Red-shifted Ha from two active galaxies within the coma supercluster detected using an SII filter (Tim Hawkes)

Celestial hemisphere: Northern · Constellation: Coma Berenices (Com) · Contains: IC 3943 · IC 3946 · IC 3949 · IC 4051 · NGC 4848 · NGC 4854 · NGC 4860 · NGC 4865 · NGC 4874 · NGC 4881 · NGC 4889 · NGC 4895 · NGC 4907 · NGC 4908 · NGC 4911 · NGC 4919 · NGC 4921 · NGC 4926 · NGC 4927

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Red-shifted Ha from two active galaxies within the coma supercluster detected using an SII filter

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Red-shifted Ha from two active galaxies within the coma supercluster detected using an SII filter

ZOOM in (click and drag) to see red Ha signal only within the two galaxies marked with the green arrows.

Newtonian (f=1000mm, F = 5.0) OSC RGB image 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. Only two galaxies. NGC4848 (barred spiral at Z =0.0235) and IC4040 (barred spiral at Z =0.0266) , could clearly be identified as active and showing bright Ha regions.

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 detect Ha emission from the coma cluster.

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Red-shifted Ha from two active galaxies within the coma supercluster detected using an SII filter

Red-shifted Ha from two active galaxies within the coma supercluster detected using an SII filter

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Red-shifted Ha from two active galaxies within the coma supercluster detected using an SII filter

Red-shifted Ha from two active galaxies within the coma supercluster detected using an SII filter

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