COMMISSION 27 AND 42 OF THE IAU
               INFORMATION BULLETIN ON VARIABLE STARS
                           Number 3811

                                                 Konkoly Observatory
                                                 Budapest
                                                 23 November 1992

                                                 HU ISSN 0374 - 0676


 PERIOD REFINEMENT OF THE NEWLY DISCOVERED W UMa SYSTEM EF Dra

The W UMa system EF Dra was detected serendipitously by the
Einstein Observatory Imaging Proportional Counter (Gioia et al.,
1987) as x-ray source 1E1806.1+6944. Fleming et al. (1989)
suspected the object to be an eclipsing binary on base of x-ray
observations. Photometric data obtained from June to August 1989
by Robb and Scarfe (1989) confirmed the supposition and yielded
the preliminary elements:

    JD hel. Min. = 2447700.7602 + 0.42400 * E         (I)

   To refine the period of the system in order to enable a long-time
running ephemeris we observed the binary in V and B colour. The
data were obtained with the 0.34 m Cassegrain telescope at
Nürnberg Observatory, using a 1P21 phototube, and the 0.35 m
Schmidt-Cassegrain telescope at F. Agerer's private observatory,
using an EMI 9781A tube.

As a result we present the following elements, calculated by the
method of least squares from all available times of minima:

   JD hel. Min. = 2447700.75868 + 0.42402394 * E      (II)
                           +-70         +-22

Since the light curve shows indeed a significant night to night
variation regarding the depth of the minima, as noted by Robb and
Scarfe (1989), in combination with some asymmetry, we determined
the times of the minima using the tracing paper method. Table 1
lists all known minima and the corresponding O-C residuals against
the elements (II).


         Table 1: Photoelectric minima of EF Draconis.

JD hel.            Epoch O-C(II)   Filt.  Observer Instr.   Reference

2447701.8201         2.5  +.0014                            Robb & Scarfe
   7715.8125        35.5  +.0010                            Robb & Scarfe
   7716.8710        38.0  -.0006                            Robb & Scarfe
   7727.8971        64.0  +.0009                            Robb & Scarfe
   7730.8650        71.0  +.0006                            Robb & Scarfe
   7739.8902        80.5  -.0024                            Robb & Scarfe
   8467.3956      1808.0  +.0016    V     Ls/Sg/Wk/Wu 34    this paper
   8475.4498      1827.0  -.0006    V,B   Ag          35    Hubscher et al.
   8488.3835      1857.5  +.0004    V,B   Ag          35    Hubscher et al.
   8491.5634      1865.0  +.0001    V,B   Ag          35    Hubscher et al.
   8502.3729      1890.5  -.0030    V     Rz/Sg/Wk/Wu 34    this paper
   8624.2819      2178.0  -.0009    V     Wk/Wu       34    this paper
   8775.446 :     2534.5  -.0014    V,B   Ag          35    this paper
   8909.4420      2850.5  +.0031    V,B   Ag          35    this paper


Abbreviations of the observer's names:

Ag = F. Agerer          Rz = R. Rosenzweig      Wk = N. Wieck
Ls = G. Lichtschlag     Sg = S. Schurig         Wu = E. Wunder


                          [FIGURE 1]

 B and V light curves of EF Dra are shown in Figure 1. SAO 017740 was 
chosen as the comparison star.



               E. WUNDER               F. AGERER
               Nurnberg Observatory    Bundesdeutsche Arbeitsgemeinschaft
               Regiomontanusweg 1      fur Veranderliche Sterne (BAV) e.V.
               8500 Nurnberg 20        Dorfstr. 19
               F.R.G.                  8311 Zweikirchen/Tiefenbach, F.R.G.



References:

Fleming, T.A., Gioia, I.M., Maccacaro, T., 1989, Astronomical Journal 98, 692. [BIBCODE 1989AJ.....98..692F ]
Gioia, I.M., Maccacaro, T., Wolter, A., 1987, In, Observational Cosmology.
     IAU-Symposium No. 124, edited by G. Burbidge (Reidel, Dordrecht), 593. [BIBCODE 1987IAUS..124..593G ]
Hubscher, J., Agerer, F., Wunder, E., 1992, BAV-Mitteilungen, No. 60, in print. 
Robb, R.M., Scarfe, C.D., 1989, Inform. Bull. on Var. Stars, No. 3370.