COMMISSION 27 OF THE I. A. U.
       INFORMATION BULLETIN ON VARIABLE STARS
                    NUMBER 636

                                      Konkoly Observatory
                                      Budapest
                                      1972 February 29


     REMARK ON THE PERIOD OF RW CORONAE BOREALIS


From the photoelectric observations published by E.F. Milone and A.J.
Wesselink (IBVS 611, 1972) I have determined the following two minima

Minimum      Julian Date              O-C        E
primary     2440748.8251+-0.0006d    -0.0039d   28011
secondary   2440749.1920+-0.0010     -0.0002    28011.5

The O-C values are computed with the linear ephemerides

Min.I.hel.=JD 2420401.3193+0.7264114d E

Hence we have

T_2-T_1-P/2=+0.0037d+-0.0010d

From Lause's visual observations (AN 254, 373, 1935) it may be possible to
obtain

T_2-T_1-P/2<0

but this value is not significantly different from its accuracy. The
differences O-C for all observed minima that I had at my disposal are shown in
figure 1. It is very easy to see that we can speak neither about a period
variation nor about an apsidal motion now.

                             [FIGURE 1]

For an accurate determination of the orbital eccentricity and for the study
of an eventual apsidal motion we need new photoelectric observations for both
primary and secondary minima. The next months of this year could be suitable
for a new set of such observations.


IOAN TODORAN
Astronomical Observatory
Cluj




                   ON THE VARIABILITY OF NGC 404


The magnitudes of NGC 404 were estimated on 15 plates (1906-1912) taken with
the Steinheil lens (f/6.7=96 mm) end 5 plates (1948-1962) taken with the
Zeiss astrograph (f/4=400 mm ). All the plates taken with given instrument
have roughly the same exposures. The magnitudes of the comparison stars were
adopted according to E.H. Geyer (IBVS 614, 1972). On all the plates the
object has non-stellar image. The results are given in the following Table.

Date         m_pg     Date        m_pg      Date       m_pg

1906 Dec. 9  11.9m   1908 Dec.15  12.1m    1912 Oct.13  11.6m
1907 Nov.21  12.0    1908 Dec.16  11.9     1948 Sep.25  11.8
1908 Sep.25  12.1    1909 Aug.19  12.1     1951 Sep.5   11.8
1908 Oct.20  12.1    1909 Aug.22  12.2     1951 Sep.27  11.8
1908 Oct.22  11.9    1909 Oct.18  11.6     1962 Oct.25  12.0
1908 Oct.23  12.0    1910 Sep. 6  11.6     1962 Oct.25  11.9
1908 Nov.17  12.0    1911 Aug. 4  12.1

It is clear that the brightness of NGC 404 shows no variability on our
plates. The variability discovered by E.H. Geyer is perhaps the result of the
photographic effects caused by specific distribution of surface brightness of
NGC 404 and differences of the instruments, exposures, plates etc.

The precise photoelectric photometry is extremely desirable.


February 20, 1972

B.V. KUKARKIN and N.E. KUROCHKIN
Sternberg State Astronomical Institute,
Moscow, 117234.