[vsnet-alert 5657] SN 2001R in NGC 5172

[Hitoshi YAMAOKA <yamaoka@rc.kyushu-u.ac.jp>]

Dear SN watchers,

  The KAIT has discovered a faint SN on the neighbouring galaxy.  The
host galaxy has produced another SN 3 years ago.

  The new object has discovered on the images taken Jan. 6.5, Feb.
3.5, and Feb 4.5, and it has been at mag 185:C continuously.  The
location is: R.A. = 13h29m16s.93, Decl. = +17o02'41".2 (2000.0), which
is about 33" west and 25" south of the nucleus of the tilted spiral
(SAB(rs)bc:) galaxy NGC 5172.  SN 2001R is superimposed on the
southwestern arm.  There are several foreground star around the host
galaxy, which are well outside of the SN:

position end figures  GSCmag rmag bmag  offset    name
  20s.41  3'47".0     13.85  14.9 15.1 41"N,17"E  GSC 1458-410
  19s.42  2'13".2      --    17.0 18.2 due 53"S   --
  18s.38  2'21".0      --   (17.8:)    46"S,10"W  --

  * The positions, rmag and bmag are taken from USNO_A2.0 except the
    last one (measured on DSS2 R image)
  * offset was measured from the nucleus of NGC 5172.

And, note that mag 12 star about 3'.3 ENE of NGC 7251 (GSC 1458-233 =
G 63-33 (G means Giclas)) has a large proper motion (dRA = -0".41/yr,
dDecl = -0".23/yr).  The photometry of NLTT stars (Ryan, 1989, AJ, 98,
1693) shows that this star's V = 12.55, B-V = 1.38 U-B = 1.10, V-R =
0.89, R-Ic = 0.93.  It can be used for the photometric standard, but
not recommended for the astrometric reference without appropriate
treatment. 

  From the recession velocity of NGC 5172, the expected maximum for
normal SN Ia is mag 15.4.  The constant brightness for almost 1 month,
however, indicate that it would be in some plateau phase, which is
typical for some of SN II.  

  This galaxy had produced another SN 3 years ago.  SN 1998cc was
discovered also by the KAIT at mag 18.1 before maximum.  It was of
type Ib (relatively rare; see vsnet-campaign-sn 149), but not
followed-up well.  The VSNET archive has an report that SN 1998cc was 
at mag 153C, however which seems too bright.  

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

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