COMMISSION 27 AND 42 OF THE IAU
                  INFORMATION BULLETIN ON VARIABLE STARS
                              Number 3810

                                                      Konkoly Observatory
                                                      Budapest
                                                      23 November 1992

                                                      HU ISSN 0374 - 0676


     CCD Photometry of the Cataclysmic Variable HV Virginis

HV Virginis was originally thought to be a classical nova 
(Duerbeck 1987) until the recent outburst first detected by Schmeer
(1992). The original outburst of this system occurred in 1929 when
Schneller (1931) reported that the system had reached a V magnitude
of 11 on 1929 Feb 1. In addition, Schneller reported a magnitude of
12.5 on 1929 Feb 3 and then noted that by 1929 Feb 9, the system was
no longer observable. The normal quiescent magnitude of the system is
19.1 (Howell, et al 1992). The current outburst also shows a rise in
magnitude up to an observed maximum of about 11.5 on 1992 April 21.
The outburst light curve compiled from IAU circulars, Bruch (1992), and
our own observations is presented in Figure 1.
   Using the High Resolution Imaging CCD camera on the 1.8 meter
ARC telescope, we observed HV Vir on April 30 and May 1 with 20
second integrations in the V band (Figure 2). Unfortunately, no other
stars were visible in the CCD frame to enable differential photometry.
The light curves were corrected for extinction and calibrated with the
standard star G 21-15. The extinction coefficient was obtained by
matching the magnitudes of the three minima seen on May 1 (on each
night, the raw light curve showed a clear linear relationship to the
airmass over time). Our observations indicate the presence of
superhumps of 0.2 mag amplitude in the V band and a superhump period
of 84.1 +- 0.4 minutes.
   The arrows in Figure 2 indicate timings of the measured superhump
maxima, which were measured by bisecting the full width at half
maximum. The superhump timings are given in Table 1. Except for the
maximum at the end of the 1st half of the May 1 data (which appears to
be undergoing a second peak), all of the superhumps appear to be the
same amplitude and width.


                              [FIGURE 1]

 Figure 1 - The outburst light curve for HV Vir compiled from IAU
            circulars, Bruch (1992) and our data. Our observations are
            indicated with an "x".


                  Table 1:  Photometric data on MV Vir

Date (1992)   Time of Maximum (UT)   H.J.D.(2448700+)   V Mag (at half max)
April 30          8:49 +- 0:05       42.8728 +- .0033      13.60 +- 0.10
May 1             5:45 +- 0:03       43.7448 +- .0021      13.62 +- 0.10
May 1             8:38 +- 0:02       43.8653 +- .0013      13.65 +- 0.10
May 1             9:57 +- 0:05       43.9198 +- .0033      13.65 +- 0.10


                               [FIGURE 2]

 Figure 2 - Light curves from the two nights of CCD photometry.


   The smaller hump feature apparent in the April 30 observations may be
a manifestation of a beat phenomenon between the orbital and
superhump periods reported by Mantel, et al (1992), but the evidence for
a similar feature is not apparent in the May 1 data. The small upturn at
the end of the first half of the May 1 observations does not match up
with an extrapolation of the orbital period from the April 30 'beat
hump.'
   The very large outburst amplitude (8 magnitudes) of HV Vir and its
high galactic latitude (65deg) are of note. Howell and Szkody (1990) are
finding a large number of large amplitude (> 6 mag) dwarf novae out of
the galactic plane, as compared to those in the plane, and most of the
large amplitude systems have orbital periods below the period gap.
   HV Vir adds to this correlation; 11 of the 12 known high galactic
latitude, large outburst amplitude dwarf novae now have orbital
periods below the gap.
   This work was supported under a National Science Foundation
Graduate Fellowship and the Danforth-Compton Foundation (D. Ingram).


                            D. INGRAM end P. SZKODY
                            Department of Astronomy, FM-20
                            University of Washington
                            Seattle, WA 98103



References:

Bruch, A.: 1992, IAU I.B.V.S. No. 3745.
Duerbeck, H.: 1987, Space. Sci. Rev. 45, 1. [BIBCODE 1987SSRv...45....1D ]
Howell, S. and Szkody, P.: 1990, Ap. J. 356, 623. [BIBCODE 1990ApJ...356..623H ]
Howell, S. et al: 1992, IAU Circ. No. 5505. [BIBCODE 1992IAUC.5505....2H ]
Mantel, K. et al: 1992, IAU Circ. No. 5517. [BIBCODE 1992IAUC.5517....2M ]
Schmeer, P.: 1992, IAU Circ. No. 5502. [BIBCODE 1992IAUC.5502....1S ]
Schneller, H.: 1931, A. N. 243, 335. [BIBCODE 1931AN....243..335S ]
Szkody, P. and Ingram, D.: 1992, IAU Circ. No. 5516. [BIBCODE 1992IAUC.5516....2S ]