SkyView is now serving the data from the WISE All-Sky Data release. The main difference with the preliminary release is coverage on the ~40% of the sky that was missing in the earlier release. However the entire dataset has been reprocessed using updated calibrations and such.
We download WISE data from IRSA in large tiles, caching each tile so that we never have to download the same tile twice. It can take a while for WISE images to be generated if there has been no request in that region before, even when you are requesting only a very small region. It can easily take a minute or more to get the files we need to generate your image. As our cache grows you’ll be more likely to hit it and access should be much faster. Once data are in the cache it takes only a couple of seconds to generate a typical image.
The WISE data give us a view of the infrared sky comparable to the DSS optical images in the optical. We anticipate WISE being one of SkyView’s most popular surveys.
Hi, WISE shows a very peculiar image artifact at 8 55 39, 19 36 44
Any idea what it is? Thanks
That’s really weird looking. To find out what it is first we check to see if it appears in all bands. There’s something really strange in every band though the appearance differs. That suggests that there is something there — it’s not just a glitch of some kind in one detector. The most likely bet is that it’s something very bright that the detectors just can’t handle properly. A quick check of the bright star catalog (in the HEASARC Xamin service) doesn’t show up anything within a few degrees.
That leaves only planets. We use the HEASARC coordinate converter to see what the ecliptic coordinates are. The ecliptic latitude is only 2 degrees, so it’s very close to the ecliptic where we expect a planet. WISE took it’s data in 2010 so it’s off to the ephemeris generators at JPL’s Horizon system to get ephemerides for the planets for 2010. WISE won’t have looked near the Sun, so we can skip Mercury and Venus. We get lucky on the first planet we try, Mars. There’s an excellent match in position with Mars on April 27, 2010.
So it looks like this is an observation of Mars at that time. Mars was about magnitude 0.5 — pretty bright.
Why is IRAS missing at 22h 35m 53s -04 25′ 17.9?
Thanks.
These coordinates point to a small slice of the sky that the IRAS did not observe.
Take a look at IRAS View of the Milky Way Galaxy to see the missing coverage.
We also have an explanation in our SkyView Survey Documentation.
I hope this clears up the mystery.
Why is IRAS missing at 22h 35m 53s -04 25′ 17.9?
Thanks.
IRAS didn’t quite manage to survey the entire sky. While I’m not an expert on that mission, many observatories need to shut down when in what is called the South Atlantic Anomaly — a region of high radiation. If so IRAS would have had fewer opportunities to cover the mid southern declinations. It looks like IRAS managed to cover about 96% of the sky. Given the IRAS lifetime and observing modes, for any given point int the there were only two to three opportunities to measure the flux. A small fraction of the sky was unlucky due to SAA passages and other issues that arose during the mission.