation probably is incorrect, with in o.n. I (16), )61) and Sp Is the from previous (Kcultdtlon'i, The diame- at least some of the features in the spectral type; the approximate eclip- ters for the other minor pknets are trace previously attributed to occul- tic 1950 position is also given. Under the best current estimates from infra- tatfon of the secondary star probably OCCULTATION, Am is the change in visu- red radiometry, polarimetry, and re- due to atmospheric seeing instead. If al magnitude a" the coalesced images lated taxonomic information. The diam- the secondary star was occulted at Am- which is expected if an 0ccu)tation eter of Mars is an average value de- bler, PA, it must have been by a sep- does occur, Dur is the duration fOr a rived from spacecraft radio signal oc- arate satellite, one whose primary oc- central occuIUtion computed Using the cultation data. Under RSOl, the dis- cultation path was north of Princeton, expected diameter of the planet, df. is tance in km from the aster"oid is given NJ, rather than by the satellite (or a measure of the diffraction effects where the gravitational attraction M debris?) which apparently occulted the for a central 0ccu)tation (It is the the asteroid is equal to that of the primary star there. time in milliseconds between fringes sun, assuming (pessimistically) that 17

the mean density of the asteroid is 1ination z.ones north of -22", be prolonged, in some cases enough twice that of the sun. Satellites are the ntmber is a B.D. number, while to possible for much greater distances, that the fade might be noticed visual- the south, it is C.D. The -22° zone ly), and in terms of diffraction since tidal or differential forces de- can be either, although the B.D. num- termine satellite capture; according fringe separation (df). For values of ber usually is used. C.D. numbers in df from 0.1 to 3, tne diffraction pat- to the theory of three-body motion, the -22" zone are about twice as large these forces are proportional to the tern will be modified enough that the as the corresponding B.D. number for stellar diameter could be computed cube of the ratio of the distances, the same star, or for stars with simi- not the square. Although some second- from an analysis of a good quality lar right ascensions. The star's dou- high-speed photoelectric record. If df ary occultations have been seen at ble star code is given under D. is less than 0.1, the diffraction pat distances greater than RSOl (the cube tern will be modified so slightly by ratio gives a distance larger than the The star's angular diameter is expres- earth's diameter for all events), they the star's diameter that a determina- sed in four ways: in milliseconds of tion will likely not be possible with are most numerous within the RSOI dis- arc (W:OOi); in meters subtended at tance of the asteroid. The position even a good quality record, but note the asteroid's geocentric distance; that none of the stars in the table angle of the asteroid's motion is giv- the geometric (ignoring diffraction) are this small (i.e., the diameters of en under PA. TIME in milliseconds for the aster- all are potentially measurable from oid's limb to cover the star's disk in suitable occultation observations). The star's B.D. or C.D. ntmber is giv- case of a central occultation (for The stellar angular diameter is com- en under the DM NO. column. For dec- nearly grazing events, this time will puted from the Warner formula (given

