596 Scheila

[1] Kopff named the asteroid after a female English student with whom he was acquainted.

[5] On 11 December 2010, Steve Larson of the Catalina Sky Survey detected a comet-like appearance to asteroid Scheila: it displayed a "coma" of about magnitude 13.5.

[6] Inspection of archival Catalina Sky Survey observations showed the activity was triggered between 11 November 2010 and 3 December.

[2] Cometary outgassing could not be ruled out until detailed spectroscopic observations indicated the absence of gas in Scheila's plumes.

[4] Observations by the Hubble Space Telescope and the Neil Gehrels Swift Observatory's ultraviolet-optical telescope make it most likely that Scheila was impacted at ~5 km/s by a previously unknown asteroid ~35 meters in diameter.

Scheila imaged by the Hubble Space Telescope on 7 December 2010, with visible features marked.
Scheila imaged by Neil Gehrels Swift Observatory 's ultraviolet-optical telescope on 15 December 2010