Last modified: 8 October 2019

URL: https://cxc.cfa.harvard.edu/ciao/caveats/hrc_focus.html

Caveat: HRC Focus


The HRC-S best focus was updated on 1999Nov06 to the current best focus estimate for grating observations. Note that in order to optimize the focus of the dispersed spectrum, the detector is deliberately moved out of focus by 100 microns towards the HRMA. Observations taken prior to 1999Nov06, other than focus test measurements, were obtained at a detector position approximately 150 microns closer to the HRMA (except for observations of Capella when the detector was moved out of focus to perform focus measurement itself; these were obsids 1167, 1244, 62410, 1246).