COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3662   

                                              Konkoly Observatory
                                              Budapest
                                              20 September 1991

                                              HU ISSN 0374 - 0676


      PHOTOELECTRIC MINIMA OF THE ECLIPSING BINARY XY BOOTIS


The variability of XY Boo (BD+20d 2874) was discovered by Hoffmeister (1935).
It was found by Tsesevich (1950) that the system belonged to the W UMa type.
The system was observed photoelectrically at the Yunnan Observatory in yellow
and blue colours using a 60 cm reflector telescope and a photoelectric
photometer equipped with an EMI 8256B photomultiplier tube and Johnson's
standard B, V filters. The integrations were controlled by a microcomputer.

Integration of each observation is twenty seconds. The comparison and
check stars are the same as that used by Binnendijk (1971).

Five minima and the values of E and O-C obtained in both B and V filters for
XY Boo are listed as follows:

JD.Hel.         Min.  Filter   E         O-C
2448334.3320     II   V        21439.5   0.1390
       .3319          B                  0.1389
2448335.2623      I   V        21442     0.1433
       .2624          B                  0.1434
2448336.3700      I   V        21445     0.1390
       .3704          B                  0.1394
2448363.2365     II   V        21517.5   0.1404
       .2360          B                  0.1399
2448364.1655      I   V        21520     0.1435
       .1660          B                  0.1440

   The O-C values were calculated using Binnendijk's ephemeris (1971):

          JD.Hel.Min.I = 2440389.7321 + 0.37055251 E.


              ZHANG YUNLIN, LIU QINGYAO, WANG BI and GU SHENHONG
              Yunnan Observatory
              Academia Sinica
              Kunming, P.O. Box 110
              People's Republic of China

References:

Binnendijk, L.: 1971, Astron.J. 76, 923. [BIBCODE 1971AJ.....76..923B ]
Hoffmeister, C.: 1935, Astron. Nachr. 255, 401. [BIBCODE 1935AN....255..401H ]
Tsesevich, V.P.: 1950, Astron. Circ. Kasan (No. 100), 18.