COMMISSION 27 OF THE I. A. U.
            INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3169

                                        Konkoly Observatory
                                        Budapest
                                        29 March 1988

                                        HU ISSN 0374-0676


         NEW OBSERVED TIMES OF MINIMA FOR MR Cyg, V477 Cyg

  Photoelectric observations of these two Algol class eclipsing binaries were
carried out at the 0.4 meter telescope at the Morgan-Monroe Station of the
Goethe Link Observatory of Indiana University. V477 Cyg and MR Cyg were observed
on September 14 and October 4, 1987 (UT), respectively.
  The photometric equipment consisted of a 1P21 photomultiplier tube in a dry
ice cooled housing, pulse counting electronics, with microcomputer control of
data acquisition and data recording. BD +47 3622 and BD +31 3926 were used as
comparison stars for MR Cyg and V477 Cyg, respectively. The times of minima
given below were obtained from light curves in U and V for the two stars.

                        MR Cyg        V477 Cyg
Hel. Primary Minimum    2447072.6211  2447052.5946
                                +/-6         +/-11

  For V477 Cyg, the period 2.346993 d of the linear approximation of O'Connell
(1970) and the epoch JD 2445139.7944 of Lacy et al. (19B7) combine with the
above result to produce an O-C value of +0.0009d +/-0.0011, verifying the usefulness
of O'Connell's approximation as updated by Lacy et al.
  For MR Cyg, the above result yields an O-C value of +0.0050 d +/-0.0006 using the
mean ephemeris calculated by Battistini et al. (1972), and an (O-C) value of
+0.0012 d +/-0.0006 using the mean ephemeris calculated by Soderhjelm (1978). However,
the period (1.6770345 d) and epoch (JD 2427013.612) of Lavrov (1965) produce an
O-C value of -0.0005 d +/-0.0006, indicating possible reversal of the abrupt period
decrease occurring circa 1966, discussed by Soderhjelm (1978).


                         C.A. WOOD

                         Department of Astronomy
                         Indiana University
                         Bloomington, Indiana 47405
                         USA

References:            

Battistini, P., Bonifazi, A., and Guarnieri, A., 1972,Astrophys.Space Sci., 19, 395 [BIBCODE 1972Ap&SS..19..395B ]
Lacy, C.H., Frueh, M.L., and Turner, A.E., 1987, Astron.J., 94(4), 1035 [BIBCODE 1987AJ.....94.1035L ]
Lavrov, M.I., 1965, Bull.Engelhardt Obs., 38, 3
O'Connell, D.J.K., 1970 Vistas in Astronomy 12, 271 [BIBCODE 1970VA.....12..271O ]
Soderhjelm, S., 1978, Astron. Astrophys., 66, 161 [BIBCODE 1978A&A....66..161S ]