COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 3105


                                    Konkoly Observatory
                                    Budapest
                                    26 October 1987

                                    HU ISSN 0374-0676



              AY LYRAE SUPEROUTBURST PHOTOMETRY


   AY Lyr is a member of SU UMa subclass of dwarf novae. Main characteristic
of this class is the occurrence of brighter and longer lasting "superoutbursts"
in addition to normal dwarf nova outbursts. During these superoutbursts SU UMa
stars show periodic light variations called "superhumps".
   Although AY Lyr has been continuously monitored by AAVSO observers for many
years and its visual light curves during eruptions are well defined (Danskin
and Mattei, 1978), only one precise photometry of a superoutburst has been 
published by now (Patterson, 1979).
   In this paper we present observations of AY Lyr made in September 1987.
We started on the night of Sept. 21/22 and found that the star was already in
superoutburst. Observations were continued on the following 8 nights (Table I).



                   Table I

       No.  Date  Run Start (UT)        Duration (hours)


1   1987-09-21     19.3    4.2
2   1987-09-22     19.2    4.0
3   1987-09-23     18.3    1.8
4   1987-09-24     18.3    2.9
5   1987-09-25     18.3    5.3
6   1987-09-27     18.0    4.5
7   1987-09-28     18.1    2.8
8   1987-09-29     20.2    2.3


  The observations were obtained with the 60 cm reflector of the Ostrowik
Station of the Warsaw University Observatory using the Double-Beam Photometer
System (Szymanski and Udalski, 1987). The comparison star, BD+38 3272 was 
monitored simultaneously in the second channel in order to remove effects of
atmospheric transparency variations. Its constancy was checked for by occasional 
comparison with BD+38 3276 star on each night, We made observations in
white light with integrations lasting 10 - 30 seconds depending on weather
conditions and star brightness.


                               [FIGURE 1]


   In Fig. 1. the Sept. 21/22 light curve is presented. The superhumps with
an amplitude of 0.3 mag were clearly visible and so they were on the following
4 nights. On the subsequent two runs they were partly masked by the flickering
and finally they disappeared completely on Sept. 29/30.
   Preliminary inspection of the data yields the superhump period of 109.4 min.
This is somewhat larger than one derived by Patterson (1979) who obtained 108.8
min.

    Full details of our analysis will be published elsewhere.
This paper was partly supported by the project RR.I.11.



                        MICHAL SZYMANSKI and ANDRZEJ UDALSKI
                        Warsaw University Observatory,
                        al. Ujazdowskie 4,
                        00-478 Warszawa,
                        Poland.


References:
Danskin, K. and Mattei, J. (1978), J. Am. Assoc. Var. Stars Obs. 7,1. [BIBCODE 1978JAVSO...7....1D ]
Patterson, J. (1979), Astron. J. 84,804 [BIBCODE 1979AJ.....84..804P ]
Szymanski, M. and Udalski, A. (1987), In preparation. [BIBCODE 1989AcA....39....1S ]