Another group of Sharpless2 objects seen in the context of the surrounding H-alpha clouds thanks to the CMOS chip and stretching optimized with GHS. 

GHS Forum Discussion

Followed GHS Dave's suggestion to represent Hb as 20% of Ha as Blue in the coloring of this image.  I think it looks better, but hard to tell?  

Nice discussion on Cloudy Nights.

Discussion of Exposure Length of RGB filters

One more little thing I have noticed on stars is that the transmission levels (of photons) may vary very slightly even with "balanced' filters.  There is a nice discussion on Cloudy nights: 

https://www.cloudynights.com/topic/817210-lrgb-exposure-ratios-snr-balance-and-color-balance-for-qhy-600m/

"The relative signal in each passband for L, R, G, B is

RelativeSignalQHY   = {3.13, 1.00, 1.14, 1.05}   QHY QE curve"

This may not look like much, but this is 14% more G than R.  I was wondering why green was showing up in both R and B stars... maybe this is why.... of course I have different equipment, but I think the principles hold.

This resulted in my changing the exposures of my RGB to 22 19 and 21 seconds respectively.  These numbers were calculated to be optimal at 22 (sounds very low but higher blows out the centers of the stars in the ZWO) .  Anyway, in PixInsight there is now less G in these stars.... seen by holding the cursor over the star and left button clicking.

Prior Version:


Sh2 210 H-alpha RGB

From GalaxyMap:

Despite its appearance, this is an HII region ionised by an O9.5 IV star (MFJ SH 2-207 1) and not a planetary nebula.

Avedisova places Sh 2-207 and Sh 2-208 together in the star formation region SFR 151.32+1.99 along with the radio source KR 198.

Avedisova places Sh 2-210 in star formation region 152.81+2.90 with four infrared sources and the radio source RRF 1605. None of these objects have any scientific references either.

Sh 2-210 lies in the direction of a larger diffuse nebulosity containing several B-class stars. Sh 2-207, Sh 2-208 and Lynds dark nebula LDN 1407 (Barnard 12) also appear in the direction of this diffuse nebulosity, although apparently are located at different distances.

GENERAL NOTE ON SHARPLESS2 OBJECTS>>>>>>>>>>>>>

There are 313 Sh2 objects.  All now imaged.

This is my collection:

Sharpless2

Wide-Angle Hydrogen Alpha Nikon Image Sh2 79-171

Please note there is also a Sharpless2 Group with now more than 2700 examples.

Sharpless2 Group

Other useful links include:

Gary Imm's Collection

GalaxyMap's Collection

The Sharpless Catalog

The MDW H-alpha Sky Survey

Reiner Vogel's detailed observing catalog

Hope you enjoy these obscure but interesting objects...