(IAAC) NGC 3587 (M97) - 17.5" F/4.5

Observer: Yann POTHIER (France)
Your skill: advanced (many years)
Object: Messier 97, M 97, NGC 3587 (PK 148+57.1; PN G148.4+57.0; ARO 25, VV 59)
Category: planetary nebula
Constellation: UMa
Object data: Vmag=9.9; Bmag=12.0; 203"x199" (209" in IDB); type IIIa;
central star of Vmag=16.1; discovered by Mechain in 1781; ELCAT: [OIII,
496+501nm] = 12 x [Hbeta, 486nm].
RA/DE: 11h14.80m, +5501.0' (2000.0)
Date and UT of observation: 15 August 1996, 22h45UT
Location & latitude: La Clapiere Obs. (France, latN44 40 00, longE06 27 36)
Site classification: rural, alt.1650m (5500ft)
Limiting magnitude (visual in UMi): 6.2
Transparency (1 to 5 - best to worst): 1
Seeing (1 to 5 - best to worst): 3.5
Moon up (phase?): no
Instrument: Coulter 445mm/17.5" F/4.5
Magnification: 145-312x
Filters used: OIII, UHC, Hbeta

Description: at 222x, large PN, round, bord quite sharp with UHC or OIII
but diffuse without filter or with Hbeta; medium brightness, estimated on
drawing to be 3.4' in diameter (205"); its center looks darker thanks to
the two owl's eyes, oriented WNW and ESE from the very faint central star
ob about mag15 (visible only at 312x without filter with great attention);
the "eyes" have a diameter of about 50"; a mag 12 star is 1' from the N
border; both UHC and OIII provides a very good contrast gain but Hbeta is
of no use, strongly reducing the nebula's size.

I can provide a scanned drawing of Messier 97 to anyone who can read the
binhex encoding of Eudora (for Mac); just mail me to try
(yann.pothier@fnac.net), it works quite often with other configurations...

Yann Pothier
11 impasse Canart, 75012 PARIS, FRANCE

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