COMMISSION 27 OF THE I. A. U.
              INFORMATION BULLETIN ON VARIABLE STARS
                          Number 3503

                                                 Konkoly Observatory
                                                 Budapest
                                                 8 August 1990

                                                 HU ISSN 0374 - 0676


                  SOME NON-VARIABLE STARS


  Although optical variability of stars remains an excellent
indicator of unusual conditions, the non-variability of stars
that are interesting or unusual from a spectroscopic point of
view is also of interest. This paper reports on the photometric
monitoring of ten stars which might have been considered potentially 
variable from their spectra. Table I details the stars and the
reason for which they were chosen for observation.


          TABLE I

     THE PROGRAM STARS


HD 31342      Possible variable from Halbedel (1986).
   32640      Possible variable from Halbedel (1986).
   37149      Helium weak Be star.
   97859      Possible variable from Geneva photometry (Rufener &
              Bartholdi,1982); A0,
   128220     Possible variable from Geneva photometry (ibid.);
              sd0+ G0 III.
   134458     F3 V star.
   135485     B5 IIp star.
   157857     O7f star with x-ray emission. Possible neutron star
              companion.
   192641     WC+B binary system.
   210208     Spectroscopic binary with H_alpha emission (Bidelman,
              1988).


    Differential BV photometry was performed for each of the
above stars primarily with the 0.6-m, telescope of the Corralitos



                                 TABLE II

STAR        V, SE    B-V, SE   #    JD RANGE    COMPARISON STARS, V, B-V

HD 31342    9.057    +.169    14    6335-7590   HD 31380(8.985; +.213)
            (.025)   (.018)                        32316(8.117; +.287)

HD 32640    8.692    +.303    12    6331-7590   HD 33153(9.263; +.197)
            (.020)   (.019)                        33183(9.113; +.261)

HD 37149    8.052    -.095    17    6376-7234   HD 37141(8.451; +.007)
            (.018)   (.016)                        37173(7.862; -.073)

HD 97859    9.349    -.081    28    7300-8042   HD 98452(9.233; +.265)
            (.023)   (.022)                        98631(7.166; +.402)

HD 128220   8.471    +.303    19    7300-7704   HD 127667(7.821; +.499)
            (.016)   (.029)                        128254(8.444; +1.071)

HD 134458   8.767    +.460    29    6866-7326   HD 133772(7.469; +.075)
            (.017)   (.016)                        134214(7.473; +.354)

HD 135485   8.158    -.058    28    6866-7326   HD 135637(8.036; +.282)
            (.013)   (.018)                        136276(7.933; +.397)

HD 157857   7.777    +.216     6    6867-7703   HD 157499(8.074; +.922)
            (.014)   (.035)                        158119(9.094; +.431)

HD 192641   7.901    +.292      9   7313-7703   HD 192661(6.571; +1.307)
            (.019)   (.032)                        192745(8.177; +.025)

HD 210208   7.959    +.072     15   7790-7881   BD+42 4298(8.613; +1.027)
            (.017)   (.022)                     BD+42 4301(8.563; +.738)




Observatory and its uncooled single-channel photon-counting photomultiplier 
which utilizes an EMI 9924A tube. Several magnitudes
were also obtained with the Kitt Peak Observatory #2 0.9-m. telescope 
and its automated filter photometer and 1P21 tube. There
was excellent consistency between the Kitt Peak and Corralitos
systems: 0.003 magnitudes in Delta_V & Delta_B-V, a difference not 
considered significant. The average standard errors about the mean for
the comparison stars for all the stars concerned were 0.017 and
0.020 magnitudes in V and B-V respectively. Therefore, the average
external errors of the program stars may be considered to be 
comparable.
   Table II details the mean magnitudes, comparison stars utilized, 
and time periods of observation for the program stars. All
were considered to be non-variable over the time periods over which
they were observed. Remarks on individual stars follow.
   HD 31342, 32640: Although stated to be possibly variable by
Halbedel in a previous paper, sustained series of observations have
revealed that they are essentially constant. HD 31342, however,
has a higher standard error in V than the other stars and may be
microvariable at the limits of detection of the Corralitos system.
   HD 97859: Photometric observations at Geneva showed a possible 
microvariability in V magnitude. This was not confirmed over
the time period stated.
   HD 128220: Found to be microvariable in V and colors at Geneva,
HD 128220 was also found to be non-variable over the JD range
2447275-7328 by Hooten et al. (1989) for 88 observations over 47
nights.


                                        E.M. HALBEDEL

                                        Corralitos Observatory
                                        P.O. Box 16314
                                        Las Cruces, NM 88004
                                        U.S.A.




REFERENCES

Bidelman, W.P. (1988) Pub. Astr. Soc. Pacific, 100, 1084. [BIBCODE 1988PASP..100.1084B ]
Halbedel, E.M. (1986) IBVS No. 2919.
Hooten, J.T. et al., (1989) IAPPP Com. No. 38, 19. [BIBCODE 1989IAPPP..38...19H ]
Rufener, F. & Bartholdi, P. (1982) Astr. & Astrophys. Sup.,
    48, 503. [BIBCODE 1982A&AS...48..503R ]