Central Bureau for Astronomical Telegrams
IAUC 6742: 1997dd; GRB 970815; C/1997 N1
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Circular No. 6742
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 1997dd IN NGC 6060
P. Garnavich and S. Jha, Harvard-Smithsonian Center for
Astrophysics; and R. Kirshner, University of California at Santa
Barbara, report: "Spectra of SN 1997dd (cf. IAUC 6724) were
obtained by P. Berlind with the 1.5-m Tillinghast telescope on Sept.
10.1 UT. Strong absorption lines have developed at 581.2, 660.0,
and 699.1 nm, corresponding to He I with a photospheric velocity of
8000 km/s. The photospheric velocity of H-alpha is 12 000 km/s.
The spectrum is similar to that of SN 1996cb about 1 month after
outburst and confirms the prediction by Phillips and Suntzeff (IAUC
6725) that SN 1997dd would transform into a type-Ib supernova."
GRB 970815
J. Greiner, Astrophysical Institute, Potsdam, reports: "A
17 000-s ROSAT observation of the RXTE error box of GRB 970815 (cf.
IAUC 6718) during Aug. 20-22 reveals ten x-ray sources within the
HRI field-of-view. One faint source is detected at R.A. =
16h08m47s.7, Decl. = +81o31'53" (equinox 2000.0), which just falls
on the border of the RXTE error box. Using a power-law model with
photon index 2 and the galactic absorbing column N_H = 4.7 x 10E20
cmE-2, the observed countrate of 0.00073 +/- 0.00025 counts/s
corresponds to an unabsorbed ROSAT flux (band 0.1-2.4 keV) of 5 x
10E-14 erg cmE-2 sE-1. This source is too faint to make any
variability analysis. However, its flux level is consistent with a
t**(-1) flux decay, suggesting that it may be the afterglow of GRB
970815. One of the x-ray sources detected outside the RXTE error
box is located at R.A. = 16h06m51s.5, Decl. = +81o30'28",
consistent with the ASCA detection (IAUC 6722). Its countrate of
0.0035 +/- 0.0005 counts/s corresponds to an extrapolated flux in
the band 2-10 keV that is comparable within a factor of 2 with the
ASCA source flux. No optical object is found within the 10" error
boxes of both x-ray sources on the digitized POSS and on Whipple
Observatory images (IAUC 6721). The x-ray image is posted at
http://www.aip.de:8080/~jcg/grb970815.html."
COMET C/1997 N1 (TABUR)
S. Nakano, Sumoto, Japan, reports that H. Abe (Yatsuka) was
unable to locate this comet (cf. IAUC 6714) on several CCD images
obtained with a 0.26-m reflector around Sept. 8.44 UT, though
stars of mag 15 were visible near the comet's predicted position.
(C) Copyright 1997 CBAT
1997 September 12 (6742) Daniel W. E. Green
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