1979 UNIVERSAL P L A N E T S T A R OCCULTATION EI M 0 0 N 9a.Te t.ime. !!Am£ _[.jl_ aAu. sad no m,,, & r=a.(i95q)q,c,c.· s!!! La' 9£ P Possible Area Sun E.1 %_Sn.1. !!E Jan 26 15h25" Amphitrite 10.9 2.65 109262 5.7 AO Oh29"8 6°41' 5.2 6 10 79 n.e. Europe?s 64 86 4- none jan 27 9 08 Laetitia 1).0 2.48 110311 8.5 GS 2 oi;o )222.6 71422 New Guinea, mid-Pacific 82 95 ) - none Feb 28 3 41 Egeria 12.2 3.05 92603 9.5 GS I 41 .6 11032.8 7 9)8 w. North America 49 29 3" W) 24°W Mar 16 20 00 Pa11as 10.5 4.03 126160 9.) K5 20 42.1 610 1.7 15 11 )1 central Austra1ia?n 46 103 92- all Mar 17 11 25 Fortuna )1.9 2.76 11.1 K2 2 08.0 12301.2 5 718 Indonesia; Phi1ippines?n 38 175 87- none Apr 6 0 18 Laetitia 11.5 3.29 10.8 F8 3 36.4 10561.2 4 929 e. USA; e. Canada?n 40 68 65" all Apr 24 19 20 Pallas )0.4 3.63 10706) 6.8 F5 21 18.9 10 07 3.6 23 16 10 sc Asia;Phi1ippines;japan?n 70 5] 4- e138 E Apr 27 6 58 Psyche )1.1 2.73 163921 8.1 GS 20 47.8 - 15 42 3.1 ]3 16 16 central S. America 86 96 1 + none May 19 17 45- 54 Interamnia 11. 3 2. 50 164174 8.1 KO 21 6.3 - ]1 01 3.3 25 23 I] n.w. Australia; Indonesia; Japan?n 102 22 42- e105 E May 23 5 41 Parthenope 12.0 3.45 78)48 9.4 F5 6]2.4 22102.7 4 933 n.e. Pacific; Hawaii?s 32 67 9- none May 31 11 19 Patientia 12.8 3.47 129290 9.0 F5 ]22.8 -517 3.8 910 )5 (Mexico:Arizona; N.Mex.)?n 53 114 27+ none Jun 9 7 13 Melpomene 11.5 3.08 8.8 KO 82).6 18032.8 4 933 New Zea1and?n 46 118 98" all Jun 21 ]0 21 Dembowska 11.9 3.34 10.5 G510 55.3 1137 1.6 615 33 New Guinea; n. Austra1ia?s 72 109 10- none Jun 27 8 39 Themis 13.2 3.93 10.5 AO 404.0 20572.8 5 927 Brazil 32 64 8+ none Jun 28 19 11 Flora 11.5 2.83 10.7 F5 10 27.1 14 34 1.2 510 27 s. Atlantic 57 I) 1 7+ al I ju7 15 20 13 Metis 11.] 2.89 77128 8.5 KJJ 519.0 22542.7 3 727 e. Australia 32 66 57- all Jul 20 10 06 Dembowska ]2.0 3.70 118857 9.4 GO I] 23.6 7412.7 411 37 Australia 52 94 I 3- none Jul 29 21 35-51 Interamnia 10.2 1.79 144829 9.0 K5 20 45.9 -3 47 1.5 27 21 8 w.Indonesia?n;centr.Africa 165 122 28" W 5 E Aug 5 5 36 Metis 11.1 2.76 78005 8.2 B8 605.0 23453.0 4 826 n.w. Africa 41 175 88+ none Sep 19 4 53 Antigone 12.8 3.76 97988 8.9 GO 8 35.5 14 304.0 317 47 s. Atlantic 48 24 4- e 0 Sep 27 5 00 Juno 9.2 }.90 114497 8.5 AO 6 47.9 919 1.2 10 11 I] Brazil 81 146 30+ none oct 6 23 33-40 Mars ).2 1.69 98024 6.3 A2 8 37.6 19 43 0.0 230 9 0 c.Europe; U.S.S.R. 66 98 98- all oct ]7 20 36-57 Cybele 13.2 3.41 9.7 M2 6 33.2 19 27 3.5 56 6516 Mideast;e.Europe?n,cen.Asia 106 70 9- e95 E Nov 8 11 41-46 Herculina 11.4 2.97 190681 9.1 F8 21 48.2 -27 57 2.4 17 26 20 Australia 95 136 79- e150 E Nov 23 20 12 Hebe 10.5 3.13 161146 8.5 GS 18 07.8 -17 09 2.2 4 8 24 Azores?n 32 20 18' all Dec 8 5 28-43 Euterpe 9.1 0.97 77426 8.9 K2 5 39.2 22 35 0.9 17 2912 n.e. Europe?s; Arctic 170 43 80- all Dec 11 8 05-17 Metis 10.0 1.50 80950 6.8 B9 9 36.} 20 31 3.2 29 47 14 nwS.America;e.Caribbean?n 119 26 52- all Dec 11 8 52-87 Juno 8.2 1.28 115946 9.0 KO 7 45.4 0360.46658 7 Canada; n&w USA; Hawaii?s 136 52 52- e145 Id 1979 MINOR PLANET S T A R STELLAR DIAMETER COMPARISON DATA MOTIONAPPARENT DATE .N,0, N,a,m,e, km-diam-" RSOI .PA. SAD Nq DM No. D ,M M Timtj Stf. S AGK3 No Shift Time °/Day RA. Dec.

