41.  RY SERPENTIS   (UG)   Range: 13.2-18.0P
     Position:   17 23 07.20  -12 48 09.4  (J2000, from .dat file)
     Magnitude:  V=15.865  B-V=0.783       (in .dat file)

ID     RA  (2000)   DEC      X    Y   N    V      ERR     B-V    ERR 

a) Comparison star sequence

1   17 23 01.2  -12 50 00   -88 -111  3  12.648  0.017   0.749  0.021   
2   17 22 58.4  -12 50 04  -129 -115  3  12.986  0.000   1.020  0.007   
3   17 22 51.1  -12 43 32  -235  277  4  13.415  0.005   0.752  0.011   
4   17 22 59.2  -12 45 05  -117  184  5  13.785  0.000   1.094  0.007   
5   17 23 09.2  -12 48 53    30  -44  4  14.212  0.005   0.853  0.009   
6   17 23 11.6  -12 49 16    64  -67  4  14.436  0.005   1.504  0.006   
7   17 23 17.9  -12 48 20   156  -11  4  14.675  0.005   1.412  0.012   
8   17 23 00.6  -12 47 21   -97   48  4  14.918  0.000   1.436  0.008   
9   17 23 22.3  -12 47 32   220   37  3  15.258  0.000   1.327  0.003   
10  17 23 07.5  -12 47 45     5   24  3  15.625  0.006   0.984  0.002   
11  17 23 07.2  -12 48 09     0    0  3  15.865  0.452   0.783  0.112   
12  17 23 13.6  -12 46 56    94   73  3  15.963  0.011   1.358  0.013   
13  17 23 06.4  -12 47 46   -11   23  3  16.418  0.011   1.203  0.022   
14  17 23 07.7  -12 48 35     7  -26  3  16.651  0.014   1.468  0.021   
15  17 23 09.3  -12 48 32    30  -23  3  17.226  0.031   1.175  0.051   
16  17 23 08.1  -12 48 09    13    1  3  17.874  0.022   1.102  0.049   
17  17 23 06.2  -12 48 20   -15  -11  3  18.833  0.055   1.298  0.136   


b) Wide-colour extension for CCD calibration

    17 23 19.8  -12 44 03   184  246  3  15.835  0.011   0.489  0.011   
    17 22 46.4  -12 44 31  -305  218  4  14.492  0.019   1.890  0.020   
    17 23 06.4  -12 51 41   -12 -212  4  13.753  1.164   2.012  0.038   


Notes:

1. Star 11 is the Downes and Shara candidate for RY Ser. There is no doubt
that this star does vary, as the v err value above shows. Unfortunately the
star itself it too red to be a dwarf nova. However a close inspection of
the UK Schmidt SERC-J plate taken 7 July 1988 shows that the image of this
star is slightly elongated when compared to other star images on this
plate. A check of another plate taken one week later, on July 15, shows no
hint of elongation. The elongation noted on 7 July implies a companion to
star 11, located some 2 arcsec to the SW. This companion is my candidate
for RY Ser.

2. The wide colour star with V=13.753 is actually the Mira variable RX Ser, 
with a range of 13.3-<17.3B

Bruce Sumner
Revised 2 August 1999