WISE has released a new dataset. It is a re-processing of the data taken from 1 Oct 2010 to 1 Feb 2011 after all the hydrogen coolant was gone. During this “warm” WISE period only the 3.4 and 4.6 micron channels worked. A preliminary version of this data using the “cold” WISE calibrations and point spread functions was released earlier. This new version uses calibrations and PSFs based on the warm WISE data.
WISE has released an all-sky image atlas and catalog of objects in bands infrared bands at 3.4, 4.6, 12 and 22 microns. The scientific data are available at the Infrared Science Archive. Here is a cool zoomable all-sky image.
I got up at 6 in the morning and saw WISE pass over Los Angeles from North to South. It was
easily visible in binoculars. WISE reached its maximum altitude of 80 degrees in the Western sky, while the Sun was 10 degrees below the horizon, giving a 70 degree phase angle.
You too can see WISE using the tools of the Heavens Above web site. First enter your position (remember West longitudes are negative so all of the Americas have negative longitudes), then bookmark the page. The URL in the bookmark will save your position.
Then click on “select another satellite from the database”. Enter WISE into the satellite name and search. You will only get one results “WISE in Earth orbit”. Click on that, then click on “passes”. Click on the date-time of a pass to get the pass details. Find a pass where WISE is high in the sky, the Sun is well below the horizon, and WISE is West of the zenith for morning passes or East of the zenith for evening passes. This will only work in the wintertime: Dec-Jan for the Northern hemisphere or June-July in the South. Use the star maps to line up binoculars and wait for the appointed time.
The Heavens Above web site is great for brighter satellites like the HST, visible from LA but not from farther North, and the International Space Station, which gets brighter than Jupiter on good passes.
WISE has discovered a new Y class of brown dwarf stars, the y dwarfs, which show methane, water and ammonia absorption. These stars have effective temperatures as low as 300 K, about room temperature.
Today (Feb 17, 2011) at 20h UT I sent the command to turn off the WISE telemetry transmitter. No further telemetry passes are currently planned. The telescope interface flange temperature has risen to 184.1 K (from 73.5 K) due to looking at the Earth for half the orbit since we stopped the survey scans on Feb 1.
WISE has completed its survey of the main belt of asteroids and is going into hibernation mode today. While it is sad to see a functioning space infrared telescope shut down, WISE has observed the whole sky – twice! – and is pushing the confusion limit in its shortest band, so the value of additional surveying is limited. Unless one is searching for transients or variability of course.
WISE flew through the Moon’s shadow over the North pole during the 04 Jan 2011 solar eclipse. The plot below shows the number of coarse digital Sun sensors giving usable output, and the number fell to zero during the eclipse.
Since this eclipse was much shorter than the eclipses by Earth around the June solstice, the battery was easily able to make up for the lost solar array power.
WISE just found two Near Earth Objects in the last two days: a potentially hazardous asteroid (PHA) 2010 XP69 and a half km object that can get within 10 million km (just outside the limit for PHAs), 2010 XZ67. WISE has been observing in a two band mode without any coolant since October.
And WISE just finished a year in orbit on Dec 14.
Today (18 Nov) marks 21 years since the COBE launch. 21st birthdays in the US are often marked by binge drinking. So we could have a joke:
Spacecraft walks into a bar, and says “Bartender, I just turned 21.”
Bartender: “Great, what’ll you have?”
Spacecraft: “Give me 700 liters of liquid helium.”