NICMOS Status
Abstract
We provide an overview of the most important calibration aspects of the NICMOS instrument on board of HST. We describe the performance of the instrument after the installation of the NICMOS Cooling System, and show that the behavior of the instrument has become very stable and predictable. We detail the improvements made to the NICMOS pipeline and outline plans for future developments. The derivation of the absolute photometric zero-point calibration is described in detail. Finally, we describe and quantify a newly discovered count-rate dependent non-linearity in the NICMOS cameras. This new non-linearity is distinctly different from the total count dependent non-linearity that is well known for near-infrared detectors. We show that the non-linearity has a power law behavior, with pixels with high system, or vice versa, pixels with low count rate detecting slightly less than expected. The effect has a wavelength dependence with observations at the shortest wavelengths being the most affected (~0.05-0.1 mag per dex flux change at ~1 micron, 0.03 mag per dex at 1.6 micron).
Cite
@article{arxiv.astro-ph/0604394,
title = {NICMOS Status},
author = {Roelof S. de Jong and Santiago Arribas and Elizabeth Barker and Louis E. Bergeron and Ralph C. Bohlin and Daniela Calzetti and Ilana Dashevsky and Mark Dickinson and Anton M. Koekemoer and Sangeeta Malhotra and Bahram Mobasher and Keith S. Noll and Adam G. Riess and Alfred B. Schultz and Megan L. Sosey and Thomas Wheeler and Tommy Wiklind and Chun Xu},
journal= {arXiv preprint arXiv:astro-ph/0604394},
year = {2007}
}
Comments
12 pages, 10 figures. More information on the newly discovered NICMOS count-rate dependent non-linearity and how to correct for it can be found at http://www.stsci.edu/hst/nicmos/performance/anomalies/nonlinearity.html