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IAUC 7740: 2001fb; 1998ff

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                                                  Circular No. 7740
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
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     A. Rest, University of Washington, reports the detection of an
apparent supernova (at magnitudes g' = 20.0, r' = 19.0) on Sloan
Digital Sky Survey (SDSS) images taken with the SDSS 2.5-m
reflector on Oct. 10.3 UT.  SN 2001fb is located at R.A. =
0h10m06s.15, Decl. = -0 26'18".2 (equinox 2000.0), which is 7".2
west and 8".7 south of the nucleus of the host galaxy.  The new
object is not present in SDSS images taken on 1998 Sept. 19.3, to
limiting magnitudes g' = 23 and r' = 22.5.  Follow-up observations
taken at the ARC 3.5-m reflector at Apache Point Observatory on
Oct. 24.1 by A. Miceli and R. Covarrubias confirm the existence of
the new object.

          S. Beckwith, Space Telescope Science Institute, on behalf
of the 'Supernovae at High Z Team' (which includes also A. Riess,
F. Boffi, S. Casertano, R. Doxsey, H. Ferguson, A. Fruchter, M.
Giavalisco, R. Gilliland, I. Griffin, A. Koekemoer, M. Livio, B.
Margon, G. Meylan, N. Panagia, V. Platais, K. Sahu, and D.
Soderblom), reports the discovery of an apparent supernova in the
'Hubble Deep Field South' (HDFS) on WFPC2 images taken with the
Hubble Space Telescope (HST) and filter F814W in Sept. and Oct.
1998:  "SN 1998ff was found by differencing the 1998 images with
new HST images taken during 2001 Oct. 2 and 3, also with F814W.
The new object appeared with a starlike point-spread function,
offset 0".08 west of the core of an early-type galaxy (number 2285
from Casertano et al. 2000, A.J. 120, 2747) whose nucleus is
located at R.A. = 22h32m48s.90, Decl. = -60o34'04".8 (equinox
2000.0; uncertainty +/- 0".04).  SN 1998ff had a mean magnitude of
[F814W] = 25.3 +/- 0.1 during the HDFS campaign and was seen to
decline by a few tenths of a magnitude during the 12 days  of the
campaign.  SN 1998ff was independently detected in each of eight
separate, 1-day epochs between 1998 Sept. 28 and Oct. 9.  A
photometric redshift of z = 1.20 for the host galaxy was given by
Fontana et al. (2000, A.J. 120, 2206) by employing photometry from
ultraviolet wavelengths through the K band.  Low-resolution
spectroscopy of the host galaxy (so as to refine further the
host-galaxy redshift and knowledge of the underlying stellar
population), as well as analysis of deep images of the HDFS taken
in the later half of 1998, may prove valuable."

                      (C) Copyright 2001 CBAT
2001 October 26                (7740)            Daniel W. E. Green

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