The Oct 10 discovery of this object was announced on MPEC:2004-T55 under
the asteroid designation 2004 TU12. Mag 14 at discovery and with q=1.23 this object was clearly unusual in its large size. Within a
day of the discovery announcement, Genny Sansaturio identified this object with several isolated observations over four earlier
oppositions, confirming the unremarkable Amor type orbit of five year period, and the unusually large size of ~5km.
Discovery images of P/2004 TU12 taken with the Uppsala 0.5-m Schmidt on 2004 Oct 10. The frames were exposed for
20 secs with a separation of 14 mins between each. (c) ANU/RSAA 2005
Animated image, please wait for all frames to load.
The real surprise came on Nov 12 when amateur astronomers Gianluca Masi et al. and Juan Lacruz noted a faint narrow tail
extending from the otherwise asteroidal body as the object passed through perihelion (IAUC 8436). This insignificant tail was only present
for a couple of weeks, but has the consequence of making the object officially a comet. It is now designated 162P/Siding Spring.
The tail of P/2004 TU12 is over 9 arcmins long on these images taken with the ANU 40-inch reflector at SSO on
2004 Nov 17. A total of 18 frames have been utilised each exposed for 20 sec. The animation was created from three stacks of six
frames using Astrometrica's "Track & Stack". (c) 2004 ANU/RSAA
Animated image, please wait
for all frames to load.
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