Central Bureau for Astronomical Telegrams
IAUC 6019: 1993e; 1994I
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Circular No. 6019
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)
T. Rettig, J. Hahn, S. Tegler and G. Sobczak, University of Notre
Dame; and M. Mumma and M. DiSanti, NASA Goddard Space Flight Center,
communicate: "Preliminary analysis of images of the cometary fragments
(excluding fragments T = 4 and P1 = 8a) obtained with the Hubble Space
Telescope wide-field camera between January and July shows that the
inner 0".3 regions have remained relatively constant or have slowly
decreased in brightness (by some 0.1-0.4 mag) over the seven-month
period. Similar results are noted with diaphragms of diameter
1".1 and 2".1. The fragments show minimal brightness activity
through the May observations. However, for six fragments observed
during June and July, we measure a rather dramatic brightness
decrease from the May observations. In the 1".1 diaphragm,
five fragments (W = 1, V = 2, S = 5, R = 6 and H = 14) show a brightness
decrease of some 0.8-0.9 mag, and fragment U = 3 shows a brightness
decrease of about 0.4 mag. Also in the June and July images, the
brightness profiles of fragment 8b = P2 show a very much more
distributed source of dust within the inner 1". These profiles indicate
that the central source may have been disrupted and may suggest initial
tidal dispersal of the swarm material. We note that between May and
June most of the fragment images have become elongated in the direction
of Jupiter."
SUPERNOVA 1994I IN NGC 5194
W. H. G. Lewin, Massachusetts Institute of Technology; H.-U.
Zimmermann and W. Pietsch, Max-Planck-Institut fur Extraterrestrische
Physik; and R. Beck, Max-Planck-Institut fur Radio Astronomie, report:
"The x-ray observatory ROSAT observed (with the HRI) SN 1994I in M51
for 9400 s on May 22. SN 1994I is a type Ib/c supernova (IAUC 5964,
5966, 5972, 5978, 5981), and its position is about 18" from the
x-ray-bright nucleus (IAUC 5961). It was not detected at x-ray
wavelengths. Assuming a thermal bremsstrahlung model, an absorbing
column density N_H = 1.7 x 10**20 cm**-2 and a temperature kT = 5
keV, an upper limit (95.4-percent-confidence level) for the unabsorbed
flux from the supernova in the energy range 0.1-2.4 keV is 2.06 x 10**-14
erg cm**-2 s**-1. At a distance of 7.7 Mpc, this corresponds to an
unabsorbed soft x-ray luminosity of 1.5 x 10**38 erg/s. The given values
are not very sensitive to the assumed temperature (for kT = 1 keV they
are about 20 percent lower). Our upper limit on day 53 after outburst
is an order of magnitude lower than the detected soft x-ray luminosity
of SN 1993J (type IIb) in M81 at the same age."
1994 July 14 (6019) Brian G. Marsden
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