SN2001bt   in  IC4830    ( 19hm13mn48.6ss  -59°17'40" )                                                                                                                          CTIO  Nick  Suntzeff

offset  14.2" ouest  17.1" nord    magnitude  15.0                                                                                 http://www.ctio.noao.edu/~nick/sn/sn2001bt/sn2001bt.html

Telescope  LX200  12"  f/d 2.7  ST7E   UAI173  Ste Clotilde  REUNION   ISLAND                                                                                  CTIO  Pablo Candia

http://ctios6.ctio.noao.edu/~candia/tabla/sn2001bt/tab01bt_1.html

discovery image 2001/05/24.02  unflated    binning 2x  60s	reference image 2001/05/5.03  unflated       limiting mag 19  binning 2x  60s
confirmation image 2001/05/24.94  mag 15.0   180s	referenced  image  DSS  UK Schmidt 1975/05/10.7    limiting mag 21

Circular No. 7633
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)


SUPERNOVA 2001bt IN IC 4830
     R. Chassagne, Ste. Clotilde, Ile de Reunion, reports the discovery of an
apparent supernova (mag about 15.0) on unfiltered CCD images taken with a
0.30-m f/2.7 telescope on May 24.0 and 24.9 UT.  The object is located at
R.A. = 19h13m46s.75, Decl. = -59o17'22".8 (equinox 2000.0), which is 27".7
west and 17".1 north of the nucleus of IC 4830.  An image of the same field
taken on May 5.0 showed nothing at this position (limiting mag 19).  The
U.K. Schmidt image in the Digital Sky Survey (1975 May 10.7 UT) also showed
nothing at this position (limiting mag 21).

Dear SN watchers,

  Further succeeding bright SN discoveries by amateurs.  SN 2001bt was
discovered by an French (in Reunion islands, south Indian Ocean)
amateur R. Chassagne.  It is his 7th discovery, the latest one was SN
2001ba.  SN 2001bt is a southern object, and now at mag 15.0.

  The position of SN 2001bt reported on IAUC 7633 is: R.A. =
19h13m46s.75, Decl. = -59o17'22".8 (2000.0), and the offset from the
nucleus of the host galaxy is reported as 27".7 west and 17".1 north.
These values are, however, inconsistent.  If the offset is correct,
R.A. would have end figures 44s.75 or so.  If the coordinate is
correst, the offset would be 14" west.  In any case, SN lies on the
midway between the nucleus and a foreground star GSC 8772.758 (GSCmag
15.1). 

  The host galaxy IC 4830 is a barred-spiral (SB(r)b) galaxy, and SN
is superimposed on the disk region.  The expected maximum of typical
SN Ia is mag about 15.5, but the discovery magnitude (mag about 15.0
at May 24.0 and 24.9 UT) is already exceed this value.  It can be
intrinsically bright SN, or the distance can be nearer than the
estimate from the recession velocity.  Further photometry and spectral
classification is urgently needed.

Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp