From GalaxyMap:

Avedisova says this nebula is ionised by the O9.5 III giant LS II +26 6 at a distance of 4500 +/- 1000 parsecs.

(Note, however, that several other authorities have concluded that LS II +26 6 is not an ionising star for Sh 2-90. [[url=http://galaxymap.org/cat/view/sharpless/90#note_1]1])

Avedisova places Sh 2-90 in the star formation region SFR 63.18+0.45 along with the infrared HII region IRAS 19471+2641, a water maser and at least 3 molecular clouds.

Humphreys gives a similar distance estimate for LS II +26 6 (4550 parsecs) but a distance for Vul OB1 of only 2000 parsecs. If LS II +26 6 is the ionising star for Sh 2-90 then either this nebula is not associated with Vul OB1 or the distance estimates for LS II +26 6 or Vul OB1 are incorrect.

A blister on a 60 thousand solar mass molecular cloud.[[url=http://galaxymap.org/cat/view/sharpless/90#note_2]2]

Sharpless 90 is associated with Vul OB1 and contains a cometary elephant trunk structure on its eastern edge which appears to have originated from a past disturbance from the southwest.[[url=http://galaxymap.org/cat/view/sharpless/90#note_3]3] 1. ^ Forbes, D. (1989). "Photometry and spectroscopy of stars in northern H II regions", Astronomy and Astrophysics Supplement Series, Vol. 77, 439-445. [[url=http://adsabs.harvard.edu/abs/1989A%26AS...77..439F]1989A&AS...77..439F]  2. ^ Lafon, G., Baudry, A., de La Noe, J., et al. (1983). "The molecular cloud-H II region complexes associated with SH 90 and SH 235", Astronomy and Astrophysics, Vol. 124, 1-10. [[url=http://adsabs.harvard.edu/abs/1983A%26A...124....1L]1983A&A...124....1L]  3. ^ Turner, D. G. (1986). "The large globule LYNDS 810 as a possible member of the Vulpecula OB1 complex", Astronomy and Astrophysics, Vol. 167, 157-160. [[url=http://adsabs.harvard.edu/abs/1986A%26A...167..157T]1986A&A...167..157T]

Processing:

RGB:

GHS: RGB (Color stretch too saturated... see last Version) then set darkpoint and add saturation separately

StarXterminator ro get background for use in

/* RGB Stars-to-Narrowband Transfer using PixelMath - V11by Bill Blanshan */

H-alpha:

StarXterminator->BlurXterminator->NoiseXterminator (monitoring with GHS to prevent clipping... these is best permutation of AI in my hands)

GHS standard stretch (Pretty much 7.0 and 3.0 on first two parameters and tweaking of SP set with cursor to dull areas of image)

PI script to add in Blue to Red for 2nd H-beta channel for use in

 /* RGB Stars-to-Narrowband Transfer using PixelMath - V11by Bill Blanshan */

Prior Version:

With the Tak 180 ED 7 years ago combined in wide angle with Sh2 89:


Sh2 89/90 H-alpha RGB