Four constellations and three double stars

The measured sky brightness Thursday night was sqml=21.58, which is about 0.1 mpsas brighter than the two preceding nights.  There is a hint of green and purple airglow in the unprocessed wide-angle images, so that probably explains it. 

The constellation shots that follow were obtained with a Samyang AF 35mm f/1.8 lens and Hoya Softon filter, mounted on a Sony A7iii camera, ISO 1600, 30 s.  On a star-tracker mount, of course.

The Big Dipper, the most prominent part of Ursa Major.

 

The constellation Boötes, and Arcturus.

Arcturus is the fourth brightest star in the night sky.  This portion of Boötes forms an asterism known as "the Kite".

 

credit: IAU

The constellation Virgo, and its brightest star, Spica.

credit: IAU

The constellation Leo and Mars (lower right).

Mars is currently about 1.3 times brighter than Regulus, the brightest star in Leo.

The Celestron C8 telescope was already set up on the outside mount, which provided an easy opportunity to photograph some famous double stars.

Polaris and its companion. Stack of 3 images. ISO 400, 1 s.

 The North Star, Polaris, is a very tricky double star in small telescopes.  I spent a long time staring at it with a 60mm refractor on Wednesday night and was unsuccessful in seeing the magnitude-8.7 companion star.  With the 8-inch SCT it was relatively easy, but did take a few moments to become apparent.  The angular separation is 18.2 arcsec.

Castor.  Celestron C8 + 2x Barlow.  Stack of 3 images, ISO 800, 1/10 s.

 Castor, Alpha Geminorum, is actually a sextuple-star system.  The two stars seen here are both unresolved doubles.  A third, much fainter companion star (not seen here) is also a double.

Porrima.  Celestron C8 + 2x Barlow. Stack of 3 images, ISO 800, 1/10 s.

 Porrima, Gamma Virginis, consists of two stars orbiting each other with a 169 year period.  It is currently resolvable in moderate-size scopes.