[vsnet-chat 4675] UBVRI sequence for WZ Sge

["Bruce Sumner" <b.sumner@bom.gov.au>]

UBVRI sequence for WZ Sge

For those observers performing differential photometry during this
current outburst here is a UBRVI sequence to assist you in reducing
your instrumental photometry to the UBVRI Standard System.

This sequence has been derived from Arne Henden's single night bright
star field photometry, and errors are estimated to be in the order of
+/-0.02 magnitudes.

All stars in this list, except #5, are shown on Reinder Bouma's recent
charts. In addition the AAVSO/RASNZ charts show all the comparison
stars except #7, #11 and #12.

Bruce Sumner

No     RA (J2000) DEC         X    Y nobs   V     B-V    U-B    V-R    R-I
1   20 07 33.7  +17 40 01   -39 -134  1   8.719  0.174  0.146  0.044  0.089
2   20 08 01.5  +17 40 12   357 -123  1   9.675  1.031  0.850  0.507  0.499
3   20 08 00.9  +17 38 00   349 -255  1  10.843  0.679  0.191  0.351  0.362
4   20 07 33.6  +17 39 16   -42 -179  1  11.760  0.197  0.153  0.049  0.108
5   20 07 45.1  +17 42 38   123   23  1  12.568  0.507  0.116  0.259  0.321
6   20 07 53.3  +17 42 03   240  -12  1  12.782  0.968  0.864  0.531  0.482
7   20 07 38.1  +17 37 05    23 -311  1  13.022  0.731  0.255  0.369  0.370
8   20 07 45.8  +17 40 01   133 -134  1  13.087  0.589  0.110  0.305  0.342
9   20 07 29.5  +17 43 36  -100   81  1  13.214  0.810  0.386  0.376  0.383
10  20 07 35.6  +17 45 10   -13  175  1  13.343  0.660  0.210  0.364  0.381
11  20 07 48.1  +17 38 55   166 -200  1  13.582  0.617  0.167  0.329  0.364
12  20 07 48.5  +17 42 18   172    3  1  13.678  0.705  0.342  0.368  0.358
13  20 07 36.2  +17 44 50    -4  155  1  13.897  0.443  0.284  0.268  0.312
14  20 07 38.5  +17 42 30    28   15  1  14.104  1.334  1.938  0.722  0.636

Notes:

1.	Krzeminski and Kraft (ApJ 140, 921, 1964), have three comparison
stars in common with this sequence. Note that Henden's B-V and U-B colours
match well for those three stars, but V differs by roughly 0.04 magnitude
for all three, in the sense that Henden's values are brighter.

         No    V    B-V   U-B
          1   9.70  1.11        Tycho-2 transformed
              9.68  1.03  0.85  Henden 1 night
              9.72  1.03  0.76  Krzeminski 2 nights

          2  11.77  0.43  0.19  Henden 1 night
             11.84  0.39  0.22  Krzeminski 2 nights

          4   8.76  0.15        Tycho-2 transformed
              8.72  0.17  0.15  Henden 1 night
              8.76  0.16  0.13  Krzeminski 6 nights

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