ASAS 102522-1542.4 - Light curve analysis

ASAS 102522-1542.4 was discovered by ASAS3V (Grzegorz Pojmanski, Warsaw University Astronomical Observatory) at RA = 10h 25m 22s DEC = -15d 42'.4 (J2000), on 2006, Jan 26.245 UT at V=12.22.
I was able to confirm the new dwarf nova on 2006, Jan 27.986 UT using a 0.35-m f/6.3 telescope and ST-7XME CCD camera, and carried out time-series photometry that same evening.

Initial outburst stage - orbital humps

The initial outburst stage of this object has been very well covered by CBA observations from Tom Krajci, Lew Cook and myself. We collected 3 observation sets, with a total of 1236 observations, all characterised by double-peaked "early superhumps" (or orbital humps). The duration of this stage must have been pretty short : the discovery of ASAS 102522 was made on Jan 26.2 UT (on Jan 25.2 UT, the variable was still below ASAS' detection limit), and early superhumps lasted till Jan 28.5 UT. An analysis of this initial part of the light curve yields early superhumps with a period Porb = 0.0615 +/- 0.0010 d, and with an amplitude of 0.04 mag (ANOVA method, Peranso).

ASAS 102522-1542.4 combined light curve (zero-averaged, detrended) during initial outburst 
stage. Observations from Tom Krajci (black), Lew Cook (red) and Tonny Vanmunster (blue).

ANOVA period analysis yielding an orbital period of 0.0615d

Phase diagram showing double-peaked early superhumps, by folding 
all observations over a period of 0.0615d, then averaged per 10 obs.


Main outburst stage - regular superhumps

Starting Jan 29.0 UT, ASAS 102522 went into a different outburst stage, characterised by the appearance of regular (full) superhumps. We announced the detection of superhumps, establishing the SU UMa dwarf nova nature, in an email message of Jan 29th (Tonny Vanmunster, CVnet-outburst). So far, we have collected 5 observation sets (Tom Krajci, Pierre de Ponthiere, myself), with a total of 2220 observations, covering this stage. The resulting light curve clearly shows how superhumps have grown from an amplitude of less than 0.1 mag (Jan 29.0 UT) to over 0.25 mag (Jan 30.5 UT). Using the ANOVA method, we find a superhump period Psh = 0.0637 +/- 0.0002 d.

The superhump period excess of ASAS 102522 thus becomes : (Psh - Porb) / Porb = 3.58%, a value that is very well in line with expectations for a system with an orbital period of about 1.5 hrs.

ASAS 102522-1542.4 combined light curve (zero-averaged, detrended) during
main outburst 
stage. Observations from Tom Krajci (black), Pierre de Ponthiere (olive) and Tonny Vanmunster (blue).

ANOVA period analysis yielding
a superhump period of 0.0637d

Superhump phase diagram by folding the observations over a period of 0.0637 d





Copyright © 2006 - Tonny Vanmunster.