COMMISSION 27 OF THE I. A. U.
                 INFORMATION BULLETIN ON VARIABLE STARS
                             Number 3546

                                                       Konkoly Observatory
                                                       Budapest
                                                       5 December 1990

                                                       HU ISSN 0374 - 0676


                "NOVA" PQ And - FURTHER OUTBURSTS

   PQ And was discovered by McAdam (1988) on photographs taken on 1988
March 21. Further observations by several authors (IAU Circ. Nos. 4570,
4577, 4579, 4620, 4628 and 4629) show a novalike decline from 10.0m (March
21) to 18.8m (July 9), see Fig. 1. Spectral data are very poor: According to
Wade (1988) the post eruption spectrum resembles WZ Sge.
   Therefore and because Hurst (1988a) suspected a second eruption in 1976
Oct. 19 (which, however, he revised soon after, 1988b), the object was examined 
on 1725 Sonneberg plates taken between 1928 and 1989. The plate limit
is mostly between 13m and 14m. The magnitudes were determined by linking the
comparison stars (Fig. 2) to the photoelectric sequence by Johnson (1954) of
the nearby cluster M34:

                           star    B

                           r      10.87
                           a      11.50
                           b      13.00
                           c      14.05
                           d      14.50

   Neither the 1988 eruption nor that particular 1976 eruption could be
checked, for lack of plates; but it turned out that additional outbursts
took place in 1938 and 1967 (see Table I). Of course, these data are too
poor to get any reliable estimation of the true cycle length of eruptions by
statistical methods described by Wenzel and Richter (1986). Formal application 
of their formula leads to the following results:
   Taking the plate limit to be 14.0m (fainter magnitudes are mostly only
marginally visible and are easily overlooked), we have:

Number of plates N = 1725
Number of plates with brightenings ]14.0m  n = 6
Time interval t = 62 a
Effective time interval T = 46.5 a
Duration of outbursts ( ]14.0m) L = 30 d
Poisson parameter lambda = 2.82


                             [FIGURE 1]
                             [FIGURE 2]


   With these data we obtain the following estimations:

C1 = Lambda T/n = 21.9 a
C2 = LN/n = 23.6 a

In reality, the mean cycle length C will be probably smaller, between about
10 a and 20 a.

   According to the A-log C relationship of Richter (1986) the cycle
length is about 12 years, if the amplitude is 8.8 mag.



                         Table I

date              JD         B         date            JD         B
                 2429..                                2439..

1938 Aug. 6      117.54    [13m5       1967 Mar. 7     557.28     10m8
         23      134.55     11.0                 7     557.31     10.9
     Sep. 2      144.46    [13              Apr. 2     583.32    [14.5
         20      162.57     14.4:
         20      162.60     14.5::
         21      163.53     14.0
         21      163.55     13.9::
         23      165.53     13.9
         23      165.55    [13.9
         25      167.56     14.8::
         26      168.55     14.7::


   To sum up it can be said that PQ And, which has an amplitude of nearly
9 mag, is either a recurrent nova or a long cyclic U Geminorum star, the
latter being more probable because its spectrum resembles that of WZ Sge as
already mentioned.


                                   G.A. RICHTER

                                   Zentralinstitut fur Astrophysik
                                   Sternwarte Sonneberg
                                   O-6400 Sonneberg
                                   Germany



References:

Hurst, G.M.: 1988a, IAU Circ. No. 4577. [BIBCODE 1988IAUC.4579....1H ]
Hurst, G.M.: 1988b, IAU Circ. No. 4579. [BIBCODE 1988IAUC.4577....3H ]
Johnson, H.L.: 1954, Astrophys. J. 119, 185. [BIBCODE 1954ApJ...119..185J ]
McAdam, D.: 1988, IAU Circ. No. 4570. [BIBCODE 1988IAUC.4570....2H ]
Richter, G.A.: 1986, Astron. Nachr. 307, 221. [BIBCODE 1986AN....307..221R ]
Wade, R.A.: 1988, IAU Circ. No. 4629. [BIBCODE 1988IAUC.4629....1W ]
Wenzel, W., Richter, G.A.: 1986, Astron. Nachr. 307, 209. [BIBCODE 1986AN....307..209W ]