Chandra HRC-S degapping corrections

Abstract

The HRC-S is a microchannel plate detector on board Chandra and is primarily used for spectroscopic observations with the Low Energy Transmission Grating Spectrometer (LETGS) in place. Photons are detected via signals read out from evenly spaced wires underneath the plates and positions are computed by centroiding around the strongest amplifier signals. This process leads to gaps in between the taps where no events are placed. A deterministic correction is then made during ground processing to these event locations to remove the gaps. We have now developed a new, empirical degap corrections from flight data. We describe the procedure we use, present comparisons between the new degap and lab-data based degap, and investigate the temporal stability of the degap corrections.

EXTENDED EMISSION FROM THE PSR B1259–63/SS 2883 BINARY DETECTED WITHCHANDRA

“…The presence of asymmetric extended emission at distances 1 ′′ from the pulsar is also supported by Figure 4, which shows the result of subtraction of the simulated point source image from the observed one. In addition to the asymmetric extended emission, the subtracted image shows some azimuthally asymmetric systematic residuals of both signs within ≈ 1 ′′ from the point source position, resembling those reported recently by Juda & Karovska (2010) and Kashyap (2010) 4 . This means that the actual PSF core is different from the azimuthally symmetric model; this difference, however, makes no effect beyond 1 ′′ from the point source position 5 .…”