This image is a higher resolution version of the previous wide-field image, seen here. This image was taken in LRGB, with also deep Ha images, taken in order to better display the HII regions. These deep red, HII regions, are so conspicuous that they even have been catalogued in NGC or IC Catalogs (like NGC 604, the largest one at bottom left, NGC 595 on the upper right of the center of the galaxy, or IC 142).
This galaxy belongs to the Local Group, and it is its third largest (one third of the Milky Way in size and 1/8th of its stars in number).
Name(s): M 33. NGC 598
Type: Spiral galaxy
RA: 01h 33m 51s
Dec: +30º 39’ 21.6”
Size (arcmin): 69×42
Distance: 2,800,000 ly
Date: 2018-09-11 to 2018-10-13
Location: Sierra Remote Observatory (SRO) near Alder Springs, CA, USA
Size (arcmin): 30×29
Telescope: Officina Stellare RC500 Pro (20” f/8)
Camera: Apogee Alta U16M-HC (4096x4096pix)
Guiding: Astrodon MonsterMOAG off-axis guider
Total exposure: 27 hours (L: 17x20m; Ha: 7x40m; R: 8x20m; G: 8x20m; B: 24x20m))
Processing: CCDStack, Photoshop CC 2018 and PixInsight 1.8