COMMISSIONS 27 AND 42 OF THE IAU
             INFORMATION BULLETIN ON VARIABLE STARS
                         Number 3935

                                                 Konkoly Observatory
                                                 Budapest
                                                 13 September 1993

                                                 HU ISSN 0374 - 0676


             NEW TIMES OF MINIMA OF W UMa TYPE STARS


  The W UMa star systems ER Ori, YY Eri, and RZ Tau have been observed 
photoelectrically to obtain accurate times of minima in order to increase the time span of the
minima reported. These stars were observed during several seasons as seen in Table I.
The methodology followed in the observations and data reduction for the data obtained at
the Observatorio Astronomico National at San Pedro Martir, B.C., Mexico (OAN-SPM),


                               Table I
-------------------------------------------------------------
STAR         HJD 2440000+      Type of   Equipment   Observer
                               minimum
-------------------------------------------------------------
ER ORIONIS           6775.7990 I         A           1
                     6777.9180 I         A           1
-------------------------------------------------------------
YY ERIDANI           6774.7457 I         A           1
                     6774.9090 II        A           1
                     6778.7648 II        A           1
                     6798.6983 II        B           2
                     6799.6610 II        B           2
                     6818.6288 II        B           2
                     7458.8953 I         B           3
                     7459.8550 I         B           3
-------------------------------------------------------------
RZ TAURI             7827.9828 II        A           4
                     7828.8143 II        A           4
                     7835.8790 II        A           4
                     7837.9562 II        C           1
-------------------------------------------------------------

   Equipment: (A) A cooled photoelectric photometer with the
   Johnson's V filter attached to the 0.84m telescope of the
   OAN-SPM.
   (B) Photoelectric photometer with the Johnson's V filter
   attached to the 0.50m telescope of the OJAB.
   (C) uvby multiphotometer attached to the 1.50m telescope
   of the OAN-SPM.

   Observers: (1) J.H. Pena and R. Peniche.
              (2) M. Rios H. and M. Rios B.
              (3) O. Lopez and A. Montenegro.
              (4) L. Maupome and E. Rodriguez.

is described in Pena et al. (1993) while for the observations made at the Observatorio
Jose Arbol y Bonilla at Zacatecas, Zac. Mexico (0JA13), they are described in Pena
et al. (1987). The times of minima were determined from the minima obtained from a
mathematical fit to the light curves around the times of occultation.


                          Marco A. HOBART
                          Fac. de Fisica
                          Universidad Veracruzana
                          Apartado Postal Nu. 270.
                          91190 Xalapa, Ver. Mexico

                          Jose H. PENA and
                          Rosario PENICHE
                          Instituto de Astronomia-UNAM
                          Apartado Postal No. 70-264
                          04510 Mexico, D.F.

                          Manuel RIOS-HERRERA and
                          Manuel RIOS-BERUMEN
                          Universidad Autonoma de Zacatecas
                          Apartado Postal No. 275
                          Zacatecas, Zac. Mexico

                          Eloy RODRIGEZ
                          Instituto de Astrofisica
                          de Andalucia
                          Apdo. Correos 2144
                          E-18080 Granada, Spain

                          Omar LOPEZ-CRUZ
                          Department of Astronomy
                          University of Toronto
                          60 St. George Street
                          Toronto, Ontario
                          M5S 1A7 Canada



References:

Pena, J. H., Peniche, R., Arellano, A., Rios-Berumen, M. and Rios-Herrera, M., 1987,
   Acta Astronomica, 37, 63 [BIBCODE 1987AcA....37...63P ]
Pena, J. H., Hobart, M. A. and Rodriguez, E., 1993, Rev. Mexicana Astron. 
   Astrof., in press [BIBCODE 1993RMxAA..25...63P ]