Friday 2 April 2010

2010 March notes: WISE and Pan-STARRS

Generally poor observing conditions throughout March hampered observing but a number of new NEOs were followed, after they had been posted on the Minor Planet Center's NEO confirmation page (NEOCP), which is now at this new address:

Although the majority of new objects in March were discovered as usual by the Catalina Sky Survey/Mt. Lemmon telescopes, the WISE Infrared Space Telescope has started to make a significant contribution. About 1 in 5 of the objects added to the NEOCP in February and March were WISE discoveries, however, these are likely to be "extra" objects. WISE is in a polar orbit and scans a great circle aligned 90 degrees from the Sun and so most if not all of the WISE discoveries are unlikely to have been found at that time by the other NASA funded surveys that tend to cover the opposition area of the sky, though some may eventually have been picked up by the ground based surveys as the objects tracked across the sky.

WISE uses a 16" mirror to observe in four bands in the infrared and converting the measured IR brightness into likely visual band magnitudes to be included on the NEOCP for Earthbound observers is tricky, some objects being relatively bright in the IR and others fainter. Many of the WISE discoveries are being listed with V magnitudes of 22-23 but some are brighter than these  estimates would indicate and potentially in reach of amateurs.

Going after a WISE discovery with amateur equipment involves taking a large number of exposures and having to be resigned to the fact that there is a good chance that the effort will be for nothing if the object is too faint to be detected. However, WISE's IR eye is very good at picking up comets just as IRAS was 27 years ago. So if a WISE object is bright enough to be picked up it is well worth checking the images for signs of cometary activity. Three out of five WISE objects detected in March from Great Shefford turned out to be comets (P/2010 D2, C/2010 D4 and C/2010 E3).

The first Pan-STARRS 1.8-m telescope on Hawaii with its 1.4 gigapixel camera has also started submitting many hundreds of positions of minor planets to the Minor Planet Center this year and it can't be long before this gives all the other surveys some keen competition too.