COMMISSION 27 OF THE I. A. U.
       INFORMATION BULLETIN ON VARIABLE STARS
                    NUMBER 642

                                        Konkoly Observatory
                                        Budapest
                                        1972 March 15


       UBV OBSERVATIONS OF FU Ori, SU Tau AND OJ 287


One set of observations each was obtained for FU Ori, SU Tau and OJ 287 on 25
January 1972 U.T. at the No. 1 36-inch reflector of Kitt Peak National
Observatory during an observing session on another photometric program. A
refrigerated photomultiplier (KPNO No. CT11919/5) together with standard UBV
filters (V filter no. 232; B filter no. 233; and U filter no. 315) and 14
UBV standard stars chosen from the list of Johnson and Harris (1954) placed the
observations on the UBV system. Standard observation and reduction procedures
were followed (Landolt 1968). The external probable errors of the photometry,
as defined by the UBV standard stars, were +-0.020m in V, +-0.007m in (B-V),
and +-0.013m in (U-B).

Each of the three objects observed is quite interesting in its own way; hence,
observations made from time to time are worthwhile. (a) FU Ori was observed to
brighten rapidly in 1936 by some 6 magnitudes; see Herbig (1966) for a thorough
discussion. The magnitude and color indices shown in Table I remain similar to
those reported by Herbig (1966).

Table I

Object    JD hel.     V     B-V     U-B
         2441000+
FU Ori  341.6742   9.06   +1.36   +0.92
SU Tau  341.6818  11.50   +1.48   +1.00
OJ 287  341.7544  12.51   +0.37   -0.68

(b) SU Tau is a R CrB variable which entered a minimum early in 1971 (IAU
Circular Nos. 2316 and 2318). The star still seems to be 2 magnitudes fainter
than its normal brightness. (c) The radio source OJ 287, an optically variable
quasistellar object, has recently been discussed by Dyck et al. (1971) and
by Kinman and Conklin (1971). The magnitude and color indices given in Table I
are quite similar to those published.

I thank the Director of the Kitt Peak National Observatory for the observing
time. These observations were made during an observing program funded by
National Science Foundation Grant No. GP-31504.


ARLO U. LANDOLT
Louisiana State University
Observatory

References:

Dyck, H.M., Kinman, T.D., Kockwood, G.W., and Landolt, A.U. 1971, Nature
   Physical Sciences 234, 71. [BIBCODE 1971NPhS..234...71D ]
Herbig, G.H. 1966, in Vistas in Astronomy, edited by A. Beer and K.Aa. Strand
   (London: Pergamon Press), 8, 109. [BIBCODE 1966VA......8..109H ]
Johnson, H.L., and Harris, D.L., III 1954, Ap. J. 120, 196. [BIBCODE 1954ApJ...120..196J ]
Kinman, T.D., and Conklin, E.K., 1971, Astrophys. Letters 9, 147. [BIBCODE 1971ApL.....9..147K ]
Landolt, A.U. 1968, Astron. J. 73, 705. [BIBCODE 1968AJ.....73..705L ]