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(IAAC) Obj: M4 - Inst: Naked eye, 7x50 binoculars



Observer: Lew Gramer
Your skills: Intermediate
Date and UT of Observation: 1997-07-4/5, 03:20 UT
Location: Savoy, MA, USA (42N, elev 700m)
Site classification: rural
Limiting magnitude: 7.1 (zenith)
Seeing: 4 of 10 - medium good, intermittent cumulus
Moon up: no
Instrument: Naked eye, 50mm Simmons binoculars
Magnification: 1x, 7x
Filters used: None
Object: M4
Category: Globular cluster
Constellation: Sco
Data: mag 5.9  size 26'
RA/DE: 16h24m  -26o32m
Description:
Just visible to the naked as a slightly unusual star in
the thorax of the Scorpion, M4 was also readily found in
binocs, as the S apex of a pretty triangle whose other
vertices are alpha (Antares) & sigma Scorpii. To binocs
under dark skies, M4 is a BRIGHT, loose "ink spot" of
white light, with a 15' halo which surrounds a broadly
concentrated 15' core. No hint of resolution can be seen,
but the cluster lies amid a stunning field of stars.