The M81 and M82 galaxies in Ursa Major showing the background Integrated Flux Nebula.
These are a well known and popular pair of galaxies and can be seen with binoculars. I’ve imaged them here in a very wide field with a DSLR camera lens – the Samyang 135mm connected to a G2-8300 CCD camera and filter assembly using Astrodon LRGB filters
The cloudy dust that is visible is not passing cloud! Rather, it is the extremely faint dust and gas that exists in the space between the galaxies – in intergalactic space. Hence it is called the Integrated Flux Nebula or IFN. It is extremely faint and is only visible with very long exposures and integration times. Careful processing is needed not to inadvertently cut it out of the image.
Imaged in my back yard in Nottingham in March 2020 with Samyang 135mm and G2-8300 CCD camera on a NEQ6 mount. I used a separate guide scope. I only got round to processing this data set in 2023 having completely forgotten about it!
All exposures 300 seconds in length and binned 1×1.
Lum > 24 ; Blue > 15; Red > 15; Green > 14
This gives a total of Lum > 120mins; Blue > 75mins; Red > 75 mins; Green > 70 mins
For a total integration (exposure) time of 5 hours and 40 minutes for the image.