COMMISSION 27 OF THE I. A. U.
       INFORMATION BULLETIN ON VARIABLE STARS
                   Number 2377

                                    Konkoly Observatory
                                    Budapest
                                    1 August 1983

                                    HU ISSN 0374-0676



       THE ORBITAL PERIODS FOR SIX CATACLYSMIC BINARIES



  The orbital periods for VW Vul, V380 Oph, CM Del, TW Vir, V794 Aql, and
SY Cnc have been determined from radial velocity variations of their Halpha 
emission lines. All observations were obtained using the Mount Lemmon 1.5 m 
reflector equipped with a Robinson-Wampler Image Dissector Scanner^1. The 
radial velocities were measured using the method described by Shafter^2. TableI
summarizes the results of the radial velocity studies of the six binaries.


                               Table I*
--------------------------------------------------------------------------
Object Designation  Date(s) of   Duration of    Orbital       K_1     Ref.
                    Observation  Observations   Period       (km/s)
                                    (hrs)       (days)
--------------------------------------------------------------------------
VW Vul    UG?       13-Jul-82        5.1        0.073         100:     3
V380 Oph  NL?       10-May-83        4.5        0.16          100:     5
CM Del    UG?       21-Jul-82        5.4        0.16          150:     3
TW Vir    UG        27-Jan-82        1.7        0.18266(66)   88+-5    4
                    28-Jan-82        3.0
                    31-Jan-82        3.6
                    28-Apr-82        5.6
                    29-Apr-82        3.8
V794 Aql  UG?       15-Jul-82        5.0        0.23:         100:     3
SY Cnc    ZC        12-Feb-83        3.3        0.38           90:     4
                    13-Feb-83        7.4
                    16-Feb-83        4.0
--------------------------------------------------------------------------

* A colon indicates an uncertain value. The references are for finding charts 
  and coordinates.

  The only system with a sufficiently accurate period to warrant giving an
ephemeris is TW Vir. For this system we find following expression for the
time (T) of superior conjunction of the broad Halpha emission (i.e. the accretion
disk surrounding the white dwarf):

            T = HJD 2445088.7121 + 0.182666 E.
                         +-.0022  +-.000066

  A more elaborate discussion of the above systems will appear elsewhere.
In particular, additional radial velocity data on V794 Aql. TW Vir, and
CM Del obtained by K. Horne, P. Szkody, and the author using the coude

Spectrograph of the Mount Wilson 100" reflector will be included to improve
the accuracy of the orbital elements.
  I thank P. Etzel for the use of his Spectroscropic Binary Orbit Program.
This work has been partially supported by NSF grant AST 80-19745 to Roger K.
Ulrich.





                ALLEN W. SHAFTER

              Department of Astronomy
              University of California
              Los Angeles, CA 90024
              U.S.A.





References:

1. Robinson, L.B., and Wampler, E.J. 1972, P.A.S.P. 84, 161 [BIBCODE 1972PASP...84..161R ]
2. Shafter, A.W. 1983, Ap. J. 267, 222 [BIBCODE 1983ApJ...267..222S ]
3. Vogt, N., and Bateson, F.M. 1982, Astronomy and Astrophysics Suppl. 48, 383 [BIBCODE 1982A&AS...48..383V ]
4. Williams, G. 1982 (Ph.D. Dissertation Univ. of Michigan)
5. Kukarkin, B.V. et.al. 1969, General Catalogue of Variable Stars (Moscow:
   Sternberg State Astr. Inst.) [BIBCODE 1969gcvs.book.....K ]