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.

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.

Thanks.

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.

Any idea what it is? Thanks