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Sequence issue near AA Aurigae - possible new variable!

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#1 Astrojensen

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Posted 15 February 2021 - 11:22 AM

Hello! Here's a copy of a post I just posted in the AAVSO forum:

 

 

 

I'm quite new in the variable star business, though I've been an amateur astronomer for over three decades. I've been visually estimating variables for about a year now.

 

Last night, February 14th, 20.40 UT, I was trying to estimate the brightness of AA Aurigae with a 12" dobsonian at 90x and 169x, when I noticed something was off. Star 122 on the chart (X26200BCF) was as bright, or even a hair brighter, than 114! It was much brighter than stars 125 and 127. AA Aur itself was a little fainter than 114, but 122 was brighter than it, which obviously doesn't make sense. 

So, obviously something is wrong here, if I'm not mistaken. A quick look at Digitized Sky Survey seems to show that 122 was indeed fainter than 114 at that time.

 

It's overcast here tonight and will likely be for the whole week, so I can't take another look until it clears again.

I ask of you to go out and take a look at the stars 114 and 122 near AA Aur (and of course also AA Aur, now that you're there anyway) and let me know what you see. 

 

X26217C.png

 

 

Clear skies!

Thomas, Denmark


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#2 pbealo

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Posted 15 February 2021 - 12:18 PM

Were you sing a V filter? Could 114 be redder and be perceived as dimmer visually? Those charts are V magnitudes.

Peter



#3 Astrojensen

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Posted 15 February 2021 - 12:31 PM

Were you sing a V filter? Could 114 be redder and be perceived as dimmer visually? Those charts are V magnitudes.

Peter

I was observing visually, so I guess you could say I was using a V filter... 

 

And if 114 really should look dimmer, then that doesn't explain why 122 was MUCH brighter than 125 and 127. 122 didn't look half a magnitude brighter than 125 and 127, but more like at least a full magnitude. If it had truly been 12m2, then it should have been just a tad brighter than 125, just like 125 is slightly brighter than 127, yet it was clearly much brighter.

 

As stated in the OP, I was using a 12", so all the stars were easily, continuously visible and not just intermittently glimpsed. 

 

 

Clear skies!

Thomas, Denmark


Edited by Astrojensen, 15 February 2021 - 12:33 PM.


#4 jeffreym

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Posted 15 February 2021 - 12:40 PM

Thomas,

The chart looks off to me.  Is the label for Aur50 supposed to be Aur55 (psi4 Aur)?

Jeff



#5 Astrojensen

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Posted 15 February 2021 - 01:11 PM

Thomas,

The chart looks off to me.  Is the label for Aur50 supposed to be Aur55 (psi4 Aur)?

Jeff

The "50" just means the star is mag 5m0, it has no connection to star names or designations. 

 

 

Clear skies!

Thomas, Denmark


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#6 KMAO

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Posted 15 February 2021 - 01:45 PM

Hi Thomas
your observation may be quite right
check old glory AAVSO chart.
best wishes
KMA

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#7 KMAO

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Posted 15 February 2021 - 01:46 PM

aa aur

#8 Astrojensen

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Posted 15 February 2021 - 01:47 PM

Oooooh! Now that's INTERESTING!

 

 

Clear skies!

Thomas, Denmark



#9 Astrojensen

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Posted 15 February 2021 - 02:57 PM

AAVSO urges me to report the observation. They didn't specify where, but presumably AT. How do I do that? Or do I need to do it somewhere else?

 

 

Clear skies!

Thomas, Denmark



#10 munkacsymj

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Posted 15 February 2021 - 02:59 PM

That star (GSC 02953-01495) is actually a close double, according to GAIA EDR3 (which puts the two stars about 1/2 arcsecond apart). And, as the old AAVSO chart indicates (also captured in the AAVSO VSX database), at one time it was a suspected variable. There are actually a lot of V-band photometry measurements in the AAVSO database, showing some "odd" behavior (mostly dimming). My own review a few minutes ago of ASAS-SN and ZTF monitoring of this star over the past few years doesn't show anything particularly interesting (although the ZTF periodogram has a peak at a period of about 45.25 days, and the "periodicity" in the data is a brightening with that cycle).

 

Clearly, though, it would seem to be worth some long-term continued monitoring.

 

- Mark M

 


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#11 Astrojensen

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Posted 15 February 2021 - 03:47 PM

It's apparently a known variable, though extremely obscure, but why has AAVSO then used it as a comparison star???  

 

 

Clear skies!

Thomas, Denmark



#12 pbealo

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Posted 15 February 2021 - 04:23 PM

People, even AAVSO members, occasionally make mistakes.

 

As a person and AAVSO member, I know this well personally!

 

Peter


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#13 Astrojensen

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Posted 15 February 2021 - 04:25 PM

Currently trying to get a remote scope on it. Hopefully it's still in eruption. If it's brighter than 12m2, then that would nail it.

 

 

Clear skies!

Thomas, Denmark



#14 Astrojensen

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Posted 16 February 2021 - 04:33 PM

Sadly, the images showed nothing unusual. It was, however, immediately and strikingly obvious to me that the field now looks different, than on February 14th, simply because the star is now fainter. 

 

 

Clear skies!

Thomas, Denmark



#15 Rutilus

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Posted 19 February 2021 - 11:05 AM

Thomas -I tried to image the star field on the night of your post, but the star was virtually at my Zenith.

After only two minutes of trying I had to give up as the pain in my spine was just to bad. Observing objects 

at the Zenith is a real problem for me nowadays. When the star field is better placed I will add it to my  list

of objects to monitor.


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#16 Rich (RLTYS)

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Posted 21 February 2021 - 12:47 PM

Hi Thomas
your observation may be quite right
check old glory AAVSO chart.
best wishes
KMA

Haven't seen one of those charts in a long time.


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#17 KMAO

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Posted 22 February 2021 - 12:36 PM

It may be interesting to find out
a time of first reported brightening.
The star is GSC 02953-01495 and
reported in AAVSO OBS.
It may not be a binary (?) but
short period of "lensing effect".
Similar (but much shorter duration) to GSC 03656-01328.
Best wishes to all
KMA

BTW
Nice AAVSO report on AA Aur Thomas
congrats
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#18 Rich (RLTYS)

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Posted 01 March 2021 - 04:16 PM

On 2-21-21, I imaged the area of AA Aur with the Slooh Canary 2 wide field scope and it appears normal. I would be interested in reimaging the area for possible changes in brightness.


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