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IAUC 7865: 2002by; Poss. SN IN NGC 7714

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                                                  Circular No. 7865
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
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SUPERNOVA 2002by IN ESO 139-G34
     R. Chassagne, Ste. Clotilde, Ile de Reunion, reports his
discovery of an apparent supernova (mag 14.5) on an unfiltered CCD
frame taken on Mar. 31.02 UT (and confirmed on frames taken on Apr.
2.04) with a 0.30-m automated telescope.  SN 2002by is located at
R.A. = 17h50m18s.58, Decl. = -59o33'51".6 (equinox 2000.0), which
is 24".9 west and 13".4 south of the center of ESO 139-G34.  The
new object does not appear on unfiltered images taken by Chassagne
on Feb. 25 (limiting mag about 18) or on a U.K. Schmidt plate taken
on 1975 June 14 (limiting mag 21.0).

     S. Mattila and P. Meikle, Imperial College, London; N. Walton,
Institute of Astronomy, Cambridge; R. Greimel, Isaac Newton Group,
La Palma; S. Ryder, Anglo-Australian Observatory; and C. Alard,
DASGAL and Institut d'Astrophysique, Paris, report the discovery
(7-sigma detection) of a possible supernova (mag 17.3) in an
archival U.K. Infrared Telescope (UKIRT) K-band image obtained with
IRCAM3 on 1998 Sept. 5.4 UT; images taken 3 min apart showed no
detectable movement (seeing 0".8).  The new object was located in
the nuclear region of the starburst galaxy NGC 7714 at R.A. =
23h36m14s.0, Decl. = +2o09'24" (equinox 2000.0), which is 2" west
and 5" north of (or 1 kpc from) the galaxy nucleus.  The new object
was apparent via image-subtraction techniques when compared with
later K_s-band images obtained on 2001 Sept. 1.0 at the William
Herschel Telescope (+ INGRID) and on 2000 Oct. 21 by A. Lancon and
collaborators at the New Technology Telescope (+ SOFI), when no
point source was visible at the location.  Subtraction techniques
reveal no object (limiting mag 18.5) at this location on a UKIRT
H-band image obtained on 1998 Sept. 5 (NTT reference image).  If
this was a normal core-collapse supernova at any epoch, or a slow
decliner (Mattila and Meikle 2001, MNRAS 324, 325) at an early
epoch, an estimate of the H-K color limit implies an A_V towards
the supernova of at least 6 mag.  Alternatively, such a red H-K
color could be produced by a slow-decliner type (e.g., SN 1998S) at
a late phase with a much lower A_V.  The search of archives for
other detections of this possible supernova is encouraged.
     W. Li, University of California, finds no object at the
location of the possible supernova on KAIT images from 1998 Oct. 22
(limiting mag 19.0), and T. Puckett, Mountain Town, GA, finds
nothing on his image taken on 2000 Nov. 11.16 that is not present
on a red Digitized Sky Survey image.

                      (C) Copyright 2002 CBAT
2002 April 3                   (7865)            Daniel W. E. Green

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