171  QW SERPENTIS     (UGSU)   Range: 12.8-~18.0p
     Position:   15 26 13.99  +08 18 03.3  (J2000, from .dat file)
     Magnitude:  V=13.283  B-V=-0.078      (in .dat file)
                                                            
ID      RA  (2000)   DEC       X    Y  N    V      ERR     B-V    ERR 

a) Comparison star sequence

1    15 25 55.0  +08 24 00  -281  357  2  11.770  0.000   0.525  0.005   
2    15 26 33.0  +08 13 15   283 -288  2  11.977  0.008   0.946  0.008   
3    15 26 31.4  +08 14 37   258 -206  2  13.120  0.012   0.722  0.013   
4    15 26 08.9  +08 18 57   -75   54  2  13.411  0.006   0.637  0.004   
5    15 26 22.7  +08 14 38   130 -205  2  13.464  0.000   0.863  0.003   
6    15 26 22.5  +08 13 01   126 -302  2  14.419  0.008   0.913  0.007   
7    15 26 18.1  +08 17 51    61  -12  2  14.599  0.000   0.638  0.005   
8    15 26 00.1  +08 20 25  -206  142  2  14.932  0.012   0.854  0.021   
9    15 26 05.9  +08 21 34  -120  211  2  15.097  0.006   1.063  0.006   
10   15 25 56.7  +08 18 10  -257    7  2  15.627  0.006   0.613  0.008   
11   15 26 04.5  +08 16 20  -140 -103  2  16.416  0.000   0.763  0.006   
12   15 26 01.8  +08 18 37  -182   34  2  17.550  0.023   0.409  0.040   
13   15 26 08.0  +08 17 32   -89  -31  2  18.648  0.008   0.379  0.035   


b) Wide-colour extension for CCD calibration

     15 26 25.5  +08 22 01   171  238  2  17.222  0.068   0.088  0.045   
     15 26 34.8  +08 20 23   309  140  2  13.723  0.010   1.464  0.007 


Notes:

1. There is a bright star in this field at 15h 26m 24.9s +08d 21' 52" 
not included in the field photometry. This is HD 137532 = ADS 9635, a 
2.5" separation nearly equal double. The Tycho-2 magnitudes for each 
component are V=9.98 +/-0.04 and V=10.18 +/-0.05, resulting in a combined 
magnitude of about 9.7. 

2. There is a second bright star in the NW corner of the field at 
15h 25m 47.4s +08d 24' 33" with a reliable Tycho-2 magnitude of V=9.83 
+/-0.04.

3. This sequence differs slightly from that given by Bouma and van Dijk,
which they also derived from the same original data. In particular I have
not included their 137 (13.723/1.464) as it is too red for this sequence.
However it is included here as one of the extended colour stars in b)
above. Also I have not included Bouma and van Dijk's 155 and 157, as those
two stars are not necessary to the sequence and lie a considerable distance
from the variable.

4. The quiescent magnitude is an estimate from a DSS image.


Bruce Sumner
14 July 2000