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Daily Reports (2026/10/6-13, NIKA2 run 81, Cryo run 93)

Observers on-site: Rémi, Giorgos, Mairi, Miren

AoD: Ioannis

Operators: Pedro, Sergio

Focus sequences

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
  20261007s25-29	Mars	1.85 mm	1.71 mm	1.70 mm	no	with run92.ini and old DAFs
  20261007s33-37	Mars	1.76 mm	1.63 mm	1.59 mm	no	with run92.ini and old DAFs
  20261007s43-47	1156+295	2 mm	1.75 mm	1.75 mm	no	with run92.ini and old DAFs
  20261007s48-52	1156+295	2.2 mm	1.75 mm	1.8 mm	no	with run92.ini and old DAFs
  20261007s53-57	1156+295	2.05 mm	1.78 mm	1.8 mm	no	with run92.ini and old DAFs
  20261007s58-62	1156+295	2.3 mm	1.85 mm	1.83 mm	no	with run92.ini and old DAFs
  20261007s65-69	1641+399	2.35 mm	1.7 mm	1.74 mm	no	with run92.ini and old DAFs
  20261007s70-74	1641+399	1.9 mm	1.75 mm	1.75 mm	no	with run92.ini and old DAFs
  20261007s75-79	1641+399	1.9 mm	1.69 mm	1.71 mm	no	with run92.ini and old DAFs
  20261007s80-84	1641+399	2.22 mm	1.93 mm	1.96 mm	no	with run92.ini and old DAFs, with the original focus script (0.4 mm steps)
  20261007s97-101	1641+399	2mm	1.5mm	1.52mm	no	with run92.ini and old DAFs, with the original focus script (0.4 mm steps), a2 not well constrained
  20261007s162-166	2200+420	1.05 mm	0.7 mm	0.71 mm	no	with run92.ini and old DAFs

  Focus sequences
  Scan nr	Target	Ar2	Ar1	Ar3	Polarized?	Notes
  20261008s1-5	Uranus	1.36 mm	1.09 mm	1.09 mm	no	with run92.ini and old DAFs
  20261008s11-15	Uranus	1.55 mm	1.09 mm	1.10 mm	no	with run92.ini and old DAFs. Starting on A1 value. Not great at 2mm. Using peak values
  20261008s16-20	Uranus	1.55 mm	1.18 mm	1.18 mm	no	with run92.ini and old DAFs. Starting on A2 value. Using peak values
  20261008s25-29	Uranus	1.51 mm	1.09 mm	1.11 mm	no	with run92.ini and old DAFs. Starting on A1 value. Using peak values
  20261008s31-35	Uranus	1.41 mm	1.14 mm	1.14 mm	no	with run92.ini and old DAFs. Starting on A2 value. Using peak values
  20261008s40-44	Uranus	1.47 mm	1.09 mm	1.08 mm	no	with run92.ini and old DAFs. Starting on A1 value. Using peak values
  20261008s45-49	Uranus	1.51 mm	1.17 mm	1.17 mm	no	with run92.ini and old DAFs. Starting on A2 value. Using peak values
  20261008s56-60	Uranus	1.32 mm	1.11 mm	1.11 mm	no	with run92.ini and old DAFs. Starting close to A2 value. Using peak values
  20261008s67-71	Uranus	1.43 mm	1.05 mm	1.06 mm	no	with run92.ini and old DAFs. Starting close to A1 value. Using peak values
  20261008s67-71	0316+413	1.34 mm	0.99 mm	0.99 mm	no	with run92.ini and old DAFs. Starting close to A1 value. Using peak values
  20261008s75-79	Uranus	1.43 mm	1.05 mm	1.06 mm	no	with run92.ini and old DAFs. Starting close to A1 value. Using peak values
  20261008s218-222	Uranus	1.24 mm	0.89 mm	0.88 mm	no	with run93.ini new DAFs. Starting close at fz=1mm. Using peak values

  Focus sequences
  Scan nr	Target	Ar2	Ar1	Ar3	Polarized?	Notes
  20261009s5-9	Uranus	1.38 mm	1.11 mm	1.13 mm	no	with run93.ini new DAFs. Starting at 1.2
  20261009s10-14	Uranus	1.46 mm	1.13 mm	1.14 mm	no	with run93.ini new DAFs. Starting at 1.6
  20261009s21-25	Uranus	1.61 mm	1.25 mm	1.24 mm	no	with run93.ini new DAFs. Starting at 1.75 to reach Ar2 circularity. Peak value are reported but we use fz=1.95 afterwards.
  20261009s32-36	Uranus	1.66 mm	1.3 mm	1.3 mm	no	with run93.ini new DAFs. Starting at 1.4.

