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Outburst of VSX J213806.5+261957 (ugwz in Pegasus)

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capricornus's picture
Outburst of VSX J213806.5+261957 (ugwz in Pegasus)

I have detected this star at magnitude 9.7 (visual) at 01:25 UT October 22. The previous outburst occurred in May 2010.

The star was fainter than magnitude 13.8 at 03:11 UT October 21.

Carey (CCY)

MUY's picture
Outburst of VSX J213806.5+261957

Very nice catch Carey!!! And already confirmed. This is a big surprise! An UGWZ star with a recurrence-period of only 4,5 years! About the same like in EZ Lyn.

Eddy (MUY)





wkl's picture
Outburst of VSX J213806.5+261957

Hi Carey,

I can confirm your observation -  Congratulations!!

Visual 9m,8  - 317/1500mm Newton V = 170x   2014 10. 22. 19:30 UT

Klaus Wenzel (wkl)

PYG's picture
Nice work Carey. However as

Nice work Carey.

However as not everyone reads AAVSO forum postings, I wonder why this outburst wasn't announced on CVnet (or vsnet)?  The more people getting data on important oubursts (especially the early stages)  the better surely!  I do not believe that this forum 'alone' is the right place to announce rare outburst detections (others may disagree). Having said that, congratulations on the observation!

Gary [PYG]

cpmalo87's picture
Congrats, Carey.  I've added

Congrats, Carey.  I've added this to my observing program until it fades back to 15th mag (below my scope's magnitude range).  I hope others will also.  I wonder:  how was it known to be a UGZ and not a classical nova if this is only the second outburst?  Spectroscopy? 

I'd have done a visual estimate last night, but was prepping for today's eclipse :).




BPO's picture
VSX J213806.5+261957

It's looking like a clear night here, I should get some quality imaging done of this star.

Thanks for the alert (baa-vss) Gary.


capricornus's picture
Thanks to everyone for your

Thanks to everyone for your subsequent observations. It was very exciting to see this star in a bright outburst, since it was one I expected I'd have to watch for decades before it did anything again! If I remember correctly an earlier outburst (in 1942) was found in archival photographs.


To answer Gary Poyner's question - my internet access is very poor at night and it took me about an hour to submit my observation (via WebObs) and the message above using my telephone. I assumed that by notifying AAVSO immediately I would be "getting the word out" as best I could, but I do welcome other suggestions. Someone advised me to not subscribe to vsnet because of the overwhelming flood of messages, so I don't have access to that group.


-Carey (CCY)



hambsch's picture
Time series data reveal superhumps



I have taken time series data remotely from my observatory ROAD. SUperhumps were visible. Data are normally submitted to AAVSO and VSNET.

I will keep watching the star until end of season.


Josch (HMB)

mrv's picture
VSX J213806.5+261957 companion


Since the recent outburst of VSX J213806.5+261957 has renewed interest in this star, I was wondering if precise BVRcIc magnitudes had been determined for the mag 15 companion close to the variable?  I recall you mentioning that high res images of VSX J213806.5+261957 had been obtained with one of the larger professional telescopes back in 2010 and that you were going to do PSF photometry on them.



HQA's picture

Hi Bob,

I looked back on the 2010 outburst of this star; interesting to have such a short recurrence!  I looked through various CBET and publications, as well as my own logs, and don't see any high-resolution imaging mentioned.  This was long enough ago that I have forgotten anything that I might have said!

Given that, the most likely source of professional imaging for this period is either from SDSS, the ING, or CFHT.  If someone wants to data-mine, I'll be happy to psf fit any image that you find, though if there is SDSS data, their automated psf fitting is about as good as my manual stuff.


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