First light for WISE!

Bad Astronomy
By Phil Plait
Jan 7, 2010 1:28 AMNov 20, 2019 3:51 AM


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The Wide-field Infrared Survey Explorer (WISE) has seen first light -- in other words, taken its first image from space!

[Click to embiggen and get access to a big TIFF version.] Nice. It may not look as pretty as a Hubble or Spitzer shot at first glance, but to an astronomer it's the Mona Lisa. The images are sharp (it's in focus), the stars are not overexposed, diffuse sources are detected, and the diffraction spikes (the crosshairs centered on stars) are clean. In other words: bingo! This is an engineering image, not a science one. So it's not supposed to be gorgeous or ready for publication or anything like that. It's more like an aliveness test, to make sure the spacecraft is operating as expected. And it is! This image is an 8-second exposure of a region in the constellation Carina. Normally, WISE will always be on the move, constantly sweeping the sky and taking data. But in this case, they pointed it at one spot to make sure everything was working. WISE works in the infrared, and this picture is actually a composite of three images: blue represents light at 3.4 microns (about 5 times longer than what we can see with our eyes), green is 4.6 microns, and red is 12 microns. This is well into the IR, and shows stars and warm dust in that region. To give you an idea of the scale, the image covers the same area of the sky as three full Moons, so WISE takes big swaths of the sky when it looks around. That's why it's called a survey explorer. It will take millions of images of the sky, which can be stitched together to make mosaics. WISE launched last December, and we've been waiting for news that it's working. This image shows it is, so we can expect very cool stuff coming from the orbiting observatory in the future. The mission is actually quite short, only 10 months long. In October, it's expected run out of the frozen hydrogen (!) being used to cool the detectors -- warm objects emit infrared light, and you don't want your telescope glowing in the light you want to see. In this case, the hydrogen keeps WISE's cameras at a bone-crushing 8 Kelvin, or -445° F. You can read more about this in my earlier post about WISE. My congrats to the team!

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