NGC 1491

NGC 1491 = LBN 704 = Sh 2-206
04 03 13.6 +51 18 58
Size 3x3

17.5" (3/2/02): at 100x, this is a moderately bright, roundish glow,~3' 
diameter, mostly west of a mag 11 star.  Excellent contrast gain with an OIII 
filter as it appears bright, with an irregular surface brightness and it wraps 
around the mag 11 star, particularly on the north side.  There is a subtle bite 
cut out of the nebulosity from the east side that creates a darker hollow 
extending just west of the star.  At 220x (unfiltered), about a half dozen stars 
are involved or at the edges.  The nebulosity is quite irregular with a high 
surface brightness region preceding the star.  Faint, elongated haze extends 
from this patch to the NE past the star giving an elongated appearance.  A pair 
of mag 13-14 star are at the northern end and another pair are just off the 
western edge.

17.5" (12/8/90): at 140x with OIII filter appears as a bright, moderately large, 
circular nebulosity involving a mag 11 star.  The brightest portion lies to the 
west of the star and is elongated 3:2 ~N-S.  There appears be a dark gap just 
west of the mag 11 star.  Two very faint stars are superimposed near the edges.

13": bright emission nebula just E of a mag 10.5 star, extends SW-NE, 
interesting shape.

8": bright, large, ~6' diameter.  A mag 10.5 star is at the E side.

- by Steve Gottlieb

NGC 1491 is a diffuse nebula found by WH.  His description is very good, as is
his position.  Dreyer nevertheless used the micrometric position measured by 
Engelhardt.  This is refers to a star about 1.5 arcmin east of the brightest 
part of the nebulosity; WH mentions the star explicitly: ``... a pL star in it
towards the following side, but unconnected.''  The position we've adopted 
follows WH, and applies to the center of the nebula. - Dr. Harold G. Corwin, Jr.

As with all corrections to the NGC and IC Catalogues, there is a certain margin
for error, even though the evidence supporting the correction may be strong and
compelling. It is with this in mind that we ask the user to use this information
as 'Most Probable', but never to assume the correction is 'Absolute'.  All
published corrections are based on an exhaustive 'paper chase' of the historical
record back to the original discoverer's published notes/papers, and are
therefore based upon the historical accuracy (or inaccuracy) of those particular
notes/papers. In short, Caveat Emptor! - Robert E. Erdmann, Jr.