COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 2097

                                Konkoly Observatory
                                Budapest
                                1982 March 3

                                HU ISSN 0374-0676





 THE OPTICAL VARIABILITY OF PU VULPECULAE (KUWANO'S OBJECT)

                  IN 1979 - 1981



  The variable star PU Vul has been discovered in 1979 by
Y. Kuwano (1) and M. Honda (2). The star made a gradual flaring
up of five magnitudes for 1977-1979 (3). Photoelectric UBV 
photometry has been carried out in Crimea during 1979-1981. The 
observations were made with the use of the 64 cm telescope of the
Crimean Astrophysical Observatory and the 60 cm reflector of the
Crimean station of Sternberg Astronomical Institute. These 
observations were partly published in (4). Figure 1 shows the 
composite light curve in V and the colour curves in B-V and U-B,
where the Crimean measurements and the photoelectric observations
of other authors (5-12) are presented by dots and crosses, 
correspondingly.
  As seen from Figure 1, during 1979 the brightness of PU Vul
changed around V ~ 8.9m, the half amplitude was DeltaV~ +- 0.15m.
Dr. D. Chochol from Skalnate Pleso Observatory (Czechoslovakia)
determined (private communication) the following elements
from the photometry in 1979: Min. J.D. 244 4173.38d + 76.4d. The
variations of colour index B-V corresponding to periodic V light
change are obvious, but for U-B such conclusion is impossible.
Besides, in 1979 both colour indices slowly increased from
~ +0.40m to ~ +0.70m in B-V and from ~ +0.20m to ~ +0.50m in U-B.
  The rapid decrease of brightness of PU Vul started in
February, 1980. During the phase of full decline between 
J.D. 244 4290 - ...4480 the amplitude DeltaV was estimated as equal
to ~ +4.8m with the rate DeltaV/Delta t ~ +0.025m per day (this decline
rate was obtained in (11) on the initial part of fading). Meanwhile 
noticeable colour indices variations also occurred. Before
the end of the declining phase in V they achieved the maximum
values B-V ~ +1.0m and U-B ~ +0.80m in time interval
J.D. 244 4340-...4360 and then both B-V and U-B decreased.


                         [FIGURE 1]


  From our observations PU Vul had a light minimum (V ~ 13.65m)
in the time interval J.D. 244 4480 -...4490. In this time, B-V
and U-B decreased to ~ +0.45m and ~ 0.0m, respectively. The next
brightening of PU Vul had twin stages. At first, in the time
interval J.D. 244 4490 -...4670 it was characterized by the
brightening at a rate DeltaV/Delta t ~ -0.008m per day on average. By the
end of this stage colour index B-V decreased downward ~ +0.20m.
The variations of U-B occurred symmetrically in this time interval
(see Figure 1).
  Further, in the time interval J.D. 244 4670 -...4830 the brightening 
of PU Vul was characterized by noticeably greater rate,
DeltaV/Delta t ~ -0.023m per day. This value is similar to that of the
light decrease to the minimum. With the beginning of this stage
the colour indices increase rapidly as B-V ~ +0.92m and U-B ~ +0.50m
around J.D. 244 4760. After this moment U-B slightly changed on
average, but B-V decreased to ~ +0.76m at J.D. 244 4830. By this
time the systematic light increase of PU Vul had been finished
and its brightness equalled on average V ~ 8.5m. Thus the star
was brighter than during its maximum of 1979. The time span of
light decrease of PU Vul was about 500 days. Note also that our
observations from J.D. 244 4830 permit us to suspect the existence
of periodic light variations of the star with shorter period and
smaller amplitude than in 1979.
  The results of the detailed analysis of the photometric 
observations of PU Vul carried out in 1979-1981 will be published
elsewhere.






E.A. KOLOTILOV                   T.S. BELYAKINA
Crimean Station of Sternberg     Crimean Astrophysical Observatory,
Astronomical Institute, 334413,  334413, p/o Nauchny, Crimea,
p/o Nauchny, Crimea, USSR        USSR


              
Rreferences :

 (1) Y. Kuwano, IAU Circ. No. 3344, 1979. [BIBCODE 1979IAUC.3344....1K ]
 (2) M. Honda, IAU Circ. No. 3348, 1979. [BIBCODE 1979IAUC.3348....2A ]
 (3) M. Honda, K. Ishida, T. Noguchi, Y. Norimoto, N. Nakagiri,
      T. Soyano, Y. Yamashita, Tokyo Astron.Bull.
      No. 262, 2983, 1979. [BIBCODE 1979TokAB.262.2983H ]
 (4) T.S. Belyakina, Yu.S. Efimov, E.P. Pavlenko, V.I. Shenavrin,
      Soviet Astron. Journal, 59, No. 1, 1982. [BIBCODE 1982SvA....26....1B ]
 (5) C.A. Whitney, IAU Circ. No. 3348, 1979. [BIBCODE 1979IAUC.3348....2A ]
 (6) R.E. Zissel, IAU Circ. No. 3355, 1979. [BIBCODE 1979IAUC.3355....2Z ]
 (7) S.S. Mims, T.L. Mullikin, IAU Circ. No. 3380, 1979. [BIBCODE 1979IAUC.3380....3M ]
 (B) T.E. Margrave, IAU Circ. No. 3421, 1979. [BIBCODE 1979IAUC.3421....2M ]
 (9) H.S. Mahra, S.C. Joshi, J.B. Srivastava, S.L. Dhir,
      IBVS No. 1683, 1979.
(10) A. Bruch, IBVS No. 1805, 1980.
(11) M. Nakagiri, Y. Yamashita, Tokyo Astron.Bull.
      No. 263, 2993, 1980. [BIBCODE 1980TokAB.263.2993N ]
(12) A. Purgathofer, A. Schnell, IAU Circ. No. 3604 and No. 3610, 1981.
				[BIBCODE 1981IAUC.3604....2P ]
				[BIBCODE 1981IAUC.3610....2P ]