[Aavso-photometry] Detection of the eclipsing dwarf nova nature of SDSS J122740.83+513925.0

[Tonny Vanmunster]

Dear colleagues,

Yesterday evening I was informed by Patrick Schmeer about his detection of
an outburst of SDSS J122740.83+513925.0 on June 4.106 UT at unfiltered mag
15. This object was discovered in the course of the SLOAN Digital Sky Survey
and is reviewed in "Cataclysmic Variables from Sloan Digital Sky Survey. V.
The Fifth Year (2004), Szkody et al." Based on a communication today with
Arne Henden, one of the co-authors of this paper, SDSS J122740.83+513925.0
is known as a CV, and is probably a high-inclination dwarf nova with a low
orbital period.

Following Patrick's announcement, I started time-series CCD observations of
SDSS J122740.83+513925.0 on June 4/5, 2007 at CBA Belgium Observatory, using
one of the observatory's 0.35-m f/6.3 telescopes. I have just concluded an
analysis of my CCD observations, covering a time span of 3.0 hours. They
clearly show the presence of two eclipses, superimposed on another periodic
modulation, hence classifying SDSS J122740.83+513925.0 as an eclipsing dwarf
nova. Using Peranso, I find an orbital period of 0.0624 +/- 0.0001 d or 90
min (extremum determination based on the Kwee-van Woerden method and on a
Polynomial fit). The eclipses have a depth of 0.5 mag.

SDSS J122740.83+513925.0 appears to be a very interesting system, so I
encourage follow-up photometry, to further determine the characteristics of
this system.

I have posted my lightcurve on my website at www.cbabelgium.com, including a
graph showing the orbital period analysis.

Thanks to Patrick Schmeer and Arne Henden.

Best regards,
Tonny Vanmunster

Tonny Vanmunster
CBA Belgium Observatory
http://www.cbabelgium.com 
 
PERANSO : The Light Curve and Period Analysis Software
http://www.peranso.com