COMMISSION 27 OF THE I. A. U.
            INFORMATION BULLETIN ON VARIABLE STARS
                         Number 3426

                                             Konkoly Observatory
                                             Budapest
                                             1 February 1990

                                             HU ISSN 0374 - 0676




        FG Vir, Additional Photoelectric Observations

  In a study of blue stragglers stars of old disk population, Eggen
(1971), detected four additional variables that presented behaviour
like Delta Scuti stars. One of them was FG Vir (HD 106384) where,
with one night of observation, Eggen proposed a period of 0.07 d
and an amplitude of 0.05 mag. in V (measured peak to peak). Later on,
Lopez de Coca et al. (1984) confirmed the pulsational character of
this star where, with three nights of observation, they confirmed
the Delta Scuti behaviour for FG Vir (they showed in their figures,
for example, that the maximum light appears together with the
maximum temperature). Additionally, they found, with Fourier
analysis, that there existed at least one period of about 0.079 d
that lead Mv of 1.73 max. approximately (via P-L-C of Breger, 1979).
However, they pointed out that more observations are needed, in
order to find the whole period content of the star. Hence, with
the aim to obtain in the future the whole periodic content of FG
Vir, we present in this paper additional photoelectric observations
for this Delta Scuti star, although more photometric observations are
considered in the near future.

  FG Vir was observed on March 28, 1986 in the V Johnson's filter
using the 84 cm telescope of San Pedro Martir Observatory, Baja
California, Mexico, a refrigerated 1P21 photomultiplier was used,
C1=BD -4d3219 and C2=BD -5d3487 where chosen as comparison
stars, the observational sequence was C1, V, C2, V, C1,... and this
was followed through the whole night, with an internal average
between successive observations of the variable star of 5 minutes.
Each observation consisted at least of 5 integrations of 10 seconds
of the star, followed by one 10-seconds integration of the sky.

  Table I shows the differential photometry obtained for FG Vir
minus BD -4d3219 in the V filter, the accuracy of each observation
is better than 0.003 mag, time is given in Heliocentric Julian Day, and
its precision is 0.001 d; these values are shown plotted in Figure 1


                           [FIGURE 1]

      Fig. 1.- Differential photoelectric photometry for
              FG Vir - (BD -4d3219)


     TABLE I: Differential photometry of FG Vir

HJD	DeltaV		HJD	DeltaV		HJD	DeltaV
2446517.+
0.701	-0.691		0.758	-0.681		0.810	-0.664
0.705	-0.696		0.762	-0.682		0.814	-0.662
0.710	-0.700		0.765	-0.691		0.822	-0.663
0.714	-0.693		0.768	-0.694		0.826	-0.659
0.718	-0.687		0.772	-0.693		0.830	-0.656
0.722	-0.678		0.775	-0.692		0.834	-0.663
0.726	-0.669		0.778	-0.693		0.837	-0.675
0.729	-0.658		0.782	-0.690		0.841	-0.682
0.733	-0.651		0.786	-0.687		0.844	-0.684
0.736	-0.654		0.790	-0.688		0.848	-0.690
0.740	-0.645		0.794	-0.683		0.851	-0.694
0.744	-0.655		0.797	-0.687		0.854	-0.693
0.747	-0.660		0.800	-0.674		0.857	-0.705
0.751	-0.660		0.803	-0.675		0.861	-0.698
0.755	-0.671		0.807	-0.676		0.865	-0.698


(the photometric behaviour of the comparison stars was highly
constant, the sigma for the difference C2 - C1 was 0.005 mag). In this
figure we can see that the amplitude is approximately the same
than that reported by Eggen. A Fourier analysis of this data,
indicate a period of 0.079d in agreement with the period given by
Lopez de Coca et al. (1984).


                S.F. GONZALEZ-BEDOLLA (1)
                E. RODRIGUEZ (2)

          (1)Instituto de Astronomia, UNAM, Mexico.
          (2)Instituto de Astrofisica de Andalucia.
              Granada, Spain.



  References:

Breger, M. 1979, Pub. Astr. Soc. Pac. 91, 5. [BIBCODE 1979PASP...91....5B ]
Eggen, O.J. 1971, Pub. Astr. Soc. Pac. 83, 762. [BIBCODE 1971PASP...83..762E ]
Lopez de Coca, P., Garrido, R., Costa, V. and Rolland, A. 1984,
         IBVS No. 2465.