COMMISSION 27 OF THE I.A.U.
               INFORMATION BULLETIN ON VARIABLE STARS
                            Number 2939

                                                    Konkoly Observatory
                                                    Budapest
                                                    6 October 1986

                                                    HU ISSN 0374 - 0676


          UBVRI OUTBURST OF THE DWARF NOVA AH Her

AH Her is a cataclysmic variable, of type Z Cam, with a
mean outburst period of 19.6 days (Beyer, 1967). Its magnitude
varies within the range 10.2 to 14.7 (Kukarkin, 1969).
   We present further UBVRI photometry of AH Her during the
outburst of the second week of June 1986.
   The star was observed during the week of the 11th to 18th
June 1986. The observations were obtained at the Cassegrain
focus of the 1m telescope at the Observatorio del 'Roque de
los Muchachos', in La Palma (Canary Islands), using the People's
photometer, a two channel photoelectric photometer and UBVRI
filters in the Cousins System (Jones D., 1984).
   The star was exposed in alternate channels with simultaneous 
sky measurements. The integration time was 17 sec in each
filter. The average output of the two channels was used to
reduce the data. Standard stars, selected from the available
list in the Observatory, were observed to determine the
atmospheric extinction, and used to reduce the magnitudes to
a standard system. Our error is 0.01 magnitude.
   We list in Table I the date, the mean universal time, the
V magnitude ad U-B, B-V, V-R, V-I colours for each observation.

                 TABLE I

Date UT (h m)     V      U-B     B-V    V-R    V-I

12    1  12     11.87   -0.55   -0.26   0.18   0.35
13    4  38     11.78   -0.72   -0.25   0.16   0.38
14    1  25     11.84   -0.59   -0.23   0.20   0.40
15    1  38     11.78   -0.53   -0.22   0.21   0.40
16   22  24     11.85   -0.60   -0.24   0.19   0.41
18    1  45     11.99   -0.61   -0.24   0.20   0.37



                        [FIGURE 1]


   In the graph, the U, B, V, R, I magnitudes are plotted against
the date.
   The existence of two maxima, whose behaviour depends on
the wavelength is clear. A more detailed study, which includes
IR measurements, is being prepared.


             C. LAZARO and M.J. AREVALO

          Instituto de Astrofisica de Canarias
                38071 La Laguna, Tenerife,
                       Spain



References:

Beyer, M.: 1967, Astron. Nachr. 290, 29 [BIBCODE 1967AN....290...29B ]
Jones, D.: 1984, R.G.O./ La Palma, Technical Note No. 10
Kukarkin, B.V.: 1969, General Catalogue of Variable Stars, Moscow [BIBCODE 1969okpz.book.....K ]