File:MACS J0717 5+3745 (15763671868).png

English: The ACS data have been collected for the third Frontier Field, the impressively massive galaxy cluster MACS J0717. Said to be the largest known gravitational lens, it certainly is a sight to behold. Check out this post at the Frontier Fields blog. (Watch out, it's snowing over there!)

As a personal observation, the lensed galaxies in this image seem much thinner or wispier, like more of them have been stretched more extremely than average in the previous two fields.

I think I managed to process this one better, too. More faint objects are visible and there is less noise. I ended up accomplishing this first by simply being more careful with my curve adjustments and second by having the F814W layer duplicated and set to luminosity. That means this isn't a perfect representation of the brightness levels throughout the image but it's a fair trade for how much clearer things are made. For example, the delicate shells and a swarm of globular clusters are easily visible around the large, whitish elliptical galaxy a little left and below center.

I don't know if it's just me but the quality of the data seems somewhat improved for this iteration, also. As always, the Frontier Fields data is a pleasure to work with. It's a joy to zoom up close, pan around, and just let oneself be awed by the unfettered majesty of the heavens.

FITS files can be found here: archive.stsci.edu/pub/hlsp/frontier/macs0717/images/hst/v...

Red: ACS/WFC F814W (hlsp_frontier_hst_acs-30mas-selfcal_macs0717_f814w_v1.0-epoch1_drz) Green: ACS/WFC F606W (hlsp_frontier_hst_acs-30mas-selfcal_macs0717_f606w_v1.0-epoch1_drz) Blue: ACS/WFC F435W (hlsp_frontier_hst_acs-30mas-selfcal_macs0717_f435w_v1.0-epoch1_drz)

North is NOT up. It is 9.9° clockwise from up.