I tried to highlight this "corkscrew" aspect of the core. For some reason it is S-II, which makes it tricky to isolate. The blue is all O-III and the stars RGB.
Prior Ha effort:
Sharpless2 206 ICC 433 in H-alpha with RGB (AKA Jellyfish Nebula) From
GalaxyMap:NGC 1491 is an older, evolved HII region ionised by the O5 star
BD +50 886. SIMBAD gives a slightly cooler O6 class for this star.
Contains the infrared star cluster [url=
http://simbad.u-strasbg.fr/simbad/sim-id?Ident=[BDS2003]+62&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id][BDS2003] 62[/url].
A very good visual frequency image of this nebula is available
here and a recent WISE infrared image
here (Sh 2-206 (NGC 1491) is on the right).
GENERAL NOTE ON SHARPLESS2 OBJECTS>>>>>>>>>>>>>
There are 313 Sh2 objects. As of the date of this image I had imaged all 313 (100%).
Some of the challenges with this series are FOV size and low declination:
There are 11 too diffuse/large to image well with my set up (Sh2 111, 117, 122, 131, 132, 145, 178, 218, 230, 268 and 310). I have imaged the first 6 of these mostly in the Nikon Wide angle shot referenced below and 178 and 230 as part of other images.
There are 5 that are never above 14 DEG (Sh2 2-6) but as of 7/12/21 I can get these now with pier upgrades and the images are completed as best as I can.
Many were taken with my old Tak 180 ED, which had a wide field of view, but was replaced with my Stellarvue 130, which is more narrow field. I have also taken two very wide field HA images with my Nikon D800 and a 50mm lens. I transitioned from my CCD SBIG 8300M to a CMOS ZWO ASI6200M Pro in September 2021.
The first one was taken on December 23, 2013 and the series completed October 17, 2019.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 1500 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...
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