Abell 28 (PK 158+37.1) is a 13.5 mag planetary nebula in the constellation Ursa Major with very low surface brightness and a diameter of about 5.5 arcmin. The brightness seems to be uneven distributed over the disk. The PN has a rather bright rim in the SE, while it is getting dimmer to the NW. The blue central star ( 17.4 mag) is quite out of the center.
To reveal the PN, about 25h of Ha data have been sampled which have been used as luminance. The response in OIII was very poor, thats why only Ha was captured. North is up in this image.
Telescope: RCOS 14.5" f/8
Mount: ASA DDM85
Detector: Apogee U16M
Filters: Astrodon Gen 2, 3nm/5nm Narrowband
Exposures: HaRGB 1480:160:160:160 min (30/20 min subs)
Observatory: ROSA, France