COMMISSIONS 27 AND 42 OF THE IAU 
             INFORMATION BULLETIN ON VARIABLE STARS 
                          Number 3785 
 
                                           Konkoly Observatory 
                                           Budapest 
                                           5 October 1992 

                                           HU ISSN 0374 - 0676 
 
     GSC 5198.00659, THE NEW VARIABLE IN AQUARIUS IS A 
                       W UMA SYSTEM


 During a test phase run with the recently completed high speed 
photocounting double beam photometer at the 1 m Cassegrain/Nasmyth 
telescope of the Hoher List Observatory, we observed the new variable 
in Aquarius GSC 5198.00659 (RA 2000 = 21h21m24.9s, Dec. 2000 = 
-3d09'38.4") on 8 nights in August/September, 1992 in V spectral 
range. The variability of this object was recently announced by R. 
Gil Hutton in IBVS No. 3723. 
 
 As the double beam photometer allows the simultaneous observations of 
two stars only within the telescope field of 20 arcmin, we had to use 
another comparison star than those given by Hutton namely SAO145329: 
RA 2000 = 21h21m46s, Dec. 2000 = -3d11'58". The measurements were 
carried out with a time resolution of 1 sec in blocks of 5 to 10 min 
length, with relevant 2-3 min interruptions for sky-, dark- and 
lightsource observations and recentering the objects. Due to the 
northern latitude of the Hoher List Observatory the variable could be 
observed no longer than 5-6 hours per night. 


                            [FIGURE 1]

 Fig.1: The composite V-lightcurve of GSC 5198.00659 obtained on the
 nights August 5, 6, 7, 8, 27 and September 16 and 17, 1992. Each
 point is the average of 30 one second integrations.

 
               Table I 
 
JD Hel 
2440000+                O-C    Weight 
              Min I 
8842.5161::           +0.0046    1 
8883.3281             -0.0065    3 
              Min II 
8840.4544             -0.0011    3 
8841.5749:            -0.0088    1 
8843.4507             +0.0005    3 
8850.5641::           -0.0031    1 
8862.5514             +0.0091    3 
8882.3932             -0.0032    3 
8883.5173             -0.0013    3 
 
 
 The observations yield a light curve of W UMa type (Fig. 1), having a 
total 'occultation' minimum (Min II) with an amplitude of about 0.37 
mag. Its form and depth was changing within 40 days by 0.04 mag. The 
'transit' minimum (Min I) was well observed up to now only once, and 
has a depth of about 0.40 mag. 
 
 Light curve variations outside the eclipses, especially before and 
after Min I and after Min II of about 0.05 mag were also present 
within the above mentioned observing run. This indicates that both 
components show strong chromospheric activity presently in the 
inner Langrange point region. On account of these outstanding 
lightcurve variations the system should also be a variable X-ray 
source. 
 
 From 7 observed Min II, given in Table I, we derived the following 
light elements: 
 
            Min II = JD_hel 2448840.4548 + 0.374460d x E         (1). 
 
 An objective prism plate of 75 min exposure, taken by V. Mette with 
our 35/50/137.5cm Schmidt camera does not show clear spectral lines on 
account of the rapid rotational line broadening. Comparing this 
smeared 'continuous' spectrum with those of the neighbouring stars we 
conclude that the spectral type is conform with the B - V = 0.70 +/- 
0.065 colour given by Hutton, indicating a G5 type. 
 

                                        J. SCHIRMER 
                                        E. H. GEYER 
                                        Observatorium Hoher List 
                                        der Universitat Bonn 
                                        D-5568 Daun, F. R. Germany