[vsnet-alert 25674] ZTF21aanehlz superoutburst (since Feb. 24): second rebrightening (Apr. 6)

[Patrick Schmeer pasc1312-aavso@yahoo.de via vsnet-alert]

 ZTF21aanehlz (= ASASSN-21ci) (UGWZ)
https://www.aavso.org/vsx/index.php?view=detail.top&oid=2215559
 
ZTF light curve, data, and images (via Lasair):
https://lasair.roe.ac.uk/object/ZTF21aanehlz/
ZTF21aanehlz 20210404.4620 18.69zg ZTF
ZTF21aanehlz 20210406.4457 14.98zr ZTF

Recent ASAS-SN Sky Patrol light curve and data:
https://asas-sn.osu.edu/sky-patrol/coordinate/ce7dc089-5f57-4e65-aeef-dfc0115f234d
ZTF21aanehlz 20210405.255 >17.03g ASN
ZTF21aanehlz 20210406.409 14.99g ASN

Unfortunately the latest AAVSO data are from March 13:
https://app.aavso.org/webobs/results/?star=ZTF21aanehlz
 
The first rebrightening was observed on 2021 March 28.
 
Time-resolved photometry is still encouraged (or at least
daily/nightly snapshots).
 
Clear skies,
Patrick
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References:
All-Sky Automated Survey for Supernovae (ASAS-SN) Sky Patrol:
- Shappee et al., 2014ApJ...788...48S
- Kochanek et al., 2017PASP..129j4502K
Lasair:
- Smith et al., 2019RNAAS...3...26S
Zwicky Transient Facility (ZTF):
- Masci et al., 2019PASP..131a8003M
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     Am Sonntag, 28. März 2021, 13:39:14 MESZ hat Patrick Schmeer pasc1312-aavso at yahoo.de via vsnet-alert <vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp> Folgendes geschrieben:  
 
  ZTF21aanehlz (= ASASSN-21ci) (UGWZ)
https://www.aavso.org/vsx/index.php?view=detail.top&oid=2215559
 
ZTF light curve, data, and images (via Lasair):
https://lasair.roe.ac.uk/object/ZTF21aanehlz/
ZTF21aanehlz 20210324.423 18.15zr ZTF
ZTF21aanehlz 20210324.458 18.71zg ZTF
ZTF21aanehlz 20210328.421 15.18zr ZTF
 
Recent ASAS-SN Sky Patrol light curve and data:
https://asas-sn.osu.edu/sky-patrol/coordinate/005ee710-7d7c-494d-a7d8-98789830274f
ZTF21aanehlz 20210325.282 <16.59g ASN
 
Unfortunately the latest AAVSO data are from March 13:
https://app.aavso.org/webobs/results/?star=ZTF21aanehlz
 
Taichi Kato wrote (see below):
> So it looks more likely to me an EG Cnc-like object (i.e. WZ Sge-type object).
The long superoutburst duration is also characteristic of WZ Sge-type dwarf novae
(the typical duration of a standard UGSU outburst is ~14 days).
 
Follow-up observations are required.
 
Clear skies,
Patrick
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References:
All-Sky Automated Survey for Supernovae (ASAS-SN) Sky Patrol:
- Shappee et al., 2014ApJ...788...48S
- Kochanek et al., 2017PASP..129j4502K
Lasair:
- Smith et al., 2019RNAAS...3...26S
Zwicky Transient Facility (ZTF):
- Masci et al., 2019PASP..131a8003M
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    Am Dienstag, 16. März 2021, 04:02:27 MEZ hat Taichi Kato <tkato at kusastro.kyoto-u.ac.jp> Folgendes geschrieben:  
 
 ZTF21aanehlz: superhump period and type

  Tonny Vanmunster, Itoh-san and Josch Hambsch have
reported observations.  The superhump period since
Mar. 10 (following a dip in Mar. 8-9) is 0.06258(3) d.
(Compare vsnet-alert 25534).

  Please note that a similar dip was seen in EG Cnc
during the 2018 superoutburst.

See
http://adsabs.net/abs/2021PASJ...73....1K

  So it looks more likely to me an EG Cnc-like object
(i.e. WZ Sge-type object).  The mean amplitude of
superhumps is small (0.09 mag), suggesting that
the object has a low mass ratio.  Probably due to
the low mass ratio, the disk failed to maintain
the hot state and a dip occurred before superhumps
appeared.  The superhump period is also similar
to that of EG Cnc and further observations will be
interesting.