(IAAC) Abell 4 (PK 144-15.1; PK 144-15 1; PN G144.3-15.5) - 17.5" F/4.5

Observer: Yann POTHIER (France)
Your skill: advanced (many years)
Date and UT of observation: 29 December 1997, about 18h45 UT
Location & latitude: La Clapiere Obs. (France, latN44 40 00, longE06 27 36)
Site classification: rural, alt.1650m (5500ft)
Limiting magnitude (visual in UMi): 6.4 with indirect vision 25% of the time
Transparency (1 to 5 - best to worst): 1
Seeing (1 to 5 - best to worst): 3 (stellar stars until 160x)
Moon up (phase?): no
Instrument: Coulter 17.5" (445mm) F/4.5
Magnification: 211x
=46ilters used: OIII, UHC, Hbeta
Object: Abell 4 (PK 144-15.1; PK 144-15 1; PN G144.3-15.5)
Category: planetary nebula
Constellation: PER
Object data: Vmag=3D14.4; Bmag=3D16.7; dim.22"x22" (33"x33" according to IDB=
type IIIb; central star of V=3D19.3; discovered by Abell in 1966; ELCAT: OII=
[496+501nm]=3D 15 x Hbeta [486nm]
RA/DE: 02h45.4m, +42=B033' (2000); Uranometria 62;
Description: at 211x and OIII, medium sized PN, very faint, round and
homogeneous with fuzzy borders; seen since 74x and OIII; detectable at 125x
without filter, and visible without any doubt at 211x without filter;
estimated diameter about 21"; mag12 star 1.6'S and mag9 star 3'SE; UHC
filter has a small contrast gain, OIII has a good one and Hbeta has none.
I can provide a scanned drawing of Abell 4 to anyone who can read the
binhex encoding of Eudora (for Mac); just mail me to try
(ypothier@abi.snv.jussieu.fr), it works sometimes with other
Yann Pothier
11 impasse Canart, 75012 PARIS, FRANCE
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