Central Bureau for Astronomical Telegrams
IAUC 4612: Occn BY PLUTO
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Circular No. 4612
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-495-7244/7440/7444
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
OCCULTATION BY PLUTO
P. M. Kilmartin, Mount John University Observatory, communicates:
"The June 9 occultation was photoelectrically monitored at Mt. John
with three telescopes by W. H. Allen (1-m reflector, 0.5-s
integrations), P. M. Kilmartin (0.6-m, 1-s), and A. C. Gilmore (0.6-m,
1-s). A slow decline began about 10h38m50s UT and levelled out at
10h39m15s. A slow rise began about 10h39m32s and ended at 10h39m50s.
The depth of the event was about 0.2 mag in V. The night was excellent
with no cloud visible from dusk to dawn.
R. D. Watson, University of Tasmania, reports that observations
at Hobart by K. M. Hill, S. W. Dieters and himself showed an
occultation centered at 10h41m00s UT. White-light photometry showed a
smoothly declining and rising curve lasting 115 s from beginning to
end. The FWHM of the event was 55 s, and the mid-event flux dropped
to 55 perecent of that before the occultation.
G. L. Blow, Carter Observatory, provides the following reports:
"Observations at the Auckland Observatory (Long. = +174D46', Lat. =
-36D 52') by W. S. G. Walker, B. F. Marino, D. G. Dix and G. Urquhart
(0.50-m reflector, no filter, EMI 9502 phototube and photon-counting
system) yielded an atmospheric occultation of 21.8 s observed both
before and after the main occultation by Pluto; there is some
indication of a shallow atmospheric event extending for a further 15 s
on either side. A planetary occultation was observed lasting about
84.5 s. The total duration of the event appears to have been about
128.1 s with a total drop of 1.83 mag.
"A. A. Page and P. Mitropoulos observed the event at the Mt.
Tambourine Observatory, North Brisbane, using a voltage-to-frequency
system and chart recorder. Monitoring was carried out through a
Johnson B filter and using an EMI 6256B phototube cooled to -40 deg C.
An occultation by Pluto's atmosphere was observed beginning at
10h39m43s.2 UT, with a planetary occultation from 10h39m46s.2 to
10h41m52s.2 UT. Atmospheric egress was completed by 10h41m57s.6 UT.
"K. Mottram, H. Kennedy, D. Hickey and T. Murphy, Darling Downs
Institute of Advanced Education, Toowoomba, Queensland, observed with
a 0.36-m Schmidt-Cassegrain (no filter, SSP-3 photometer). An
atmospheric occultation was observed beginning at 10h39m42s UT,
with a planetary occultation from 10h39m48s to 10h42m00s UT. The star
regained full brightness by 10h42m06s UT. The total drop in
brightness was approximately 2.1 mag."
1988 June 13 (4612) Brian G. Marsden
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