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ASASSN-21gk - spectra urgently required

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Robin Leadbeater's picture
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Joined: 05/03/2014 - 00:50
ASASSN-21gk - spectra urgently required

https://groups.io/g/spectro-l/topic/asassn_21gk_strange_light/82501723?

Originally suspected to be a gravitational microlensing event, the light curve over the past week is very odd  with  large rapid swings

A bit low for me but observers further south might have better luck

Robin Leadbeater's picture
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Last seen: 33 min 8 sec ago
Joined: 05/03/2014 - 00:50
"normal star"

A spectrum has now confirmed it an "ordinary star" so the source of the variability is unclear.

https://www.astronomerstelegram.org/?read=14593

A series of spectra covering a period of variability could be interesting. (The clouds rolled less  than a minute after I finally got the star on the slit of the ALPY600 when it finally cleared the rooftop at 16 deg altitude). Although extremely noisy, the spectrum is also consistent with the "normal star" description)

Cheers

Robin

Robin Leadbeater's picture
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Last seen: 33 min 8 sec ago
Joined: 05/03/2014 - 00:50
a better spectrum

Had another go at this one. Here it is in  the BAA database overlaid on Pickles G0v)
https://britastro.org/specdb/data_graph.php?obs_id=9503&std_spectra_id=p_g0v
(One of the most frustrating observations I have tried to make. It literally skimmed along the roof line just arcminutes below it for over an hour before it finally popped up just as  the sky was starting to brighten.) It was still at air mass 3.5 and there was thin cloud so the SNR is poor but consistent with the  type reported previously (late F /early G) 
https://www.astronomerstelegram.org/?read=14593

Cheers
Robin

GraemeCoates's picture
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Joined: 05/02/2019 - 20:37
Odd..

This appears to be a strange object - at first sight of the AAVSO light curve, it almost looks like a poorly sampled eclipsing variable with a period of about a day and a bit: but it makes little sense that it has suddenly started to vary having apparently been non-variable up to this point - and with at least half a magnitude of variation as well now! Odd!