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Daily Reports (2026/02/17-24, NIKA2 run 79, Cryo run 91)

Observers on-site: Sunayana Bhargava, Andrés Zuleta, Vito Aberham, Miren Muñoz (until Friday), Albrecht Sievers (from Friday on)

Astronomer on Duty: Ioannis Myserlis (and Miren Muñoz on AoD training)
Pool Manager: Angel Bongiovanni

Operators: Joaquín Santiago (night), Sergio Amaya (day)

Organization of shifts:
21:00-03:00 LT: Sunayana Bhargava
03:00-09:00 LT: Miren Muñoz / Albrecht Sievers
09:00:15:00 UT: Andrés Zuleta
15:00-21:00 UT: Vito Aberham

Important

Focus offsets shall be measured on Ar1
Pointing offsets shall be measured on Ar2

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 ; nikaw-25 in this case).

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

Focus and Beam maps accounting

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

• Focus sequences (NOTE: Ar2 is very noisy and this might influence the A2 focus value)
  Scans nr.	Target	Ar2	Ar1	Ar3	Pol?	Notes
  20260217s127-131	Uranus	?	0.45	0.98	Y	started focus @ 0.25mm
  s167-171	Uranus	0.57	?	?	Y	started focus @ 0.45mm
  s172-176	Uranus	0.63	?	?	Y	started focus @ 1.3mm
  s177-181	Uranus	?	1.62	1.86	Y	started focus @ 1.9mm
  s203-207	3C84	?	1.35	1.55	Y	started focus @ 1.62mm
  20260218s16-20	3C279	?	1.52	1.85	N	started focus @ 1.35mm
  s23-27	3C279	?	1.55	1.75	N	started focus @ 1.85mm
  s30-34	3C279	0.55	?	?	N	started focus @ 0.55mm
  s38-42	3C279	?	1.66	1.90	N	started focus @ 1.55mm
  s99-103	Uranus	0.64	?	?	Y	started focus @ 1mm
  s104-108	Uranus	?	1.62	1.91	Y	started focus @ 1.7mm
  s119-123	Uranus	?	1.51	1.67	Y	started focus @ 1.62mm
  s134-138	Uranus	?	1.27	1.52	Y	started focus @ 1.51mm
  20260219s69-73	1757-240	0.50	?	?	N	started focus @ 1mm
  s74-78	1757-240	?	1.58	1.80	N	started focus @ 1.7mm
  s89-93	MWC349	?	1.83	2.3	N	started focus @ 1.58mm
  s103-107	MWC349	?	1.54	1.76	N	started focus @ 1.83mm
  s111-115	MWC349	?	1.39	1.62	N	started focus @ 1.54mm
  s118-122	MWC349	?	1.3	1.6	N	started focus @ 1.39mm
  s148-152	Uranus	?	1.09	1.3	Y	started focus @ 1.3mm
  s177-181	Uranus	?	1.36	1.60	Y	started focus @ 1.49
  s211-215	1226+023	?	1.18	1.39	Y	started focus @ 1.36mm
  20200220s10-14	1807+698	?	1.43	1.64	N	started focus @ 1.31mm
  s36-40	1928+738	?	1.49	1.75	N	started focus @ 1.43mm
  s55-59	2251+158	?	1.45	1.71	N	started focus @ 1.49mm
  s75-79	2251+158	?	?	0.61	N	started focus @ 1.45mm
  s80-84	2251+158	?	0.46	0.61	N	started focus @ 0.61mm
  20260220s102-106	2251+158	?	0.30	0.49	N	started focus @ 0.46mm
  20260220s112-116	2251+158	?	0.55	?	N	started focus @ 0.29mm
  20260220s117-121	2251+158	?	0.62	0.81	N	started focus @ 0.69mm
  20260220s132-136	Uranus	?	1.09	?	Y	started focus @ 0.62mm
  20260220s137-141	Uranus	?	0.97	1.26	Y	started focus @ 1.09mm
  20260220s155-159	Uranus	0.24	1.48	?	Y	started focus @ 0.97mm
  20260220s160-164	Uranus	?	1.37	1.6	Y	started focus @ 1.40mm
  20260220s185-189	Uranus	?	1.50	1.72	Y	started focus @ 1.37mm
  20260221s24-28	1226+023	0.4	?	?	N	started focus @ 0.57mm; bad fitting for Ar1 and Ar3
  20260221s39-43	1226+023	0.45	1.36	1.57	N	started focus @ 1.5mm; Ar2 from FWHM only
  20260221s47-51	1757-240	?	1.35	1.59	N	started focus @ 1.38mm
  20260221s62-66	2251+158	0.53	1.43	1.75	N	started focus @ 1.35mm; Ar2 from FWHM only
  20260221s79-83	2251+158	?	0.6	0.92	N	started focus @ 1.44mm
  20260221s85-89	2251+158	?	0.6	0.95	N	started focus @ 0.58mm
  20260221s103-106	Uranus	?	0.27	0.47	Y	started focus @ 0.58mm
  20260221s108-118	Uranus	?	0.18	0.37	Y	started focus @ 0.27mm
  20260221s114-118	Uranus	?	0.16	0.38	Y	started focus @ 0.18mm
  20260221s152-156	Uranus	?	1.02	1.27	Y	started focus @ 1.40mm
  20260221s174-178	Uranus	?	1.23	1.48	Y	started focus @ 1.02mm
  20260221s194-198	Uranus	?	1.26	1.46	Y	started focus @ 1.23mm
  20260221s212-216	1226+023	?	1.40	1.76	Y	started focus @ 1.31mm
  20260222s18-22	1226+023	0.69	1.9	?	Y	started focus @ 1.4
  20260222s23-27	1226+023	0.9 ?	1.75	2.03	Y	started focus @ 1.8
  20260222s30-34	1226+023	0.66	?	?	Y	started focus 0.9
  20260222s37-41	1807+698	0.69	?	?	N	started focus @ 0.9
  20260222s57-61	1757-240	?	1.43	1.65	N	started focus 1.5
  20260222s73-77	2241+158	?	1.32	1.56	Y	started focus 1.43
  20260222s95-99	2241+158	?	0.95	1.18	Y	started focus 1.32
  20260222s100-104	2241+158	?	0.89	1.19	Y	started focus 0.95
  20260222s119-123	Uranus	?	0.50	0.72	Y	started focus @ 0.89
  20260222s155-159	ALFORI	?	0.58	0.84	Y	started focus @ 0.50mm
  20260222s164-168	Uranus	0.3	?	?	Y	started focus @ 0.58mm
  20260222s169-173	Uranus	?	0.80	1.05	Y	started focus @ 0.98mm
  20260222s191-195	Uranus	?	1.08	1.30	Y	started focus @ 1.18mm
  20260223s8-12	1226+023	0.41	?	?	Y	started focus @ 1.08mm
  20260223s13-17	1226+023	?	1.41	1.71	N	started focus @ 1.41mm
  20260223s18-22	1226+023	?	1.46	1.65	N	started focus @ 1.71mm
  20260223s24-28	1226+023	0.57	1.46	1.77	N	started focus @ 1.46mm; Ar2 from FWHM only
  20260223s30-34	1226+023	0.65	1.55	1.74	N	started focus @ 1.77mm; Ar2 from FWHM only
  20260223s36-40	1226+023	0.53	?	?	N	started focus @ 0.4mm
  20260223s49-53	1928+738	0.61	1.62	1.9	N	started focus @ 0.4mm; Arr3 from FWHM only
  20260223s59-63	1757-240	?	1.74	2.1	N	started focus @ 1.60mm
  20260223s65-69	1757-240	?	1.61	1.84	N	started focus @ 1.74mm
  20260223s81-85	2200+420	?	1.27	1.50	Y	started focus @ 1.61mm
  20260223s126-130	Uranus	?	0.07	0.12	Y	started focus @ 0.27mm
  20260223s173-177	Uranus	0.49	?	?	Y	started focus @ 0.07mm
  20260223s178-182	Uranus	?	0.61	?	Y	started focus @ 0.47mm
  20260223s182-187	Uranus	?	0.62	0.88	Y	started focus @ 0.87mm
  20260223s192-196	ALFORI	-0.32	0.78	1.08	Y	started focus @ 0.62mm
  20260223s200-204	Uranus	?	0.88	1.40	Y	started focus @ 0.78mm
  20260223s214-218	Uranus	0.10	1.15	?	Y	started focus @ 0.88mm
  20260223s219-223	Uranus	?	1.05	1.28	Y	started focus @ 1.15mm
  20260224s9-13	1226+023	0.68	?	?	Y	started focus @ 1.05mm
  20260224s14-18	1226+023	?	1.56	1.76	Y	started focus @ 1.68mm
  20260224s27-31	1253-055			1.9	Y	started focus @ 1.76mm
  20260224s33-37	1253-055	0.7	-	-	Y	started focus @ 0.7mm
  20260224s41-45	1928+738	0.78	1.69	1.99	Y	started focus @ 1.56mm; Ar3 from FWHM only
  20260224s56-60	1757-240	?	1.66	1.91	N	started focus @ 1.68mm