Beam maps

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

• Beam maps (99 sub-scans)
  Scan Nr	Target	Focus	Notes
  20261007s30	Mars	1.71 mm (Ar1)	run93, new sweep
  20261007s39	Mars	1.63 mm (Ar1)	run93, new sweep
  20261007s181	0316+413	0.8 mm (Ar1)	run93, new sweep, pointing on ???
  20261008s8	0316+413	1.1 mm (Ar1)	run93, new sweep, pointing on Ar1
  20261008s23	Uranus	1.18 mm (Ar1)	run93, new sweep, pointing on Ar1
  20261008s38	Uranus	1.14 mm (Ar1)	run93, new sweep, pointing on Ar1
  20261008s52	Uranus	1.51 mm (Ar2)	run93, new sweep, pointing on Ar2
  20261008s63	Uranus	1.11 mm (Ar1)	run93, new sweep, pointing on Ar1
  20261008s90	Uranus	1.05 mm (Ar1)	run93, new sweep, pointing on Ar2
  20261008s224	Uranus	0.89 mm (Ar1)	run93, new sweep, pointing on Ar2 (but Ar1/3 are now aligned)
  20261009s16	Uranus	1.46 mm (Ar2peak)	run93, new sweep, pointing on Ar2
  20261009s27	Uranus	1.95 mm (Ar2circ)	run93, new sweep, pointing on Ar2. Focus to maximize Ar2 circularity of the beam.
  20261009s38	Uranus	1.3 mm (Ar1)	run93, new sweep, pointing on Ar2 (but Ar1/3 are now aligned)

Changes in sweep

Please keep track of sweep changes: it makes our life easier when building the DAFs/Kidpars.

• Changes of sweep
  Sweep	Scan Nr	Time	Notes
  OLD	up to 20261007s29		for pointing & focus
  NEW	20261007s30		beammap
  OLD	20261007s31-38		for pointing & focus
  NEW	20261007s39		beammap
  OLD	20261007s42-		for pointing & focus
  NEW	20261007s180-		beammap
  OLD	20261007s182		for pointing & focus
  NEW	20261008s7-		beammap
  OLD	20261008s9		for pointing & focus
  NEW	20261008s22-		beammap
  OLD	20261008s24		for pointing & focus
  NEW	20261008s37-		beammap
  OLD	20261008s39		for pointing & focus
  NEW	20261008s51-		beammap
  OLD	20261008s55		for pointing & focus
  NEW	20261008s62-		beammap
  OLD	20261008s65		for pointing & focus
  NEW	20261008s89-		beammap
  OLD	20261008s91		for pointing & focus
  NEW	20261008s97-		beammap

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.

October 6th, 2026, Tuesday

10:30-15:30 : 3/4 observers arrived at the telescope. Rémi planned to arrive later today. Weather horrible. Maintenance ongoing.

Antenna parked all day, clouds, wind, and rain.

October 7th, 2026, Wednesday

07:00LT: pointing and focus tests with old sweep (run92). Difference between Ar2 and Ar1 ~0.35 mm. Difference between Ar3 and Ar1 practically 0.

10:00 - 11:30LT: new sweep by M. Calvo. We now have new run93.ini files.

11:45LT Miren and Ioanns : starting NIKA2 observations to get beammaps for the new sweep. Back to run92 for pointing and focus on Mars. DAQ started, lost KIDs Ar1/Ar2/Ar3: 129/6/14; traces look fine. Opacity between 0.3 - 0.5. Peak-to-peak in Ar2 +/- 4-5 Jy/beam. Focus differences: Ar1 - Ar2 = -0.14 mm, Ar1 - Ar3 = 0.01 mm.

12:45LT: moving to run93 for beammaps. Lost KIDs Ar1/Ar2/Ar3: 21/8/30. To be understood if box I is lost or not. Beammap (20261007s30) focused on Ar1.

13h25LT: back to run92 for pointing and focus before another beammap. Lost KIDs Ar1/Ar2/Ar3: 140/7/15. Moving back to run93 for beammaps. Beammap (20261007s39) focused on Ar1.

