astro-ph/9512098 14 Dec 1995 eemnto fiseteafo ih uvsi impossibl is curves insigni®c light so from become extrema has its modulation of rotational The determination mag. 1 its with now 1979) (Patterson photometry optical in dominating ria period orbital cmd n ab18)rvae htteojc a ninterm an was object the period spin that ob the revealed polarimetric stil 1988) is outburst, Lamb nova its and The after Schmidt technique. years CCD Twelve the to observed. due observati possible for de suitable is However, object this an mag. and be 18 to to appears now still faded it years, ness, twenty last the of nova oin naot10yas nti iesaetesa ilb will star believed commonly the now time-scale Semeniuk is this by It On state. Herculis the AM years. pre-outburst of 170 synchronization about indicating in increase motions of rate the Liebert Schmidt, with 1991, Stockman and (Schmidt increasing be e words: stil Key stable. can be star to the continues mag, period 18 day about 0.1396 of being outburst, after years yesa.Te17 xlso a rkndw h spin/orbit just the the for was down observed outburst broken period photometric has decreasing explosion quickly 1975 the The star. type erpr nCDpooer fNv 10 yn bandi Ju in obtained Cygni V1500 Nova of photometry CCD on report We 10 yn Nv yn 95,tebihet ats n th and fastest brightest, the 1975), Cygni (Nova Cygni V1500 aswUiest bevtr,A.Uadwke4 048W 00-478 4, Ujazdowskie Al. Observatory, University Warsaw C htmtyo oaV50CgiTet er After Years Twenty Cygni V1500 Nova of Photometry CCD tr:idvda:V50Cg±bnre:coe±nve cata novae, ± close binaries: ± Cyg V1500 individual: Stars: .Semeniuk .Olech c e l O A. k, u i n e m e S I. P tal. et P orb spin P e-mail:(is,olech,nalezyty)@sirius.astrouw.edu.pl qa o019 as usqety h pnpro appeare period spin the Subsequently, days. 0.1396 to equal spin n17 ro oisotus 10 y a nA Her AM an was Cyg V1500 outburst its to prior ± 1977 in fiswiedafcmoetbigaot2 hre hnthe than shorter 2% about being component dwarf white its of ic 97te019 a ria ouainhsbeen has modulation orbital day 0.1396 the 1977 Since . eevdDcme ,1995 1, December Received .Introduction 1. ABSTRACT by and eosre ihsaltlsoe.The telescopes. small with observed be l .NaleÇ y Çz t e y l a N M. n ihsaltelescopes, small with ons ulapiuereaching amplitude full y19 oso httwenty that show to 1995 ly evtos(Stockman, servations rttosaosafter seasons two ®rst CAASTRONOMICA ACTA oainladorbital and rotational .Nvrhls,the Nevertheless, e. lsi variables clysmic Vol. n tcmn1995) Stockman and rzw,Poland arszawa, ht±a suggested as ± that otwiet be to worthwhile l eunn oits to returning e ycrns and synchronism daeplrwith polar ediate otintriguing most e pt fisfaint- its of spite 45 n htadirect a that ant 19)p.0±0 pp. (1995) to d Vol. 45 1
evolution of the rotational velocity of the white dwarf in the system can be traced P photometrically as a change of a beat period between Pspin and orb . Our lastobservations ofNova V1500Cygni madeat the Ostrowikstationwith a photoelectric photometer were performed in October 1976 (Semeniuk et al. 1977), when the star was of about 12 mag. Afterwards the star became inaccessible for the Ostrowik photoelectric photometry. In this paper we present new Ostrowik observations of V1500 Cygni obtained there for the ®rst time after an about 19 year interval. Although the star faded now to 18 mag, it could be successfully observed with our 0.6-m telescope due to the CCD technique. With our observations we would like to call attention of other CCD observers on small telescopes to this faint but still interesting object.
2. Observations
We have observed V1500 Cygni on three nights of July 27, 28 and, 29, 1995 at the Ostrowik station of the Warsaw University Observatory with the 0.6-m telescope equipped with a Tektronics TK512 CCD camera, described by Udalski and Pych (1992). The observations were made in white light with the exposure timeof300 s and a dead time of 20 s between frames. The data reductions have been performed with a standard procedure used at the Warsaw University Observatory based on the IRAF package. The pro®le photometry has been done with the DAOphotII
package. m Fig. 1 presents the light curves of V1500 Cygni. denotes the difference of the instrumental magnitudes between the variable and comparison stars. The com- parison was the star C1 from the ®nding chart of KaøuÇzny and Semeniuk (1987).
The UBVRI photometry performed by these authors gives for the star C1 the fol-
= U B = B V = V R =
lowing parameters: V 15 67, 0 55, 1 00, 0 58,