—
AIROPA
AIROPA stands for Anisoplanatic and Instrumental Reconstruction of Off-axis PSFs for AO
AIROPA is a PSF fitting package that models how the adaptive optics PSF varies over the field of view. AIROPA can be used to model the spatially-variable PSF for AO images of crowded stellar fields. AIROPA is built on top of a modified version of StarFinder (v1.6.1) and the atmospheric modeling package, Arroyo.
AIROPA can be downloaded and installed from bitbucket. Several group members have written an installation guide here. Note: installation depends sensitively operating system specs (i.e. macOS/linux version, Boost/gcc/idl etc versions).
Repository
Papers
AIROPA I: https://ui.adsabs.harvard.edu/abs/2016SPIE.9909E..1OW/abstract
AIROPA II (Ciurlo et al. 2022): https://doi.org/10.1117/1.JATIS.8.3.038007
AIROPA III (Turri et al. 2022): https://doi.org/10.1117/1.JATIS.8.3.039002
AIROPA IV (Terry et al. 2023): https://doi.org/10.1117/1.JATIS.9.1.018003
AIROPA Variable-PSF Demonstration
AIROPA has the capability of measuring the spatially dependent PSF across an entire image. By including knowledge of the instrumental aberrations (via phase maps) and atmospheric information (via MASS/DIMM weather data), the size and shape of the resulting PSF can be modeled at any position for a given image.
In theory, this allows more precise astrometry and photometry to be performed on point sources at significant distances from the on-axis position (i.e. center of the image). The algorithm will produce a grid of PSFs, with a user-defined grid resolution. Further, the FWHM, Strehl Ratio, and other PSF characteristics can then be measured for each PSF in the grid.
Figure 1a. Instrumental MTF map, using 2017 phase map.
Figure 1b. Atmospheric MTF map for turbulence profile with 0.65” seeing.
Due to angular anisoplanatism, the shapes of the MTF and PSF profiles are elongated in the direction of the position of the laser guide star (typically on-axis), with larger effects at larger separations from image center.
The FWHM of the PSF improves in the direction of the tip/tilt guide star, as is expected. Further, the brightness and location of the PSF reference stars seem to have a marginal effect on the level of AO correction (and corresponding FWHMs) on the grid at larger separations from image center.
AIROPA on Microlensing Data
Beyond the Galactic Center, AIROPA has also been used to analyze a few gravitational microlensing target fields. These fields are typically moderately crowded, however they offer many fewer PSF reference stars than the Galactic Center datasets. Testing the performance of AIROPA in these less-crowded fields and with fewer PSF reference stars will give insight into the reliability of the code for use in fields outside the Galactic Center.
OGLE-2015-BLG-0029
This target is a black hole microlensing candidate and has subsequently been observed with NIRC2 several times. One image from 2015 and the corresponding PSF grid generated from AIROPA variable-PSF mode are shown below: