COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2260 Konkoly Observatory Budapest 1983 January 6 HU ISSN 0374-0676 POSITIONS OF FOUR NOVAE* The importance of the determination of coordinates and proper motions of novae has been pointed out by Artyukhina and Kholopov (1962). Positions of the novae RR Pic, CP Pup and T Pyx, which are included in Artyukhina and Kholopov's list, were determined. In addition, the position of Nova Aquilae 1982 was measured. The observations were carried out with the GPO astrograph of the European Southern Observatory, La Silla, Chile. The focal length of the telescope is 9 m, corresponding to a scale of 51.5 "/mm. The observational data are given in Table I. AGK3 stars for Nova Aql and SAO stars for the other novae were Table I Observational Data Plate Object Date Emulsion/ Filter 3353 RR Pic 1979 Jan 12 098/ Red 3354 RR Pic 1979 Jan 12 098/ Red 4419 CP Pup 1981 Jan 7 2aO/ - 4420 T Pyx 1981 Jan 7 2aO/ - 5673 N Aql 1982 1982 Jun 15 2aO/ - 5674 N Aql 1982 1982 Jun 15 2aO/ - *Based on observations collected at the European Southern Observatory, La Silla, Chile. used as reference stars. The plates were measured with the KOMESS of the Bonn Observatory. Our reduction model contains terms up to the third order in the coordinates X and Y. For the plates of Nova Aql only quadratic terms were used because the third order terms were not significant: The errors of the plate constants were larger than the plate constants themselves. No colour equation was found; a magnitude equation could not be detected because the reference stars are in a narrow magnitude range. Table II gives the results of our Table II Nova Positions Object Epoch alpha delta Cat. N sigma sigma of obs. 1950 1950 alpha delta (0.01") (0.01") RR Pic 1979.0 06h35m09.799s -62deg35m49.28s SAO 20 32 21 CP Pup 1981.0 08 09 52.037 -35 12 04.35 SAO 13 53 27 T Pyx 1981.0 09 02 37.151 -32 10 47.41 SAO 22 47 43 N Aql 1982 1982.5 19 20 50.142 +02 23 35.32 AGK 3 16 24 33 N = number of reference stars measurements. The errors in columns 7 and 8 are the mean errors of the nova positions provided from the least square solution for an individual plate. These are mainly caused by the local errors of the reference stars in the field. The internal error resulting from the comparison of the results from different plates (Nova Aql and RR Pic) is about 0.1". In the fields of T Pyx and RR Pic, 6 stars from the Perth 70 catalogue were included in our measurements. The mean differences between the catalogue positions and our positions are given in Table III. Table III Mean differences between Perth 70 positions and our positions in the sense Perth 70 - our positions Number Field Delta alpha(0.01") Delta delta(0.01") of stars T Pyx -05 +/- 20 -72 +/- 24 6 RR Pic -37 +/- 10 -39 +/- 14 6 It should be noted that the "astrometric position" of RR Pic as given by Wyckoff and Wehinger (1978) does not refer to the nova, but to the nearby SAO star 249586. While finding charts of RR Pic, CP Pup and T Pyx are given by Wyckoff and Wehinger (1578), Pettit (1954), and Humason (1938), respectively, a finding chart of Nova Aql 1982 is given in Figure 1. This reproduction from [FIGURE 1] Figure 1 Finding chart for Nova Aql 1982. This reproduction from the Palomar Observatory Sky Survey red plate 323 shows a star of R ~ 18m close to the position of the nova. the Palomar Observatory Sky Survey shows a faint star (B ~ 20mag, R ~ 18mag, the eastern component of a pair with a separation of ~ 10") close to the position of the nova. The derived amplitude of ~ 13mag is near the mean amplitude of novae; the red colour can at least partly be explained by interstellar extinction. Acknowledgement: We thank Dr. W.C. Seitter for her participation in the observations. H.W. DUERBECK and M. GEFFERT Observatorium Hoher List der Universitats-Sternwarte Bonn D-5568 Daun Federal Republic of Germany References: Artyukhina, N.M., Kholopov, P.N., 1962, Astr. Zh. 39, 1129 [BIBCODE 1962AZh....39.1129A ] Humason, M., 1938, Astrophys. J. 88, 228 [BIBCODE 1938ApJ....88..228H ] Pettit, E., 1954, Publ. Astr. Soc. Pacific 66, 145 [BIBCODE 1954PASP...66..142P ] Wyckoff, S., Wehinger, P.A., 1978, Publ. Astr. Soc. Pacific 90, 557 [BIBCODE 1978PASP...90..557W ]