COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2346

                                      Konkoly Observatory
                                      Budapest
                                      6 June 1983

                                      HU ISSN 0374-0676




        NEW MINIMUM TIMES OF THE W UMa SYSTEM RW Dor




  The variability of the W UMa system RW Dor (HV 2435 = HDE 269320) was
discovered by Miss Leavitt (1908) on plates taken on the Large Magellanic
Cloud. The first classification was made by Miss Cannon (1921), who found a
spectral type of K5. However, from our photometric observations we have found
(B-V) = 0.84, which is in agreement with Eggen (1960) who measured (B-V)=0.81
indicating that the star is considerably earlier. This fact was recently
corroborated by Bidelman and Sanduleak (1982) who estimated the star to be a
late type G dwarf on a low dispersion (580 A/mm at H_gamma) objective-prism plate.

  Photographic minima were published by Hertzsprung in 1928. More recently
we published (1981) eight times of minimum obtained from 500 UBV observations.
The observations were carried out with the 154-cm reflector at the Bosque
Alegre Station of Cordoba Observatory. A conventional photometer with RCA 1P21
photomultiplier refrigerated with dry ice was used. These observations were
supplemented by latter ones made with the same instrument and telescope above.
A total of 880 observations in each pass-band have been obtained and fifteen
new times of minimum were derived.

  The colour-averages of the photoelectric times of minimum are listed in
Table I (mean errors are in parenthesis) together with the photographic minima
published by Hertzsprung (1928). A linear least squares ephemeris using all
available photoelectric times of minimum light gives,


      Min I = J.D. Hel. 2444695.10270 +  0.28546371*E'
                           +- 0.00018 +- 0.00000021


while, including the photographic minima, the least squares ephemeris gives,

      Min I = J.D. Hel. 2430938.60167 +  0.2854638109*E
                           +- 0.00042 +- 0.0000000086


                               Table I
----------------------------------------------------------------------
Min   Colour   J.D. Hel           E            (O-C)     (O-C)'    Remarks
               (2400000+)
----------------------------------------------------------------------
II    Pg       11298.8350      -68799.5        0.0008              1
II    Pg       14168.8830      -58745.5       -0.0044              1
II    Pg       15621.9010      -53655.5        0.0028              1
II    Pg       16013.8360      -52282.5       -0.0040              1
II    Pg       16489.7140      -50615.5        0.0058              1
I     Pg       17075.9030      -48562.0       -0.0051              1
I     Pg       23784.6000      -25061.0        0.0069              1
I     Pg       24172.5370      -23702.0       -0.0014              1
II    BV       44313.5813       46853.5        0.0009     0.0008   2
II    BV       44464.8764       47383.5        0.0002     0.0002   2
I     UBV      44581.7728       47793.0       -0.0008    -0.0008   2
I     UBV      44608.6063       47887.0       -0.0009    -0.0009   2
II    UBV      44608.7488       47887.5       -0.0011    -0.0011   2
II    UBV      44609.6063       47890.5       -0.0001     0.0000   2
I     UBV      44609.7493       47891.0        0.0003     0.0002   2
II    UBV      44610.7487       47894.5        0.0006     0.0005   2
I     UBV      44825.8462(8)    48648.0        0.0011     0.0011   3
II    UBV      44826.8442(4)    48651.5       -0.0001     0.0000   3
I     UBV      44873.8038(6)    48816.0        0.0007     0.0008   3
I     UBV      44874.6594(3)    48819.0       -0.0001     0.0000   3
II    UBV      44874.8010(4)    48819.5       -0.0012    -0.0011   3
I     UBV      44958.5851(4)    49113.0       -0.0007    -0.0006   3
II    UBV      44961.5843(6)    49123.5        0.0011     0.0012   3
I     UBV      44961.7239(6)    49124.0       -0.0020    -0.0019   3
I     UBV      44962.5815(7)    49127.0       -0.0008    -0.0007   3
II    UBV      44962.7267(5)    49127.5        0.0017     0.0018   3
I     UBV      45021.6738(3)    49334.0        0.0005     0.0006   3
II    UBV      45049.5058(6)    49431.5       -0.0002    -0.0001   3
I     UBV      45049.6486(8)    49432.0       -0.0002     0.0000   3
II    UBV      45050.6484(3)    49435.5        0.0005     0.0006   3
I     UBV      45076.4815(4)    49526.0       -0.0009    -0.0007   3
--------------------------------------------------------------------

Remarks: 1. Hertzsprung (1928), 2. Marton, Grieco (1981), 3. Present observations.
The cycles E and residuals of these elements are listed in columns (4) and
(5) of Table I, while residuals (O-C)' in column  (6).



                 A. GRIECO ^+
                 S.F. MARTON ^++
                 Observatorio Astronomico
                 Laprida 854 - 5000 Cordoba
                 Argentina
                 +  Fellow of CONICOR
                 ++ Fellow of CONICET

References:

Bidelman, W.P., Sanduleak, N., 1982, I.B.V.S. No. 2122
Cannon, A.J., 1921, Harvard Bull., 754
Eggen, O.J., 1960, Royal Observatory Bull., 31
Hertzsprung, E., 1928, BAN IV, 146 [BIBCODE 1928BAN.....4..153H ]
Leavitt, H., 1908, Harvard Annals, 60 [BIBCODE 1908AnHar..60...87L ]
Marton, S.F., Grieco, A., 1981, I.B.V.S. No. 1960