COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2264 Konkoly Observatory Budapest 1983 January 11 HU ISSN 0374-0676 PHOTOELECTRIC UBV OBSERVATIONS OF PU Vul IN 1982 The following observations are a continuation of similar measurements performed on the same object in 1981 (IBVS No. 2071). All data presented were obtained with the 24 inch Ritchey-Chretien telescope of the L. Figl Observatory. Except for the addition of a digital counter (R70) and a printer the same equipment was used for the observations as described in our first paper. BD +21deg4165 = SAO 88548 (star A) was used as primary comparison star which in turn was checked in most nights against BD +20deg4533 = SAO 58572 (not SAO 88573 as erroneously written in IBVS No. 2071). A slight systematic light variation of about DeltaV = +/- 0.01mag between these two stars seems to be present. No final conclusion could be drawn on the nature of this variation. With regard to this we plan to follow both objects more closely during the next observing season. As in 1981 all measurements were reduced to star A with its adopted magnitudes V = 9.300, B - V = + 0.520 and U - H = + 0.030. This is somewhat arbitrary since we have not yet performed an accurate tie-in of this star to the UBV system. Since star A is very close to the variable no correction for extinction was applied. Table I shows the numerical results. All errors quoted are the mean errors of the mean. n gives the number of comparisons in each colour. In several nights with very poor sky conditions only V magnitudes could be obtained. During the whole observing period lasting from early April to December PU Vul was always at maximum light. This means that the actual maximum has been lasting already 130 days longer than the previous one. Compared to the last year the object showed much more structure in the light curve, which is plotted for V, B and U in Figure 1. In general the variations behave more similar for V and B compared to U. This is even more evident from the two colour diagram (Figure 2) producing a pronounced scatter in the vertical direction. The most remarkable activity started around September 7 with a steep decrease of the B and V brightnesses followed a few days later by the U brightness. The respective gradient for Table I UT 1982 JD V n B - V n U - B n 2445... 04 06,10 065,60 8,567+/-0,004 10 0,669+/-0,004 10 0,450+/-0,004 10 17,13 076,63 8,599 2 14 0,669 4 12 0,448 4 7 05 15,03 104,53 8,581 2 10 0,698 2 11 0,481 4 10 16,02 105,52 8,556 3 10 0,711 3 10 0,477 5 10 17,03 106,53 8,578 3 10 0,708 4 10 0,490 3 12 18,02 107,52 8,590 7 6 0,730 7 6 0,471 8 3 19,02 108,52 8,589 2 10 0,706 4 10 0,500 5 10 27,03 116,53 8,562 3 10 0,709 4 10 0,502 6 10 28,02 117,52 8,561 5 10 0,720 6 10 0,485 8 10 31,02 120,52 8,558 3 9 0,710 3 10 0,493 4 10 06 01,05 121,55 8,545 1 5 0,717 3 5 0,493 6 5 06,00 126,50 8,563 3 10 0,705 3 6 0,496 3 6 08,98 128,48 8,548 9 10 0,717 9 10 0,459 13 4 07 02,89 153,39 8,664 6 6 02,95 153,45 8,658 3 12 0,738 4 10 0,487 2 10 03,00 153,50 8,672 3 7 05,92 156,42 8,657 3 12 0,710 4 10 0,476 4 10 08,97 159,47 8,612 4 10 0,700 5 8 0,482 7 9 10,93 161,43 8,611 2 13 0,699 3 10 0,479 6 9 14,89 165,39 8,581 2 10 0,694 3 11 0,473 4 10 21,90 172,40 8,604 2 7 0,683 3 3 0,534 11 5 29,99 180,49 8,692 4 10 0,682 10 9 30,96 181,46 8,713 2 4 08 01,95 183,45 8,743 3 18 0,685 4 13 0,408 5 12 04,01 135,51 8,796 5 17 05,93 187,43 8,738 3 10 0,682 5 10 0,413 9 10 10,95 192,45 8,645 10 4 11,87 193,37 8,625 3 12 0,725 4 11 0,497 6 8 15,87 197,37 8,607 3 10 0,706 4 11 0,509 7 9 18,82 200,32 8,631 2 5 0,729 6 6 0,539 8 5 22,81 204,31 8,654 4 12 0,699 7 5 0,519 10 6 25,80 207,30 8,622 3 9 0,688 5 6 09 03,91 216,41 8,599 3 10 0,684 4 8 0,523 7 8 04,85 217,35 8,567 2 6 0,691 4 7 0,569 10 6 13,85 226,36 8,625 6 9 0,710 8 10 0,484 5 9 14,33 227,33 8,665 5 10 0,700 7 10 0,477 11 10 Table I cont. UT 1982 JD V n B - V n U - B n 2445... 