14h30LT Miren and Mairi: focus tests with run92. Using the original focus script (with 0.4 mm step) starting from scan 20261007s80.

16h55LT: we try a mini pointing session making use of the sources in the PCCS catalogue provided by S. Berta (we have had to remove the "G" from the names in the end... 13 characters otherwise...) Opacity is ~ 0.35 (tau225 GHz), but a lot of clouds. We can not point, p2p fluctuations @Ar2 of +/- 20 Jy/beam.

19h00LT: We resume. Sky is stable (<5 Jy/beam) and tau around 0.3.

Summary:

October 8th, 2026, Thursday

00:30LT Miren: Stable (=/-2 Jy/beam) and good opacity (~ 0.25). Better beammaps are needed. We move to 0316+413 for first beammaps, waiting Uranus to be high.

01:00 - 07:00 LT, Rémi : stable weather, clear sky and opacity ~ 0.25 for the entire shift.

• 2 beam maps on 0316+413 with focus and pointing optimized for A1, plus several pointing and focus
• 2 beam maps on Uranus with focus and pointing optimized for A1, plus several pointing and focus
• 1 beam map on Uranus with focus and pointing optimized for A2, plus several pointing and focus
• 1 skydip (using the new sweep): scan 20261008s53
• 1 beam map on Uranus with focus and pointing optimized for A1, plus several pointing and focus

• Remarks:

  • 1) the focus offset difference between A1/3 and A2 is about 0.3. However, the A2 (FWHM_x x FWHM_y)^1/2 is alway >21" and the beam is elongated: at best we have ~20"x25". The shape is not the same as the one we use to have. Issue with the current DAFs? The dichroic? Lateral focus (but this should also affect A1/3)? Other? 2) The best focus can vary by up to 0.1mm for A1/3 depending if we start from the current A1/3 or A2 value: systematic positive shift when starting with A2 value.

07:00 - 13:00 LT, Giorgos :

• finish the beammap of Remi's shift and back to old sweep
• IM: After a short chat in the morning with SB, realized that the beam maps should be pointed on Ar2 (as we do with the science observations). I tried to optimize for Ar1 (both focus and pointing), which was not the best practice (sorry!). So, the ones taken during the night with pointing on Ar1 might not be useful. There is one from the Rémi's shift that could be used (20261008s52, see beam maps table above) and I take another two with the proper setup (poi corr on Ar2, focus corr on Ar1) in the morning (20261008s90 and 20261008s98), starting at an elevation of about 35 degrees. Data processing for new DAFs are in progress by SB.
• start test scans of project 092-26. Opacity increasing. Ar2 beam very elongated.

13:00 - 19:00 LT, Mairi : Taking over shift from Giorgos. Continuing test scans for project 092-26. One repetition completed (s112 and 113). Unstable sky (+/-10Jy/beam), waiting to see if improves before continuing.

18:00 LT, SB. I've been processing the beam maps taken during the last night/morning with good weather and on Uranus and 0316+413. The result is good for Ar1. Ar3 is still downloading and I will then process it later tonight. And about Ar2... oh well, the beam is confirmed to be very elongated, even when supposedly "on focus". The position angle (PA) of the beam ellipse is rotating in AzEl, I guess as a function of Elevation. To give you an idea, here I include the sequence of Ar2 beam maps f.o.v., in the hope that this will help the instrument/hardware experts to figure out what is happening.

CK: As Array 2 was moved by 17mm, is it possible that Array 2 is now very far out of focus ? SB: yes I had this thought as well. It will be tested tonight

19:00 - 01:00 LT, Ioannis :

• weather improves around 19:30, so we start with pointing and focus on 2251+158
• stability gradually improves and we decide to have a closer look on the focus and the extended beam of Ar2
• we noticed with focus scans of the previous days that there is a mismatch between the peak position of the focus curve in Ar2 and the position where one would "expect" the array to be focused based on the beam symmetry. The "symmetry" best focus position seems to be about +0.4mm from the "peak" best focus position.
• note that the above cannot be concluded by the "FWHM" focus curve (white focus curve), which usually seems in good agreement with the "peak" focus curves (green and red focus curves), possibly because the "FWHM" focus curve estimates the quadratic sum of the major and minor beam sizes and cannot assess the beam ellipticity
• so to summarize the Ar2 focus situation we see: Ar2 becomes best focused "peak-wise" at a certain focus position (this is the position that is about +0.35mm from the Ar1 optimal focus position) BUT seems to become best focused "ellipticity-wise" (i.e. more circular) at another position, which is another +0.3mm to +0.4mm from the best "peak-wise" focus position (and about +0.6mm to +0.7mm from the Ar1 optimal focus position)
• another note: apart from the focus difference, there is a X-Y pointing difference between Ar2 and Ar1/Ar3. it is more evident in elevation with [Ar2_elv minus Ar1/3_elv about -11" to -12"] and less profound in azimuth with [Ar2_azi minus Ar1/3_azi about -5"]
• to investigate the focus situation across the arrays, I ran a series of focus sequences covering an extended range of focus offsets to see the beam behavior in all three arrays. below I describe the procedure and findings:

