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| Paper: |
Position Refinement of Spitzer-Space-Telescope Images |
| Volume: |
351, Astronomical Data Analysis Software and Systems XV |
| Page: |
169 |
| Authors: |
Laher, R.; McCallon, H.; Masci, F.; Fowler, J. |
| Abstract: |
Position-refinement methods have been developed and are currently used in operations at the Spitzer Science Center to optimally register infrared astronomical images taken by the Infrared Array Camera (IRAC), one of the three science instruments onboard the Spitzer Space Telescope. The methods routinely involve frame-to-frame optimal matching of point sources in overlapping images and point-source matching to absolute-astrometric 2MASS-catalog sources. A recentlystudied case consists of Spitzer observation campaign IRAC006800, in which 44,173 raw images were acquired in all four IRAC channels (corresponding to infrared spectral bands centered at 3.6, 4.5, 5.8, and 8.0 μm). An analysis demonstrated that, for images in the two shortest wavelength bands, the average radial separations between image sources and their absolute matched counterparts are reduced from ≈0.34 arcseconds to ≈0.17 arcseconds as a result of position-refinement processing. There are also improvements for images in the two longer wavelength bands, although not by as much (only a factor of ≈1.2 reduction) because the matched stars are fainter and the image data are noisier. An additional capability that will soon go online, called the super-boresight pipeline, is the simultaneous refinement of IRAC images from all four of its wavelength-band channels. This allows the pointing information gained from the shorter wavelength channels to benefit those at longer wavelengths. |
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