(IAAC) M 57 (NGC 6720) - 4.25" F/7.8
Observer: Yann POTHIER (France)
Your skill: advanced (many years)
Object: NGC 6720 (M 57; PK 063+13.1; PN G063.1+13.9; ARO 9, VV 214)
Category: planetary nebula
Object data: Vmag=8.8; Bmag=9.7; 83"x59" (88"x63" in IDB, 160"x145" for
outer shell); type IV+III; central star of Vmag=14.7; discovered by
Darquier in 1779; ELCAT: [OIII, 496+501nm] = 18 x [Hbeta, 486nm].
RA/DE: 18h53.56m, +33°01.8' (2000.0)
Date and UT of observation: 11 July 1991, 01h00UT
Location & latitude: La Clapiere Obs. (France, latN44 40 00, longE06 27 36)
Site classification: rural, alt.1650m (5500ft)
Limiting magnitude (visual in UMi): 6.0
Transparency (1 to 5 - best to worst): 1
Seeing (1 to 5 - best to worst): ?
Moon up (phase?): no
Instrument: Japanese Newtonian 4.25" (114mm) f/7.8
Filters used: -
Description: at 36x, bright nebulous patch, small but unmistakable; at 72x,
the ring is obvious (already discernable at 36x) with a darker center; at
150x, the center is not as dark as the sky background; a mag12 star is to
the SE, near.
I can provide a scanned drawing of M 57 to anyone who can read the binhex
encoding of Eudora (for Mac); just mail me to try (firstname.lastname@example.org),
it works quite often with other configurations...
11 impasse Canart, 75012 PARIS, FRANCE
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