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

• Beam maps
  Scan Nr	Target	Focus	TP (99 subscans) or Pol (95 subscans)	Notes
  20260218s22	3C279	1.52	TP	Ar1
  20260218s29	3C279	1.75	TP	Ar3
  20260218s37	3C279	0.55	TP	Ar2
  20260221s17	3c273	1.53	TP	Ar1
  20260221s18	3c273	1.75	TP	Ar3
  20260221s29	3c273	0.5	TP	Ar2
  20260222s28	3c273	1.75	Pol	Ar1
  20260222s29	3c273	2.03	Pol	Ar3
  20260222s35	3c273	0.66	Pol	Ar2
  20260223s29	3c273	1.46	TP	Ar1
  20260223s35	3c273	1.75	TP	Ar3
  20260223s41	3c273	0.66	TP	Ar2
  20260224s24	3C279	1.56	Pol	Ar1
  20260224s32	3C279	1.88	Pol	Ar3
  20260224s38	3C279	0.7	Pol	Ar2

Tuesday, 17th February 2026

10:30-15:30: All observers arrived safely at the telescope. Weather prediction looks amazing for the week and we are all excited to make progress with the NIKA2 pool projects! Maintenance time.

15:30-21:00 all: Starting with NIKA2-Pol observations, project 084-25. Tuning good with 11/5/11 bad kids (Ar1/2/3).

