This page contains information, utilities, and procedures related to astrometry and distortion correction for NIRC2. We collect these tools as provided by observers.
An updated distortion solution is available for the narrow camera from M. Service and J. Lu. This solution is appropriate for data obtained after the NIRC2/AO re-alignment work of 2015 April 13. The Yelda et. al (2010) solution should still be used for all pre-realignment data. Details regarding the new solution can be found in a paper by Service et al. 2016. The new solution can be downloaded from this Github page.
Please, use the solution described in S. Yelda et al. 2010, ApJ, 725, 331 for narrow camera data taken before the NIRC2/AO re-alignment work of 2015 April 13 this section provides results from the GC group:
Many thanks to the UCLA Galactic Center Group for making this information available.
Hai Fu has generously provided a distortion solution for the wide camera based on observations of M92, using stars between 11.5 < I < 15, and fitting 5th-order 2D polynomials to both delta-X and delta-Y from all of the 15 images of M92 that Alan Stockton took on 2011 Aug 28.
This section provides IDL source code (graciously provided by Keck Observer Brian Cameron) for removing geometric distortion from NIRC2 images. The use and methodology of the code is well described in the comment headers.
Source code:
Brian Cameron also provided this related report.
| M92 | 17h 15.6m +43° 12 | Procedure TBD | Data Sets TBD |
| M15 | 21h 27.6m +11° 57 | Procedure | m15_090814.tar.gz
(graciously donated by Hai Fu) |
Publications that report NIRC2 PA accuracy measurements.
