Visual observation of PG 0943+521: A New Dwarf Nova in the Palomar Green Survey

                  Visual observation of PG 0943+521:
            A New Dwarf Nova in the Palomar Green Survey

                        Makoto Iida (VSOLJ)
                  e-mail: QFG00456@niftyserve.or.jp

              (submitted to VSOLJ Variable Star Bulletin)

     PG 0943+521 was discovered as an ultraviolet-excess object, and was
spectroscopically confirmed to be a cataclysmic variable (Green et al. 1986).
In spite of its brightness (B=14.16, Green et al. 1986), the object went
little observed.  The author noticed that the object coincides with a
V=13.3 magnitude star (R.A. 09h 47m 11.82s, Decl. +51deg 54' 08.9", J2000.0)
in the Guide Star Catalog.  The large difference between these materials
suggests a variable nature of the object, and the author started visual
observations to clarify the nature of its variability.

     The observations were done using a 25-cm reflector.  The magnitudes of
the comparison stars were taken from the Guide Star Catalog (Figure 1).
The results are given in Table 1.  A light curve contructed from the
observtions in 1993 is displayed in Figure 2.

     These results clearly demonstrate that the object is indeed a dwarf
nova with a visual range of 12.3 to fainter than 14.2.  The outbursts of
this object are characterized by initial brightness peaks usually reaching
mv=12.5, and protracted fading lasting ten days or more.  Such behavior
may be analogous to short standstills sometimes observed in some Z Cam-type
dwarf novae, but the largest observed decline rate (0.7 mag/day) is slightly
atypical for this group of dwarf novae.  The outburst cycle length is
rather difficult to be concluded because of the gaps in the light curve,
but is definitely shorter than a month.

     Further observations are strongly encouraged to get a more detailed
outburst charactersitics and physical parameters of the cataclysmic binary.

References:

Green, R. F., Schmidt, M., and Liebert, J., 1986, Ap.J. Suppl., 61, 305.

Table 1   Visual magnitude estimates of PG 0943+521

Date(UT)      Mag.(*)
92 04 20.53  [13.5
   04 21.51  [13.3
   04 22.52  [13.3
   04 26.52   12.5 
   04 27.46   12.3 
   05 01.50   12.5 
   05 04.51   12.5 
   05 05.51   13.2 
   05 06.51   13.1 
   05 21.51  [12.5
93 01 12.51   12.5 
   01 12.51   12.5 
   02 10.53   13.4 
   02 15.52   13.8 
   02 18.51  [14.0
   02 19.53  [13.0
   02 20.54  [14.2
   02 24.56  [13.4
   02 25.51  [14.0
   02 28.50   12.4 
   03 01.51   12.9 
   03 02.52   13.2 
   03 03.51   13.2 
   03 10.45   13.4 
   03 10.52   13.3 
   03 17.52  [14.1
   03 20.53  [14.1
   03 21.53  [14.1
   03 22.52   13.4 
   04 01.52   13.2 
   04 08.47   13.2 
   04 09.52  [14.0
   04 12.52   13.2 
   04 14.49   12.6 
   04 15.50   13.2 
   04 22.53   13.0 
   04 26.48   13.4 
   05 16.49   13.4 
   05 18.51  [13.5
   05 26.49   12.9 
   05 27.50   12.4 
   06 07.51   12.9:
   06 09.50   13.0 
   06 11.51   13.0 

(*) The mark '[' indicates the upper limit (the variable was not detected).