• Pointing, focus and calib_1scan (20260217s133, for IP) on Uranus. Focus difference between Ar1 and Ar3 seems to be increased to about 0.55mm. Let's see how it evolves this week.
• 1 rep on G139.9091 with stable sky (+/- 2 Jy/beam in Ar2).
• Going back to Uranus for IP calib_1scan (20260217s145), no need to refocus.
• 2nd and last repetition on G139.9091 with stable sky (+/- 0.5 Jy/beam in Ar2).
• Since 6pm local time, telescope oscillations alarm/problem appeared 4 times, interrupting the observations. Only finished scan 1/6 before another interruption.
• Telescope oscillations problems continue and happen always after the 1st scan of the map.

• To finish the last map of G139.9091 for project 084-25, we load each scan separately. We tried to send all of them in the queue and the problem still occurs after the 1st (individual) scan is finished. It seems that we need to restart the control system before every single scan is sent to the telescope! Oh god!

• Right before the end of the shift telescope oscillations/stuck scan problem resolved with the intervention of AJ (thanks!). Let's hope for a smooth evening & night of NIKA2 observations.

21:00-03:00 Sunayana: Change to project 015-17, still in NIKA2-Pol mode. Sky conditions excellent (< 2 Jy/beam in Ar2) and opacity great (< 0.15).

• pointing, focus and calib_1scan (20260217s183, for IP) on Uranus. Focus difference between Ar1 and Ar3 restored to previously expected value (0.24mm). Ar2 vs Ar1 focus difference about 1mm.
• 1 repetition on NGC2024N
• Back to Uranus for IP calib_1scan (20260217s191), no need to refocus, Ar1 and Ar3 focus very good.
• 1 repetition on NGC1333S
• Back to Uranus for IP calib_1scan (20260217s199).
• Starting project 146-25. Pointing and focus on 0316+413 (3C84). Beam is a bit elongated but not too bad. Sky conditions remain stable (+-2 Jy/beam)
• Calib_1scan (20260217s209, for IP) done on 0316+413 (3C84).
• Doing a second calib_1scan (20260217s212, for IP) on another weakly polarised source (1226+023)
• One repetition of S255IR
• Calib 1scan (20260218s8, for IP) on the same source 1226+023. Beam still a bit elongated as before the science sequence. Sky conditions still very favourable at +-2 Jy/beam
• Skydip calibrations (20260218s9)
• Change to NIKA-2 total power mode

Wednesday, 18th February 2026

03:00-09:00 Miren: Starting total power (10, 5, and 14 bad KIDs). Opacity < 0.15 or ~ 0.15 during the shift.

• Focus on 1253-055 (3C279) before each beammap (3C279), optimising focus for each array + pointing corrections. Ar1 beammap: 20260218s22. Ar3 beammap: 20260218s29. Ar2 beammap: 20260218s37.
• Focus again for Ar1 and move to project 197-25. Started with a nearby source pointing (1807+698). Good sky conditions: opacity below 0.15, p2p +/- 1 Jy/beam @Ar2. Array1 beam: 11.1 x 11.6 arcsec. EDFN_CL3 is already at an elevation of 50 deg, so we start with 1 repetition on this source. The presence of clouds may explain the p2p of +/-7 Jy/beam @Ar2 we observe in the pointing scan at the end of the repetition.
• We move to nika2w-25 for a skydip (20260218s53) and check again the stability with a pointing on 1807+698, p2p back to +/- 0.5 Jy/beam @Ar2. Beam for Ar1 11.4 x 12.7 arcsec, ready to resume project 197-25.
• Project 197-25: 1 more repetition on EDFN_CL3.

09:00-15:00 Andres: Continue with total power, trying to focus first.

• Focus and pointing scans for various targets at different directions give high tracking errors. Wind speed is increasing (spikes 1t 12-14 m/s).
• Around 10:00 (local time) tracking errors too high to process with PIIC. Clouds pass by.
• We change to EMIR to compare with its tracking error results.
• We got an alert due to tracking errors, we will stop observations (10:06 UT).

15:00-21:00 Vito: Telescope remains parked due to high wind gusts (15:10 LT).

• Briefly tried again with EMIR at 16:00 LT, tracking errors due to wind appeared right away. We stop observations again.
• Trying again at 19:30 LT, now switching to NIKA2-Pol mode (bad kids 10/6/16 for Ar1/2/3). Go to Uranus to check pointing and focus. Tracking errors lower now but still present for certain scans. Focused on Uranus yields value of 1.62mm.
• We're moving forward with project 015-17. calib_1scan (for IP) on Uranus (20260218s110)
• Pointing on nearby source: Atmosphere looks good with +/-2 Jy/beam. Beams for ar1 and ar3 are elongated (probably artifacts from sunset), with sizes 12x13" and 11x14", respectively, while ar2's beam is very elongated (17x27").
• 1 rep with observe_ngc2024n_polar

21:00-03:00 Sunayana:

