COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS NUMBER 52 Konkoly Observatory Budapest 27 April 1964 INVESTIGATION OF THE LIGHT VARIATIONS OF THE QUASI-STELLAR RADIOGALAXY 3C 273 ON HEIDELBERG PLATES The radiogalaxy 3C 273 is visible on 105 plates of the Heidelberg plate collection and its brightness was estimated by eye using SMITH and HOFFLEIT's comparison stars. Most of these stars are identical with those used by SHAROV and EFREMOV. The bulk of the observations lies between 1892 and 1915 (91 plates) where they are most needed, and were obtained at two instruments: the 6 inch double astrograph (A-plates) and the 16 inch Bruce double astrograph (B-plates). Therefore, nearly without exceptions, the observations consist of two exposures and in many cases three or more plates are available per night. For the brightness of the comparison stars WARNER and SWASEY photographic magnitudes were used, slightly corrected to fit our estimates to the best: Comparison 6 inch Bruce- Star Telescope Telescope Remarks m_pg m_pg A' 12,07 12.07 Sharov and Efremov's B 12.33 12.34 a-star C 12.65 12.62 b- " D 12.81 12.84 c- " E 13.04 13.06 d- " The following table gives the individual magnitude estimates of all plates investigated. Telescope J.D. m_pg Telescope J.D. m_pg 241.... 241.... A 2179.375 12m.23 A 6194.507 12m.52 A 2179.472 12.18 A 6194.534 12.46 A 2179.472 12.14 A 6554.596 12.57 A 2182.370 12.20 A 6554.619 12.61 A 2182.370 12.14 A 6554.619 12.54 A 2182.455 12.14 A 6913.452 12.49 A 2182.455 12.07 A 6913.494 12.49 A 2182.548 12.14 A 6918.547 12.52 A 2182.548 12.07 A 6918.567 12.57 A 2541.445 12.43 B 7273.574 12.48 A 2544.415 12.28 B 7273.574 12.45 A 2544.415 12.32 B 7291.466 12.41 A 2916.415 12.36 B 7291.466 12.39 A 2916.415 12.42 A 7303.382 12.52 A 3270.452 12.70 A 7303.367 12.57 A 3270.452 12.52 A 7303.418 12.58 A 3270.515 12.57 A 7667.361 12.26 A 3656.459 12.27 A 7668.383 12.41 A 3656.459 12.33 A 7668.383 12.27 A 4725.445 12.58 B 8024.460 12.73 A 4725.445 12.52 B 8024.460 12.59 A 4727.444 12.60 A 8419.504 12.39 A 4727.444 12.57 B 8445.424 12.39 A 5108.418 12.26 B 8445.424 12.45 A 5108.418 12.20 A 8745.411 12.29 A 5110.454 12.28 A 8745.442 12.49 A 5110.454 12.20 A 8745.486 12.46 A 5129.412 12.26 B 9127.517 12.56 A 5129.412 12.16 B 9127.517 12.56 A 5457.438 12.39 A 9505.361 12.71 A 5457.469 12.46 A 9505.394 12.71 A 5457.512 12.40 A 9505.427 12.52 A 5813.414 12.49 B 9510.535 12.68 A 5813.442 12.41 B 9510.535 12.64 A 5813.473 12.39 A 9828.427 12.58 B 5814.504 12.45 A 9828.457 12.57 B 5814.504 12.48 A 9828.487 12.58 B 5815.556 12.50 B 9861.409 12.48 B 5815.556 12.48 B 9861.409 12.45 A 5848.384 12.57 B 9882.434 12.73 A 5848.451 12.57 B 9882.434 12.68 A 5852.397 12.46 A 5852.397 12.52 242.... A 6194.486 12.57 B 0221.429 12.55 Telescope J.D. m_pg Telescope J.D. m_pg 242.... 243.... B 0221.429 12m.62 B 0456.387 12m.51 A 0222.480 12.68 B 0456.387 12.45 A 0222.480 12.73 B 0461.398 12.55 B 0579.429 12.29 B 0461.398 12.66 B 0579.429 12.27 B 0463.405 12.66 B 0953.488 12.41 B 0463.405 12.68 B 4612.444 12.45 B 6287.480 12.78 B 7158.376 12.95 B 7469.429 12.68 B 7158.376 12.91 B 7534.446 12.44 B 7534.446 12.48 E. H. GEYER Landessternwarte Heidelberg-Konigstuhl Literature: Information Bull. On Variable Stars 27 (1963) [BIBCODE 1963IBVS...27....1D ] Huth, H.: MVS 2, Heft 1 (1963) Sandage, A.: Astrophys. J. 139, 416 (1964) [BIBCODE 1964ApJ...139..416S ] Sharov, A. S. and Efremov, Y. N.: Inform. Bull. on Variable Stars 23 [BIBCODE 1963IBVS...23....1S ] 1963; Russ. Astron. J. 40, 950 (1963) [BIBCODE 1963AZh....40..950S ] Smith, H. J. and Hoffleit, D.: Astron. J. 68, 292 (1963); [BIBCODE 1963AJ.....68S.292S ] Nature Vol. 198, 650 (1963), [BIBCODE 1963Natur.198..650S ] Sky and Telescope XXVIII, 8/ 1964