Central Bureau for Astronomical Telegrams
IAUC 6733: SUNGRAZING COMETS; GRB 970828; 1997dc
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Circular No. 6733
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUNGRAZING COMETS
C. St. Cyr, Naval Research Laboratory, on behalf of the SOHO-
LASCO Consortium (cf. IAUC 6685), reports the discovery of two more
probable Kreutz sungrazing comets. Measurements by St. Cyr and D.
Biesecker have been reduced by G. V. Williams and are given on MPEC
1997-R03 and 1997-R04, together with tentative orbital elements by
B. G. Marsden. C/1997 Q1, with no evidence of a tail and peak
magnitude about 7, was discovered by Biesecker in C3 coronagraph
data, which were interrupted when the comet was at an apparent
solar distance of about 12.5 radii, 13 hr after the first
observation, due to the closing of the telescope doors. C/1997 Q2,
discovered by K. Schenk in C3 data nine days earlier, is one of the
brighter SOHO discoveries, peaking at mag 4 or brighter; it
developed a tail, which was at least 1.5 deg long in the C2 images,
26-30 hr after the initial C3 detection. As with other SOHO comets
with extensive observed arcs, the orbital solution for C/1997 Q2
does not fit the complete arc, but Marsden notes that the two
comets were clearly in the same Kreutz-type track, with T = Sept.
1.3 and Aug. 24.1 TT, respectively.
1997 UT R.A. (2000) Decl. Comet
Aug. 31.399 10 15.1 + 7 16 C/1997 Q1
22.771 9 39.3 + 9 52 C/1997 Q2
GRB 970828
A. Guarnieri, C. Bartolini, N. Masetti, and A. Piccioni,
University of Bologna, communicate: "A preliminary analysis of CCD
images of the GRB 970828 field (IAUC 6728), obtained with the
Bologna University 1.5-m telescope (+ RCA) in B and R bands
(limiting mag about 21 for both) on Aug. 29.86, 30.84, and 31.83
UT, and in the R band on Sept. 1.82, shows no object with a rise or
a decline of > 0.2 mag."
SUPERNOVA 1997dc IN NGC 7678
C. Y. Peng, University of Arizona; R. R. Treffers, M. Modjaz,
and A. V. Filippenko, University of California at Berkeley; and
M. W. Richmond, Rochester Institute of Technology, report that SN
1997dc (cf. IAUC 6715-6717) is visible in prediscovery CCD images
obtained as part of the Lick Observatory Supernova Search (cf. IAUC
6627) on July 26 and Aug. 1 and 5 UT. It might be present on July
21, as well. The object was in all cases fainter than the
threshold for automatic detection.
(C) Copyright 1997 CBAT
1997 September 4 (6733) Daniel W. E. Green
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