Central Bureau for Astronomical Telegrams

IAUC 5742: 1993J

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                                                  Circular No. 5742
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)


SUPERNOVA 1993J IN NGC 3031
     H. G. Corwin, California Institute of Technology, provides the
following UBVRI (R, I on the Cousins system; observers are requested
to indicate if they are not using this system) photometry for stars
GSC 4383.n in the vicinity of the supernova: n = 0224, V = 11.85, B-V =
+1.30, U-B = +1.29, V-R = +0.68, V-I = +1.29; 0308, 11.78, +0.69, +0.16,
+0.40, 0.80; 0434, 12.45, +0.63, +0.11, +0.39, +0.76; 0928, 11.90, +0.50,
-0.08, +0.30, +0.60; 1023, 14.73, +0.46, +0.12:, +0.36, +0.60:; 1031,
11.62, +0.53, -0.04, +0.33, +0.69; 1123, 13.65, +0.57, -0.09:, +0.34,
+0.69.  Mean internal standard deviations are no more than +/- 0.03 mag,
and none of the stars shows evidence of variability.  The GSC V
magnitudes of the seven stars are 11.17, 11.86, 12.00, 11.42, 14.36,
11.16 and 13.23, respectively.

     A. C. Porter, Kitt Peak National Observatory, reports: "Harris VRI-
band CCD photometry by A. W. Neely, Silver City, NM, yields
Mar. 31.21 UT, V = 10.33; Apr. 1.18, 10.60; 2.15, 10.97 (+/- 0.03;
comparison GSC 4383.0928 with GSC V).  The R and I band
photometry, not yet calibrated, indicates that the supernova is reddening,
with the maximum occurring progressively later in redder bands: R faded
by 0.07 and 0.25 and I by 0.04 and 0.16 mag during Mar. 31-Apr. 1 and
during Apr. 1-2, respectively.  Unfiltered magnitudes confirm that maximum
occurred on about Mar. 31: Mar. 29.18 UT, 11.2; 31.21, 9.9; Apr. 1.18,
10.5; 2.15, 11.0.  The Mar. 28 magnitude on IAUC 5740 was measured
relative to GSC 4383.0340 (GSC V = 14.59).  Preliminary
Thuan-Gunn photometry from CCD images obtained by J. G. Cohen with the
1.5-m Palomar reflector on 1985 Jan. 21 shows the presumed progenitor at
r = 21, g-r = +0.9.  The measurements were made with a 5" aperture and
5"-wide sky annulus to minimize background contamination.  The
uncertainty in the color may be as large as +/- 0.25 mag because of the
galaxy background, but the redness is certain, and the value derived
suggests a spectral type of about M0."

     P. Prugniel, Observatoire de Haute Provence, reports that several
1-min CCD images of the progenitor during Mar. 16.90-23.10 do not
show evidence for variation.  R (Cousins) = 20.0 +/- 0.2.  The object is
at the detection limit in B and fainter than a star measured at B = 21.0
+/- 0.3.

     Photometry by D. Hanzl, Copernicus Observatory, Brno: Mar. 31.961
UT, V = 10.97 +/- 0.04; B-V = +0.33 +/- 0.03; Apr. 1.816, 11.19 +/- 0.01,
+0.32 +/- 0.03 (comparison HD 86677, V = 7.876 +/- 0.031, B-V = +0.510
+/- 0.015).  Single-channel UBVRI photometry by M. Mikolajewski and
B. Wikierski, Copernicus University, Torun: Apr. 1.86, V = 11.32,
U-B = -0.56, B-V = +0.26, V-R = +0.37, V-I = +0.37.


1993 April 3                   (5742)              Brian G. Marsden

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