NGC 2420


Ron Brecher

Ontario, Canada

SBIG STL-11000M camera, Baader RGB filters, 10″ f/6.8 ASA astrograph, Paramount MX. Guided with QHY5 camera and and an 80 mm f/6 guide scope. Focused with FocusMax. Acquisition and guiding with TheSkyX. Automation with CCD Commander. All prep-processing and processing in PixInsight. Shot from my SkyShed in Guelph, Ontario. Gibbous moon. Very good transparency and poor seeing throughout.

10x5m R, 10x5m G, and 10x5m B, all unbinned frames (total=2hr30m).

Complete processing details at

NGC2420 is an open cluster located in Gemini. It is usually overlooked because there are other, richer open clusters nearby, for example M35 and NGC2158. NGC2420 contains about 1,000 stars packed into an area with a diameter of about 30 light years. It lies about 7,000 light years from using the Perseus arm of the Milky Way Galaxy. If you look closely, you will also find many galaxies around this image, which is surprising given how bright the Moon was during this imaging session. A nice example of an edge-on spiral galaxy lies above the cluster, halfway to the top edge. There’s a pair of galaxies to the lower right of NGC2420, in the 5-o’clock direction. All the galaxies in this image are far, far in the distance. Every star in the image is in the foreground, namely within our own Milky Way galaxy.

This image was acquired on the night of March 19-20, 2016. Several friends from my local astronomy club came over to do some observing. While we were gawking at the moon, Jupiter and some star clusters, I had my imaging scope acquiring this shot. I was following my own advice ( about making good use of the 2 weeks each month when the Moon can interfere with imaging of faint objects. In addition to choosing a brighter target not too near the Moon’s position in the sky, I used shorter exposures than usual (5m vs my usual 15-20m).