75   V522 SAGITTARII   (N/UG?)   Range: 12.9-17.0p
     Position:   18 48 00.49  -25 22 12.7 (J2000, .dat file, extrapolation)
     Magnitude:  B=18.2   B-R=1.2         (USNO A2.0) 

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

a) Comparison star sequence
    

1    18 47 43.1  -25 23 27  -235  -73  1  10.922  9.999   0.242  9.999   
2    18 48 16.1  -25 23 30   211  -77  1  11.959  9.999   1.213  9.999   
3    18 48 06.9  -25 23 16    87  -63  1  12.896  9.999   0.745  9.999   
4    18 47 49.0  -25 24 13  -156 -120  1  13.369  9.999   0.830  9.999   
5    18 48 01.6  -25 24 03    14 -110  1  13.839  9.999   0.700  9.999   
6    18 47 58.6  -25 22 49   -26  -36  1  14.387  9.999   0.773  9.999   
7    18 47 58.3  -25 23 10   -30  -57  1  14.830  9.999   0.774  9.999   
8    18 47 59.5  -25 21 40   -14   33  1  15.127  9.999   1.059  9.999   
9    18 48 02.8  -25 23 23    31  -70  1  15.459  9.999   1.032  9.999   
10   18 47 59.5  -25 22 32   -13  -19  1  15.904  9.999   0.505  9.999   
11   18 48 00.5  -25 22 22    -1   -9  1  16.701  9.999   0.883  9.999   
12   18 48 02.6  -25 22 49    29  -36  1  17.152  9.999   1.128  9.999   


b) Wide-colour extension for CCD calibration

     18 47 48.6  -25 24 57  -162 -164  1  15.003  9.999   0.465  9.999   
     18 47 54.5  -25 22 10   -82    3  1  14.217  9.999   0.516  9.999   
     18 47 57.9  -25 22 18   -36   -5  1  12.489  9.999   1.653  9.999   
     18 47 40.6  -25 21 33  -270   40  1  13.918  9.999   1.851  9.999   

Notes:

1. This sequence based on photometry obtained on only one night. Nominal
errors for both magnitudes and colours are +/-0.02 magnitudes.

2. Duerbeck in his 1967 atlas and Downes, Webbink and Shara in their 1997
catalogue, both identify the star here called #11 (V=16.70) as the variable. 
However from its colour (B-V=0.88) and its spectrum (G-K star, see Ringwald, 
et.al. MNRAS,281,192, 199600, it seems  that this star cannot be V522 Sgr, 
but appears to be an ordinary field star.

3. This variable was discovered by J. G. Ferwerda in August 1931. Precessing 
his position, as quoted in Duerbeck, to a J2000 position, identifies a star 
some 10 arcsec north of star #11 as the variable. This star appears
at about magnitude 17.5B on five DSS plates taken in 1950, 1974, 1984, 1987
and 1992. No hint of variability is evident. However it should be noted
that this star is quite red with B-R=1.2 in the USNO A2.0 catalogue.
Despite its being red, I have used this star as the variable star candidate,
and it is this star whose details appear in the above title block.

4. The real position and the exact nature of this variable star remains to be 
determined.


Bruce Sumner 
Posted 020119