COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                   Number 2001

                               Konkoly Observatory
                               Budapest
                               1981 August 17

                               HU ISSN 0374-0676





PHOTOGRAPHIC OBSERVATIONS OF THE NEWLY DISCOVERED X-RAY EMITTING
              DWARF NOVA 1E 0643.0 - 1648


The hard X-ray source 1E 0643.0 - 1648 has been discovered with
the Einstein Observatory and identified with a bright uncatalogued
variable star 9'south of Sirius (Chlebowski et al. 1981).
I observed the star on about 130 plates of the Sonneberg field
iota CMa. In maximum brightness the star is also visible on good
sky patrol plates.
From its optical behaviour the star seems to be a normal dwarf
nova. The outbursts recur approximately every 15 days, which is
consistent with the visual observations by the AAVSO (Chlebowski
et al. 1981).

                         [FIGURE 1]


Two intervals well covered by observations are shown in the figure.





                      L. MEINUNGER

                Sonneberg Observatory of
                Central Institute for
                Astrophysics of Academy
                of Sciences of the GDR





Reference:

Chlebowski, T., Halpern, J.P., Steiner, J.E.: ApJ 247,
          L35-38, 1981. [BIBCODE 1981ApJ...247L..35C ]