COMMISSION 27 OF THE I.A.U. INFORMATION BULLETIN ON VARIABLE STARS Number 3229 Konkoly Observatory Budapest 17 August 1988 HU ISSN 0374 - 0676 UBV(RI)c OBSERVATIONS OF SN 1987A * SN 1987A was observed in 1987 from November 30 to December 14 with the 50 cm ESO Cassegrain reflector at La Silla. The telescope was equipped with a single-channel photon-counting cooled photometer using an RCA 31034 tube, HD 39062 (=CP -61d517 = SAO 243350) and HD 37297 (=CP -64d456 = SAO 249309 = HR 1917) were used as comparison and check stars, respectively. The observations were corrected for atmospheric extinction and were transformed to the UBV(RI)c system by observing Cousins E-region standard stars (Vogt et al., 1981). The following magnitudes were derived for the comparison and check stars, which showed no variability larger than 0.02 mag in any of the wavebands (the standard deviation in units of .001 mag. is given within parentheses): Star U B V R I HD 39062 10.063(20) 8.685(11) 7.402(8) 6.754(12) 6.193(10) HD 37297 7.239(13) 6.384(8) 5.350(6) 4.807(11) 4.326(9) Table I Nightly mean JD_Hel, V magnitude and colors of SN 1987A, At the bottom of each column the typical standard deviation is reported in units of .001 mag. JD_Hel V U-B B-V V-R V-I (2447000.+) 129.8058 5.881 1.574 1.273 1.162 1.642 130.7534 5.887 1.566 1.275 1.163 1.634 131.7469 5.902 1.558 1.275 1.158 1.632 132.7392 5.911 1.529 1.276 1.164 1.635 133.7037 5.925 1.510 1.268 1.168 1.634 134.7190 5.938 1.518 1.261 1.163 1.634 135.7974 5.947 1.532 1.259 1.160 1.633 136.7402 5.959 1.524 1.262 1.168 1.638 137.7905 5.964 1.522 1.260 1.161 1.627 138.7057 5.966 1.507 1.259 1.160 1.616 139.7656 5.973 1.500 1.254 1.154 1.620 140.7719 5.987 1.185 1.248 1.154 1.619 141.6943 5.997 1.490 1.238 1.158 1.626 142.7228 6.009 1.480 1.234 1.159 1.625 143.7636 6.012 1.478 1.237 1.157 1.617 ------------------------------------- 3 6 4 4 4 [FIGURE 1] Figure 1: V observations of SN 1987A in 1987 from November 30 to December 14. The magnitudes of HD 37297 and HD 39062 are in very good agreement with those reported by Rucinski (1983) and Gouiffes (private communication) respectively. Figure 1 shows the V light curve. In Table I the mean JDhel, the V magnitude and the U-B, B-V, V-R and V-I color indices are presented. Each value is the average of at least three different measurements (SN 1987A - HD 39062). Comparing our results with those obtained by Whitelock et al.(1988), we note systematic shifts (present paper - Whitelock magnitudes) of the order of: +0.04 mag in U, +0.01 in B, +0.04 in V, +0.03 in R and +0.1 in I. Although the difference in the I band is quite high, the shifts between the two data sets could be simply due to differences in the zero point. * Based on observations obtained at the European Southern Observatory, La Silla, Chile G. CUTISPOTO Catania Astrophysical Observatory v. le A. Doria, 6 I-95125, Catania, Italy References: Rucinski, S.M., 1983, Astron. Astrophys. Suppl. Ser. 52, 281. [BIBCODE 1983A&AS...52..281R ] Vogt, N., Geisse, H.S., Rojas, S., 1981, Astron. Astrophys. Suppl. Ser. 46, 7. [BIBCODE 1981A&AS...46....7V ] Whitelock, et al., 1988, South African Astronomical Observatory, preprint