NGC 55 Star Halo in Sculptor

Image Title: The magnificent NGC 55, an edge-on spiral galaxy in Sculptor showing structure in the galaxy's star halo

Copyright: Niall MacNeill

Date image was taken: September 18, 2025

Location: Wattle Flat, NSW 2795, Australia

Data Acquisition Method: Personal Telescope Setup

Description and Details: NGC 55 is one of the jewels of the Southrn Hemipshere. It has a relatively large apparent size given its relative proximity to the Milky Way (6.5 Mly). It is apparently a spiral galaxy but its edge-on aspect makes it very interesting as we see a somewhat displaced central core with more yellow older stars bulging each side and blue spiral arms edge on. Equally there is a lot of dust lane detail to be seen in these spiral arms. Ha data were captured and the signal is really strong. Once again with the edge-on aspect the Hydrogen clouds that produce the Ha emissions are clearly strewn through the spiral arms and engendering the star formation and young stars that produce the blue colour. The Continuum Mapping process was used to add the Ha.
Interestingly, a lumpiness was noticed in the halo on each side of the plane of the galaxy. This was initially considered to be noise, but identical structure was found in the images of others (Hagar, Benson). This was proven to reflect the variable density of unresolved stars in the halo by blink animating against a HST image. (See the AstroBin post...https://app.astrobin.com/i/ptr4h6)
OTA: C11 EdgeHD
Camera: SBIG 16803
Filters: Astronomik LRGB & Ha 50mm square unmounted
Total Integration Time: 30.7 hours (LRGB 21.7 hours, Ha 9 hours)
Luminance: 40 x 600 secs
Red: 30 x 600 secs
Green: 30 x 600 secs
Blue: 30 x 600 secs
Ha: 18 x 1800 secs
Bias: 35
Darks: 35
Flats: 20 per colour channel per camera change

Name: Niall MacNeill

Website or Facebook Profile: http://app.astrobin.com/i/ptr4h6