COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2031

                                  Konkoly Observatory
                                  Budapest
                                  1981 October 29

                                  HU ISSN 0374-0676




DETECTION OF PERIODIC LIGHT VARIATIONS OF THE OLD NOVA BD Pav *


BD Pav was discovered by Boyd (1939) when it had risen during
4 days from invisibility (m_p >16.4m) to a maximum brightness
of 12.4m on Sept. 7, 1934. In the following 6 days the star
declined to 12.85m and finally became fainter than 15.5m, 20 days
after maximum. Boyd classified BD Pav as a nova.

During two observing periods at the European Southern Observatory 
at La Silla, extended high speed photometry and spectroscopy 
of BD Pav have been performed, the observational details
are given in Table I.


                         Table I

Date          HJD - 2444000    Telescope    Filter    Int.time
              Start      End
--------------------------------------------------------------
1980-06-13/14 404.87  404.88     1.5m ESO     Spectrum     15m
1980-06-21/22 412.643 412.820     1m ESO       R(RG 665)     3s
1980-06-21/22 412.643 412.820    1.5m Danish   white       2.9s
1981-07-01/02 787.535 787.866     1m ESO        B,R          4s
1981-07-02/03 788.560 788.910     1m ESO        white        2s
1981-07-06/07 792.583 792.909     1m ESO        V,I          1s*
1981-07-07/08 793.585 793.917     1m ESO        U,V          2s


* Simultaneously spectroscopic observations at the 1.5m ESO
 telescope. Exposure time: 15-20 min.


A strictly periodic light-variation with an amplitude up to
0.5m could be detected. The mean light curve is characterized

* Based on observations collected at the European Southern
Observatory.

by two humps of different shape and amplitude. A period
analysis was applied to the data spanning a time interval of
about 1 year. The only two humps observed in 1980 were somewhat 
distorted due to changing atmospheric transparency. If
the identification of the higher hump in the 1980 lightcurve
is taken to be correct the error of the photometric period is
5. 10^-7. The time for the deeper light minimum after the
brighter hump is given by the following ephemeris:

    HJD(lower minimum ) = 2444412.676 + .1793015 * E
                                  +-1        +-5


                       [FIGURE 1]

 Figure 1: Variation of intensity of BD Pav according to
           the given ephemeris.


A phase diagram combining all data (for the nights with two
color photometry we took the bluer range) is shown in Fig. 1.
Before averaging into 200 bins the data of each night were
normalized to obtain an average intensity of zero and equal
hump amplitude.

There is a small humplike feature preceding the deeper minimum. 
The minimum itself frequently is very steep. Flickering,
a characteristic property of cataclysmic variables, is found
with timescales of minutes in the individual light curves.
The spectrum is characterized by broad Balmer emission lines
with complex structures, superimposed on broad shallow 
absorptions. Strong V/R variations with the photometric phase
are shown. The intensity of the double peaked emission lines
of H and HeII decreased strongly between June 1980 and July
1981.
A detailed analysis of the photometry and spectroscopy of
BD Pav will be published elsewhere.



                           H. BARWIG
                           R. SCHOEMBS
                           Universitats-Sternwarte
                           Scheinerstr. 1
                           D-8000 Munchen 80
                           Germany




References:

Boyd, C.D., 1939, Harv. Ann. 90, 248
Kukarkin, B.V., 1969, General Catalogue of Variable Stars [BIBCODE 1969okpz.book.....K ]
Payne-Gaposchkin, C., 1957, The Galactic Novae