COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3605 Konkoly Observatory Budapest 17 May 1991 HU ISSN 0374 - 0676 BVI photometry of the symbiotic star C-1 in the Draco dwarf galaxy The carbon giant C-1 in the Draco dwarf galaxy was discovered by Aaronson et al. (1982) to show emission lines of H I, He I and He II. It has been classified among symbiotic stars by Allen (1984). The symbiotic nature has been confirmed by Munari (1991) who observed marked spectroscopic changes in the emission spectrum and strong variability of H alpha radial velocity and shape which suggested orbital motion. A number of plates have been exposed on C-1 with the 67/92 cm Schmidt telescope of the Asiago Astrophysical Observatory in the period 1987-1990. The magnitude of C-1 has been estimated by comparison with a set of reference stars derived from the photometry of Baade & Swope (1961), Stetson (1979 ) and Carney & Seitzer (1986). A journal of the observations and resulting magnitudes are given in the table. BVI photographic photometry of C-1 date J.D. plate filter B V I 24 July 1987 2447001.425 103a-O GG 13 18.6 26 July 1987 2447003.506 I-N RG 8 15.4 7 July 1988 2447350.533 103a-O GG 13 > 17.9 14 Aug.1988 2447388.426 103a-O GG 13 > 18.8 5 May 1989 2447652.528 I-N RG 8 15.7 28 May 1989 2447675.555 I-N RG 8 15.0 9 June 1989 2447687.586 I-N RG 8 14.5 2447687.549 103a-O GG 13 18.6 3 Aug.1989 2447742.417 I-N RG 8 14.7 9 Aug.1989 2447748.398 103a-O GG 13 > 19.2 2447748.445 I-N RG 8 ::14.7 4 Sept.1989 2447774.386 I-N RG 8 15.6 2447774.423 103a-O GG 13 > 18.6 20 July 1990 2448093.480 103a-O GG 13 18.9 2448093.506 103a-D GG 14 16.8 28 July 1990 2448101.400 103a-O GG 13 > 16.5 18 Aug.1990 2448122.409 103a-O GG 13 18.4 2448122.439 I-N RG 8 15.6 14 Oct.1990 2448179.291 I-N RG 8 15.5 2448179.324 103a-O GG 13 > 18.5 C-1 appears faint on many of the plates. Consequently, appreciable errors are to be expected in the reported photometry, which can be considered accurate on the average to 0.35 mag in I, to 0.25 in B and to 0.15 mag in V. Together with the photoelectric data reported by Aaronson et al. (1982) there are in all 12 mag estimates in B, 10 in I and 3 in V. In view of the involved large errors and paucity of data it is hazardous to derive any firm conclusion about the variability of C-1. Anyway some variability seems established in the B band if the observations on JD 2447748.398 and 2448122.409 are compared. The data in the table could support a ~1.0 mag variability in the I band which could be described as a bright phase in the summer of 1989. In any case the data in table show a quiet photometric evolution during 1981-90 with no outburst recorded in the period 1987-90. ULISSE MUNARI Asiago Astrophysical Observatory I-36012 Asiago (VI) Italy References Aaronson, M., Liebert, J., Stocke, J.: 1982 Ap.J. 254, 507 [BIBCODE 1982ApJ...254..507A ] Allen, D.A.: 1984 Proc.A.S.A. 5, 367 [BIBCODE 1984PASAu...5..369A ] Baade, W., Swope, H.: 1961 Astron. J. 66, 300 [BIBCODE 1961AJ.....66..300B ] Carney, B.W., Seitzer, P.: 1986 Astron. J. 92, 23 [BIBCODE 1986AJ.....92...23C ] Munari, U.: 1991 Astron. Astrophys., submitted [BIBCODE 1991A&A...251..103M ] Stetson, P.B.: 1979 Astron. J. 84, 1149 [BIBCODE 1979AJ.....84.1149S ]