|
Description
The 2013 NEOWISE Post-Cryo Data Release is comprised of data taken during the four month period following the complete exhaustion of cryogens in the Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010) payload. During this period, known as the NEOWISE Post-Cryo mission phase, data were collected by the 3.4 and 4.6 um detectors at sensitivities similar to those achieved during the full cryogenic phase. WISE scanned approximately 70% of the sky during the Post-Cryo phase, completing a survey of the inner Main Asteroid Belt and a second coverage of the inertial sky.
WISE is a NASA Astrophysics Division Medium Class Explorer mission that conducted a sensitive mid-infrared imaging survey of the entire sky in 2010 and 2011. WISE mapped the sky with a 40 cm telescope and camera equipped with four 1kx1k array detectors that imaged the same 47'x47' field-of-view at 3.4, 4.6, 12, and 22 um (W1, W2, W3 and W4) simultaneously. The WISE telescope, optics and detectors were cooled by a two-stage solid hydrogen cryostat. WISE surveyed the sky 1.2 times between January 7 and August 6 2010, during its full cryogenic mission phase, when both inner and outer cryogen tanks held hydrogen ice and all detectors operated at full sensitivity. Data collected during this phase make up the March 2012 All-Sky Data Release, which is the best compendium of information about the static mid-infrared sky. WISE continued to survey an additional 30% of the sky between 6 August and 29 September 2010 UTC, the 3-Band Cryo phase, using the W1, W2 and W3 detectors after the hydrogen ice sublimated in the outer cryogen tank, but while the detectors were still cooled by cryogen in the inner tank. Data collected during this phase comprised the June 2012 supplemental 3-Band Cryo Data Release.
The NEOWISE Post-Cryo mission phase began on 29 September 2010 UTC after the solid hydrogen in the inner cryogen tank was exhausted and the focal plane assemblies, optics and telescope gradually warmed to approximately 73.5 K. The W1 and W2 HgCdTe detectors remained fully operational during this time with sensitivities close to those observed in the cryogenic mission phases (Figures 1 and 2), although the number of high noise pixels increased as the detectors warmed. No useful data were collected by the W3 and W4 Si:As detectors that were above their operating temperatures and were saturated by thermal emission from payload. WISE surveyed approximately 70% of the sky in the Post-Cryo mission phase until 1 February 2011 UTC when data collection was halted.
|
