COMMISSION 27 OF THE I.A.U.
                 INFORMATION BULLETIN ON VARIABLE STARS
                              Number 2923

                                                         Konkoly Observatory
                                                         Budapest
                                                         5 August 1986

                                                         HU ISSN 0374 - 0676


                  PHOTOGRAPHIC OBSERVATIONS OF V651 Mon

The central star of NGC 2346 was observed from October, 1982 until the
end of last observing season, 1986, during which 270 photographs were taken
with 25cm camera of 120cm focal length and Tri-X emulsion. A yellow-green
filter was used to get the brightness very close to visual magnitude.
   All the measurements are shown in Figure 1 in smaller scale, and the
drastic change of the star in four observational periods is shown in Figure
2, obtaining mean light curves in appropriate periods, usually one or two
months. In Figure 2, the first light curve by L. Kohoutek (1982) is shown
as curve 1. The others are all from the results of the writer. The values
fainter than about 14.5 mag. are not reliable because of interference by the
faint nebulosity. There would be much possibility that the real brightness
is more or less below 15.0 mag., as was pointed out by Kohoutek (1983).
   Since February, 1986, the brightness variation seems to be ceased and
stays at maximum brightness having not more that 0.1 mag. amplitude. This 
suggests the end of the drastic change in last five years.
   I determined the time of some maxima which had enough observations
around them. The observations by L. Kohoutek, (1982, 1983) R.H. Mendes et
al. (1985), B.F. Marino and H.O. Williams, (1983, 1984) were also used.
The mean period in these years is obtained as follows.

            Max. = J.D. 2445001 + 16d.089E

The O-C values are shown in Figure 3. It seems to have cyclic change of
roughly four year period. However, this would not be regarded as the O-C
changes in normal eclipsing binaries, considering the nature of the obscuring 
cloud of this system. This change might have caused by irregular movement 
of dark cloud, or by uneven distribution of the cloud surrounding the
system.

                          [FIGURE 1]

                          [FIGURE 2]

      Figure 2. Mean light curves in appropriate periods



      Curve No.      Period          Curve No.      Period

      1 (Kohoutek)   1982 Feb        6              1984 Oct
      2              82 Oct-Nov      7              85 Jan-Feb
      3              83 Jan-Feb      8              85 Oct-Nov
      4              83 Nov-Dec      9              86 Feb-Mar
      5              84 Jan-Feb


                          [FIGURE 3]

                     Figure 3. O-C values

The detailed report will be published elsewhere.


                          MASAAKI HURUHATA
                            Hodozawa 88
                            Gotemba-shi
                             412 Japan



References :

Kohoutek, L., 1982, IBVS, No. 2113.
Kohoutek, L., 1983, M.N.R.A.S., 204, 93. [BIBCODE 1983MNRAS.204P..93K ]
Marino, B.F. and Williams, H.O., 1983, IBVS, No. 2266.
Marino, B.F. and Williams, H.O., 1984, IBVS, No. 2583.
Mendes, R.H. et al., 1985, Rev. Mex. Astron. Astrof. 10 Espec., 187. [BIBCODE 1985RMxAA..10..187M ]
Schaefer, B.E., 1985, IAUC No. 4047. [BIBCODE 1985IAUC.4047....2S ]