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Confirmation of probable new WZ Sge star AT2019vww

PostPosted: Thu Dec 12, 2019 11:55 pm
by Robin Leadbeater
AT2019vww was discovered by the amateur Italian Supernova Search Project. 2019-11-30 It was considered a possible supernova as it was close to galaxy IC11775 . However it was confirmed from the redshift to be a galactic source, a probable CV using my ALPY 200 2019-12-01
The confirming spectrum taken at ~mag 15.5 can be seen here
and an Atel confirming the discovery has now been issued

Nothing is visible in deep images so the outburst must be >mag 7 so probably a WZ Sge type dwarf nova, though perhaps a classical nova cannot be ruled out as it cannot be distinguished from the width of the H alpha line in this low resolution spectrum


Re: Confirmation of probable new WZ Sge star AT2019vww

PostPosted: Sat Dec 14, 2019 12:57 am
by Robin Leadbeater
Photometry by Tonny Vanmunster now confirms it is a new SU Uma Dwarf Nova

-----Original Message-----
From: Tonny Vanmunster via vsnet-alert
Sent: Saturday, December 14, 2019 12:41 AM
To: ; 'Taichi Kato' ; 'ALERT, VSNET' ; ; ; 'vsnet-outburst' ;

Subject: [vsnet-alert 23781] AT 2019vww: new SU UMa-type dwarf nova

Dear colleagues,

I have just concluded the analysis of 4 nights of unfiltered CCD photometry observations of AT 2019vww: 2019, Dec 04/05, Dec 06/07, Dec 07/08 and Dec 09/10. The observations of Dec 04/05th were made at CBA Belgium Observatory, using a 0.40-m f/10.0 telescope and STT-3200ME CCD camera, while the observations on the 3 other nights were made at CBA Extremadura Observatory, using a 0.40-m f/5.1 telescope and SX-46 CCD camera.

AT 2019vww was detected on 2019, Nov 30.7 UT by observers at Montarrenti Observatory, Siena, Italy (Simone Leonini et al.) and subsequently identified as a cataclysmic variable by Robin Leadbeater, using a modified ALPY spectrograph at Three Hills Observatory, UK [ATEL #13345].

No significant modulations were seen in my lightcurves of AT 2019vww during the first 3 nights. However, the lightcurve of Dec 09/10th shows the presence of superhump-like modulations with an amplitude of 0.17 mag. The observations were obtained under quite unfavourable photometric conditions (strong moonlight, hazy sky), but nevertheless allow to classify AT 2019vww as a new SU UMa-type dwarf nova. A period analysis using the ANOVA, Lomb-Scargle and PDM methods (Peranso), yields a combined superhump period of 0.0746 +/- 0.0018d.

The object was at mag 16.56 (CV) on Dec 10th, and further declined to mag 16.70 (CV) on Dec 10/11th (observing conditions during that night did not allow time series photometry). The average decline rate of AT 2019vww during the observing window from Dec 04th till Dec 10th was 0.155 mag/day, which is quite typical for an SU UMa-type variable.

The rather long waiting time for superhumps to appear does not exclude that AT 2019vww actually is a (long period) WZ Sge-type dwarf nova. However, this is something I can not derive from my Dec 09/10th lightcurve, due to noise caused by the unfavourable photometric conditions.

Follow-up observations are highly recommended to further study this variable.

Best regards