Wide-field Infrared Survey Explorer

How WISE will scan the sky

The WISE orbit will be a Sun synchronous polar orbit with a 6 AM or 6 PM ascending node like IRAS or COBE. It will scan the great circle perpendicular to the Earth-Sun line at a rate of 1 revolution per orbit. Every 11 seconds it will take a snapshot of a 47' FOV. Moving at the orbital rate of 0.7 degrees in 11 seconds leads to a small overlap between adjacent frames within one orbit, as shown in the picture to the right. The next orbit will have a large overlap, and after a day of observing most points at the ecliptic are observed from 8 to 11 times. Points near the ecliptic poles will be observed more often, as shown in the wide angle view below.

Note that both the field of view and the spacing between frames are exagerrated in this figure.

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