Object: NGC 6781 (PK 041-02.1; PN G041.8-02.9; ARO 32)
Your skill: advanced (many years)
Category: planetary nebula
Constellation: AQL
Object data: Vmag=11.4; Bmag=11.8; >109"; type IIIB+III; central star of
Vmag=16.2; discovered by Herschel in 1830; ELCAT: [OIII, 496+501nm] = 13 x[Hbeta, 486nm].
RA/DE: 19h18.44m, +06°32.5' (2000.0)
Date and UT of observation: 06 July 1994, 01h00 UT
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): 4
Moon up (phase?): no
Instrument: Coulter 445mm/17.5" F/4.5
Magnification: 45-145x
Filters used: UHC, OIII
Description: at 125x, large PN, medium to bright, about
2.1' in diam.
(126"); SW border fuzzier and less annular than the others;
W, NW, NE, E
and SE borders are well defined; the ring is 3/4 of the
nebula's edges,
like a crescent, 38" wide at the maximum (on the N side);
the nebula is
seen at 45x without filter, medium in brightness and
large, homogeneous;
frankly annular at 74x without filter and at 45x with
OIII (difficult); at
145x, annular nearly with direct vision; the UHC gives
a good contrast gain
and OIII a very good one; at 145x and OIII, annular with
direct vision;
mag15 star in the ring to the W (and a little S) and
another just outside
to the ENE; a mag12 star is 4.8' to the WNW.