COMMISSION 27 OF THE I. A. U.
              INFORMATION BULLETIN ON VARIABLE STARS
                            NUMBER 58

                                             Konkoly Observatory
                                             Budapest
                                             30 June 1964


             THE BRIGHTNESS OF THE QUASI-STELLAR RADIO
                 SOURCE 3C 48 ON HEIDELBERG PLATES

     The light variation of the quasi-stellar radio source 3C 48 -
like that of the radio galaxy 3C 273 - can be traced back over 60 years.

     The variability of 3C 48 was discovered by SMITH and HOFFLEIT (3) 
and by MATTHEWS and SANDAGE (1). On a pair of plates of
the Heidelberg plate collection taken in 1902 with the 16" Bruce astrograph 
the object is clearly visible. In 1963 twelve plates were taken by
SCHMIDT (2) with the same instrument for aberration measurements of
3C 48. All these plates were measured with the Sartorius iris-diaphragm 
photometer of the Heidelberg Observatory. The magnitudes of
our comparison stars were derived by comparison with Selected Area 45,
lying within the field of our plates. For the comparison stars B and D,
MATTHEWS and SANDAGE's photoelectric B-values - fitting well into
our sequence - have been adopted as photographic magnitudes. Not all
of our comparison stars are identical with those used by SMITH and
HOFFLEIT for the investigation of 3C 48 on Harvard plates. On three
good plates we compared also these stars with our magnitude sequence.
There exists a scale difference of +0.75 magnitudes between SMITH
and HOFFLEIT's and our system in the range of 15m.5 to 16m.5.

     The mean magnitudes of the comparison stars are inserted in
Table I. Table II. contains the magnitudes for 3C 48 obtained on our
plates.

                          Table I

     Comparison stars
  SMITH    Heidelberg  m_pg      Remarks
HOFFLEIT
    C                 13.30
    D                 14.31
    E          B      14.03      MATTHEWS and
                                 SANDAGE's
                                 comp. star
   E'                 14.71
   F           D      15.20      MATTHEWS and
                                 SANDAGE's
                                 comp. star
   F'          a      15.08
   G                  15.18
   G'          c      16.07
   H                  16.44
               b      15.99
               d      16.26


                    [FIGURE 1]


                           Table   II

    J. D.          3C 48               J. D.     3C 48
                   m_pg                          m-pg
241 6019.428       15.85           243 8321.469  16.12
    6019.428       15.95               8357.456  16.07
243 8226.505       15.95               8370.295  16.03
    8234.520       16.11               8380.498  16.10
    8237.517       16.32               8382.283  16.10
    8241.537       16.15               8399.381  16.08
    8290.476       16.25               8411.290  16.30

Literature
1/ MATTHEWS, T. A. and SANDAGE, A. R.: Astrophys. J. 138, 30 (1963) [BIBCODE 1963ApJ...138...30M ]
2/ SCHMIDT, Th.: Zeitschrift f. Astrophys., in print (1964) [BIBCODE 1964ZA.....60..106S ]
3/ SMITH, H. J. and HOFFLEIT, D.: Publ. Astr. Soc. Pacific 73, 292 (1961) [BIBCODE 1961PASP...73..292S ]

                                                 E. H. GEYER
                                              Landessternwarte
                                            Heidelberg-Konigstuhl