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

                   NUMBER 449

                            Konkoly Observatory
                            Budapest
                            1970 July 15


        PHOTOGRAPHIC LIGHT ELEMENTS OF TX Cnc

      Haffner^1 demonstrated that TX Cnc is a variable of
the W UMa type. Properties of the system, which is a member
of the Praesepe cluster, have been discussed by various
authors (2, 3, 4). TX Cnc is a zero age W UMa variable and
its position in the period colour diagram defies current
theoretical explanation (5). It may be that a new spectroscopic 
determination of the masses of the components is
desirable.
      With this in mind, photographic observations were
made at Herstmonceux using the 26" f/10 refractor and IIaO
emulsion to check existing light elements. This system is
a good approximation to the B magnitude. The plates were
reduced by iris photometer against Johnson's (6) magnitudes
for Praesepe and give B= 10.65 - 11.02. Combined with
Haffner's light elements quoted by Popper (3), the new
observations give


                JD_min  =  2440 597.7605 + 0d.3828813
                                    +-25          +-3                    


                      K.P. TRITTON
                      R.A. BRETT
                      Royal Greenwich Observatory
                      Herstmonceux

References

 1.  H. Haffner, Z.f.Ap.14, 285, 1937 [BIBCODE 1937ZA.....14..285H ]
 2.  H. Haffner, A.N. 276, 233, 1950 [BIBCODE 1948AN....276..233H ]
 3.  D. M. Popper, Ap.J. 108, 490, 1950 [BIBCODE 1948ApJ...108..490P ]
 4.  F. Lenouvel and J. Daguillon, J. des Obs. 39, 1, 1956 [BIBCODE 1956JO.....39....1L ]
 5.  J. Hazelhurst, D.L. Moss and J.A.J. Whelan, M.N. in
        press
 6.  H.L. Johnson, Ap.J. 116, 640, 1953 [BIBCODE 1952ApJ...116..640J ]