COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                    Number 2251

                                      Konkoly Observatory
                                      Budapest
                                      1982 December 20

                                      HU ISSN 0374-0676



               NONCIRCULAR ORBIT OF TU Cam


   TU Camelopardalis (HR 2027) is a Beta Lyrae type eclipsing binary of visual
magnitude mV = 5.1. One secondary and two primary minima were observed in the
period December 1977 - January 1980. The observations were performed by the
0.6 m photometric reflector at the Skalnate Pleso Observatory. The star was
observed in B and V filters of the standard UBV system and in two intermediate
band filters centered at 472 and 527 nm. Times of the observed minima are
listed in Table I, which contains also two photoelectric minima published
earlier by Wood (1951) and West (1968).



                                 Table I


        JD (hel.)          (O-C)        Cycle       Source
       2432633.655        0.0000         0        Wood (1951)
       2438051.3755       0.0000         1847     West (1968)
       2443495.4960     - 0.0007         3703     This paper
       2444174.5778     + 0.0349         3934.5       "
       2444243.4751       0.0000         3958         "




From the minima listed in the first and in the last lines of Table I, we
derived the following ephemeris:


         JD (Min I) = 2 444 243.4751 + 2.933 2542d x E.


The value of the period is equal to that found by West (1968). The (O-C)
values corresponding to our ephemeris are given in column 2 of Table I. There
is a notable high value of (O-C) for the secondary minimum observed at
JD 2 444 174, that corresponds to the phase 0.512. West (1968) did not find




any displacement of the secondary minimum, and hence he assumed a circular
orbit for the TU Cam system. His observations, however, do not cover 
satisfactorily the vicinity of the secondary minimum.
  Spectroscopic orbits for TU Cam were computed by Harper (1924), Luyten
(1936) and Mannino (1954) with the eccentricities 0.030, 0.040 and 0.037,
respectively. As West pointed out, the mean value of the eccentricity,
e = 0.035 from these spectroscopic orbits leads to the shift of the secondary
minimum to the phase 0.522.





              J. ZIZNOVSKY

              Astronomical Institute
              Slovak Academy of Sciences
              059 60 T. Lomnica
              Czechoslovakia





References:

Harper, W.E.: 1924, Publ. Dom. Ap. Obs. Victoria 3, 159 [BIBCODE 1924PDAO....3..159H ]
Luyten, W.J.: 1936, Astroph. J. 84, 90 [BIBCODE 1936ApJ....84...85L ]
Mannino, G.: 1954, Asiago Contr. No. 53
West, R.M.: 1968, Bull. Astr. Inst. Netherlands, Suppl. Ser. 2, No. 5 [BIBCODE 1968BANS....2..259W ]
Wood, F.B.: 1951, Astron. J. 56, 53 [BIBCODE 1951AJ.....56...53W ]