• Took over for observations on project 015-17. However, strong wind alarms (~12 m/s) are going off towards the end of the first repetition on NGC2024N.
• [IM] Noticed a small drift of 2% in the phase lock of the HWP (52% instead of 50%) that was not there at the beginning of the repetition on NGC2024N. After stopping the HWP, moving it out and into the optical path again and restarting it, the drift goes away and the behavior goes back to normal. Not sure how the last NGC2024N repetition might have been affected (maybe partially only).
• Back to Uranus for pointing and calib_1scan (20260218s118, for IP).
• Redid the focus on Uranus, followed by a second calib_1scan (20260218s125, for IP)
• 1 repetition on NGC1333S. Opacity still good at ~ 0.2 now. Slight wind alert at the end of scan 129 (the second of three scans).
• Back to Uranus for pointing and calib_1scan (20260218s133, for IP). Focus has deteriorated in Ar1 and Ar3, so will redo focus.
• Second calib_1scan (20260218s140, for IP) on Uranus.
• A second repetition on NGC2024N.
• By the time the second repetition had finished, Uranus had reached an elevation of ~10 degrees, which was considered too low to bracket with the calib_1 (IP) scan. No calib_1 scan was performed. The last scan of this repetition unfortunately also shows a lot of noise and sky variations up to +- 20 Jy/beam (!!) possibly due to wind spikes and worsening weather conditions (see below).
• Moving to project 146-25, and just after the first track and pointing, conditions appear to have significantly worsened due to fog.
• 01:50 LT - operator has decided to park the telescope for at least the next 20 minutes until conditions improve.
• 02:24 LT fog has passed and observations have resumed on project 146-25.
• After doing the first pointing scan, sky conditions are highly unstable, with variations of 15-20 Jy/beam. As this is above the advised limit of 5 Jy/beam maximum variations, we will leave the project 146-25 and revert to calibrations for the nika2-25 pool.
• Performed a focus sequence for the three arrays. Best focus for Ar1 is at 1.21. Using this value and subtracting 1mm, the best focus for Ar2 appears at 0.31. Finally, adding 1.2 to the Ar2 focus, we obtain a best focus for Ar3 at 1.52. This confirms that the difference of 1mm between Ar1 and 2, and the difference of 1.2mm between Ar2 and Ar3 are accurate (20260219 s8-23).
• skydips to finish (20260219s24)

Thursday, 19th February 2026

03:00-09:00 Miren:

• Sky is unstable (+/- 20 Jy/beam @Ar2) and we move to EMIR backup project 102-25. We start with calibration and pointing, but wind affects significantly the pointing, so we move to "test" project. Tried several focus and pointings, but wind is strong.
• At ~ 05:00 LT operator decides to park the telescope.
• 06:10 LT observations have resumed. We start by checking the pointing and move to EMIR backup project 102-25 for 2 repetitions.
• Opacity is still very good (~ 0.1) and EMIR pointings are also reasonable, so we move to NIKA2.
• Telescope oscillations problems continue and happen always after the 1st scan of the map, so we can not focus.

09:00-15:00 Andres:

• NIKA2 TP resumed.
• At 10:00 LT telescope was parked due to wind speeds, which reached a maximum of 23.5 m/s.
• Wind speeds went down. Resuming at 10:37 LT.
• Wind speeds went up. Tracking errors up to 10". The telescope was parked at 11:14 LT.
• Resuming observations at 12:06 LT.
• Oscillation and tracking errors at 12:21 LT. Telescope parked.
• 12:42 - We will test if issues are diminished at directions perpendicular to the wind.
• It seems to work and we continue observations on these directions.
• Flux calibrations (calib_1scan) on MWC349 (20260219s123), NGC7027 (20260219s126) and CRL2688 (20260219s129)

15:00-21:00 Vito:

Taking over with NIKA2 Total Power observations in progress (opacity at ~ 0.122, 14:00 UT).

• Project 196-25 currently in progress: observe_Cl0024 repetition 2/28. Apparently there have been tracking errors caused by high wind gusts throughout the previous shift, which is why we're now constantly monitoring the wind direction to avoid scans that involve aligning the antenna with the wind, which naturally constrains the number of eligible targets / projects.
• Repetition 2/28 done. Changing to nearby pointing source SMA_0010+109, beams for ar1 and ar3 are still very close to circular while ar2's beam almost hasn't changed compared to previous pointing.
• We're doing another repetition (3/28) for project 196-25: @ ~/196-25/observe_Cl0024. The plan is to change to NIKA2-Pol after this scan has been completed, selecting a project that contains targets close to the best calibration source for polarization (Uranus).
• Opacity has been constantly increasing over the past hour, now at ~ 0.165 (15:15 UT), matching the predictions however.
• We're now switching to NIKA2-Pol (15:30 UT)! Tuning is good with bad KIDs 14/4/14 for ar1/ar2/ar3.
• Choose project 015-17 (target NGC1333 is close to Uranus)
• Pointing and Focus on Uranus. Atmosphere is extremely stable with just +/-0.5 Jy/beam. We find a focus difference of about 0.2mm between Ar1 and Ar3.
• calib_1scan (for IP) on Uranus (20260219s153).
• Pointing on nearby source yields excellent atmospheric stability (same as above) and tau is ~ 0.15 (16:30UT). Ar1's beam is perfectly circular (12x12"), Ar3 almost circular (11x12") and Ar2 is elongated.
• Running 1 rep of @~/015-17/observe_ngc1333s_polar for the next hour.
• Pointing on Uranus: Atmosphere still very stable even though we're close to sunset (18:00UT), +/-0.5 Jy/beam. Beam sizes haven't changed so no need to refocus.
• calib_1scan (for IP) on Uranus to close the bracket (20260219s162).
• Secondary pointing on nearby pointing source 0333+321. Atmosphere still stable and tau ~ 0.13 (18:10UT). Ar1 and Ar3 beams remain pretty much circular (11x12", 12x12") while Ar2 has not gotten worse than it already was.
• We're moving ahead with another repetition of @~/015-17/observe_ngc1333s_polar
• [IM] Noticed that receiver cabin light was on for the last few (3-4?) hours. No noticeable effect was seen in the data. Just mentioning in case anyone can have a look at particular data.
• Move to Uranus for pointing: Atmosphere is extremely stable now (less than +/- 0.5 Jy/beam). Beams of ar1, ar3 are now elongated while ar2's beam has not changed any further. We have to refocus for the next project.
• calib_1scan (20260219s170) for IP to close the bracket.
• Switching to project 084-25, targeting W3H2O. Pointing on Uranus confirms atmospheric stability similar to above and beam elongation.
• Focus on Uranus with initial value of 1.09mm.
• calib_1scan (for IP) on Uranus (20240219s183)

