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Daily Reports (2026/01/06-13, NIKA2 run 78, Cryo run 90)

Observers on-site: Beth Jones, Michael Logue, Remi Adam, Tuan-Anh Duong

Astronomer-of-Duty: Stefano Berta Pool Manager: Angel Bongiovanni

Operators: Kike (day), Frederic (night)

Organization of shifts:
trac 21:00-03:00 UT: Tuan-Anh
03:00-09:00-10:00 UT: Remi
09:00:15:00 UT: Beth
15:00-21:00 UT: Michael

Preparatory notes

Please fill the Table with the Ar1,2,3 focus values as follows. At best, make one table per day.

• Focus sequences
  Scan nr	Target	Ar2	Ar1	Ar3	Polarized?	Notes
  20260107s29-33	Uranus		~0.6	~0.8	yes	using old make-imbf, Ar2 out of range; started at 1.2 mm
  20260107s55	3C273	-0.18			yes	Using A2 and shift the value by 0.6 to center on A1

Similarly, if any beam maps (total power) are taken:

• Beam maps (99 sub-scans)
  Scan Nr	Target	Focus	Notes

Pool-Account usage: Accounting of observing times

• Calibration observations like pointing, focus, and calib_1scan (the latter in case of NIKA2-Pol only, aimed at characterizing the instrumental polarization) which are conducted before and during project observations are part of the project time. Note that all proposals include such overheads in the time and sensitivity estimates. This holds for total power and polarimetry observations.

• Other calibration observations which are important for all projects like beam maps, skydips, or calib_1scan for absolute flux calibration may be accounted under the pool account (nikaX-YY, where X = s,w and YY = year).

• When conditions are unstable and it is unclear whether project observations make sense at all, calibrations may be accounted to the pool account.

Tuesday 6th January 2026

@9:30 UT: the team arrived safely to the telescope. Blue skies, low tau, strong winds.
Short briefing to share important mountain information and recommendations. We re-organize the shifts (see top of this page).

@13:30 UT: system checks finished, Dave goes back to Granada. Starting the rotation of the HWP required to reboot the DAQ few times and also the mppsync server.
NIKA2 system setup completed: DAQ running, HWP rotating, NIKA2 window open, PaKo running, QL monitors x6 running, make-imbf new/old running. We wait only for the wind to calm down.

@14:00 UT Alessandro and Martino ask for some time to remotely check the amplifier of the noisy Box C (Ar2). They think that this enhanced noise might be due to the polarization of the Box C amplifier, that needs to be re-set from time to time. Alessandro and Martino check the amplifier. In Alessandro's words: "The gain of the amplifier C is too low. (...) I could fix it by playing with the parameters of the amplifier C but now with the parameters that worked in June 2025 it is not working anymore (...) it seems that the third stage of the amplifier C (YL026, the one that we have installed in June) is not working. The gain must thus be much lower, and adding noise. Just the less gain doesn't explain what we observe", though.

@15:00-21:00 UT Michael + all. Taumeter tau < 0.1. The telescope is parked because of the high wind. We take the chance to have a long explanation about NIKA2 operations. In the next days we hopefully will be able to put in practice what we learned.

@21:00-03:00 UT Tuan-Ahn + Stefano. We start observing at 22:30 UT. It takes some time to set everything. We need to reboot crates 3 and 1, the DAQ and the HWP rotation. All good now. Lost KIDs: 18/7/12 in Ar1/2/3. The first pointing scan is at 23:05 UT: 20260106s17.

The secondary mirror (M2, subreflector) is a capricious tonight and sends errors at every scan, including tracks:

• we suspect that PaKo might be sending some conflicting information.

• the PaKo green window seems to be missing some info? We're not 100% sure, tbh.

• we reboot PaKo and set it up manually, because the ini.pako file cannot be edited with emacs even if we change the permissions to "rw". Weird.

  • More specifically: the ini.pako file has project nikas-25 and the catalogs are all commented out. This should not affect M2, though!
• we try again with a new track scan (nr 21). It seems now to work... uhm, nope, subreflector "vertical 2" error again.
• we compare the nikaw-25 ini.pako to the nikas-25 ini.pako and they're identical. It was working in S25, it should work now too. Besides, it was working also in W25 in the December pool week. Therefore the problem is not the ini.pako file.
• we edit the NIKA2 ini.pako file with nano and we can modify it normally. We fix the project and un-comment one catalog.
• we try a couple of scans with EMIR, without switching NIKA2 off. No M2 errors appear. The chopper does not work, though, not even in manual mode.
• sending an EMIR calibration with a manually changed Z-focus position in EMIR produced again the M2 error
• we try a sequence of short EMIR scans with Z-focus of +0.5, +1.0, +1.5, -0.5, -1.0, -1.5 -2.0 mm and no M2 error appears. Maybe these movements have unlocked something that was obstructing M2?
• side note: today's temperature reached -17 C
• we switch again to NIKA2 and try again. Focus Z=1.0 X=1.9 Y=-0.78 mm. Immediate M2 error
• new test
  • we comment out the XY focus offsets in the NIKA2 ini.pako file

  • we start PaKo again and perform a track on Uranus. All fine, no M2 errors. We switch PaKo off.

  • we comment out only the Y focus offset in the NIKA2 ini.pako file

  • we start PaKo again and perform a track on Uranus. All fine, no M2 errors. We switch PaKo off.

  • we comment out only the X focus offset in the NIKA2 ini.pako file

  • we start PaKo again and perform a track on Uranus. All fine, no M2 errors. We switch PaKo off.

  • we keep the XY focus offsets in the NIKA2 ini.pako file, as in the very beginning.

  • we start PaKo again and perform a track on Uranus. All fine, no M2 errors.

  • what just happened??? it's all fine! 2 hours lost out of this problem and we don't know how we solved it and what we solved. Sigh.

Now the observations can start. But the DAQ has lost part of Ar3. We tune again. After 4 tuning with Boxes P and Q completely lost, we stop the HWP rotation and reboot the DAQ. KIDs lost: 15/7/12. We finally start the observations at 1:09 UT

Obviously the new make-imbf ain't working. I try to produce by hand the imbf of scan 26 and it tells "LD_LIBRARY_PATH unbound variable". Same for some old_ldpath. This was with Stefano's account. We try with the operator's account. It gives the same message. We have to work with the old one for now. We're in polarimetry and we should focus on Ar1 -> very slow. Perfect weather!

Not bad this NIKA2 2026 start! We had every possible hic-hup in one night. The next 6 weeks can only be smooth

Pointing, focus, calib_1scan on Uranus (although now at low elevation). 1 rep on 015-17 and one calib_1scan on 3C286

Wednesday 7th January 2026

03:00-09:00 UT Remi

Start with pointing on 3C286, with the goal of doing calibration on 3C286, 3C273 and 3C279 (in polarization mode). The imbits files are very long to create. Cannot reduce the pointing. We lose 30mn of time due to this issue. On A2, channel C is extremely noisy. A focus is needed. Go to 3C 273 and focus. Do calib_1scan on 3C273 and 3C279. Switch to total power. Lost KIDs 12/8/8 Pointing on 1807+698. The beam is reasonable at 2mm. Switch to project 197-25. Repetition 1 on 1st target. Pointing on 1807+698, beam acceptable (17x19). Repetition 2 on 1st target. Pointing on 1807+698, beam acceptable (17x19). Repetition 3 on 1st target.