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Preparation notes for the re-commissioning campaign (cryo run 93, NIKA2 81th; last update: 2026/09/22):
A report about the second intervention on dichroic and Ar2 shims to try compensating 2mm-1mm focus difference can be seen here. The dichroic was flipped and some shims were introduced on Array 2 mount for compensating the expected distortion of the former after the cool-down. Arrays 1 and 3 were not touched during the cryostat intervention. Therefore, it is likely that only the reference pixel and scale of Matrix 2 have changed. Similar focus corrections are expected for all three arrays.
First NIKA2+ tests will be performed during sparsed observing slots on week 40 (cf. project T21-26 here). NIKA2 account t22 should be used.
- A new sweep for all arrays would be prepared (with the support of Martino and Alessandro) on Tue. 29th after 13:30 CEST (TBC). We would start pointing/focus using the DAFs corresponding to cryo run 92, likely using the Array 1 data as a driver in the worst case.
- Possibly check optics alignments. There's the laser "optical" alignment, that allows checking that the warm optics components are properly aligned with the telescope optical axis, and the "radio" alignment, that allows including the cold optics, which is not only important for the pointing but even more for the illumination of the primary mirror (pupil alignment), to make sure we don't have spillover degrading the background level. The optical alignment can be done anytime, it doesn't require having NIKA2 ready for observations. The radio alignment requires to have NIKA2 on a very stable sky and to slide eccosorb in front of its window.
PIIC DAFs status
DAFs for the current official cryo run (92) were installed on 2026/03/24 by Stefano Berta. When setting up the PIIC environmental variables with gagpiic and starting PIIC, the environment variable $MOPSIC_DAFS points by default to /sw/gildas/mopsic/dafs.
Main Goals
- Preliminary verification of the system in the sky, obtaining the first pointing/focus corrections and quantifying the first focus deviations (hopefully very small).
- Prepare a new sweep (cryo run 93)
- Determination of the optimal Z-axis focus position and setting the focus routine accordingly.
- Produce high-quality DAF/RPP and Kidpars.
- Produce new NEFDs, in total power and polarization (if possible) and providing a new estimate of the fraction of valid KIDs per array.
- Refine pointing offsets.
Observation priorities
- Obtaining high-quality beam maps (at least 2) in total power/polarimetry.
- Getting calib_1scan maps on Uranus, Mars and secondary flux standards/QSOs (at different elevations, day/night) in total power/polarimetry + skydips.
- Performing a pointing session
- Getting a small deep field centered on a moderately bright source (a few hours) in total power and a bunch of polarimetry scans (3C286/Crab).
- Carrying out pending tests for projects 092-26 (N2EDF; high scan speed) and 093-26, both in total power.