[vsnet-alert 24066] Re: ASASSN-20ci: SU UMa nature unconfirmed

[Tonny Vanmunster tonny.vanmunster@gmail.com via vsnet-alert]

My Feb 28th unfiltered observations were obtained at CBA Belgium
Observatory, which has a telescope with a much smaller field-of-view than
the CBA Extremadura Observatory telescope, which I used for my Feb 27th
unfiltered observations. As a consequence, I had to use a set of different
comparison stars between both nights, i.e. my Feb 27th observations were
reduced using AAVSO comp stars, whereas for my Feb 28th observations I had
to use UCAC4 comp stars. I have now reduced both datasets using the same
UCAC4 comparison stars, to eliminate differences introduced by the
comparison stars. The resulting decline in this case is 0.28 mag per day,
which is still above the regular decline rate of SU UMa dwarf novae, but
much smaller than the value mentioned below.

Hence, I see no reason at this stage to conclude that the superhump
detection is spurious. Looking  forward to a next superoutburst of
ASASSN-20ci ...


-----Original Message-----
From: vsnet-alert [mailto:vsnet-alert-bounces at ooruri.kusastro.kyoto-u.ac.jp]
On Behalf Of Taichi Kato
Sent: maandag 16 maart 2020 1:14
To: suuma at yahoogroups.com; 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-alert 24062] ASASSN-20ci: SU UMa nature unconfirmed

ASASSN-20ci: SU UMa nature unconfirmed

   Tonny Vanmunster reported second-night observation on Feb. 28.  The
object faded by 0.5 mag per day (at 16.6 mag on Feb. 28).  Such rapid fading
is incompatible with a superoutburst.
I conclude that the claim of superhump detection (vsnet-alert 24017) was
spurious (see also vsnet-alert 24022).  The object may be more likely an SS
Cyg star.