Jan 26 29 Amphitrite 195 0.10 838 66 109262 "06° 64 L 0.22 429 14 1.3 P 0.390 Oh31"3 "6°50' Jan 27 39 Laetitia 163 0.09 681 62 110311 "00 341 0.28 501 22 1.6 S N01° 222 0'.'15n +1"0 0. 300 2 OZ;S '1 30 Feb 28 13 Egeria 241 0.11 1210 61 92603 "10 232 0.15 328 9 1.0 X Nil 171 0.07s +0:2 0.398 1 43.2 +11 12 Mar 16 2 pallas 538 0.18 5487 71 126160 "05 4596 0.49 1432 40 3.6 S N06 2804 0.82n -0.8 0.290 20 43.5 +6 19 Mar 17 19 Fen-tuna 221 0.11 877 71 "12 294 0.12 236 5 0.7 A NR 232 0.536 2 09.5 +12 39 Apr 6 39 Laetitia 163 0.07 699 73 "10 465 0.05 118 3 0.3 S N10 367 0.417 3 38. 0 +11 01 Apr 24 2 palias 538 0.20 5495 6] 107061 "09 4786 Q 0.31 819 35 2.2 S N10 2885 0.214 21 20.3 +1015 Apr 27 16 Psyche 252 0.13 1466 74 163921 -16 5709 0.28 561 28 1 .7 S 0.242 20 49.4 -15 35 May 19 704 Interamnia 339 0.19 2318 40 164174 -ii 5533 0.47 849 63 2.7 S 0.17/3 2] 07.9 -10 54 May 23 11 Parthenope 152 0.06 639 89 78148 '22 1245 0.09 235 6 0.6 X N22 669 0.35n +0.2 0.405 6 14.1 "22 09 May 31 451 Patientia 327 0.13 2265 74 129290 -05 254 0.11 284 8 0.8 S 0.340 1 24.3 -5 08 Jun 9 18 Melpomene 135 0.06 682 98 "18 1934 0.29 640 17 1.9 X NIB 860 0.16n -0.6 0.4]1 8 23.2 +)7 58 jun 21 349 Dembowska 145 0.06 713 121 '12 2277 0.09 227 9 0.6 X Nil 1271 0.05n -0.1 0.245 10 56.9 +]1 28 Jun 27 24 Themis 210 0.07 1218 79 "20 700 0.02 70 2 0.2 X N20 371 0.06n -0.1 0.353 4 05.7 +21 02 Jun 28 8 Flora )53 0.07 593 113 0.05 106 3 0.3 X N14 1123 0.32n -0.7 0.390 10 28.7 +14 ?5 jul 15 9 Metis 153 0.07 5)1 83 77128 "22 884 2.09 4390 96 13.1 X N22 520 0.52n -0.) 0.526 5 ?0.7 t2? 56 jul 20 349 Dembowska 145 0.05 715 119 118857 "08 2504 0.11 298 9 0.8 X N07 1537 0. 23n +0.1 0.30? )1 25.1 +/ 31 jul 29 704 lnteramnia 339 0.26 2237 281 144829 -04 5264 0.51 666 53 2.5 S 0.?30 20 47,4 -3 4() Aug 5 9 Metis 153 0.08 511 88 78005 +23 1208 0.08 167 4 0.5 X N23 610 0.45s -0.0 0.513 6 06.8 a2:) 44 Sep 19 )29 Antigone 115 0.04 504 102 97988 +14 1937 0.14 381 11 1.0 X N14 930 0.09n -1.2 0.309 8 37.1 o14 24 Sep 27 3 Juno 256 0.19 1058 )06 1)4497 '09 1404 0.07 100 4 0.4 S N09 782 0.49s +0.8 0.4?6 6 49.5 "9 17 oct 6 Mars 6782 5.53 103 98024 "20 2171 V 0.24 290 10 1.1 X 0.576 8 39.3 '19 37 Oct )7 65 Cybele 309 0.12 2661 108 "19 1399 0.52 1287 231 3.5 X NIB 599 O.Iln -0.4 0.054 6 34.9 +19 25 Nov 8 532 Herculina 217 0.10 1318 55 19068] -2817479 0.11 232 18 0.7 S 0.143 21 49.9 -27 49 Nov 23 6 Hebe 183 0.08 768 96 )61146 -17 5052 0.24 534 12 ).5 S 0.465 18 09.6 -1 7 09 Dec 8 27 Euterpe 116 0.16 313 273 77426 "22 999 0.31 2}8 32 ].1 X 0.231 5 41 .0 +22 35 Dec 11 9 Metis 153 0.14 526 71 80950 "20 235] 0.13 147 28 0.6 P N20 1121 0.20n +2.5 0.114 9 37.8 "20 23 Dec )1 3 Juno 256 0.28 1}]1 247 115946 +00 2091 0.31 288 75 1.3 S NOD 1022 0.875 "0.8 0.100 7 46.9 -2 31 IB in Mon. Not. ROyal Astron. Soc.. 158, maps such as those in Norton's Star A stippled line marks the moonrise or IP, 1972) using photoelectric B and V Atlas or those published monthly in moonset line, if either is present. magnitudes for the stars from SKYMAP Sky and Telescope would be shown (such The expected diameter (if the minor (o.n., i (16) 161). For stars not in maps are presumably available to all planet, in km and in arc seconds, is SKYMAP, the catalog photovisua) magni- ens. readers). (:Ie detailed map, show- given in the caption. The nomona1 tudes have been assumed equal to the ing stars to about 9¶ mg., would be paths were computed using data for the V-mags., while B-V values have been published at a more gemrous scale, stars obtained from the sources indi- inferred from the spectral types. but would cover an area only 3° Or 4° cated under the S column of the second on a side. See also the comments about table, and accljrate astrometric ephem- The source used for the star's posi- finder charts in the article about the erides which I computed using precise tion and proper motion is given under Melpomene occultation On p. 15. The osculating orbital elements supplied S, according to the following codes: path of the asteroid will be shown, by the minor planet centers in Cincin- X, USNO XZ-cataiocl for stars within ' with Qh U.T. marked for four dates nati and Leningrad; some exceptions to 6"40' of the ecliptic and north of starting with the date two days before obtain improved predictions, when bet- declination -3" (P or S, described be- the date of the event. Hence, there ter data have been available from oth- loW, d'C'used by X7 for