Possible Nova in UMa Mag 11.8

[Michel Verlinden]

R.A. 10h24m02.89s, Decl. +48°08'51.2" (J2000.0)
2019 May 25.4972 UT, 11.8 mag (CCD, unfiltered)
Discoverer: Tadashi Kojima (Gunma-ken, Japan)
9 mag amplitude
More details here:
https://www.aavso.org/tcp-j102402894808 ... ursa-major
Spectra are welcome.
Cheers.
M. Verlinden

[etienne bertrand]

si ça peut aider un champ de l'objet.
Pas le ciel pour moi pour la faire...

[Olivier GARDE]

With Pascal Le Dû, we are on the target, but not a good weather in Southern France (many clouds)

[Olivier GARDE]

Only one exposure of 600s for this object with bad weather condition (clouds)



So, we don't think it's a Nova .....With bad weather condition, it may have a doubt about the correct positioning of the target, but this is the only star that we can see in the field of view of our guiding CCD with the right magnitude.

[etienne bertrand]

Bonjour Olivier,
Bravo pour le spectre. C'est curieux qu'est ce qui expliquerait cette baisse de magnitude ?

[Robin Leadbeater]

Looks like a dwarf nova from the spectrum. (Hot continuum, weak broad Balmer absorption. H alpha very weak/filled with emission?). At mag 12 the progenitor should have been visible in deep images though ?

Robin

EDIT: just looked at the AAVSO reference. There is a probable mag 19 progenitor so ~mag 7 increase, consistent with a dwarf nova

[Olivier GARDE]

here's Steve's comment on the interpretation of our spectrum :

"This looks like a WD with, perhaps, some emission (Halpha), very little extinction (if any) and a very hot system. The He I lines are weak but there, at least some (4471, 5876, it takes imagination to see 6678), no He II 4686,5411, and otherwise nothing that seems out of the ordinary for a weak cataclysmic. If the emission were stronger I might say it's a polar (or AM Her) but this is definitely not a nova. There's some asymmetry on the Balmer profiles that could be real but, again, nothing particular. If this is an active system, it might have shown some mass loss outburst but there's nothing particular here. Nice spectrum!"

[Robin Leadbeater]

Yes, given the progenitor it was unlikely to be a classical nova. (Patrick Schmeer's AAVSO alert was for probable DWARF NOVA, not a nova.) The alert would have been better posted in the cataclysmic variables alert section. Perhaps it can be moved there ?

Cheers
Robin

[etienne bertrand]

Un spectre tout frais, on dirait qu'il y a un début de raies d'émission ?
Est ce réel ou est ce du bruit ?

[etienne bertrand]

Bonsoir,
Un peu plus de poses sur cet objet :