M55 – Globular Cluster in Sagittarius

Telescope: LXD75 SC8 @ f/6.3, LX65 mount, altaz mode

Camera: Baader modified Canon 600Da, interval timer

Filter: GSO IR Blocking Filter

Guide scope: None

Exposure: 28x10sec, ISO 1600, saved as RAW

Darks: Internal (Long Exposure Noise Reduction On)

Flats: 32×1/25sec, Tee shirt flats taken at dusk

Average Light Pollution: Red zone, Bortle 8, poor transparency, moonlight

Lensed Sky Quality Meter: 18.3

Stacking: Mean with a 1-sigma clip.

White Balance: Nebulosity Automatic

Software: Deep Sky Stacker, Nebulosity, Photoshop

M55 is a large, relatively sparse, class 11 globular cluster in Sagittarius. Its low surface brightness and far southern declination makes it something of a challenge in small telescopes from mid northern latitudes, but it lies to the east of the Milky Way which helps to improve the contrast with the background sky. In a large telescope it blossoms into a soft patch of stardust.

This is one of a series of images that I have been taking to explore using relatively simple equipment and techniques. This is a nice example of going after a relatively challenging target under challenging conditions.

M55 is currently low in the south at sunset.