southern will be three marks on the side of the er sources, have been noted when ap- StaFs): p, Perth 70; S, SAD; A, AGK3; occulted star before the event, and propriate. Asterisks show the loca- and G, Albany General Catalog (via one mark after. Close double stars tions of observatories from which pho- SAD; positions especially poor). will be underlined.lf you have any toelectric occultation observations coments about this plan, or other have been attempted in the past, as · If the star is in the AGK3 catalog, ideas for improving our finder charts far as I know. The regional maps are but another source is given under S, in the limited space available, let us "false" projections, plotted with d AGK3 comparison data are listed. IT know. Volunteers are sought to make constant linear scale (constant de- only an AGK3 position is available, no good ink drawings of finder charts grees per centimeter) in both longi- comparison data are given, but the and/or world maps traced from SOma's tude and latitude, so that the observ- AGK3 number is listed. AGK3 positions computer plots, for publication in Oc- er could, for example, plot updated are often better than SAD positions, cultation Newsletter. computed path points which might be but are generally inferior to XZ and computed by Gordon Taylor. Note that Perth 70 positions. The path shift world Maps. Mitsuru SOma, TOkyo, ja- the width of the occultation path can based on AGK3 data is given under pan, has produced world maps by com- be estimated on the map frOm the ex- Shift, which is expressed in seconds puter, showing the paths of occulta- pected angular diameter. Regional maps 0"Ta"rc, "n" or "s" indicating whether tions of stars by minor planets. The will be published in o.n. only for the shift is to the north or south, three closely spaced parallel lines areas with many subscribers. They of- respectively. For instance, 1!'005 show the predicted central occultation ten will be distributed as separate would mean that the path would be at line, and the northern and southern pages to those in areas with relative- the southern edge of the possible area limits, with U.T. marked at one-minute ly few subscribers, such as japan, described in the first table, accord- intervals and written at five-minute southern Africa, and Australia. Maps ing to the AGK3. Besides a path shift, intervals. The two parallel dashed of South American events will be shown there is a correction to the time of lines show the central occultation in Occultation Newsletter en Esp'ahol. the event if the AGK3 position of the path in case the minor planet passes star is used for a comparison. The 1':O north or south (measured perpen- Notes about 1979 Events. Observational value in minutes to be added to the dicularly to its path in the sky) of strategies and recomendations are Universal Time is given under Time. its predicted path with respect to the discussed in an article in o.n. i (16) Gordon Taylor uses AGK3 data fOr all star. Combined epheiaeris and star po- 162-163, and in the article about the of his predictions, except South of sition errors can cause path shifts occultation by Melpomene in this is- declination -3", where he uses SAD da- greater than 1", as the occultation by sue. Unfortunately, the elongations ta. A few months before the occulta- Herculina on June 7 demonstrated. The from the sun for many of this year's tion, he often takes plates to improve sunrise and/or sunset terminator is events are relatively small. This both the asteroid and star position, shown, with hatches indicating the causes difficulties for observing the to compute a better prediction. The side of nighttime visibility. The star occultation and for obtaining good as- next column gives the asteroid's angu- and asteroid are in the zenith for an trometry to improve the prediction. lar motion, in degrees per day. Multi- observer at a site indicated by the Also, the geographical area of possi- ply the listed numbers by 2.5 to ob- center of the circular projection of ble observations is narrowed. Early tain the angular rate in seconds of the earth; the objects are on the ho- astrometry is impossible for events arc per minute, which is useful for rizon fOr sites at the edge of the with small elongation in the morning estimating when the asteroid's and circle. The altitude ajove the horizon sky, unless it is done several months star's images will