21:00-03:00 Sunayana: Taking over, starting with project 084-25. Sky conditions are quite stable with variations of +-2 Jy/beam in Ar2. Opacity good at < 0.2.

• One repetition on W3H2O.
• Calib_1scan done on Uranus (20260219s194 for IP)
• Second repetition on W3H2O.
• Calib_1scan done on Uranus to bracket the observations (20260219s205, for IP)
• 23:17 LT - Uranus is at an elevation of 30.9, so we can no longer use this as a polarisation calibration target to bracket observations. We will hence skip 015-17, instead moving to project 146-25.
• Two weakly polarised calibration targets chosen, 0316+413 and 1226+023. No need to refocus at this point, as we have good values in Ar1 and Ar3 - 11"x12" and 12"x13" respectively.
• Calib_1scan done on 0316+413 (20260219s208, for IP)
• Calib_1scan done on 1226+023 (20260219s221, for IP)
• First repetition on S255IR
• Calib_1scan done on 1226+023 to bracket the science sequence (20260220s5, for IP).

• 02:06 LT - Sky conditions have remained very encouraging, with atmospheric stability of +- 1 Jy/beam throughout. Opacity has stayed consistently at <= 0.2 (much below the predictions for this time!)

• A second repetition of S255IR is not possible as it is now below 30.
• Skydip calibrations (these were accidentally performed from within the last project account, i.e. 146-25, rather than the nika2w-25 pool account, agh. Sorry!), that is scan 20260220s7
• Switching to TP mode.
• Moving to project 197-25. EDFN-CL3 is currently just above 30 degrees, but given the low opacity and stable atmosphere, this may be sufficient prior to reaching 35 degrees.

• 1 repetition on EDFN-CL3

Friday, 20th February 2026

03:00-09:00 Miren:

• Took over, finishing the first repetition on EDFN-CL3 (project 197-25). Sky variations of +/- 1-2 Jy/beam in Ar2 and opacity ~ 0.22.
• The pointing after the first repetition confirms the stability of the sky. Beams have not changed since previous pointing.
• Second repetition on EDFN-CL3. Sky was stable and opacity ~ 0.23 throughout the repetition, but strange features were seen in scan 20260220s27. This scan needs to be checked. This problem is not present in the following scans.
• A new pointing confirms the stability of the sky (+/- 1 Jy/beam in Ar2). Beams of three arrays unchanged since previous two pointings (11.1" x 11.8" for Ar1), so we go for a third repetition on EDFN-CL3. Scan 20260220s33 needs also to be checked, some KIDs seem to have problems in several subscans. The following two scans (last scans of the repetition) don't show these features.
• During the last two repetitions, we had the imbfits creation alarm, once per repetition. We wonder if this is correlated to the problematic scans.
• 06:20 UT: we move to project 137-25. Focus and Pointing. Ar1 beam 11.2" x 11.9", and peak to peak variations of +/- 1 Jy/beam @Ar2.
• Some imbfits take a long time to be created. We retune NIKA2 KIDs.
• Opacity ~ 0.23. Finishing 1 repetition on L1241 (137-25) with the last scan (3/3), as indicated in the README of the project.
• We start a new repetition, but wind speed is increasing and PIIC can not process the first scan (20260220s45) due to too high tracking deviations. Telescope is parked before the end of the second scan (08:08 LT).

Note about scans 20260220s27 and 20260220s33: this is a similar problem that happened during the previous pool weeks. It was believed to be due to something touching the cryostat. Again happening on the same sky direction here.

