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Wavelength Calibration Accuracy & Flexure
This page is focussed on the wavelength calibration accuracy and the IFS flexure compensation.
Extended Objects: Europa Observations
Europa, satellite of Jupiter was observed on November 18, 2013 from 08:42:16 (airmass=1.63) to 08:48:16 (airmass=1.64) under average seeing conditions (DIMM seeing~0.6-0.8) in K1 band, and direct mode (no coronagraph, no apodizer). Eleven data cubes with a true integration time of 8.73 s were processed by M. Perrin using the recipe listed below.
Recipy used to process Europa Data
GPI is a complex instrument and the performance is changing quickly with improvements in data reduction and the instrument wavefront sensor control loops. The performance has been broken down into the following areas:
Our understanding of performance and calibration is a work in progress; these pages will continue to be updated as more on sky calibrations are taken and analyzed.
Backgrounds (Sky and Thermal)
Sky frames were taken from the 13th-17th of November, 10th December and were reduced using the following primitives:
Subtract Dark Background
Load Wavelength Calibration
Assemble Spectral Datacube
Interpolate Wavelength Axis
The sky flux was then calculated as the median value within each spectral channel, divided by the integration time per coadd (ITIME keyword).
We find that after correcting for distortion, the average positional residual drops from 0.26 spaxels to 0.04 spaxels.
The time available on each of Gemini North and South is distributed according to the Observatory partners' shares . To maintain overall balance amongst the partnership, the allocations are adjusted each semester as a result of actual time charged in prior semesters. The allocations are approved at the Operations Working Group meeting prior to the Call. Historically, around 5% of each semester's science time is used to complete highly ranked programs from the previous two semesters to which the ITAC granted rollover status.