NIKA2 Re-Commissioning

March 18th-25th + ...

NIKA2 run 72
Cryo run 84

Tuesday, March 18th, 2025

@10:30 a.m. Angel, Carsten, Monica, Stefano and maaany others arrived at the Telescope. There is a lot of snow 2-3m or more, accumulated by the wind in some spots), the windows of the dining room are completely covered. The sky is cloudy, but it seems that it might clear up a bit later. No precipitation at the moment

In the morning we check the NIKA2 traces:

• Ar1 looks fine.
• Ar3 has a big noise bump at ~0.3 Hz, common to all KIDs
• Ar2 has noisy KIDS in Box C. There is also a noise peak at ~10 Hz for a number of KIDs and a new spike at 6 Hz for KID KA156.

TBD We will upload some pics later

We have a briefing to make the point of what needs to be done first.

• the make-imbf is ready to be started and used. Both new and old versions are set to the current commissioning run
• New sweep: done on Wed 12/3. Ar1 OK. Ar3 noise bump. A second sweep was done on Fri 14/3, adjusting the Ar3 one. It looks better. Ar2 has the original sweep, defined in October 2024.
• Radio alignment check. the weather is not good enough. Maybe on Thursday we will have a chance. At the beginning we will start the operations without checking the alignment. Meanwhile we'll ask Dave if he'd be available on Thursday.
• check DAQ on sky. This is the first operation we will do:
  • Point a bright source (Mars, a QSO, or else, depending on the time of the day). and start an OTF
  • Check traces to verify that we see the source
  • check also the beam width on the traces

  • this will already tell us if a) we are on source; b) there are any problems with the dichroic and the beam

• small beam map: we will observe a small beam map (script already prepared by Nicolas and Angel), to be used by Nicolas to produce preliminary KIDPARS for the IDL pipeline
• with this, Nicolas will produce the first Kidpars.
• meanwhile we might observe already a first standard beam map for preliminary PIIC DAFs
• once the preliminary KIDPARS are ready, we proceed with pointing, focus, standard beam map, to be used to produce KIDPARS and DAFs for the whole array(s)
• with the big (standard) beam maps, Stefano will produce preliminary DAFs and Nicolas the KIDPARS
• once they're ready, we can start the PIIC Ql and we can give some peaceful time to Nicolas
• the standard beam map will give us already the followingnpieces of information:
  • DAFs/KIDPARS
  • flat field (i.e. is the dichroic healthy?)
  • focus difference between the three arrays
• we'll then loop on pointing, focus, primary calibrators and calib_1scan, with the aim to collect enough statistics for:
  • determine the new absolute flux calibration factors
  • study the difference of focus between the three arrays
  • derive new P2 and P7 values for the pointing model (Manuel is here and can help with this)

We decide also that if we have dead times, there's no problem: we will avoid to put ourselves under pressure/stress and we will take the needed time to tackle possible problems/mistakes, discuss ideas and analyze the situation.

@13:15 LT: De-icing is switched on full power, but it's not fully working, there's some ice on the dish.

@15:25 LT: the Ar3 bump moved from 0.3 Hz to 0.6 Hz

@17:20 LT: it's still slightly snowing. Sometimes we see blu patches of sky. We check the main dish: it's mostly clean, except the upper-right rim and one of the four sub-reflectors supports. We park the antenna facing the "faint" sun, hoping it helps.