merge, and how long can be estimated for any site shown on in advance, before the asteroid and it will be before they might be re- the map. The cosine of the altitude is star are in conjunction with the sun. solved again. Normally, a separation the distance of the site from the cen- Unfortunately, bui7jings and trees ob- of one or two seconds of arc will be ter of the circle divided by the ra- struct the western horizons of some of needed to resolve the objects, but if dius of the circle. The sun altitude the observatories where many astromet- seeing conditions are very good, a can be estimated by the distance from ric plates are taken, making last-min- fraction of a second of arc might be the terminator. ute astrometry of small-elongation resolved. The last two columns give evening events impossible from these the star's apparent R.A. and Dec. com- Regional Maps. The more detailed re- sites. Small elongations also mean Puted for the time of geocentric con- gional maps were prepared with a com- that the asteroids are fainter than junction, for direct use with setting puter program written by Fred Espenak, usual, so that large tlm's occur, mak- circles. Bowie, MD, using path data on magnetic ing all but two of the listed events tape generated by me at USitO. The par- potentially observable visually, Un- Maps and Finder charts. Worldwide and allel curves represent the path of the fortunately, the asteroid motions are more detailed regional area-of-visi- center of the occultation shadow, con- then also rapid, shortening many of bility maps for many of these events, sidering several different shifts of the occu1tation durations to the point especially the ones occurring early in the minor planet from its predicted where inaccuracies of visual timings the year, will be published in the path with respect to the star. The start to become troublesome. For these next issue, which we expect to dis- nominal path is labeled "0". The par- reasons, although there are many op- tribute before the end of February. hie allel curves show the central path for portunities this year, especially in also plan to include finder charts for multiples of O':i shifts of the aster- Australia, T don't think that we will some of the early events in that is- oid frOm its predicted path in the get as many observations in 1979 as we sue. hie plan to change the finder sky, measured perpendicularly to the got in ]978, unless even more events charts. The wide area chart would be path. Curves are labeled in the map are identified. On this last point, more like the Atlas Coeli, showing margins at 0'.'2 intervals, "N" or "S" plate scans conducted at Lowell for (I) Ceres, and manual comparison of stars to 7th mag., so that it would showing shift direction. Dashed curves ephemerides with the SAD b,y Wallentin- correspond approximately to the view show predicted U.T. of central occul- in many finder scopes. Perhaps only tation. Low star altitude or twilight sen, could turn up additional events. Notes about individual events are giv- one bright star, labeled on the sky boundaries are drawn when appropriate. r

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19

i I Sr 3Q?3m member of the Praesepe cluster. The Ant componentr. I hopr that the µrt'dictrd { will be only 0.()1, although effective- paths for the' occuKations by PhcAm·, 'i FC? 28: :nis event occurs )'8 days aft- Iy it. will be higher, since Mars' disk and Deimos can be computed and pub- ,. er d total solar eclipse. and may be will be at lease partly resolved. The lished in a 5utu:'e issue of (an. In visible from the vicinity Of the effective Am should be computed from a any case, an occultation by a current- eclipse path. as indicated by the map. part of Mars' disk equal in size to 'ly unknown satellite is possible. Dur- the atmospheric seeing disk. FOr a 1" ing the occultation of e Geminorum in Mar 16: Gordon Taylor indicates "Indo- seeing disk, the effective Dm would be 1976, a dip in a photoelectric record nesia" as the possible area. 0.3; with very good seeing, the Dm obtained at Vi1]anova University may might even be noticed visually. Howev- be due to a large close satellite. Mar 17: Tay)nr and I agree on the er. it would be impossible to make a path, both having used ephemerides reliable visual timing of the star's Oct 17: The asteroid's motion is very computed from orbital elements com- relatively gradual fade as