The IRIS Exposure Time Calculator (ETC) was designed to be a publicly available aid to the astronomical community in the development of science cases for the Infrared Imaging Spectrograph (IRIS) and future proposal planning. The IRIS ETC is developed from the IRIS simulator in which the signal-to-noise calculation is done pixel-by-pixel for 2D and 3D data. The IRIS ETC makes use of simulated Narrow Field InfraRed Adaptive Optics System (NFIRAOS) point spread functions sampling the performance at key positions across the focal plane of the IRIS imager and Integral Field Spectrograph, with varying adaptive optics performances and atmospheric conditions. Like the IRIS simulator, we model the near-infrared background with variable OH emission lines and thermal emission from the atmosphere to provide accurate noise estimates. The IRIS ETC is designed to work with the hundreds of modes given the combination of filters and grating selection. The framework, developed in Python and making use of Astropy and Photutils, can handle any 2D or 3D data input and therefore can be easily adapted for any current or future near-infrared instrument.
The progress achieved in implementing Point Spread Function reconstruction (PSF-R) capability at W. M. Keck Observatory (WMKO) is discussed. Observations of low-mass binary systems have been used to evaluate the improvements in astrometry and photometry using reconstructed PSFs. The on-sky performance of PSF-R is discussed by comparing the binary-fitting analysis using the reconstructed PSFs with the standard methods. We show that the PSFR in the NGS provides comparable performance to having a close reference star in the imaging science instrument. The on-sky troubleshooting efforts and the recent PSF-R technical developments are also presented. We find that the PSF-R reconstruction is more of a systems science problem that a post-processing problem. We close by discussing the lessons learned in the context of existing and future extremely large telescopes.
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