Ahhh! I'm stumped!
I've tried. Seriously, I've tried. I've tried to identify those circles and find out what stars made them.What stars made the circles???
Well, I'm stumped. I've tried to judge the brightness of individual circles, the color of individual circles, and the relative position of each circle and then compare them with the position, apparent magnitude and B-V index of stars in the vicinity of Polaris with the help of my software. That way I hoped to identify the stars that made the individual circles.
This picture is centered on the absolute north of the sky, which would be +90.00 00.0 degrees. There are five second magnitude stars within +90 00 00.0 and +55 00 00.0 degrees of the sky. Only five.
At the very, very least two of them have to show up in today's APOD, and possibly all of them are there. But if so, where are they? Remember that you are looking for five bright circles - or make that four, because you have already found one circle, the one made by Polaris. Where are the other four?
These are the five stars (Polaris, which we have found, and four others which we haven't):
Polaris: Mag: 1.97 Dec +89 15 50.9
Kochab: Mag: 2.07 Dec +74 09 19.7
Dubhe: Mag: 1.81 Dec +61 45 04.0
Mirak: Mag: 2.34 Dec +56 22 56.4
Alioth: Mag: 1.76 Dec +55 57 35.4
Of these stars, Alioth and Mirak would make blue circles in today's APOD, and the other stars would make whitish circles.
Well? Can you find these stars here? Can you identify the circles? Neufer! Chris! This is my challenge for you, or for anyone else who might be interested. Where are these stars in today's APOD? Are Dubhe, Mirak and Alioth even part of today's APOD? Where is Kochab? And please, if Alioth and Mirak aren't part of the picture, what stars made the two bright blue outer circles here? Third-magnitude B2III star Beta Cephei (mag 3.23, dec +70 33 38.5)?
To help you with the identification, here is a picture of the Big Dipper and the Little Dipper:
Polaris is the end star of the Little Dipper's handle. Kochab is the bottom star in the Little Dipper's bowl. Dubhe is the topmost star of the Big Dipper's pointer stars. Mirak is the bottom star of the Big Dipper's pointer stars. Alioth is the middle star of the "straight part" of the Big Dipper's handle.
There aren't just five second-magnitude stars
between 90 00 00.0 and 55 00 00.0. There are nine second-magnitude stars
instead (and now I sure hope I haven't missed any others). The four that I missed are the following:
Alderamin, Alpha Cep: Mag: 2.45 Dec: +62 35 07.8
Gamma Cas: Mag: 2.15 Dec: +60 43 00.3
Caph, Beta Cas: Mag: 2.28 Dec: +59 09 00.8
Schedar, Alpha Cas: Mag: 2.24 Dec: +56 32 14.7
Thanks a billion to alter-ego for making me see my mistake!