COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                       Number 2292

                                                    Konkoly Observatory
                                                    Budapest
                                                    1983 March 10

                                                    HU ISSN 0374-0676


       PHOTOELECTRIC TIMES OF MINIMA OF ECLIPSING BINARIES




   Photoelectric V-filter observations of selected eclipsing binaries
were continued with the 40-cm f/18 Cassegrain reflector at the Blue Mountain 
Observatory during the 1982 observing season. The observing procedure
was identical to that described in Margrave et al. (1978).
   Following past practice, least-squares parabolic fits were made to
the observations. Table I contains the resultant Heliocentric Julian Date



          Table I. Heliocentric Times of Minima


Star     Hel. JD - 2,440,000       E       O-C          Remark

KO Aql   5209.7844+ 0.0003       1160    +0.0082d          P
RZ Cas   5204.7352+ 0.0008      12825    -0.0016           P
         5217.8828+ 0.0008      12836    -0.0017           P
TV Cas   5256.8056+ 0.0002       2020    +0.0067           P
TW Cas   5207.8303+ 0.0001       2240    -0.0028           P
PV Cas   5164.5753               1962    -0.0022           S
         5165.4760               1963    +0.0022           P
         5253.8509+ 0.0004       2013    -0.0008           S
XX Cep   5206.7625+ 0.0008       1569    +0.0088           P
         5220.7876+ 0.0004       1575    +0.0099           P
SW Lac   5201.7407+ 0.0005       5431    -0.0063           S
         5203.8264+ 0.0009       5438    -0.0053           P
         5204.7892+ 0.0006       5441    -0.0046           P
AT Peg   5219.8562+ 0.0005       4199    +0.0064           P



(minus 2,440,000) for each eclipse along with its probable error, cycle
number E, and O-C value. The data for the first two eclipses of PV Cassiopeiae
were kindly supplied by Dr. Alvaro Gimenez (1982). The letters P and
S in the Remark column denote a primary or secondary eclipse, respectively.
The references for the ephemerides used to calculate the O-C values are
given in Table II.



         Table II. Ephemerides References

Star       Reference

KO Aql    Margrave (1980)
RZ Cas    Herczeg and Friboes-Conde (1974)
TV Cas    Margrave (1980)
TW Cas    Margrave (1980)
PV Cas    Gimenez and Margrave (1982)
XX Cep    SAC 53
SW Lac    Faulkner and Bookmyer (1978)
AT Peg    Margrave (1981)





   The residuals for RZ Cassiopeiae appear to have reversed the trend
towards more negative values that was exhibited during the preceding two
seasons. The residuals for XX Cephei continue to become more positive,
which indicates that the period given in SAC 53 needs to be increased.
   The quadratic elements for AT Pegasi cited in Table II provide much
smaller residuals for the eclipse time given here and those given in the
previous notes from this observatory than do the quadratic elements given
in SAC 54. In the case of the AT Pegasi eclipse reported here the SAC 54
quadratic elements yield O-C = -0.0821d. Those who plan to observe this
system should make allowance for this discrepancy if they use the SAC 54
quadratic elements.


   The author would like to acknowledge the financial support provided by
a University of Montana Research Grant, which made it possible to secure the
Blue Mountain observations reported herein.




               THOMAS E. MARGRAVE

               Blue Mountain Observatory
               University of Montana
               Missoula, Montana 59812
               USA




References:

Faulkner, D. R. and Bookmyer, B. B. 1978, IBVS No. 1503.
Gimenez, A. 1982, private communication.
Gimenez, A. and Margrave, T. E. 1982, Astr. J., 87, 1233. [BIBCODE 1982AJ.....87.1233G ]
Herczeg, T. and Friboes-Conde, H. 1974, Astr. and Ap., 30, 259. [BIBCODE 1974A&A....30..259H ]
Margrave, T. et al. 1978, IBVS No. 1478.
Margrave, T. 1980, IBVS No. 1869.
Margrave, T. 1981, IBVS No. 1930.
Rudnicki, K. 1982, Supplemento ad Annuario Cracoviense No. 53, Krakow.
Rudnicki, K. 1983, Supplemento ad Annuario Cracoviense No. 54, Krakow, p. 102.