COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2236 Konkoly Observatory Budapest 1982 November 29 HU ISSN 0374-0676 PHOTOGRAPHIC PHOTOMETRY OF V 1515 CYGNI In the course of the programme to discover and investigate flare stars and other nonstable objects in the gamma Cygni region, a great number of monitoring photographic plates have been obtained in u-, b- and v-bands in the period 1976-1982. The observations were made with the 20 in./28 in. Schmidt-telescope of National Astronomical Observatory of the Bulgarian Academy of Sciences at Rozhen and with the 40 in./52 in. Schmidt-telescope of Byurakan Astrophysical Observatory, of the Armenian Academy of Sciences, U.S.S.R. On 120 plates the magnitudes of V 1515 Cygni - a member of the very interesting group of FU Orionis stars, the fuors - could be also measured. The following telescopes and plate-filter combinations were used: for u- ORWO ZU2+UG1 or ZU21+UG1 40"/52" for b- Kodak IIAO+GG385 or ZU21+GG385 Schmidt-telescope for v- Kodak ID+GG495 for u- ORWO ZU21+UG2 20"/28" for b- ORWO ZU21+GG13 Schmidt-telescope for v- RPI+GG11 The measurements were carried out with an Ascorecord type Ascoris (Carl Zeiss, Jena) photometer. To our photographic photometry we used 11 stars from UBV-photoelectric standard stars in Cyg OB2 association from the catalogue of Kazanassmas et al. (1981) and 3 photographic standard stars from the work of Reddish et al. (1966). The iris readings for V 1515 Cygni were corrected for inhomogeneous background according to the method of Argue (1960). The mean error of an individual measurement is 0.12mag. Table I gives our estimates of magnitudes of V 1515 Cygni. We have to note that the star sometimes changes its brightness with an amplitude of 0.5 mag during one hour. J.D.244.... v b u J.D.244.... v b u 3019.408 13.58 4570.205 16.20 3020.442 13.83 4570.251 16.14 3021.364 13.70 9703.584 14.31 3399.183 15.52 4704.541 14.15 3399.331 15.54 4708.559 15.52 3399.351 15.26 9726.534 15.70 3400.353 13.99 4728.522 16.19 3400.361 13.68 4735.503 15.32 3400.369 12.10 4756.551 15.44 3400.385 12.10 4759.944 15.40 4143.416 13.71 4761.551 15.53 4187.209 14.64 4764.542 12.34 4187.250 14.56 4765.472 15.98 4187.337 14.75 4785.386 15.98 4188.196 14.46 4785.428 15.80 4217.190 14.50 4787.463 15.90 4407.526 15.14 4788.520 15.59 4408.476 15.31 4789.436 15.78 4409.452 15.35 4789.539 14.30 4409.578 15.21 4817.420 15.83 4430.565 15.02 4818.395 15.18 4934.409 15.20 4818.549 14.23 4434.509 15.46 4819.372 15.12 4435.396 15.58 4820.358 15.28 4435.445 15.08 4822.521 15.77 4435.500 15.40 4825.435 15.50 4435.560 15.59 4826.457 15.92 4436.455 15.18 4827.440 15.33 9437.365 15.01 4838.404 15.78 4438.539 15.12 4844.287 15.30 4459.411 15.80 4846.324 15.55 4463.365 16.01 4846.455 15.76 4464.397 15.09 4868.376 15.15 4464.444 15.40 9869.260 15.60 4466.380 15.82 4869.325 15.52 4466.432 15.60 4869.372 15.56 4466.530 15.87 4870.291 15.30 4468.476 15.61 4870.338 15.40 4983.365 15.69 4870.385 15.98 4988.361 15.76 4870.478 15.71 4489.302 15.98 4872.272 15.01 4492.236 15.90 4872.381 15.52 4492.264 15.93 4874.349 15.17 4492.292 14.47 4877.292 15.73 4492.304 14.63 4898.353 15.03 4493.309 15.92 4901.240 15.62 4493.335 14.50 4907.217 15.63 4493.348 12.79 4933.192 15.84 4494.264 12.64 5210.510 15.19 4494.278 12.76 5218.258 15.03 4494.294 12.77 5219.274 15.09 4495.270 16.07 5220.259 15.08 4496.342 16.11 5220.298 13.93 4517.933 16.26 5228.298 14.96 4520.273 16.03 5228.320 14.02 4521.360 16.26 5229.303 15.50 4524.292 15.78 5230.368 15.45 4542.276 15.99 5231.278 15.14 4543.291 16.34 5231.391 14.37 4549.250 15.88 5232.408 14.40 Figure 1 presents the light curve in u-, b- and v-bands in the period 1976-1982 according to our photographic photometry (denoted with dots) supplemented with photoelectric observations of Stone (Herbig, 1977), Landolt (1977), Kolotilov (1979), Kolotilov and Petrov (1981) (denoted with "x"). [FIGURE 1] Kolotilov and Petrov (1981) noticed a brightness decrease in V 1515 Cygni. Recent observations of Kolotilov (private communication) and our ones showed that the star decreased its brightness with an amplitude of 1.8 mag in u-band from the beginning of 1980 to the beginning of 1981. Since that time its brightness has been increasing, although till the autumn 1982 V 1515 Cygni did not reach the magnitude it had at the end of 1979. KATYA P. TSVETKOVA Department of Astronomy with National Astronomical Observatory, Bulgarian Academy of Sciences Sofia-1184, Lenin Str. 72, Bulgaria References: Argue A.N., 1960, Vistas Astronomy, Pergamon Press, 3, 184 [BIBCODE 1960VA......3..184A ] Herbig G.H., 1977, ApJ. 217, 693 [BIBCODE 1977ApJ...217..693H ] Kazanassmas M.S., Zavershneva L.A., Tomak L.F., 1981, Atlas and Catalogue of Photoelectric Standard Stars, Kiev, Naukova Dumka. [BIBCODE 1981acsm.book.....K ] Kolotilov E.A., 1979, Astr. Tsirkular No. 1037 [BIBCODE 1979ATsir1037....1K ] Kolotilov E.A., Petrov P.P., 1981, Astr. Tsirkular, No. 1167 [BIBCODE 1981ATsir1167....1K ] Landolt A.U., 1977, PASP, 89, 704 [BIBCODE 1977PASP...89..704L ] Reddish V.C., Laurence L.C., Pratt N.M., 1966, Publ. Roy. Obs. Edinburgh, 5, 111 [BIBCODE 1966PROE....5..111R ]