Interacting galaxies NGC 6872 (the big one) and IC 4970 (the small one). This is one of those woeful cases where large black boxes of missing data are present. You can see a more complete view of the pair here on the Wikipedia page. There should be a nice big image by the ESO there.
Data used:
hst_11134_11_wfpc2_f606w_wf_sci
hst_11134_11_wfpc2_f814w_wf_sci
hst_11134_12_wfpc2_f606w_wf_sci
hst_11134_12_wfpc2_f814w_wf_sci
Copyright information:
Hubble data is public domain, but I put a lot of work into combining it into beautiful color images. The minimal credit line should read: NASA / ESA / J. Schmidt
This work is licensed under a Creative Commons Attribution 3.0 Unported License.