(fwd) SN 1994D sequence

>From varstars-owner@nic.funet.fi Fri Mar 11 08:06:26 1994
Date: 	Fri, 11 Mar 1994 00:59:29 +0200
Message-ID: <Mar31@hoge.baba.hajime.jp>
From: granslo@argo.uio.no
To: "varstars@lists.funet.fi"@gollum.uio.no
Cc: GRANSLO@gollum.uio.no
Subject: Comparison stars for SN 1993D in NGC 4526
Status: R

        ***** SEQUENCE STARS FOR SUPERNOVA 1994D IN NGC 4526 *****

A supernova has erupted in the lenticular galaxy NGC 4526. It was found
on Mar. 7 U.T. by R. R. Treffers et al. during the Leuschner Observatory
Supernova Search, using an automated 76-cm telescope with a CCD camera.
The supernova is of type Ia and it may reach magnitude 11 - 12 at maximum.

The following list of photoelectric V-magnitudes and colour indices B-V,
U-B, V-R and V-I for some stars near the galaxy should be useful for
observers who wish to perform visual estimates or photoelectric or CCD
measurements. It should be noted that observing may be difficult due to
the glow from the galaxy.

HHM       Photoelectric measurements (KM)          TB   Offset from nucleus
id.    V       B-V     U-B     V-R     V-I    n    id.      of NGC 4526
 1   13.25    0.76    0.46    0.44    0.83    1    ---    140" E  590" S
 2   13.37    0.60    0.00    0.36    0.70    1    ---     10" E  525" S
 3   12.574   0.686   0.231   0.388   0.765   2    126    615" E  305" S  
 4   13.32    0.620   0.117   0.350   0.363   2    ---    550" E  145" S
 5   13.31    0.650   0.26    0.38    0.74:   2    134    360" E    5" S
 6   11.277   0.670   0.225   0.395   0.770   2    113    295" E   80" N
 7   11.98    0.51    0.02    0.31    0.60    1    120     15" W  345" N
 8   14.46    0.61    0.03    0.36    0.72    1    ---     40" W  365" N
 9   12.54    1.03    0.97    0.56    1.03    1    126     20" W   75" S
11    6.737   1.084   1.001   0.560   1.065   8     68    390" E  140" N
12   14.61    0.75    0.29    0.46    0.96::  2    146    605" E  165" S

Identifications are from Hanes, Harris and Madore (1976) [HHM] and Thompson
and Bryan (1989) [TB]. The photoelectric measurements are due to Kilkenny
and Malcolm (1984) [KM]. Their work should be used in preference to the HHM
photometry as the latter measurements are affected by systematic errors.
These difficulties have been pointed out in a recent e-mail message by
Brian Skiff (Lowell Observatory) via the Nova network.

Photometric measurements listed with three decimal places are expected to
be accurate to a standard deviation (S.D.) of less than 0.015. Two decimals
indicate a S.D. from 0.015 to less than 0.05, a colon after the measurement
implies a S.D. from 0.05 to less than 0.10, while a double colon indicates
a S.D. of 0.10 or more. Measurements from a single night only (n = 1)
should be treated with caution.

The 2000-coordinates for NGC 4526 is R.A. = 12h 34m.0, Decl. = + 7d 42'.
SN 1994D is located 9" W and 7" E from the nucleus of the galaxy.

The star HHM 11 is SAO 119479 = HD 109417. There is also a bright field
star (HD 109285 = SAO 119466) with V = 6.91 and B-V = +1.04 and it is
located 445" W and 90" S from the center of the galaxy.

References:
Hanes, D. A., Harris, W. E., and Madore, B. F., 1976: "UBV Sequences for
  Selected Virgo Galaxies", Mon. Not. R. Astr. Soc., 177, 653.
Kilkenny, D., and Malcolm, G., 1984: "Four UBVRI Sequences near Bright
  Virgo Galaxies", Mon. Not. R. Astr. Soc., 209, 169.
Thompson, G. D., and Bryan, J. R., Jr., 1989: "The Supernova Search Charts
  and Handbook", Cambridge University Press.

                                            Bjorn H. Granslo