(IAAC) Obj: Castor (alpha Gem) - Inst: 8" f/10 SCT on fork

Observer: Lew Gramer
Your skills: Intermediate (some years)
Date/time of observation: 1998-03-10/11 01:15 UT
Location of site: Medford, MA, USA (Lat 42oN, Elev 5m)
Site classification: Suburban
Sky darkness: 5.1 <Limiting magnitude>
Seeing: 5 <1-10 Seeing Scale (10 best)>
Moon presence: None - moon not in sky
Instrument: 8" f/10 SCT on fork
Magnification: 170x, 340x
Filter(s): None
Object(s): Castor (alpha Gem)
Category: Multiple star.
Class: A1V, A2V
Constellation: Gem
Data: mag 1.9, 2.9  size 3.9" PA 72o (catalog)
Position: RA 07:35  DEC +31:53
This famous visual binary is an easy split at almost any power in the SCT: The
separation tonight was estimated at 3" (not bad), at PA 50o (pretty bad!) At a
higher magnification (340x), the comes was estimated at just under one magnitude
fainter than the primary (very good), and had a distinct lavender-blue color in
contrast with the white primary, as independently confirmed by a fellow observer.
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