its light slow, since it is near a stationary puted at the Institute of Theoretical is progressively refracted by the Mar- point. This, combined with the star's flstronomy, Leningrad. However, my cal- tian atmosphere. No dark-limb event relatively large angular diameter, im- µ1atiOn using an ephemeris computed will be evident, since at most the plies that observers with large tele- from accurate oFbital elements sup- dark crescent will be O:'S wide, and scopes will be able to see the star plied by Cincinnati Observatory shows lost in irradiation. Due to the star's fade, the duration being 052 Or more. that the path misses the earth's sur- spectral type, photoelectric observers The very slow motion also will facili- face by many earth radii! The ephemer- could profit by observing with a blue tate astrometric improvement of the ides agree in declination, but differ filter. An occultation by a Martian prediction a few days before the by 6s in RA. hie suspect that the Cin- satellite, far enough from the planet event. cinnati elements are right, so that so that the star still would be seen there will be no occultation, but an separated from Mars' edge, would be Nov 8: Taylor gives "Indonesia" as the astrometric check is needed to be noticed easily visually. An occulta- possible area. sure. tion by Phobos could last as long as I second, although just what would be Dec 8: According to Der sternenhinmel, Apr 6: The Am is small enough that it seen would depend on the unknown (but the path will cross Greece, northern might be useful to refine it by ob- probably very close) separation, p.a., Italy, and France, corresponding to a serving the magnitudes of the objects and relative brightness of the stellar shift over 2" south of my prediction. photoeiectrica11y. Bright twilight will hinder many observers, as it did for the occultation by (29) Amphitrite ""' - -- "-—--- " - i Oq last December. 195o . : ' " " . ' ' . ' c?oTr" ~ O PEG. tg . · ARIES i " Apr 24: This is the most interesting " ,L ,'\ ' I [SCES . asteroidal occultation of the year. +11 — , · b J wU " " · ""0 0 The star is A.D.S. 14893. whose Com- 0 O I vO " 5yC " ·, e :z6 , .. 0 , IT ponents are each mag. 7.7. According » 0 cm d %qcq tO F. R. West (Astrophysical journal, g 0 · I 7 W a a , ·. 3 V o , D 5" 205, 194, 1976). the orbit is highly 0 0 0 0 D 0 elliptical. He predicts that perias- "10 - ,, ,, O tron will occur during 1979, with a » P a separation of perhaps less than om. ,, , , QOm« " . "8 0 Q Even so, disappearances or reappear- 0 , ances of the two stars by Pa11as like- 0 ly will be separated by more than one "g" ·' . ' . ·S"''·· "' ' ' · 197? FEB.28 second of time. One of the components 48" 46 4; 042 -!2 23 3c 3·: i' 32m (13) Ueria Amp 5Ao ?2Co3 is, in turn, a spectroscopic binary, the third star perhaps being a white _ 0N'itok 195o RA dwarf. The time between events for the spectroscopic pair probably will be Occultation of SAD 92603 by (13) Egeria, 1979 February 28 less than 051, requiring photoelectric recording to resolve them. Observa- Diameter 241 km = 0!'11 tions of the event would be valuable tzj 3 . "" , o:'y N I for studies of Pa11as' shape, supple- / m 'p; 4 menting the information obtained dur- ? ^ aj A<) " ing the well-observed occultation by 0:2 /Y Pa11as on 1978 May 29. The stellar du- , » " 1 plicity will provide two chords for %,, g" '"=~ each observing station, as was the case for the occultation by (IB) Mel- ' "*""'1 d j i " ^ r", pomene last December. If one star dis- appears, while the other component is 45 0:2 S; / )( ) ,j,S/ > ' unocculted, the Dm will be 0.7, which L may be hard to detect visually if the A _ m t ""i K * seeing is bad. If one of the compon- T ents disappears or reappears while the I / 4 ql , ' ~E other star is behind Pallas, the Dm T ^\;" ' /':' ' =,1 " '" will be 2.9, very easily noticeable. U " "t">c A a: ' ' Since the two drops probably will oc- cur only about a second apart, both D dropS probably will be readily appar- E ent, the large drop calling the smal- ler magnitude drop to the observer's attention. Taylor computes a more northerly path for the occultation, °:" '"X "" ' citing "China" as the possible area. — I */ t I ' K_ 'J" ¢m Sep 27: The Am could be refined by photoelectric observation of the ob- Lb \s :i 5'\] tj III jects. cm -115 -ICES « = Oct 6: The star is e Cancri, a spec- mm troscopic binary and the brightest LCNGITUJE ..

