M57 (and IC1296): Stars with mass similar to that of our Sun throw off their outer gasses after fusion has stopped in their core. One of the most famous, and easily found, of these "planetary nebulae" is the Ring Nebula, M57. The appearance as a ring is really an illusion of projection - it is believed that the nebula is actually shaped like a hour-glass (we are seeing it from the end). The bluish star at the center of the nebula is the old core of the star, now evolving into a white dwarf. Nebulae of this type are called "planetary nebulae," because in older smaller scopes, they looked like small, blurry planets. It is about 2000 light years from Earth and is roughly one light year wide; it is visually in the constellation Lyra. IC1296, a magnitude 15 spiral galaxy, can be seen to the lower left of the nebula.

Technical Information:

LRGB: 200:60:60:128 (L-20x10; R&G-6x10; B-8x16). All images were unbinned.

Equipment: Meade 10" LX200 at f/12, an SBIG ST-8XE camera/CFW8 color filter wheel (image resized up 35% in linear dimensions, resulting in an effective focal ratio of f/16.5, and a resolution of about 0.44 arcseconds per pixel), guided by an SBIG AO-7 adaptive optics device, guiding at about 13 Hz (luminance) and 3-5 Hz (RGB).

Image Acquisition/Camera Control: CCDSoft V5.

Processing: All images calibrated (darks, dawn flats and flat-darks) and registered in AIP4WIN. All layers average combined in Ray Gralak's sigma reject program. Five iterations of Lucy-Richardson deconvolution routine (high-frequency components only) applied using AIP4WIN. Color combine, very gentle unsharp mask on the luminance layer, and adjustment of curves and levels, performed in Photoshop 6.0. I processed IC1296 separately to enhance it, or it would have been barely visible.

Location: All images taken from my yard in Redmond, Washington, USA, elevation 500'.

Date: Luminance images taken on the night of June 5, 2003; RGB taken on the night of June 6, 2003.

CCD Temperature: -20C

Moon Phase: Waxing crescent/first quarter

Seeing: Variable with 2.2 Arcsecond average FWHM in single calibrated image (best image had 1.8 arcsecond FWHM).

Copyright 2003 Mark de Regt