[vsnet-alert 24537] ASASSN-20jl is a new SU UMa (or WZ Sge) type dwarf nova - 2 nights of observations

Sat Aug 15 10:51:36 JST 2020

Dear colleagues,

I just finished analysing two nights of unfiltered CCD observations of ASASSN-20jl, obtained 2020, Aug 13/14 and Aug 14/15, at CBA Extremadura Observatory, using a 0.40-m f/5.1 telescope and SX-46 CCD camera under clear skies.

Small amplitude superhumps (0.04 mag) are clearly visible in my datasets, establishing ASASSN-20jl as a new SU UMa-type dwarf nova. A period analysis using the ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.0, under development), yields a combined superhump period of 0.0606 +/- 0.0003d. The object was at mag 14.4 (CV) on Aug 15th. Although the profile of the superhumps does not look double-waved, I can not rule out at this stage if the object is a WZ Sge-type dwarf nova - additional observations will be required. 

I will send my observations to AAVSO, CBA and VSNET for further analysis.

Follow-up observations are recommended to refine the superhump period.

Best regards
Tonny

--
Tonny Vanmunster
CBA Belgium Observatory
CBA Extremadura Observatory
www.cbabelgium.com
www.peranso.com

-----Original Message-----
From: cba-chat [mailto:cba-chat-bounces at cbastro.org] On Behalf Of Tonny Vanmunster
Sent: vrijdag 14 augustus 2020 22:25
To: 'Taichi Kato'; variable_star_forum at yahoogroups.com; vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp; vsnet-alert at yahoogroups.com; vsnet-campaign-dn at ooruri.kusastro.kyoto-u.ac.jp; vsnet-newvar at ooruri.kusastro.kyoto-u.ac.jp; vsnet-newvar at yahoogroups.com; vsnet-outburst at ooruri.kusastro.kyoto-u.ac.jp; vsnet-outburst at yahoogroups.com; cba-chat at cbastro.org
Subject: (cba:chat) ASASSN-20jl is a new SU UMa (or WZ Sge) type dwarf nova

Dear colleagues,

As suspected by Taichi Kato, ASASSN-20jl indeed is a new SU UMa type dwarf nova. I just examined 3hrs of unfiltered CCD observations obtained last night (2020, Aug 13/14) at CBA Extremadura Observatory. I will publish a detailed analysis of my findings later tonight, when I have also tonight's observations available, but it looks like the superhump period is close to 0.0582d. The amplitude is still small (about 0.04 mag), put the typical superhump profile is clearly present. I can't rule out that this still might turn out to be a WZ Sge-type dwarf nova - let's collect more observations.

More news to come,

Best regards
Tonny  

--
Tonny Vanmunster
CBA Belgium Observatory
CBA Extremadura Observatory
www.cbabelgium.com
www.peranso.com

-----Original Message-----
From: vsnet-outburst
[mailto:vsnet-outburst-bounces at ooruri.kusastro.kyoto-u.ac.jp] On Behalf Of Taichi Kato
Sent: donderdag 13 augustus 2020 8:14
To: variable_star_forum at yahoogroups.com;
vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp; vsnet-alert at yahoogroups.com; vsnet-campaign-dn at ooruri.kusastro.kyoto-u.ac.jp;
vsnet-newvar at ooruri.kusastro.kyoto-u.ac.jp; vsnet-newvar at yahoogroups.com; vsnet-outburst at ooruri.kusastro.kyoto-u.ac.jp; vsnet-outburst at yahoogroups.com
Subject: [vsnet-outburst 25498] ASASSN-20jl update

ASASSN-20jl update

   Is there anyone following this target?

ASAS-SN data:
https://asas-sn.osu.edu/light_curves/063bb5c4-6298-4640-85b4-03635ad12aab

   The light curve looks like to me a WZ Sge star (or less likely, a background nova).  I suspect that the CV is a fainter (possibly unresolved) companion of the V=14.7 mag star.  NUV=20.8 would be fine for a faint dwarf nova in quiescence.  If this is indeed a WZ Sge star, the age may be inconsistent with a G-type star (assuming that they are physically associated).

   As judged from the light curve, it may be already superhumping if it is a dwarf nova.  Spectroscopy is also desired (it was a pity that long rainy season in Japan prevented observation).

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