Hewett 1 is an extraordinary giant planetary nebula located in Sextans and spans 2 degrees at a distance of about 500 light years corresponds to a diameter of 17 light years. I know there are planetary nebulae that are larger than that. But surrounding it is a halo that spans about 10 degrees, corresponding to a diameter of around 100 light years! It would in fact be the largest known planetary nebula, but its status as one has been questioned according to Frew et al. 2013 (
http://arxiv.org/abs/1211.2505). I've seen a similar case of identity crisis with Kohoutek 2-1 and to me Hewett 1 is clearly a planetary nebula, with the central star cataloged as PG 1034+001. SIMBAD insists that the white dwarf is "not confirmed spectroscopically by the SDSS (sic)" according to Kleinman et al. 2004 (
http://arxiv.org/abs/astro-ph/0402209). I don't know what that really means, but it could not be that either. It may not be anything. It may not even exist. I don't know.
I applied color by adjusting the curves for each channel which are all the same image. I did not paint the colors on.
Red: 1800 2x2 OIII
Green: 1800 2x2 OIII
Blue: 1800 2x2 OIII
Data from April 13, 2015 obtained from Goofi, who sent me the FITS data as I was curious. I saw a brightening of the background but I don't know if it's a real signal and not just a gradient as it appears off-center from the few images I've seen of Hewett 1.
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