(IAAC) Obj: M1 (Crab Nebula) - Inst: 8" f/10 SCT on fork


Observer: Lew Gramer
Your skills: Intermediate (some years)
Date/time of observation: 1998-01-22/23 03:00-05:00 UT
Location of site: ATMoB Clubhouse, Westford, MA, USA (Lat 43N, Elev 146m)
Site classification: Exurban
Sky darkness: 5.7 (intermittent cirrus) <Limiting magnitude>
Seeing: 4 <1-10 Scale (10 best)>
Moon presence: None - moon not in sky
Instrument: 8" f/10 SCT on fork
Magnification: 80x, 170x
Filter(s): None, UHC
Object(s): M1 (Crab Nebula)
Category: Supernova remnant
Class: E(SNR)
Constellation: Tau
Data: mag 11.3  size 6'x4'
Position: RA 05:35  DEC +22:01
I periodically checked on the bizarre Crab tonight - in
between watching for the Shuttle's tell-tale jets on the
horizon and doing other deep-sky - as a test of the sky's
quality. This proved interesting: M1 was always visible,
but showed almost no detail early tonight. Later however,
conditions improved, and this log is mostly a result of
those more satisfying views... M1 is particularly easy to
find with an equatorial mount: beginning with zeta Tau,
sweep one wide field (40') W, then scan N no more than a
degree. Throughout the night, M1 was readily visible to
low power (80x) as a distinctive blur, even showing the
classic "S" shape of its main nebulosity to any careful
inspection. Later in the evening, as the cirrus cleared
(temporarily), low power also revealed a hint of the thin
filaments. High power+UHC (170x) confirmed these at many
spots around the edge of the "S", with one very prominent
ENE of the center, and one slightly fainter S. Also at
170x in better conditions, averted vision showed those
intriguing stellarings I've seen previously in the core:
these were especially prominent in the N, and did NOT
disappear when blinked with UHC. Are these KNOTS then,
rather than back/foreground stars? A better night with
the 20" or a friend's 25" may tell the tale! Last, as I
was hopping to this object last night, a new name for it
struck me: how does "the Jewel between the Horns" sound?
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