COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3649    

                                            Konkoly Observatory
                                            Budapest
                                            21 August 1991

                                            HU ISSN 0374 - 0676


       G326 - ANOTHER DELTA SCUTI STAR IN THE FIELD OF M4


G326 (Greenstein 1939) = A63 (Alcaino 1975) = L3316 (Lee 1977) is a field star
in the direction of the globular cluster M4. The projection distance of the
star from the center of the cluster is x = 110.3", y = 458.4". The proper
motion study shows that its Pc = 0 (Cudworth 1990). The magnitudes and
colors given by the different authors are:

    V=13.03,   B-V=0.71,                (Alcaino 1975)
      13.00,       0.76,                (Lee 1977)
      13.04,       0.71,    U-B=0.28    (Cacciari 1979)
      12.97,       0.81,                (Cudworth 1990)

If the values of E_B-V = 0.44 and E_U-B = 0.78 E_B-V are accepted, the star's
(B-V)_0 is about 0.31 and (U-B)_0=-0.06, suggesting a spectral type of F0 
(but the (U-B)_0 is too blue if it is a Pop. I dwarf star).


                               [FIGURE 1]
                               [FIGURE 2]
                               [FIGURE 3]


G326 was used as a comparison star to check the light variability of the
horizontal branch star G327 in the past. It was shown later that G326 itself
was a variable too. The CCD data and the method of reduction used in this
paper are the same as before (Yao 1991). Only the zero point shift of about
0.01m between two nights was adjusted.

The preliminary results are:


      m(t) = 0.329 + Summa i=1 to 3 (A_i sin (2 pi t/P_i + 2 pi phi_i ))

        Here

           P1 = 0.1450d        A1 = 0,00801,   phi_1 = 0.2518
           P2 = 0.1541,        A2 = 0,00698,   phi_2 = 0.4069
           P3 = 0.0675,        A3 = 0,00387,   phi_3 = 0.7569

The folded light curves are given in Figs. 1,2 and 3. Each light curve is
plotted with the data prewhitened with the other two frequencies. There is
little doubt that G326 is a new Delta Scuti star. However, the periods should
be considered as preliminary only due to the limited data.

I wish to thank Prof. A.W. Rodgers, the director of MSSSO, for allocating
the telescope time. I thank the staffs of MSSSO for help with observing. I
thank the staffs of AAO and Dr. Huang Jia-hao of Nanjing University for using
the computers. This work was supported in part by the grant from the Chinese
National Science Foundation.


                             YAO BAO-AN
                             Shanghai Observatory
                             China

References:

Alcaino, G.: 1975, Astro. Astrophys. Supp., 21, 1. [BIBCODE 1975A&AS...21....5A ]
Cacciari, C.: 1979, A.J., 84, 1543. [BIBCODE 1979AJ.....84.1542C ]
Cudworth, K.M.: 1990, A.J., 99, 1491. [BIBCODE 1990AJ.....99.1491C ]
Greenstein, J.L.: 1939, Ap.J., 90, 387. [BIBCODE 1939ApJ....90..387G ]
Lee, S.W.: 1977, Astro. Astrophys., Supp., 27, 367. [BIBCODE 1977A&AS...27..367L ]
Yao Bao-an: 1991, IBVS., No. 3622.