COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 232

                                     Konkoly Observatory
                                     Budapest
                                     1967 November 4


           IMPROVED PERIOD FOR V986 OPHIUCHI


HD 165174 was found by C.R. Lynds (1) to be a variable star of the Beta
CMa-type, and was afterwards named V986 Oph. From his rather scanty material
the discoverer derived a possible period of 0.^d2890, by far the longest known
for variables of this type at that time. Both this exceptional period-length
and the large scatter of the individual observations around the mean lightcurve
computed with it, called for a check of the proposed value. The star was
therefore put on his Boyden program by the present writer. The exceptionally
bad weather over South Africa this year and the limited telescope time
available cut the intended seven hours runs down to four runs of only 1/2 to 3
hours. They were all made by J. Eksteen, member of the staff. The reductions
were made by the author; the results are shown in Figure 1; where the abscissae
give local sidereal time (geographical longitude of Bloemfontein=1^h45^mE), and
the ordinates the differences m_y(var)-m_y(comp. star=HD 164577).

                            [FIGURE 1]

If these fragments of light curves do show anything, it is that a period near
seven hours is almost certain but that 7*P<2.^d0 instead of reaching the
2.^d023 -mark set by Lynds' period.

With this information in mind Lynds' observations were examined again and it
was found that

P=0.^d28465

was the period that best fitted the fragmentary lightcurves; allowance being
made for night to night changes in the mean brightness of the variable. This
is what Figure 2 shows.

                            [FIGURE 2]

It may be added that the slightly adjusted value

P=0.^d284653

has the further advantage of bridging correctly the 9-years gap between Lynds'
observations and ours. The precision of this determination however should not
be overestimated; the uncertainty on the value we propose rests on the fifth
decimal.


A. VAN HOOF
Astronomical Institute
University of Louvain
Belgium