Back to the NIKA2 Run 74 main page

NIKA2 Re-Commissioning (3rd. attempt)

NIKA2 run 74, Cryo run 86

Infos about the PIIC DAFs for the PIIC monitor

According to the results obtained from processing data of June 2025 NIKA2 re-commissioning given here, DAFs RPP scheme used during run 73 is kept. Therefore, two different sets of DAFs for Ar1+3 and for Ar2 are used. In practice:

• Ar2
  • open a terminal, go to the QL directory
  • gagpiic
  • export MOPSIC_DAFS=/local/users/flexible/reduce/dafs_bck/dafs_local_tmp_run73_ar2
  • start the Ar2 monitor (pf)
  • repeat in another terminal for the Ar2 monitor(m)
• Ar1 and Ar3
  • open a new terminal, go to the QL directory
  • gagpiic

  • echo $MOPSIC_DAFS -> check that it says /sw/gildas/mopsic/dafs

  • if not, then set it to that directory
  • proceed normally with the Ar1 and Ar3 monitors

July 12-13, 2025

These tests are being carried out in the framework of the first Heterodyne pool week of Summer 25. Thanks to all involved for their understanding.

Albrecht (AoD) and Angel at the telescope. Operators on Duty: Gloria (night) and Kike. Cryostat: T_MC = 0.170 K, T_Still = 1.21 K, T_4K = 8.37 K.

DAQ started with the window closed for sampling some instrumental noise traces. Bad KIDs (Ar1/Ar2/Ar3): 12, 5, 14. Screenshots of noise traces, in that order:

23:45 (LT): Starting NIKA2 session. Window open, clear sky, tau_225GHz ~ 0.23, mild wind. DAQ restarted (total power), bad KIDs: (Ar1/Ar2/Ar3): 13/953, 5/578, 29/1000.

• The first task is to obtain reliable focus corrections per array. Pointing on 1741-038 (1.64 Jy @ 1 mm, 30 days average until 10/7/2025: SMA). An issue arises: adopting MOPSIC_DAFS=/local/users/flexible/reduce/dafs_bck/dafs_local_tmp_run73_ar2 for PIIC-QL as established above, the message synchro problem or corrupted file appears. Everything goes fine with that in the case of Ar1/Ar3. 2mm-PIIC monitors restarted using MOPSIC_DAFS=/sw/gildas/mopsic/dafs: now it works. We continue on this. On the other hand, it was not possible to activate the creation of imbfits files with the old system. Albrecht is investigating possible issues, presumably related to the NCS libraries.

• Very stable atmosphere: p2p vars. in the second focus sequence of the session are ~ 2, 3, and 5 Jy/beam (Ar1, 2, 3). Relatively quiet residual background in the QL maps, compared to run #73 in general.

00:50 (LT): Changed to 1749+096 (2.33 Jy @ 1 mm, 30 days average until 09/7/2025: SMA) for new focus corrections.

01:15 (LT): Starting a first trial of flux calibrations on secondary standards:

02:13 (LT): Starting a second trial of flux calibrations on secondary standards after a new focus correction on 1749+096:

Calib_1scan maps with no apparent problems. Comparable to those obtained last April, for instance.

02:50 (LT): Trying pointing & focus on 2251+158 (3C454; 6.05 Jy @ 1 mm, 30 days average until 10/7/2025: SMA).

Although the angular position offsets between arrays are similar to those of run #73, under qualitatively better atmospheric conditions it was not possible to obtain the best focus values for this source on arrays 1 and 3 this time. KIDs rejection on arrays 1 and 3 for the 2251+158 case was significant, which prevented the fitting. As an example, the screenshots below show a scan of a focus sequence obtained during run #73 and one from the current run. This effect is more dramatic in the case of Neptune (3.57 Jy @ 230 GHz, 11.7" beam: GILDAS/ASTRO). Perhaps I should have played around with the aiming offsets:

After a few attempts, we switched to a fainter source (2230+114; 3.91 Jy @ 1 mm, 30 days average until 10/7/2025: SMA) and were able to update the focus values. The table below summarises the last focus tries of the session:

There was only time to obtain three beam maps in total power, finally on 2230+114, with focus optimised to Ar2 (scan 20250713s45) and to Ar1/3 (scans 20250713s47 and s78). For the last one, we adopted the correction of Ar1. This mini-shift finished at 07:30 (LT) with a skydip (scan s79).