(IAAC) IC 434 - 17.5inch F/4.5

Observer: Yann POTHIER (France)
Your skill: advanced (many years)
Date and UT of observation: 02 November 1994, about 02h30 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
Seeing (1 to 5 - best to worst): 2
Moon up (phase?): no
Instrument: Coulter 17.5" F/4.5
Magnification: 125x
=46ilters used: UHC, OIII
Object: IC 434
Category: Diffuse Nebula (emission)
Constellation: ORI
Object data: 90'x30'; excited by Sigma ORI (v3.73);
RA/DE: 05h41.0m, -02=B024' (2000); Uranometria 226
Description: large nebula about 27'x7', elongated NNW-SSE, somewhat
brighter around B33, the Horsehead which appears on the middle of its E
side, like a dark indentations; a mag8.5 star is against the S extension;
the all nebula stands between 20' and 50' SSSE of Dzeta ORI; the E edge is
sharper. The nebula is more visible with UHC (but not better with OIII); I
tried the Hbeta filter a year after with a gibbeous moon up and found IC434
and B33 without problems. That explains the OIII failure and the UHC
success (Hbeta flux is stronger than OIII and contributes to UHC response).
The nebula is visible at 45x and UHC, well seen without filter from 74 to
125x but invisible at 312x and more without filter.

I can provide a scanned drawing of IC 434 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	tel: 01 43 41 43 29
11 impasse Canart, 75012 PARIS, FRANCE
Email: ypothier@abi.snv.jussieu.fr
Site : http://pegase.unice.fr/~skylink/publi/cielextreme

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