(fwd) SN 1994D sequence (Skiff)

>From bas@lowell.edu Fri Mar 11 16:15:14 1994
Date: Fri, 11 Mar 1994 00:01:07 -0700 (MST)
From: bas@lowell.edu (Brian Skiff account lowell)
To: nova@nova.la.asu.edu
Message-ID: <Mar32@hoge.baba.hajime.jp>
Content-Transfer-Encoding: 7BIT
Status: R

Summary of photometry for stars near NGC 4526

     Since neither the Thompson & Bryan charts nor the Monthly Notices papers
seem to be widely available to observers, below is a summary of UBVRI
photometry for stars in the field of NGC 4526.  The stars are identified in
the first column by the numbers assigned by Hanes et al.  In the second
column are GSC numbers, followed by GSC J2000 positions.  The positions of
the two mag. 7 K-giants bracketing the galaxy come from SIMBAD.  (These are
the stars mentioned by Professor de Vaucouleurs in his recent nova-net
message as possibly interferring with observations.)  The photometry from
three sources is then listed to the precision given in each paper.
     All the data might have small problems.  Some of the Hanes et al. data
were taken in Toronto and at Siding Spring, neither of which is known as a
first-rate photometric site.  The Kilkenny & Malcolm data were done from
Sutherland directly against Cousins E-region standards.  Nevertheless, they
were affected by extinction anomalies from El Chichon.  They provide measures
of equatorial standards by way of showing there are no systematic differences
with the standard system.  K&M also give transformations for the Hanes et al.
data.  The Haggkvist & Oja data happen to have been taken from Uppsala,
another place not known as an excellent photometric site, and somewhat
paradoxically may suffer from the high culminating airmass of the field
(sec z ~1.6 compared to ~1.3 from South Africa).  I'm sure all the parties
involved did the best they could, but the systematic differences are clearly
evident even so.
     Among the entries, only star 11 (HD 109417) may be considered to be well
observed (K&M's results are based on eight measures); the remainder have only
one or two nights observation each from each source.  Given photometric
conditions, one may instead wish to use the relatively close equatorial
standards to calibrate observations of the supernova.  The stars listed here,
however, will certainly be useful for establishing reasonably good zero-points
during cloudy weather, and are entirely adequate for visual observers.
\Brian


H  GSC 0874-     RA  (2000)  Dec       V     U-B    B-V    V-R    V-I   source

1    1023     12 34 12.8  +7 31 55   13.25   0.46   0.76   0.44   0.83   (2)

2    1048     12 34 03.8  +7 33 02   13.37   0.00   0.60   0.36   0.70   (2)

3    0994     12 34 45.4  +7 36 23   12.62   0.26   0.69                 (1)
                                     12.574  0.231  0.686  0.388  0.765  (2)

4    1052     12 34 41.7  +7 39 09   13.39   0.08   0.59                 (1)
                                     13.322  0.117  0.620  0.350  0.363  (2)

5    0862     12 34 28.4  +7 41 33   13.36   0.31   0.58                 (1)
                                     13.31   0.26   0.650  0.38   0.74:  (2)

6    0871     12 34 24.4  +7 43 07   11.29   0.24   0.67                 (1)
                                     11.277  0.225  0.670  0.395  0.770  (2)

7    0870     12 34 03.8  +7 47 42   11.97    --    0.85                 (1)
                                     11.98   0.02   0.51   0.31   0.60   (2)

8    0773     12 34 01.4  +7 48 01   14.46   0.03   0.61   0.36   0.72   (2)

9    0899     12 34 02.4  +7 40 35   12.62    --    1.12                 (1)
                                     12.54   0.97   1.03   0.56   1.03   (2)

11*  0908     12 34 30.5  +7 44 07    6.77   1.02   1.08                 (1)
                                      6.737  1.001  1.084  0.560  1.065  (2)
                                      6.70    --    1.10                 (3)

12   0912     12 34 45.2  +7 38 50   14.65   0.25   0.75                 (1)
                                     14.61   0.29   0.75   0.46   0.96:  (2)

--*  0772     12 33 32.9  +7 40 43    6.91    --    1.04                 (3)


* - star 11 = HD 109417 (K2), the bright star east of the galaxy
* - last star in list = HD 109285 (K0), the bright star west of the galaxy

sources:  (1)  Hanes, D. A., Harris, W. E., and Madore, B. F. 1976 MNRAS
               177, 653.
          (2)  Kilkenny, D., and Malcolm, G. 1984, MNRAS 209, 169.
          (3)  H\"aggkvist, L., and Oja, T. 1973, A&AS 12, 381.