COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 606

                                   Konkoly Observatory
                                   Budapest
                                   1971 December 28


          A LATE TYPE VARIABLE IN NGC 6819


Barkhatova and Vasilevsky (1967) suspected that a red star, situated 4' from
the centre of the old open cluster NGC 6819; might be a variable star (Fig. 1,
star no. 352).

Photoelectric measurements of this star have been made on the UBV-system with
the 60 cm-reflector of the Lund Observatory. These measurements clearly
confirm that the star is variable. Photoelectric data and some other
measurements as well are given in Table 1 and Fig. 2.

As can be seen from Fig. 2, the star is probably a variable of irregular type.
From two objective prism plates it has been classified as an M4 giant.

The cluster diameter is 8' (of Fig. 1), and the variable star is likely to be a
physical member of the cluster. As the apparent distance modulus of the
cluster is about 12.^m6 (Lindoff (1972)) the absolute magnitude of the variable
star is (-2.^m6)-(-2.^m2). As E_B-V~=0.^m3 the intrinsic colours are
(B-V)_0~=1.^m2 and (U-B)_0~=0.^m9.

References:

Barkhatova, K.A., Vasilevsky, A.E., Var. Star. Bull 16, 171, 1967. 
Burkhead, M.S., Astronomical Journal, 76, 251, 1971 [BIBCODE 1971AJ.....76..251B ]
Lindoff, U., Reports from the Observatory of Lund, No. 4, in press.
Purgathofer, A. Mitteilungen der Universitaets-Sternwarte, Wien, Band 13, 7
   (1966). [BIBCODE 1966MiWie..13....7P ]


                          [FIGURE 1]

  Fig. 1. The open cluster NGC 6819 and the variable star no. 352.

                          [FIGURE 2]

  Fig. 2. Observed magnitudes and colours for star no. 352


Table 1

Magnitudes and colours of the variable star No. 352 in NGC 6819

Date             V          B-V      U-B   Remarks

1961           10.38        1.52     1.20  Purgathofer (1966)
1964 Oct.      10.00 10.35  1.6       -    Barkhatova, Vasilevsky (1967)
1965 Nov. 23   10.03        1.45     1.16  Lindoff, photographic plates
1968 May  23   10.34        1.47      -    Lindoff, photoelectric
1968 May  24   10.29        1.55      -      "       "
1968 May  29   10.26        1.64      -      "       "
1968 July 23   10.09:       1.69:     -      "       "
1968 July 26   10.24        1.57     1.22    "       "
1968 July 28   10.27        1.61     1.13:   "       "
1968 Aug. 20   10.20        1.62     1.12:   "       "
1968 Aug. 22   10.18        1.59      -      "       "
1968 Aug. 23   10.17        1.46     1.06:   "       "
1970 Sept.26   10.01        1.61     1.19    "       "
1970 Sept.28   10.01        1.58     1.10    "       "
1970 Oct. 23   10.11        1.55     1.11    "       "
      ?        10.00        1.59     1.14   Burkhead (1971)


ULF LINDOFF
Astronomical Observatory
S-222 24 Lund
Sweden