Newtonian (f=1000mm, F = 5.0) OSC RGB image of a small part of the coma cluster comprising frames from moonless Bortle 6 and Bortlle 4 skies. The overall integration was weighted 80% in favour of the frames from the the darker site reflecting their better SNR. A narrowband 'Ha' image of the cluster was also collected using a mono camera using an SII filter at 672 nm. The "Ha" - red channel difference image was then partly added back into the red channel of the RGB image in order to highlight any galaxies within the cluster that were bright in Ha showing as regions of red.
Here red HA bands are visible on NGC4848, an active barred galaxy at Z =0.0235 which is shown at the upper left part of the image.
At an average distance of about 350 Mly (Z = 0.025) the narrow band emission of Ha at 656nm is shifted by about 16 nm (with variations according to actual recessionary velocities) and thus an SII rather than an Ha filter was used to probe for Ha emission from the coma cluster. NGC4848 appears to be a starburst galaxy
https://www.aanda.org/articles/aa/full_html/2012/08/aa19933-12/aa19933-12.html
Comments