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Important notices


Comet C/2007 N3 (Lulin)

Comet C/2007 N3 (Lulin)

Date: 25 February 2009
Time: 22:00-23:30 HKT (15 mins interval per frame)
Place: Tsuen Wan 
Photographic Data: Accumulation type hi-sensitivity camera, 50mm focal length (diagonal field of view 11 degrees), F/3.5 focal ratio, exposure 3 mins per frame, fixed tripod photography, processed and aligned digitally


17P / Comet Holmes

Comet 17P / Holmes

Date: 16 November 2007
Time: 23:43 HKT
Place: Hong Kong Space Museum Sai Kung iObservatory 
Photographic Data: Digital Single Lens Reflex Camera, 200mm focal length, F/5.6 focal ratio, exposure 15s, ISO 1000, guided photography, processed and cropped digitally


73P / Comet Schwassmann-Wachmann 3

73P/Schwassmann-Wachmann 3 is a short period comet which orbits around the Sun every 5.4 years. As the comet can reach the orbit of Jupiter, its own orbit is prone to change by Jupiter's gravitation. In fact, the comet has been ripped into pieces by this immense force, and may vanish completely in a few decades time.

From 12 to 14 May, this mysterious string of comet will pass Earth at a mere 0.0735 astronomical unit (i.e. 29 lunar distances). Astronomers expect that the biggest fragment will shine as bright as magnitude 5. The comet will rise above horizon after 11pm and remain visible in Hong Kong throughout the night. It is advisable to observe with a pair of binoculars as the comet is not too grand after all.

73P/Schwassmann-Wachmann 3 (fragment C)


09 / 05 / 2006
00:02 (Hong Kong Time)
Tuen Mun
0.6m Cassegrain telescope, CCD camera, 20 seconds exposure.

Fragment B


Fragment G

Photo Credit: NASA


Note: Since astronomers have not fully understood the mechanism account for the brightening of comets, they can only predict by referring to past comets. The prediction may have substantial deviation from the actual situation. Observers are reminded to pay attention to the latest announcement of the International Astronomical Union.