20

The different star catalogs are in during 1979 probably will be rather by it, to check for satellites. relatively good agreement; the ephem- close to the nominal prediction, since erides which were used for the two the star is in the Perth 70 Catalog Dec 11, Juno: The small 1'\m virtually predictions must be different. Early and the ephemeris is also very good. rules out visual observation, but pho- astrometry would be useful to resolve It might be a good time for NOrth toelectric observations should be made the discrepancy. Also, the am should Americans to travel to the Caribbean, to check this. Again, the motion is be refined by photoelectric observa- to observe the event as well as to es- slow, so that astrometric prospects tions to give a better assessment of cape from the cold. Due to the slow for a good prediction"refinement are the possibility for visual observation motion, it should be possible to get excellent. Potential observers of this of the occultation. good astrometry a few days before the event also should monitor SAD 80950 event, to calculate an accurate pre- about an hour earlier, to catch possi- Dec 11, Metis: The path for this oc- diction. In any case, observers ble satellites of Metis, as discussed cultation of one of the brightest throughout the Western Hemisphere above. stars to be occulted by an astprnid should watch the star as Metis passes _ i <" """L .— must be applied. A 2.4-meter aperture us at northern elongation from Pluto, i " Space Telescope is in the design stag- eclipses should occur from now until A 3 N _ es for launch on the Space Shuttle in about 1982. Andersson gives a very ap- the 1984-85 time frame. It will have proximate ephemeris for transits of

Xb :: ',, the satellite across Pluto: (1979 Jan. 'b - 0 the ability to attach variable instru- " ¶ 5.0 + nx6a387) ± oh. Occultations and t '"% P mentation for use at viewing ports, 44. .. .. He the equipment intended to be servicea- eclipses of Charon by Pluto should oc- I· 0 , 'A ··.. ' -·4- ble by astronauts in extra-vehicular cur about midway between these times. . / , } · ' 7 ' % , '..' "0 activities. He notes: "Photometric observations of t 0 1· ·. --.L.'. rS/·., " ""' J""7> . """ itt,'," Pluto in 1979 are strongly urged." One instrument that is ideal for stud- ies of asteroidal companions is the Occultations of stars by asteroids Wide Field Camera, sporting a planned were the subjects of several papers: Rare-minute field of view, and capa- "A Possible Satellite of Herculina," ble of reaching to 26th""magnitude in a by E. Bowell and others involved in ':)'°72\"1T 'i. 30-minute integration period. I sug- the analysis, observation, and predic- gested, in a January 1978 letter to tion of this event; "A Reliable Diame- ii """1="" Bradford A. Smith (University of Ari- ter for Pallas," by L. Wasserman et al zona), who is involved with the in- (based on the seven photoelectric tim- X. 6 " ~. strumentation design team for the NFC, ings of the 1978 May 29 occultation, 'b P that it might be used in an extensive the axes of an elliptical outline were b ~ survey of the larger minor planets. determined to be 559 ± 6 and 526 ± 10 This was approximately 9 months after km); "The Shape, Albedo, and Density "12° 294 by Fortuna, 1979 Mar 17 the anomalous secondary occultdtion I of Pailas," by J. Elliot et al (based observed in connection with the (6) on the above and light-curve analysis, Hebe event. A planned program to scan YHj04Q T¢ 60 m Fa DO the mean diameter is 538 ± ]2 km; com- ¶fj '' ' 7 I the near vicinity of planetoids larger bined with Schubart's mass determined than 100 km might more easily reveal from perturbations on Ceres, the den- Use a tracing of this cosine scale to the presence or absence of satellites sity is 2.8 ± 0.5 gm/cN); "Radiomet- estimate star altitude from the world than the hit-and-miss efforts current- ric and Polarimetric Diameter and Al- maps: place the 