COMMISSION 27 OF THE I. A. U.
            INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3028


                                        Konkoly Observatory
                                        Budapest
                                        1 June, 1987

                                        HU ISSN 0374-0676


              PHOTOELECTRIC PHOTOMETRY OF HD 33798


  The star HD 33798 (=SAO 40158, = BD +47 1117) is listed as a 7th magnitude,
G5 star in The Henry Draper Catalogue. HD 33798 was listed as a suspected variable
by Fekel and Hall (1985) with chromospheric activity given as a possible mechanism
for its variability. This star was observed 39 times with the 0.4 meter telescope at
the University of Northern Iowa (UNI) Hillside Observatory during the winter and
spring of 1987. We used a STARLIGHT-1 photon counting photometer. A standard V
filter was used for all 39 observations. SAO 40213 (= BD +46 993), a G5, 8.1
magnitude star was used as a comparison.
  Observations at UNI have revealed a maximum change in brightness in HD 33798 of
0.07m. The behavior appears to be periodic. A visual examination of the data led us to
suspect a period of between 9.6 and 9.9 days. Folding the data produced the best
agreement when a period of of 9.8 days was chosen. We invite interpretations of our
data.
  The obtained differential magnitudes in the sense HD 33798 - SAO 40213 are given
in Table 1 and Figure 1. A phase diagram, assuming a 9.8 day period, is shown in
Figure 2.

                    Table 1

           J.D. 2446000+  DeltaV

            804.5404      -.7621
            811.6102      -.8138
            814.6167      -.7604
            819.5724      -.7909
            820.6084      -.8020
            826.6085      -.7573
            828.5692      -.7769
            833.5713      -.7646
            834.5735      -.7482
            835.6154      -.7467
            836.6278      -.7514
            837.6736      -.7620
            838.5812      -.7774
            838.5936      -.7838
            839.6052      -.7935
            844.5406      -.7711
            850.5778      -.8103
            852.7471      -.7566
            856.7133      -.7555
            857.5473      -.7585
            858.6878      -.7599
            859.5745      -.8168
            862.5888      -.7908
            875.6461      -.7521
            876.7089      -.7643
            888.5735      -.7885
            889.5735      -.7881
            890.5956      -.8038
            891.5995      -.7932
            892.5807      -.7573
            892.5948      -.7682
            893.6459      -.7613
            894.6117      -.7556
            901.6125      -.7654
            902.6280      -.7481
            904.6267      -.7546
            904.6417      -.7590
            911.5988      -.7829
            913.6018      -.7661



                              [FIGURE 1]
                              [FIGURE 2]



                                       AARON J. SPURR
                                       DARREL B. HOFF

                                       Hillside Observatory
                                       University of Northern Iowa
                                       Cedar Falls, Iowa 50614
                                       USA


References:

Cannon, A.J. and Pickering, E. C.,1918, The Henry Draper Catalogue: The Astronomical
  Observatory of Harvard College, Cambridge, p. 96. [BIBCODE 1918hdhc.bookQ....C ]
Fekel, F.C. and Hall, D.S., 1985, Forty Suspected Variable Stars, I.A.P.P.P., Comm. No.
      20, June, p. 37-40. [BIBCODE 1985IAPPP..20...37F ]