ASTRO: GN 19.53.3 with NGC 6857/Sh2-99/Sh2-100

I got the data for these two images in 2013 but only managed to process them
recently. As these two fields are overlapping a bit with my field of view I
tried to do a mosaic, which didn't really work because both parts had to be
processed differently as NGC 6857 is very bright while GN 19.53.3 is very
faint.
I did not find any useful information on GN 19.53.3 online. It looks like a
part of a SN remnant to me, but it doesn't seem to belong to the SNR that
Sh2-91,94,96 are part of. Bright NGC 6857 is sometimes referred to as a
planetary nebula, but Guide9 says "not a PN" and possibly a diffuse nebula
or a SNR. It certainly doesn't look like a SNR to me.
Not sure if NGC 6857 and Sh2-100 are the same, maybe NGC6857 is only the
bright part and Sh2-100 includes the fainter envelope.

Taken from Berlin in five nights in July 2013 with a 10" Meade ACF on a G11
mount, Atik 383L+ camera, nearly 15 hours of Ha and OIII in 20 minute
exposures combined to a Ha:OIII:OIII where the "green" channel hat 10% Ha
mixed in as that gave a more natural look.

Stefan

Simbad says SH2-100 contains NGC 6857 giving coordinates a bit to the southwest of the main part of the nebula. 6857 was one of my first targets with digital color. I only got 3 5 minute color images and not much more color data. Obviously I have it on my reshoot list. According to my notes from that image you picked up the planetary PK70+1.1. It is the red spot just left of a bright star about one NGC 6857 NW of the edge of the nebula.

I assume GN 19.53.3 is the nebula area to the west of a bright star in the upper image. I couldn't find it in any of my catalogs or in SIMBAD. SIMBAD does list that area as a possible SN remnant but puts its center just below the faint nebula. Google just turned up one reference to GN 19.53.3 and that was your post on a German forum. I've had that happen to me. Several times when I reshot something I decided to do more research but the only new post listed by Google was my first post which usually was also the first entry. Very frustrating.

Looks to me like you did a very good job of joining the two very different images.

Rick