90° mark at the center ly conducted. The outlined resolution bedo of 532 Herculina," by j. Cradle of the circular arc, and read the star elenent is 0.1 arc-second/pixel. Since ettational (goodresuit\;a reement"A Critiquewith theof occul-Aster- altitude at the observing site. the image is not photographic, but electronic, there should be no hazard oid Diameter Measurements," R. Millis EGERIA OCCULTATION UPDATE? involving image spillover from long et al (radiometric and polarimetrlc exposure times, allowing dim sub-arc- results were about 15% too large for David W. Dunham second adjacent images to show up. Re- Pa71as; more occultation observations peating exposures on the same asteroid are needed to see if there are system- As I plan to observe the total solar every 2 or 3 earth orbits might reveal atic errors In the other methods; ac- eclipse, I will not be able to compute satellite motion and permit elimina- curate predictions and mobile tele- an updated prediction for the occulta- tion of spurious images generated as scopes are the key to further success- tion of SAD 92603 by (13) Egeria on artifacts. Integration times would de- ful occultation observations); and 1979 February 28 U.T. If "last-minute" pend on detector sensitivity and wave- "Dynamical Features of Minor Planet astrometry is obtained, after noon of length response. Analysis of reflec- Satellites," by T. Van Flandern ("No February 25, it should be relayed to tivity in different spectral bands minor planet has been observed to oc- Robert McCutcheon in Silver Spring, could shed light on whether parent and cult a star and not show evidence of' a MD, at 301, 681-7631, or during busi- child were mutually formative by vir- satellite; the time scale for tidal ness hours, at Computer Sciences tue of similarity in albedo; captured evolution of large satellites is about Corp., 301, 589-1545, ext. 385. He satellites might be identified by jQ6 years; many satellites wm:jd have will compute an updated prediction us- large variations in thermal absorp- tidally decayed from orbit anu would ing data which I will supply him be- tion/emission. now be resting on the surfaces of fore I depart, and observers can phone their primaries; it is possible that him for the result, if there is one, A.A.S. DIVISION FOR PLANETARY comets and meteorites could be similar i.e., if anyone does obtain any last- SCIENCES: ECLIPSES OF CHARON, ETC. closely bound multiple-body systems"). minute astrometry. David Id. Dunham Van Flandern reports that most astron- PROPOSAL FOR ASTEROID STUDIES omers coming to the meeting were skep- BY SPACE TELESCOPE At the beginning of 1978 November, the tical about satellites of minor plan- American Astronomical Society's Divi- ets, but nearly everyone was convinced Paul D. Maley sion for Planetary Sciences held its after Bowell's and his presentations. 10th annual meeting in Pasadena, CA. There was considerable interest in a Conventional ground-based studies of Abstracts of the papers presented at special informal meeting about aster- asteroids in order to detect satellite this interesting meeting are published oidal occultations. They would like to companions will be permanently hin- in Bull. A.A.S. LO, #3, Part II. L. E. see more events recorded by many ob- dered as long as telescopes have to Andersson, Lunar and Planetary Lab., servers, especially photoelectrica1)y. view through the earth's atmosphere. Univ. of AZ, points out that OR-mag. Hopefully, this will give more impetus The expected close separation dis- eclipses with a duration of up to 5 to various projects to develop a rela- tances of satellites from primary as- hours will occur when the earth passes tively inexpensive photoelectric sys- teroids (on the order of an arc-second through the plane of Charon's orbit tem which could be duplicated and used or less) implies that a finer tool around Pluto. If Charon is approaching by amateur astronomers.