COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1917

                                  Konkoly Observatory
                                  Budapest
                                  1981 February 2

                                  HU ISSN 0374-0676


         PHOTOELECTRIC OBSERVATIONS OF R CrB


    The irregular variable, R CrB, prototype of its class, was
observed photoelectrically on nine nights in the Spring of 1980.
A total of 35 differential magnitudes were obtained, with four
each night except the last night when only three were obtained.
All observations were made on the 20cm f-15 Cassegrain telescope
at the Fairborn Observatory. Each measurement of the variable
was bracketed by measurements of the comparison star HD 141352.
A TRS-80 microcomputer was used to log the data and provide 
preliminary on-line reduction.
    The raw differential magnitudes were corrected for 
differential extinction and transformed to the V of the standard UBV
system, and heliocentric corrections were made to the Julian 
dates. These reductions were made on a TRS-80 computer using a
program adopted from one written by D. S. Hall. The transformation 
to standard V was based on 36 observations of the close
pair 27 and 28 LMi in V and B which provided an epsilon of 0.027.
An average nightly extinction of 0.25 was assumed. The comparison 
star V was taken as 7^m.45, and its B-V as 0^m.44 as provided by
Fernie (1980). The B-V value of the variable was taken as 0.80
based on data from Fernie, Sherwood, and DuPuy (1972). The 
reduced observations are given in Table I.

  		    	    Table I
       JD_Hel 244+   V     JD_Hel 244+  V    JD_Hel 244+  V

	4348.730    5.87    4364.683   5.84   4368.633   5.79
	4348.734    5.88    4364.687   5.83   4368.636   5.76
	4348.738    5.88    4364.692   5.81   4368.639   5.74
	4348.742    5.91    4364.693   5.83   4368.643   5.75
	4351.708    5.88    4365.657   5.91   4369.670   5.79
	4351.713    5.89    4365.661   5.86   4369.673   5.82
	4351.717    5.88    4365.666   5.89   4369.675   5.79
	4351.721    5.87    4365.669   5.87   4369.679   5.78
	4363.648    5.82    4367.655   5.73   4394.607   5.81
	4363.653    5.83    4367.658   5.71   4394.610   5.82
	4363.657    5.77    4367.661   5.71   4394.613   5.86
	4363.662    5.79    4367.664   5.74

	The mean magnitudes and standard deviations for each nights
observations were calculated as shown in Table II.

                     Table II

        Nightly means and standard deviations

 JD_Hel 244+  Mean V    SD    JD_Hel 244+    Mean U     SD

    4348       5.89    .019      4367         5.72     .020
    4351       5.88    .019      4368         5.76     .019
    4363       5.80    .026      4369         5.80     .025
    4364       5.83    .023      4394         5.83     .029
    4365       5.88    .025

These are potted versus JD in Figure 1.


                         [FIGURE 1]

    Figure 1:  R CrB V Magnitude Vs. JD. (24443+)


The variations shown were in all likelihood due primarily to 
variations in R CrB itself, although uncorrected variations in the
equipment and atmospheric conditions cannot be ruled out entirely 
as causitive factors. The apparent "saw tooth" pattern from
JD (244+) 4363 to 4369 may only be coincidental, but it could
represent a characteristic of the fine structure of the luminosity 
variations of this type of star.
                             
			      RUSSELL M. GENET
                            Fairborn Observatory
                              Fairborn, Ohio

References:

Fernie, J. D., 1980 (private communication).
Fernie, J. D., Sherwood, V., and DuPuy, D. L., 1972, AJ, 172, 383. [BIBCODE 1972ApJ...172..383F ]