NGC 246 (PK 118-74.1) Planetary Nebula in Cetus

Located at: RA 00 hours 47 minutes 04 seconds, Dec -11 degrees 52 minutes 20 seconds

Size: 4.1' Magnitude: 8.0 photographic Class: 3b

North is up

West to the right

Telescope:

14.5" f5 Newtonian reflector

Camera:

 ST-8XME, self-guided, binned 1x1, temp -25c, camera control MaxIm DL 4.56

Image:

Lumicon Red filter, 590 minutes  (59 x 10 minute subs), 12/27/30/31/2012; seeing 3.6-4.9 FWHM per CCDStack

Processing:

CCDStack 2.66.4490.32361, Photoshop CS5.1

Location:

 Rolling Roof Observatory, Thousand Oaks, CA 91360 (+34d 13m 29s -118h 52m 20s)

Notes: Same luck again with this object ... This time of year our weather is as likely to be cloudy/rainy as not. I was able to add two more nights taken in so-so conditions (for a total of three nights) ... including poor seeing and high clouds. See the 8" version.

From the NGC / IC Project:

Contemporary Visual Observation(s) for NGC 246
NGC 0246 = PK 118-74.1 = PN G118.8-74.7
00 47 03.3 -11 52 19
V = 10.4;  Size 240"x210"

18" (8/23/03): took a quick look at 160x at Chew's Ridge with an old moon up.  
Without a filter I don't remember the brighter rim being so crisply defined and 
the annularity so clear.  The superimposed stars give the planetary a 
transparent, 3-dimensional feel as if you're looking into the object.

17.5" (1/8/00): at 100x, appears as a moderately bright, 3.5' irregular glow 
with a darker center and encompassing four stars including a 12th magnitude 
central star.  Excellent contrast gain using an OIII filter, which sharpens up 
the edge of the roundish annulus and enhances the irregular surface brightness.  
The halo is brightest along the 270? arc running from SW to NE and is clearly 
weakest on the E edge of the halo.  A mag 11.5 star is embedded at the NW edge 
of the halo 2.0' from center.  The irregular central hole is much darker but 
faintly luminous.  Also superimposed is a mag 12 star SW of the central star and 
a 4th star is just inside the eastern boundary.  At 220x, the western 90? outer 
arc is brightest and there appears to be a knot embedded at the NE edge of the 
halo.

17.5" (9/19/87): fairly bright, large, 4' diameter, annular.  Four stars are 
involved including the central star.  This planetary has an irregular surface 
brightness with subtle structure.

13" (11/05/83): fairly bright with filter, clearly annular, sharper edges.  N255 
lies 15' SSE.

8": fairly faint, large, four stars involved.  No annularity was noted.

16x80 (8/24/84): faintly visible in finder.

The sign of the declination is incorrectly listed as positive in the RNGC.  NGC 
position is correct.

- by Steve Gottlieb