For comparison, this is how a good scan from the same repetition looks like:

09:00-15:00 Andres:

• Resumed observations in Total Power at 9:41 LT. Changed to nikaw-25 account.
• During scan 20260220-51 (focus), we realized one of the boxes was out of tune so the scan was cancelled. During tuning, high frequency resonances were found in Ar3.
• At ~10:20 LT we resumed observations, proceeding to perform a pointing, focus, and skydip (20260220-60). With peak to peak sky variations below +-3Jy/beam for Ar2.
• We switched to project 137-25.
• After the second repetition in 137-25 (scan 20260220-72), the nearby pointing showed elongated beam in A1 and A3 (11.4"x22.7" and 11.0"x19.1", respectively), although sky is quite stable with p2p variations between +-1Jy/beam in A2. We decided to continue with 137-25 awaiting for Uranus to have a higher elevation before switching to polarization.
• The telescope was quite out of focus, and after a focus second repetition we got reliable correction for A1 and A3, with an elongated beam (11.6"x14.7" and 11.2"x19.9" for A1 and A3, respectively).

15:00-21:00 Vito:

Taking over with observations for project 137-25 in progress in NIKA2 Total Power. Atmosphere is stable with +/- 1-2 Jy/beam, opacity ~ 0.2 (14:00 UT)

• We'll do flux calibration scans before resuming with another repetition for 137-25.
• Both Ar1, Ar3 are out of focus with elongated beams. Tried to run a focus sequence on MWC349 twice but the beams for ar1 and especially ar3 are still elongated even though the fits very much agreed for both sequences. Switching to much brighter pointing source 2251+158.
• calib_1scans on flux calibrator MWC349 (20260220s100, 20260220s107) might not be useful because beams were still elongated.
• Focus sequence on 2251+158 yielded good fits for ar1 but didn't converge for ar3. Running it again with a higher initial value of 0.29+0.40mm, yielding much better results.
• calib_1scan on flux calibrator NGC7027 (20260220s124).
• calib_1scan on flux calibrator CRL2688 (20260220s127).

• Now (16:00 UT) switching to NIKA2-Pol, opacity ~ 0.2. We select project 084-25 to continue observing W3H20.

• Observations are delayed due to additional tests being run regarding the noise within the cryostat. We wait until the instrument is tuned and ready.
• NIKA2 Pol ready at 17:10 UT: Pointing and Focus on Uranus. Atmosphere is stable (+/- 1 Jy/beam) and opacity ~ 0.25. Beams for Ar1 and Ar3 are almost circular and focus difference is about 0.3mm.
• calib_1scan on Uranus (20260220s143).
• Secondary pointing on 0133+476 (closest point source at same elevation as target): Atmosphere still very stable (+/- 1 Jy/beam). Repetition will be during sunset so we need to assess how much the focus will have changed after the next hour.
• 1 repetition on W3H2O.
• Pointing on Uranus: Atmosphere remains very stable despite sunset (+/- 0.5 Jy/beam) and ar1, ar3 beams became only slightly elongated!
• calib_1scan to close the bracket (20260220s154).
• Focus: Had to do two consecutive focus sequences, the focus difference between ar1 and ar3 has decreased to 0.25mm.

• Opacity still good (~ 0.2) so we can go for another repetition targeting W3H20.

• calib_1scan (20260220s165)
• 1 repetition on W3H2O. Repeatedly cancelled because of telescope alarm, interrupting scan 1. Operator is restarting the control system. Apparently, Emir (even though we're not using it) is interfering with the tracking, causing antenna oscillations due to some missing process.

21:00-03:00 Sunayana: Sky conditions are stable with atmospheric variations limited to +- 2Jy/beam. Opacity is also good at <= 0.2.

• Restarting the science sequence from the previous shift on W3H2O.
• Bracketing with a calib_1scan (20260220s179, for IP). Focus had deteriorated so was redone, and then repeated calib_1scan (20260220s191).
• Moving to project 015-17.
• Calib_1scan repeated on Uranus (20260220s193, for IP).
• One repetition on NGC2024N.
• Calib_1scan on Uranus to bracket the observations (20260220s201, for IP). Although, unfortunately, Uranus was already at ~20 degrees elevation at this point, so hoping it is passable given the great weather conditions. Alternatively, another calib_1scan from a previous observation may be preferable.
• Moving to project 146-25.
• Calib_1scan on 0316+413 (20260220s204, for IP). Immediately going to 1226+023 for a back-to-back calib_1scan (20260220s207, for IP)
• One repetition on S255IR.
• Calib_1scan on 1226+023 for bracketing (20260221s6)
• 02:20 LT - once again, a second repetition of S255IR is not possible as it is now below 30 degrees.
• Skydip calibrations (20260221s7)
• Re-checked pointing and focus on target 1226+023, which is looking good. Atmosphere now shows p2p variations of +- 1 Jy/beam in Ar2 and tau has remained below 0.2. The Ar2 beam is 17"x22", while Ar1 and Ar3 beams are 11.15"x11.88" and 11.12"x12.92", respectively.
• Switching to NIKA2 TP mode.

Saturday, 21st February 2026

03:00-09:00 Albrecht: Stable conditions. Opacity below 0.2 throughout the shift.

• 3x beam maps in TP mode, optimized for focus of Ar1 (20260221s17), Ar3 (20260221s18) and Ar2 (20260221s29)
• observed project 137-25: 2 repetitions of L1241
• started project 166-25: 1 repetition

09:00-15:00 Andres:

• Continuing with Total Power before sources in project 166-25 goes below 20 deg of elevation.
• Finished the second repetition of 166-25.
• At ~10:24 LT we switched to the nikaw-25 account to perform calib1_scan on MWC459 (20260221s55), NGC7027 (20260221s57), CRL2688 (20260221s58), followed by a skydip (20260221s59).
• 11:00 LT - Switching to NIKA2 Pol .
• At ~11:30 LT we started with project 170-25, for which we performed 2 repetitions.

