Horsehead Nebula 
Original image & credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA). 
Assembly and processing by Robert Gendler.
 http://www.robgendlerastropics.com/HH-HST-ESO.html

Crab Nebula 
Original image & credit: Adam Block, Mt. Lemmon SkyCenter, U. Arizona
http://apod.nasa.gov/apod/ap130905.html

Centaurs A 
Original image & credit: ESO/WFI (Optical);
MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre);  
http://www.eso.org/public/images/eso0903a/

Pencil Nebula 
Original image & credit: ESO  http://www.eso.org/public/images/eso1236a/

Tadpole Galaxy 
Original image & credit: Image produced with the HST data from the Hubble Legacy Archives.
 Processed by Bill Snyder 
http://billsnyderastrophotography.com/?page_id=2464

Andromeda Galaxy 
Original image & credit: M31 in h-alpha by Adam Evans 
http://www.flickr.com/photos/astroporn/4999978603/