Each line of the file NGC6791.dat contains the following information.  Actual values are
shown for star 7564.

Col.    type              value      explanation
----    ----              -----      -----------
1       integer           7564       sequential identification number
2       real              1067.4     x in accompanying image, increases E at 0\Sec5/pixel
3       real              1178.1     y in accompanying image, increases N at 0\Sec5/pixel
4       real              16.641     B-band magnitude
5       real              0.0009     sigma(B), standard error of the mean
6       integer           72         number of valid photometric measurements in B
7       real              15.307     V-band magnitude
8       real              0.0001     sigma(V), standard error of the mean
9       integer           945        number of valid photometric measurements in V
10      real              13.969     I-band magnitude
11      real              0.0004     sigma(I), standard error of the mean
12      integer           723        number of valid photometric measurements in I
13      real              1.236      mean value of the chi image-quality index
14      real              0.058      mean value of the sharp image-quality index
15      real              10.50      value of the sep image-isolation index
16      real              1.181      value of the variability index
17      real              870.0      weight of the variability index
18-20   h m s          19 20 51.44   Right ascension, equinox J2000.0, epoch late 1990's
21-23   deg min sec    +37 46 41.1   Declination, equinox J2000.0, epoch late 1990's
24      integer           1740       number of images used for the astrometry