09 17,82 230,32 8,927+/-0,003 10 0,699+/-0,004 10 0,381+/-0,007 10 18,82 231,32 8,949 3 10 0,674 4 10 0,357 7 10 18,85 231,35 8,939 7 3 0,685 7 3 0,340 4 3 18,88 231,38 8,931 9 3 0,676 10 3 0,349 31 3 18,90 231,40 8,930 13 3 0,688 14 3 0,356 9 3 18,91 231,41 8,941 5 3 0,662 7 3 18,94 231,44 8,928 2 3 0,675 5 3 18,95 231,45 8,947 5 3 0,654 7 3 18,98 231,48 8,924 2 3 0,670 5 3 19,00 331,50 8,921 5 3 0,679 7 3 19,81 232,31 8,870 4 10 0,680 5 10 0,389 16 12 19,84 232,34 8,875 6 3 0,681 9 3 19,86 232,36 8,882 5 3 0,656 9 3 19,89 232,39 8,864 3 3 0,689 5 3 19,91 232,41 8,886 8 3 0,675 9 3 19,93 232,43 8,883 2 3 0,679 3 3 19,95 232,45 8,889 3 3 0,672 4 3 19,97 232,47 8,886 8 3 0,667 11 3 20,00 232,50 8,876 7 3 0,677 7 3 20,82 233,32 8,845 4 9 0,699 4 8 0,401 8 9 20,95 233,45 8,826 5 8 20,98 233,48 8,824 8 5 21,01 233,51 8,824 4 6 28,87 241,37 8,612 18 12 0,684 19 17 0,483 13 10 29,78 242,28 8,600 3 12 0,682 3 11 0,464 4 12 10 03,81 246,31 8,646 3 10 0,674 5 10 0,473 8 10 07,82 250,32 8,623 3 11 0,626 4 10 0,455 7 10 11,79 254,29 8,635 6 10 0,56: 16,77 259,27 8,528 3 11 0,584 4 11 0,353 5 10 18,81 261,31 8,587 4 11 0,566 5 10 0,380 9 8 20,76 263,26 8,596 2 9 0,556 3 8 0,355 8 9 22,77 265,27 8,599 5 9 0,538 7 9 0,336 10 9 27,78 270,28 8,520 4,9 0,542 4 9 0,294 8 9 30,74 273,24 8,504 4 9 0,546 8 9 0,254 10 9 31,74 274,24 8,472 6 9 0,547 6 9 0,252 6 9 11 01,74 275,24 8,472 2 6 0,540 3 6 0,255 4 9 Table I cont. UT 1982 JD V n B - V n U - B n 2445... 11 02,76 276,24 8,464+/-0,002 6 0,535+/-0,003 6 0,244+/-0,006 7 03,81 277,31 8,480 1 5 0,526 2 5 0,227 8 4 04,75 278,25 8,464 3 6 0,516 5 6 0,225 7 7 06,72 280,22 8,467 3 9 0,522 5 7 0,229 7 9 11,72 285,22 8,469 5 9 0,500 5 9 0,226 9 9 12,73 286,23 8,976 2 9 0,506 4 9 0,245 9 9 19,73 293,23 8,497 3 8 0,521 4 9 0,285 11 3 20,68 294,18 8,508 3 10 0,517 5 6 0,270 7 6 21,72 295,22 8,507 4 9 0,506 4 9 0,267 5 9 22,71 296,21 8,487 2 3 0,511 4 3 0,289 12 3 23,73 297,23 8,495 3 7 0,517 4 9 0,271 9 13 25,73 299,23 8,489 2 7 0,517 4 4 0,266 7 9 12 03,70 307,20 8,522 4 9 0,528 4 4 0,286 3 9 05,69 309,19 8,516 4 5 0,530 4 4 0,282 5 9 10,69 316,19 8,522 29 4 [FIGURE 1] [FIGURE 2] all three colours was almost 0.1mag day^-1 . In the U band this "minimum" (DeltaU ~= 0.2mag) was only half as deep as in B and V. Two weeks later PU Vul in all three colours reached the original level again. The following increase was strongest in U (DeltaU = 0.6mag gradient about 0.016mag day^-1) while in V the brightening amounted only to 0.15mag. A new "maximum" in all three bands occured around November 6. Since then the object faded slowly with some oscillation, somewhat faster in B and V and still faster in U. Figure 2 shows the path of the variable at this long active phase in the two colour diagram. For comparison we also indicated the path of the rise of PU Vul last year according to our own observations by a dashed line. The position of PU Vul in the two colour diagram at maximum light during last year is well within the bulk for 1982. The numbers in Figure 2 refer to phases indicated in Figure 1 by arrows. The last three weeks of the slow fading are characterized by a relatively stable position in the two colour diagram. Chochol et al. (1981) suggested the presence of a 78 respectively 75 days period with an amplitude of some 0.2mag in V. Considering the observed activities we did not attempt to check this hypothesis. A. PURGATHOFER A. SCHNELL Institute for Astronomy University of Vienna Turkenschanzstrasse 17 A-1180 Vienna, Austria References: Chochol, D., Hric, L. and Papousek, J.: 1981, IBVS No. 2059 Chochol, D.: 1982, private communication Purgathofer, A. and Schnell, A.: 1982, IBVS No. 2071