Electronic Telegram No. 736
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html


EG AQUARII
     Further to CBET 734, G. Masi (Ceccano, Italy) provides details regarding
his photometric observations of superhumps seen in this variable star.  On
Nov. 8.84 UT, a few hours after the outburst of EG Aqr was announced by R.
Stubbings, Masi performed unfiltered, time-series photometry with the 28-cm
f/5 "Virtual Telescope" at Ceccano.  Real-time data reduction from the 60-s
exposures showed the clear signature of superhumps with amplitude just under
0.1 magnitude (peak-to-peak), revealing the SU UMa-type nature of this
cataclysmic variable (CV); a very quick check revealed an estimated superhump
period close to 2 hours, near the lower limit of the CV period gap.  During
the 3-hr observation arc, the star faded by about 0.15 mag (the star was
about 30 deg above the horizon, but the comparison stars showed no fading).
On Nov. 9.73, the variable was observed again with the same equipment and
found to be 0.3 mag brighter; superhumps had amplitude 0.35 mag, and an
evaluation (performed using the Phase-Dispersion Minimization method during
the 4-hr observation arc) revealed an estimated period of 1.99 hr.  On Nov.
10.73, a 5-hr observation arc showed EG Aqr to be marginally fainter than on
the previous night; the superhumps showed a different profile, with a full
amplitude of 0.3 mag, with the superhump period evidently having shortened to
1.89 hr.  As an attempt to combine the Nov. 9 and 10 data provides inadequate
results, the shortening of the period appears to be real.  (Using both the
Nov. 9 and 10 data, a mean superhump period of 1.904 hr is obtained.)


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2006 CBAT
2006 November 11                 (CBET 736)               Daniel W. E. Green