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: |
8" f5 Newtonian reflector |
| Camera: |
ST-8XME, self-guided, binned 1x1, temp -25c, camera control MaxIm DL 4.56 |
| Image: |
Red (Hoya 25A) filter, 150 minutes (15 x 10 minute subs), 12/12/2006 |
| Processing: |
CCDStack 1.1, Photoshop 7.0 |
| Location: |
Rolling Roof Observatory, Thousand Oaks, CA 91360 (+34d 13m 29s -118h 52m 20s) |
| Notes: | This image was hard to process because of an early evening round of
high clouds. The clouds were not thick enough to stop the auto guiding,
but they caused very uneven gradients in over half of the images in the
sequence. Since this was the only shot I had at NGC 246 this season, I
decided to try processing the sequence. From the NGC / IC Project: Contemporary Visual Observation(s) for NGC 246NGC 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 |