Missing Star near Mizar

[beka]

Missing star near Mizar

 

Greetings All,

 

I was in the process of aligning my scope, and while waiting for the star I wanted to image to come up from behind my house, I was looking at an image I had taken of the star field near Mizar to try to determine the magnitudes of the faintest stars. To do this I compared to SDSS images to match the stars and check the magnitudes. In so doing I noticed that a star in the SDSS images that was brighter than many in mine, was not present in my image. I have marked the place where I expect it to be, near the “star” next to it which is interestingly and Active Galactic Nucleus candidate in my image below. I tried to find other images of the star field and came up with the following.

The star is not present in this image posted to SGL on May 1^st this year by Ags.

here...

The star is present in this image on earthsky.org whose caption shows that it was taken on 02/02/2024.

here...

The star is present is this image posted on astropixels.com which is labled to have been taken in 2011.

here...

I could not find the star on Stellarium or Kstars. Cartes du Ciel reported a star at this position to be Gaia DR2 1563750420848938496 at magnitude 11.139 which seems about right. A query on AladinLite reported - No match was found on “Simbad in 42.6 arcsec around this point”.

My guess is that it is a variable star which has dimmed to become invisible in my image and that on the SGL post. But it would be curious that it has dimmed to this degree within the last three months. Any ideas?

Cheers

 

Edited June 17 by beka

[beka]

... I checked the coordinates and it seems that it is the AGN candidate that may have disappeared and is too dim to be visible in my image.

Edited June 17 by beka

[Stu]

I found this same star on SkySafari, listed as mag 11.4. Looks in exactly the right position.

[beka]

A stack of 50 by 20sec images shows the missing galaxy. What threw me was that it appeared to be of similar brightness as the adjacent star in the images linked above.

 

Edited June 25 by beka