15:00-21:00 Vito:

Taking over with NIKA2 Pol observations in progress for project 170-25. Opacity is < 0.2. Sky is stable with variations < +/- 1 Jy/beam.

• Repetition 10/13 of observe_Tycho completed. Will perform two calib_1scans to close the bracket for calibration of instrumental polarization.
• calib_1scan (20260221s98) on 2251+158 (3C454).
• calib_1scan (20260221s101) on Uranus. Beams of Ar1, Ar3 are elongated, thus running a focus sequence.
• Switching to project 084-25. Sky remains very stable (+/-0.5 Jy/beam). Pointing on Uranus still shows large and elongated beams so we run another focus sequence on Uranus.

• Due to the antenna's constant exposure to sunlight today we're witnessing an "afternoon effect" during otherwise great conditions (opacity < 0.2 and +/-0.5 Jy/beam variations in the atmosphere) manifested in beam distortions even after satisfying focus sequences. We nevertheless continue the observations.

• Focus difference between Ar1 and Ar3 remained at about 0.2mm throughout the multiple focus sequences conducted so far.
• calib_1scan (20260221s121) on Uranus for IP.
• 1 repetition (5/6) targeting W3H2O, starting at 15:55 UT.
• calib_1scan (20260221s132) on Uranus to close the bracket for IP.
• Afternoon-effect has died down, beams are now much more circular. No refocusing. We can go for another repetition targeting W3H2O.
• 1 repetition (6/6) targeting W3H2O.
• calib_1scan (20260221s144) on Uranus to close the bracket for IP.
• Now switching to nikaw-25 to perform a sky dip as planned. Opacity ~ 0.2 (18:40 UT).
• sky dip (s20260221s157)
• Opacity ~ 0.17, meeting the requirements for project 015-17. We will target NGC2024N. Almost no beam distortion. Focus difference between ar1 and ar3 is about 0.25mm.
• calib_1scan (s20260221s160) for IP
• 1 repetition on NGC2024N.

21:00-03:00 Sunayana: Atmosphere is very favourable with variations of 0.5 Jy/beam currently. Opacity is below 0.2.

• Calib_1scan done on Uranus to bracket the observation of NGC2024N started in the previous shift (20260221s168).
• Redoing the pointing and focus on Uranus - current beams for Ar2, Ar1, and Ar3 are - 17"x19", 11"x12", and 11"x14" (mildly elongated).
• Calb_1scan again for Uranaus (20260221s180 for IP)
• One repetition on OMC-2-S.
• Calib_1scan (20260221s188 for IP) to bracket the observations. Focus has deteriorated and Uranus has gone down to an elevation of 28 degrees.

• Refocusing has taken longer than expected, due to the absence of one of the pointings appearing in the focus sequence for Ar1 and Ar3. On one of the QuickLook window it shows "corrupted file." The sequence is being repeated thus a second time.

• Calib_1scan post-refocus (20260221s200 for IP). Warning: this scan was done for completeness, however Uranus' elevation was at ~22 degrees, causing unavoidable elongations in the beams of Ar1 and Ar3.
• Moving to project 146-25.
• Calib_1scan on 0316+413 (20260221s209, for IP); focus is not very good due to ongoing issues with elongated beams in Ar1 and Ar3.
• Back-to-back calib_1scan on 1226+023 (20260221s218 for IP) after refocusing - 11.5x13.5 and 11x15 in Ar1 and Ar3, respectively. Ar2 is 18x19. Ar3 beam is still considerably elongated.

• One repetition of S255IR. Unfortunately, the nearby target pointing was accidentally skipped prior to this repetition; a note has been added to the ReadMe regarding this 4th repetition.

• Calib_1scan on 1226+023 to bracket the observations (20260222s13).
• Hail Mary attempt to save the nearby pointing oversight by choosing another source at similar elevation and azimuth for a pointing (0754+100).
• Skydip calibrations (20260222s16).

Sunday, 22nd February 2026

03:00-09:00 Albrecht: Continue with polarization. Using 3c273 for the beammaps. Focus (1.75, 0.91 2.03) array 1 and 3 ok and ar2 marginal Instead of 1.4 used 1.8 as starting focus on ar1

• 3x beam maps in POL mode, optimized for focus of Ar1 (20260221s28), Ar3 (20260221s29) and Ar2 (20260221s35)
• observed project 197-25: 2 repetitions of EDFN-CL3

09:00-15:00 Andres:

• Starting the shift in TP in project 197-25.
• After finishing the ongoing repetition, we moved to project 166-25 for which we performed 1 repetition.
• We switched to nikaw-25 to perform a calib_1scan in MWC349 (20260221s67), NGC7027 (20260221s68), and CRL2688 (20260221s69), followed by a skydip (20260221s70).
• At ~10:45 LT we switched to polarimetry and restarted observations at 11:10 LT.
• We performed a pointing, sky was quite stable with p2p variations below 1 Jy/beam in Ar2. Ar1 beam:12"x12" - Ar3 beam: 11"x13". Followed by a focus and calib_1scan.
• We moved to project 015-17.
• One repetition on DR21N.
• One repetition on DR21S.

