COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1140 Konkoly Observatory Budapest 1976 June 7 OBSERVATIONS OF THREE U GEMINORUM STARS The U Geminorum stars PU, PV and V 372 Persei have been discovered at Sonneberg Observatory in a field around R.A. 2h40m; D = +37d. Only few informations on these stars have been published by C. Hoffmeister (1967) and it is interesting to collect other observations for a better knowledge of their light curve. To this purpose we have examined 67 blue (103a-O + GG 13) and 40 yellow plates (103a-D + GG 14) taken with the 67/90/210 Schmidt telescope of the Asiago Astrophysical Observatory between JD 2439145 and JD 2441975. The B and V magnitudes of the comparison stars have been determined with the U,B,V sequence established by F. Bertola (1963, 1965) near the galaxy NGC 1058. The variables PU Per - This star shows two maxima in blue light. The first, at JD 2440644, is faint (17.4) and narrow with rapid evolution; the second is brighter (15.2) and larger (duration 6 days). Table I lists the observations near the maxima. Table I I Max II Max JD 24... JD 24... 40641 <19.0 41280 <19.0 644 17.4 295 15.2 645 <19.0 298 15.2 301 16.6 303 19.0 308 <19.0 At minimum the variable presents light fluctuations near 19.0 B. The variations occur from 15.2 to <19.0. PV Per - Table II gives the list of B and V maxima observed in our material. Table II Max. B V Max. B V 24.. 24.. 39145 15.6 - 40802 15.1 15.3 732 16.7 - 940 16.1 16.0 40582 16.3 16.4 41250 15.3 - 646 16.8 - 542 15.3 - 682 16.0 - [FIGURE 1] A mean cycle of 36 days satisfies the observations. The light curve of Fig. 1 shows the occurrence of maxima faint and narrow, together with maxima bright and wide. The B-V colour is about -0.1 at maximum. At minimum V light the star is below the plate limit. The star varies between 15.1 and <19.0 in B and between 15.3 and <18.2 in V. On blue print of Palomar Sky Survey this star's apparent magnitude at minimum has been estimated about 20m. It is possible that the variations in B are between 15.1m - 20m. V 372 Per - In the present material this star is always near minimum. Fig. 2 shows that the variable presents fluctuations between 18.4 and <19.0 B. The colour B-V has been determined in the following occasions: JD B V B - V 24... 40866 18.7 18.1 + 0.6 40915 18.8 18.0 + 0.8 These values agree with the mean colour index of the U Geminorum stars near the minimum light. The presence of some galaxies around these variables suggests that the field is almost free of interstellar absorption. The B magnitude 16.5 derived by C. Hoffmeister on the Palomar blue print is probably that of an intermediate phase between the maximum and minimum. Concluding remarks: During the period of our observations the three U Geminorum stars PU, PV and V 372 Persei show the characteristics listed in Table III. Table III Var. B V B V B-V cycle max. min. max. min. PU Per 15.2 - <19.0 - - - - PV Per 15.1 15.3 <19.0 18.2 -0.1 - 36d V372Per - - <19.0 - - +0.6;+0.8 - G. ROMANO and S. MINELLO Istituto de Astronomia Universita di Padova References: Bertola, F. 1963 Asiago Contr. No. 142. [BIBCODE 1963CoAsi.142....3B ] 1965 Asiago Contr. No. 171 [BIBCODE 1965CoAsi.171....3B ] Hoffmeister, C. 1967. A.N. 290, H 1 - 2, 43. [BIBCODE 1967AN....290...43H ]