Central Bureau for Astronomical Telegrams
IAUC 5936: 1993e; N Cas 1993
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Circular No. 5936
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
PERIODIC COMET SHOEMAKER-LEVY 9 (1993e)
IAUC 5906 discusses orbits that utilize the first postconjunction
observations of nine of the nuclei. MPC 22931 contains orbits for two
more nuclei, 16 and 19, for which preconjunction data could be linked
with postconjunction data on two or more nights. MPC 23105-23107
include orbits for six more nuclei--2, 4, 8, 18, 20 and 21. However,
the pre- to postconjunction linkage for nucleus 8 was incorrect. The
correct linkage is shown on MPEC 1994-D02, which contains new orbits
for nuclei 8 and 9. Much of the recent analysis depends on measurements
by H. Weaver from images obtained with the Hubble Space Telescope (HST)
during Jan. 24-27. These images, as well as the HST image of 1993 July 1,
indicate that nuclei 7 and 8 are in fact double, the bright nucleus 7a
having a faint companion 7b currently 1".2 to the north and the moderately
bright nucleus 8b a somewhat fainter companion 8a currently 2".2 to the
west. For orbit-determination purposes the original nuclei 7 and 8 are
linked with the current 7a and 8b. The original nuclei 10 and 13 have
disappeared. Nucleus 3 still appears to exist, but there are no other
postconjunction measurements. The list of collision times with Jupiter
given on IAUC 5906 can therefore be supplemented as follows: nucleus 21,
July 16.8 UT; 20, 17.1; 19, 17.2; 18, 17.4; 16, 18.0; 9, 20.4; 8, 20.6;
4, 21.6; 2, 22.1.
NOVA CASSIOPEIAE 1993
M. Kidger, N. Devaney, K. Sahu and S. Lopez, Instituto de
Astrofisica de Canarias, report that 1.4-2.4 micron CVF spectrophotometric
and JHKL' photometric monitoring with the 1.52-m Carlos Sanchez Telescope,
Teide Observatory, shows major changes in the infrared flux distribution
consistent with the formation of a dust shell, as predicted by Shore et al.
(IAUC 5925) and coincident with the optical fading (IAUC 5934). The infrared
spectrum has been regularly monitored since 1993 Dec. 16. The strong CO
feature reported by Scott et al. (IAUC 5916) was still very prominent on
Dec. 28, but it had faded considerably by 1994 Jan. 5, when the Brackett
lines and Pa-alpha were extremely strong; these lines had weakened
considerably by Feb. 5. On Feb. 15 the continuum was observed to be very
red, consistent with blackbody emission from dust at approximately 700 K.
The spectral lines are now very weak or invisible. This spectral
evolution is very similar to that of Nova Her 1991 = V838 Her. The
infrared magnitudes H, K and L' are seen to have brightened considerably
since Feb. 2, viz.: Feb. 2.90 UT, J = 6.37, H = 6.04, K = 5.43, L' = 3.77;
15.85, 6.64, 4.80, 3.13, 1.11; 16.84, 6.55, 4.68, 2.98, 0.96 (errors +/- 0.03).
1994 February 18 (5936) Brian G. Marsden
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