COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      Number 2244

                                     Konkoly Observatory
                                     Budapest
                                     1982 December 8

                                     HU ISSN 0374-0676


             A NEW RED VARIABLE IN AQUILA

   While working on the optical counterpart of the x-ray source 4U1915-05,
a new variable was discovered on a IV-N plate exposed by one of us (JEG) at
CTIO on August 26, 1977. It is a faint, red object located at R.A. = 19h16m
02.28s, Dec. = -5deg19'44.3" (1950), approximately 4.5 arc minutes west of the
x-ray position (Fig. 1).

   Referring to an approximate blue magnitude sequence estimated from the
Palomar Observatory Sky Survey (POSS) blue print using the King and Raff
calibration (1977), we examined more than 100 Harvard plates taken with
various astrographs (25-, 40- and 60-cm apertures) between 1899 and 1949.
Although the star was mostly below the plate limits, it did brighten to
nearly B ~ 16 on several occasions and to B = 15 in 1924-1925 (Fig. 2).
Since its image is not visible on the Palomar blue print, i.e., B> 21 in
1951, the range of its variation is at least six magnitudes.


                           [FIGURE 1]

 Figure 1. Finding chart for the new variable, which is indicated by
 the larger circle. The smaller circle is the optical candidate of the 
 x-ray source 4U1915-05.


                            [FIGURE 2]

 Figure 2. Light curve of the new variable. "V" signs indicate limiting
 magnitude estimates. The deep minimum in 1951 is from the POSS blue print.


   The red magnitude of the star is about 18 on the Palomar red print.
By an approximate color relation given for the Palomar P and R magnitudes
(Minkowski and Abell, 1963), we found P-V ~ 1.9 for the star.


   The limiting magnitude of the POSS and those of several plates taken
with the 1.5-meter reflector at Harvard's Agassiz Station in 1974 and 1981
are also shown on the light curve. If the light variation is periodic, our
magnitude materials seem to indicate a period of 200-300 days.


   The above data suggest that the object is probably a long-period variable.




               J. E. GRINDLAY and C. Y. SHAO
           Harvard-Smithsonian Center for Astrophysics
              Cambridge, Massachusetts, 02138





References:
King, I.R., and Raff, M.I., 1977, P.A.S.P. 89, 120. [BIBCODE 1977PASP...89..120K ]
Minkowski, R.L., and Abell, G.O., 1963, in "Basic Astronomical Data",
   Stars and Stellar Systems, Vol. III, ed. K. Aa. Strand (Chicago,
   University of Chicago Press), p. 481. [BIBCODE 1963bad..book..481M ]