sig07-009_mac.jpg is from the nasa public domain image archive.

http://www.nasaimages.org/luna/servlet/detail/nasaNAS~12~12~64153~168545:Multiwavelength-M81?qvq=q:galaxy+or+constellation+or+hubble+or+spitzer;lc:NVA2~35~35,NVA2~32~32,NVA2~31~31,NVA2~19~19,nasaNAS~16~16,nasaNAS~2~2,NSVS~3~3,nasaNAS~9~9,NVA2~4~4,NVA2~15~15,NVA2~24~24,NVA2~29~29,nasaNAS~12~12,nasaNAS~8~8,nasaNAS~7~7,NVA2~22~22,nasaNAS~10~10,NVA2~13~13,NVA2~18~18,NVA2~27~27,NVA2~9~9,NVA2~1~1,nasaNAS~6~6,NVA2~25~25,NVA2~20~20,nasaNAS~13~13,nasaNAS~22~22,NVA2~16~16,NVA2~8~8,nasaNAS~5~5,nasaNAS~4~4,NVA2~28~28,NVA2~14~14,nasaNAS~20~20,NVA2~17~17,NVA2~30~30,NVA2~21~21,NVA2~26~26,NVA2~23~23,NVA2~44~44,NVA2~42~42,NVA2~38~38,NVA2~45~45,NVA2~39~39,NVA2~43~43,NVA2~41~41,NVA2~37~37,NVA2~49~49,NVA2~53~53,NVA2~51~51,NVA2~56~56,NVA2~47~47,NVA2~54~54,NVA2~33~33,NVA2~36~36,NVA2~34~34,NVA2~57~57,NVA2~52~52,NVA2~48~48,NVA2~50~50,NVA2~46~46,NVA2~55~55&mi=0&trs=8854

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http://www.nasa.gov/audience/formedia/features/MP_Photo_Guidelines.html