This globular cluster orbiting the Andromeda galaxy Messier 31, is one of the most massive known, equivalent to that of 10 million suns. It is 120,000 lightyears from the centre of M31 and contains an intermediate black hole, with a mass 20,000 times that of our Sun.
This inverted image measures 30 arcminutes horizontally, showing the brightest two stars. G1 is the central object of the indicated small trio, and the inset shows an enlarged view. The faintest stars in this image are around magnitude 17.
This image is the result of 2h of LRGB data capture from Horsham, on an evening in September 2025. A ZWO ASI2600 MM Pro camera was used, through an 8-inch Teleskop-Service Ritchey-Chretien reflector.
Date: 11/09/2025
Location: Horsham, West Sussex
Photographer: Graham Wilcock
