COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                       Number 2858

                                          Konkoly Observatory
                                          Budapest
                                          5 February 1986

                                          HU ISSN 0374 - 0676




           IMPROVED EPHEMERIS FOR THE SHORT PERIOD,
         ECLIPSING CATACLYSMIC VARIABLE V1315 AQUILAE



  V1315 Aquilae ( = SVS 8130 = KPD 1911+1212 ) was identified as an eclipsing binary
by Downes et al. 1986. On the basis of the strengths of the He II and C III/N III lines
they classified it as a member of a subset of cataclysmic variables, old novae with high
excitation lines.

  V1315 Aql has a V magnitude, at light maximum, of ~14.4 and a B-V of ~ +.4. The
eclipse is quite deep, 1.7 magnitudes, and lasts about thirty minutes. It is symmetric,
though there seems to be a light peak just after the eclipse. There is no evidence for
a secondary eclipse. Fig. 1 shows the typical light curve. There is strong variability of
the emission lines during the eclipse. The Balmer lines also have the peculiar property
of absorption cores occasionally appearing during the inferior conjunction of the emission
line source.


  The interpretation of this object is of a secondary losing mass to a white dwarf primary.
Most of the observed light is produced by the accretion disc, so the variations in spectral
line strengths during the eclipse are probes of the accretion disc structure.


  Downes et al. observed nine eclipses in 1984, eight with the 0.9m telescope of the
Manastash Ridge Observatory, and one with the Kitt Peak 1.3m telescope. During 1985,
three more eclipses were obtained at MRO, and the entire data set reanalyzed. The highly
symmetric eclipses lend themselves to least squares parabolic fits. Light minima were
derived analytically from the fitted parabolas and the minima were then least squares
linear fitted to yield the period. The observations are presented in Table I.

             Table I     Eclipses of SVS 8130


Observer  Location      HJD       cycle    O-C(seconds)
                    (2,445,900+)   

Mateo       MRO       002.84065      1      0.3
Downes     KPNO       006.75183     29    -12.1
Jenner      MRO       028.82167    187   -111.7
Jenner      MRO       044.74821    301     52.2
Jenner      MRO       044.88748    302     15.8
Jenner      MRO       045.72697    308    132.2
Jenner      MRO       045.86486    309    -22.9
Jenner      MRO       071.70714    494    -52.0
Meakes      MRO       395.78815   2814     -0.3
Annis       MRO       424.70424   3021     25.6
Annis       MRO       444.67928   3164    -26.6




  The long baseline of observations, covering 3100 cycles, allows determination of the
period with a formal error of two milliseconds. The improved ephemeris is :

  HJD(light minimum) = 2,445,902.700964  +.139689832E
                              +-.000084 +-.000000017

  There is no evidence for a changing period to the level of less than one second over the
course of more than a year. The position of this object near the edge of the 'period gap'


                                 [FIGURE 1]

 Figure 1. The light curve of V1315 Aql, taken during eclipse cycle 2184 
 at the Manastash Ridge Observatory. The solid line is the fitted parabola 
 used for light minimum determination.


for cataclysmic variables at 2-3 hours (Patterson 1984), where a decrease in mass transfer
dims the system considerably, makes the determination of whether V1315 Aql is edging
into the gap interesting.







                          JAMES T. ANNIS

                         Department of Physics and
                         Department of Astronomy
                         University of Washington
                         Seattle, Washington USA

References:

Downes, R. A., Mateo, M., Szkody, P., Jenner, D. C., and Margon, B.
 1986, Ap. J. , 301, in press. [BIBCODE 1986ApJ...301..240D ]

Patterson, J. 1984, Ap. J. Suppl., 54, 443. [BIBCODE 1984ApJS...54..443P ]