I'm used to seeing colour in planetary nebulae through the 20" Dob but nothing prepared me for The Blue Racquetball, NGC 6572, in Ophiuchus. It's small but bright and at 300X the colour was breathtaking, easily the most vivid colour I've ever seen in a DSO. As you can see from the original notes below, it appeared as a stunning royal blue. even at 600X it was still full of colour.
Its size, 0.3' x 0.2' and magnitude of 8.1v gives it a Mean Surface Brightness of around 13.6 Mag/arcsec2, which, I read online, means it has a surface brightness 100 times that of the Ring Nebula!
It took 900X well but 600X gave the best views. Due to seeing, I suspect, the central star wasn't visible, but at 600X the brightening along the west side (left in the sketch) was very apparent, as was the "sawtooth" detail along the south edge (at the bottom in the sketch). The central granulation is a result of sketching artifacts not an observed feature, but the rest is "real" including the fainter halo around the main body. The OIII filter added nothing to the view. The sketch is a combination of detail visible at 600X with a little at 900X and the colour at 100X and 300X.
Edited by iainp, 16 May 2018 - 12:06 PM.