How often is this place open for the public? And do the days change on which days open weekly?

They usually have public nights on Tuesdays and Thursdays. Check their website for availability because they fill up fast.

Generic schedule is Tues and Thurs evening, 830pm summer (730pm winter). Plus once a month Sat evening Open House closest to first quarter moon -- see schedule at 'tweeter' #Chamberlin_Obs spelling disguised to avoid robotic editor censors Want more public access? -- help us fund more staffing.

Not often, check website.