NICER / ISS Science Nugget
for December 17, 2020
Since the loss of operational power on channel 4B and the subsequent NICER power-down, NICER has missed 200 individual observations of celestial targets totaling approximately 200,000 seconds of on-target science time. These observations are of 35 unique objects including Sun-like stars, neutron stars, black holes, and active galactic nuclei. Some of these observations were coordinated with other observatories, including the Hubble Space Telescope. In these coordinated efforts, NICER provides X-ray data to complement data obtained at other wavelengths, completing a physical picture of these astrophysical systems. Some observations are time-critical in that they provide data at preplanned cadences to study the target's evolving X-ray emission. Nine of these 35 unique celestial targets are part of NICER's Guest Observer (GO) program, in which NICER time is competitively awarded to scientists from around the world; where possible, these commitments will be honored at a later time, but a prolonged shutdown of science operations has a downstream impact on future time-critical and coordinated observations as they compete for time with delayed and rescheduled investigations.
Figure: NICER science acquisition time lost, in various categories, due to loss of 4B operational power. Celestial target types are color-coded for X-ray binaries (XRB), tidal-disruption events (TDE), Sun-like stars, neutron stars (NS), calibration observations, black holes (BH), and active galactic nuclei (AGN). Non-time-critical observations are collected in the Science Team category; all others were time-sensitive.
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