[vsnet-alert 22836] ASASSN-18abl: new dwarf nova - likely AM CVn subtype

Fri Dec 14 07:21:57 JST 2018

Dear colleagues,

I have just concluded the analysis of my 2018, Dec 13/14 unfiltered CCD photometry session of ASASSN-18abl (=TCP J03005508+1802290). Observations were made at CBA Belgium Observatory,  using a 0.40-m f/10.0 telescope and STT-3200ME CCD camera, under a clear sky. 

The resulting light curve covers a time span of 4.1 hours and clearly reveals the presence of superhumps with an amplitude of 0.07 mag, hence classyfing this object as a new dwarf nova. A preliminary period analysis – after detrending the light curve - using the ANOVA, Lomb-Scargle and PDM methods (Peranso), yields a combined superhump period of 0.0288 +/- 0.0005d. Taking into account the short superhump period, and the shape of the phase diagram, this object is likely an AM CVn type dwarf nova, but further observations will be needed to confirm this finding.  

The object was at mag 12.60 (CV) at the start of the observations on Dec 13th, 2018, gradually increasing to mag 12.48 (CV) over a timespan of 2.5 hours to then start slowly declining again by 0.025 mag during the next 1.5 hours.

Follow-up observations are urgently required to further determine the characteristics of this interesting variable star.

Observations will be sent to AAVSO, CBA and VSNET for further analysis. 

Best regards
Tonny

Tonny Vanmunster
CBA Belgium Observatory
CBA Extremadura Observatory
 <http://www.cbabelgium.com> www.cbabelgium.com

 <http://www.peranso.com> www.peranso.com