Last night was the first night I used my Zenith Star 61ii with the ASI533MCP.  My focus last night, setting back focus, since this was the first time I used the ASI533MCP with my Zenith Star 61ii and the first night I used the Optolong L-Ultimate.  Last night I had enough clear sky and time to capture Castor and Regulus.

Castor is the second-brightest object in the zodiacconstellation of Gemini. It has the Bayer designationα Geminorum, which is Latinised to Alpha Geminorum and abbreviated Alpha Gem or α Gem. With an apparent visual magnitude of 1.93, it is one of the brightest stars in the night sky. Castor appears singular to the naked eye, but it is actually a sextuple star system organized into three binary pairs. Although it is the 'α' (alpha) member of the constellation, it is fainter than 'β' (beta) Geminorum, Pollux.Castor is a multiple star system made up of six individual stars; there are three visual components, all of which are spectroscopic binaries. Appearing to the naked eye as a single star, Castor was first recorded as a double star in 1718 by James Pound, but it may have been resolved into at least two sources of light by Cassini as early as 1678. The separation between the binary systems Castor A and Castor B has increased from about 2″ (2 arcseconds of angular measurement) in 1970 to about 6″ in 2017. These pairs have magnitudes of 1.9 and 3.0, respectively.Castor Aa and Ba both have orbits of a few days with a much fainter companion.Castor C, or YY Geminorum, was discovered to vary in brightness with a regular period. It is an eclipsing binary with additional variations due to areas of different brightness on the surface of one or both stars, as well as irregular flares.  The Castor C components orbit in less than a day. Castor C is believed to be in orbit around Castor AB, but with an extremely long period of several thousand years. It is 73″ distant from the bright components.The combined apparent magnitude of all six stars is +1.58.
Castor is 51 light-years away from Earth, determined from its large annual parallax. The two brightest stars are both A-classmain-sequence stars, more massive and brighter than the Sun. The properties of their red dwarf companions are difficult to determine, but are both thought to have less than half the mass of the Sun.
Castor B is an Am star, with particularly strong spectral lines of certain metals.
Castor C is a variable star, classified as a BY Draconis type. BY Draconis variables are cool dwarf stars which vary as they rotate due to starspots or other variations in their photospheres. The two red dwarfs of Castor C are almost identical, with masses around a half M☉ and luminosities less than 10% of the Sun.All the red dwarfs in the Castor system have emissions lines in their spectra, and all are flare stars.