COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3645 Konkoly Observatory Budapest 23 July 1991 HU ISSN 0374 - 0676 PHOTOGRAPHIC OBSERVATIONS OF THE CATACLYSMIC VARIABLE CANDIDATES PG 1445+584 AND PG 1524+622 The objects PG 1445+584 and PG 1524+622 from the Palomar-Green Survey were suspected to be Cataclysmic Variables (CVs) by Green et al. (1986). However, no information about the detailed classification or at least the possible variability was published. For this purpose, we studied the objects on 57 archival plates obtained at the 40-cm astrograph of the Crimean Laboratory of the Sternberg State Astronomical Institute. All the plates were measured by using the iris-photometer to obtain the brightness of comparison stars and to avoid possible variables among them. The instrumental system is close to B. The standard stars in SA 15 were used from the list of Brun (1957). The finding charts are shown in Figure 1 and the comparison stars are listed in Table I. The value of sigma_m corresponds to the mean-squared deviation from the mean value to estimate the scatter, but not to the standard error of the mean. The object PG 1524+622 showed distinct variability, as one may see from Table II. The brightening up to 13.9m was detected on one plate obtained at HJD 2433762.464. The deviation from the mean value, 14.8m is only 0.9m. The temporal distribution of the observations does not allow us to study the structure of the brightening and thus additional observations are needed. Four plates showed the brightness decrease with an amplitude up to 1.5m, similar to the eclipsing variables, particularly to BH Lyn = PG 0818+513 (Andronov et al., 1989). For the period search, we used the "method of characteristic times" (Andronov, 1991) and the corresponding FORTRAN routine. Because the number of points is very low (n=4), the periodogram is very noisy. For 57 values of the trial period, the maximum deviation of the phase from zero [psi_max]<=0.01, and thus the period determination is impossible from the present observations. To search for the possible orbital brightness variations, series of observations were obtained during three subsequent nights. The most prominent (but weak) peaks in the periodogram occurred at periods 1.07+-.08, 0.53+-.03 and 0.125+-.003 days. However, the shape of the light curve of PG 1524+622 changes from night to night, thus these periods seem to be unreal, despite the brightness variations at least up to 0.4m occurred with characteristic times 0.10d-0.13d. For the precise classification, additional observations are needed. A weak argument pro long period (P > 0.3^d) may be that the narrow (d<.05) deep eclipse may not be observed at short periods due to the exposure time of 30 min. However, the "minima" may be due to the "short-time excursions" to the "low state" like that observed in MV Lyrae (Andronov et al., 1988). It may be noted that IW And showed time intervals with nearly constant brightness, interrupted by rapid "switches" from high to low state (Meinunger and Andronov, 1987). In this case, high states must be observed more frequently, as compared with PG 1524+622. [FIGURE 1] Table I Comparison stars for PG 1445+584 and 1524+622 PG 1445 PG 1524 * m_pg sigma_m m_pg sigma_m a 12.74 .02 13.86 .07 b 13.16 .04 13.95 .05 c 13.67 .04 14.22 .07 d 14.07 .09 14.45 .08 e 14.64 .08 14.86 .11 f 14.84 .09 15.02 .10 g 15.04 .08 15.13 .11 h 15.57 .10 15.26 .11 k 15.82 .11 15.36 .09 l 15.84 .09 15.67 .10 m 16.08 .11 15.99 .10 n 16.13 .11 16.04 .11 p 16.18 .13 16.48 .13 q 16.63 .07 16.48 .09 r 16.70 .15 s 17.09 .34 Var 15.66 .10 14.84 .39 Table II The photographic observations of PG 1445+584 and PG 1524+622 HJD 24... PG 1445 PG 1524 HJD 24... PG 1445 PG 1524 33057.409 15.84 16.32m 47302.398 15.63 14.82 33762.464 - 13.92! 47302.430 15.53 14.85 34480.526 15.70: 14.99 47302.462 15.57 14.73 35598.400 15.64 14.83 47302.496 15.70 14.57 47207.569 15.57 14.82 47304.450 15.70 15.93m 47264.495 15.68 15.13 47305.415 15.57 14.68 47265.553 15.64 15.25 47324.418 15.75 14.63 47266.420 15.68 15.12 47351.408 15.66 14.65 47268.480 15.77 15.12 47355.408 15.68 14.84 47294.512 15.66 14.72 47615.457 15.57 14.41 47295.517 15.66 14.65 47616.539 15.57 14.60 47296.368 15.57 14.77 47619.468 15.66 14.55 47300.341 15.64 14.65 47619.534 15.57 14.88 47300.374 15.84 14.57 47620.485 15.73 14.69 47300.407 15.68 14.69 47622.538 15.84 14.71 47300.440 15.68 14.87 47647.484 15.57 14.85 47300.473 15.80 14.69 47649.498 15.57 14.63 47300.509 15.73 14.49 47650.396 15.70 14.62 47301.303 15.77 14.83 47651.414 15.73 14.68 47301.336 15.57 14.86 47657.495 15.73 14.64 47301.368 15.75 14.76 47658.426 15.70 14.72 47301.399 15.72 14.79 47678.412 15.57 14.92 47301.429 15.51 14.68 47679.316 15.75 14.59 47301.460 15.55 14.75 47734.321 15.72 14.82 47301.491 15.57 14.83 47736.337 15.41 14.70 47301.514 15.69 14.60 47739.306 15.79 15.08 47302.303 15.58 14.83 47973.524 15.55 15.95m 47302.334 15.65 14.92 47984.527 15.84 15.54m 47302.365 15.54 14.81 Remarks: the symbol ! marks the brightening of PG 1524+622, and the symbol m - the "minima", The brightness of PG 1445+584 changed from 15.51m to 15.84m on our plates. Such low amplitude may be due to the scatter of the photographic observations. This behaviour is similar to that exhibited by other PG-objects - 0834+488 and 1639+338, but the "missed" larger variations may not be excluded. The author is thankful to Yu.S. Shugarov and N.V. Metlova, who mainly obtained the patrol plates centered at SA 15. I.L. ANDRONOV Department of Astronomy, Odessa State University T.G. Shevchenko Park Odessa 270014 USSR References: Andronov, I.L.: 1991, Kinematics and Physics of the Celestial Bodies (Kiev), 7, No. 2, p.85. Andronov, I.L., Fuhrmann, B., Wenzel, W.: 1988, Astron. Nachr. 309, No. 1, p.39. [BIBCODE 1988AN....309...39A ] Andronov, I.L., Kimeridze, G.N., Richter, G.A., Smykov, V.P.: 1989, IBVS, No. 3388. Brun, A.: 1957, Atlas des 139 'Selected Areas' du Mt. Wilson. [BIBCODE 1957Brun..C......0B ] Green, R.F., Schmidt, M., Liebert, J.: 1986, Astrophys.J.Suppl. 61, 305. [BIBCODE 1986ApJS...61..305G ] Meinunger, L., Andronov, I.L.: 1987, IBVS, No. 3081.