Extended focus test procedure:

• start with a focus sequence to estimate the best focus position of all three arrays
• using the Ar1 focus as "anchor" point, let's call it f_a, run 3 focus sequences (of the "old" type, i.e with the 0.4mm steps) at the following start positions: (f_a - 1.6mm), f_a and (f_a + 1.6mm)
• this will create 15 focus "stamp images" over a focus range from (f_a - 2.4mm) to (f_a + 2.4mm)
• between focus sequences, the pointing is corrected according to the Ar2 offset
• a first test of this extended focus procedure was ran for source 2251+158 and very stable sky conditions (about 1-2 Jy/beam) and low opacity (tau_225 = 0.2-0.3). the 3 focus sequences that cover the extended focus range are 20261008s143-147 (middle part), 20261008s149-153 (left side part) and 20261008s156-160 (right side part).
• another test was done again on the same target, after the installation of the new DAFs (run93, see below). The conditions further improved (tau_225 = 0.15) and the results look of much higher quality than the first test above. The 3 focus sequences that cover the extended focus range are 20261008s184-188 (middle part), 20261008s190-194 (left side part) and 20261008s196-200 (right side part). Here is an overview of the extended focus sequences for all three arrays (Ar2, Ar1 and Ar3 from top to bottom):

• Hopefully these plots and the calibration/test data we will gather tonight will help understand the issue with Ar2

23:00 LT, SB: the new NKFR and RPP DAFs for the new sweep are now installed and running at Pico. They are still preliminary (based on one scan only), but they're fine. From now on, we are not going to use the old sweep anymore. And from now on, the run number is N2R81 and cryo run 93. The first scan (permanently) obtained with the new sweep is 20261008s176. Below here comes the f.o.v. of the adopted beam maps used for the these N2R81 RPPs. Good night

• After the new DAFs installation, the pointing offset between the three arrays is eliminated (as expected). Now all arrays agree in pointing within 1-2 arcsec. A new pointing session will also help us fix the absolute pointing offset.
• From the traces point of view, box I looks normal, i.e. if someone looked only at the traces cannot imagine that box I is dead. not sure what is happening there.

October 9th, 2026, Friday

01:00 - 07:00 LT, Rémi : opacity is very good over the shift, ~0.15. The stability is great. Some (relatively low) wind.

• Moving to Uranus
• Pointing, focus optimized for A1. Beammap. calib_1scan
• Pointing, focus optimized for A2 (maximizing the peak). Beammap. calib_1scan
• Pointing, focus optimized for A2 (maximizing the circular shape). Beammap. calib_1scan
• Pointing, focus optimized for A1. Beammap. calib_1scan.
• Skydip
• Moving to ALFORI: 12 calib_1scan, which could be used for first sensitivity estimates in good conditions
• Skydip
• Starting a new pointing session with the new DAFs using Planck sources (PCCS2_Berta2026)

• Remarks:
  • At midnight, the imbfits for pointing scan 20261009s1 (following a beammap, i.e. heavy) were never produced. Running another made it worked fine. This appened again after beammap 20261009s16.
  • For some reason piic is not reducing the ALFORI scans at 2mm.
  • XEPHEM crashed during the shift: segmentation fault (core dumped).

CK: At 2mm, is it possible that we are finding only a secondary maximum showing an elongated beam due to some astigmatism ? Do we need to scan the z-focus over a much wider range to find the main maximum, where the beam is 18" and circular ?

IM: I could run an even extended focus sequence for this but not sure of the system limitations (e.g. PaKo focus limits etc). I'll try to find out.

October 10th, 2026, Saturday

October 11th, 2026, Sunday

October 12th, 2026, Monday

October 13th, 2026, Tuesday