• One repetition on DR21N. (Note: Uranus reached > 30 deg in elevation during the observation script)

15:00-21:00 Vito:

Taking over with science scan for project 015-17 in progress. Atmospheric fluctuations +/- 0.5 Jy/beam, opacity ~ 0.19 and almost no wind.

• calib_1scan (20260222s114) on 2251+158 (3C454) for IP.
• calib_1scan (20260222s117) on Uranus, since Uranus has now reached an elevation of about 40 deg, also for IP.
• Switching to project 084-25, we want to target W3IRS4 today. Atmospheric fluctuations now at +/- 1 Jy/beam, opacity ~ 0.17.
• calib_1scan (20260222S124) on Uranus for IP.
• Additional calib_1scan (20260222s127) on 0316+413 (3C84), which is a lot closer to the target.
• 1 repetition (1/6) on W3IRS4.
• calib_1scan (20260222s138) on 0316+413 (3C84) to close the bracket for IP. Beams are circular. Opacity at ~ 0.15 now (16:30 UT).
• 1 repetition (2/6) on W3IRS4.
• calib_1scan (20260222s149) on 0316+413 (3C84) to close the bracket for IP. Beams remain circular.
• calib_1scan (20260222s152) on Uranus for IP. Telescope still focused (Ar1: 11x12", Ar3: 11x13").
• Switching to pool project for some calibrations.
• Pointing and focus on ALFORI. Focus difference is about 0.25mm.
• calib_1scan (20260222s160).
• @skydip (20260222s161).
• Daily calibrations are done, switching back to project 084-25 so we manage to get one more repetition on W3IRS4.
• calib_1scan (20260222s174) on Uranus.
• Atmosphere is very stable and opacity at ~ 0.16. Beams are slightly elliptical (post-sunset effect?).
• 1 repetition (3/6) on W3IRS4.

21:00-03:00 Sunayana: Sky conditions starting off extremely stable, with variations less than 0.5 Jy/beam in Ar2. Opacity is less than 0.2.

• Calib_1scan on Uranus to bracket project 084-25 observations on W3IRS4 started during previous shift (20260222s185, for IP).
• Refocus performed on Uranus, followed by another calib_1scan (20260222s197, for IP).
• Switching now to project 128-25.
• Uranus - pointing and calib_1scan (20260222s199, for IP).
• One repetition on L1482.
• Calib_1scan on Uranus to bracket the observations (20260222s216, for IP).
• 23:45 LT: Switching to TP mode.
• Switching to project 108-25.
• One repetition on G195.8882.
• Pointing scan on SMA_0725-009. Focus and offsets still good, no need to redo the focus.
• One repetition on G211.8773.
• 01:22 LT: Sky conditions remain extremely stable, with atmospheric fluctuations consistently below 1 Jy/beam. Opacity has also remained low at ~ 0.15.
• Pointing scan repeated on SMA 0725-009.
• 01:50 LT: The majority of targets in 108-25 are now below 25 degrees, and those which remain above are not in priority (as they have already been observed). As we will not have enough time for a third sequence, we leave 108-25.
• Moving to the nikaw-25 pool account.
• Skydip calibrations (20260223s5)
• Focus sequences for Ar1, Ar2, Ar3. The offset between Ar1 and Ar2 is shown to be close to 1mm, while between Ar1 and Ar3 the offset is approximately 0.2mm.

Monday, 23rd February 2026

03:00-09:00 Albrecht: Stable conditions. Opacity below 0.15 throughout the shift.

• 3x beam maps in TP mode, optimized for focus of Ar1 (20260223s29), Ar3 (20260223s35) and Ar2 (20260223s41)
• observed project 137-25: 2 repetitions of L1241

09:00-15:00 Andres:

• (TP) Started the shift while one repetition of 137-25 was being completed.
• Switched to 166-25 and performed one repetition on GC2.
• Moved to nikaw-25 account and performed calib_1scan on MWC349, NGC7027, and CRL2688. We followed with a skydip.
• Switched to polarimetry at around 11:05 LT.
• Started project 170-25. There were several homology problems in consecutive scans (20260223s89-92). We continued with the science observations after that.
• In total, we performed 2 repetitions on Tycho.

15:00-21:00 Vito:

Taking over with observations for project 170-25 targeting Tycho about to be finished. Atmosphere remains very stable, variations +/- 1 Jy/beam. Opacity ~ 0.12.

• Final calib_1scan (s20260223s124) on Uranus for IP.
• Switching to project 084-25. We're targeting W3IRS4 like yesterday, hopefully we can conduct the remaining three repetitions today.
• calib_1scan (s20260223s133) on Uranus for IP.
• Back-to-back calib_1scan (s20260223s136) on 0316+413 (3C84) to cross-calibrate the two polarization calibrators. Today we're trying to mitigate the afternoon effect by staying away from the Sun. Between science scans we'll only use 0316+413 (3C84) to close the calibration bracket such that we can keep the telescope away from the South, as both target and polarization calibrator move northwards and exhibit similar azimuth.
• 1 repetition (4/6) on W3IRS4.
• calib_1scan (s20260223s147) on 0316+413 (3C84). Beams now are almost circular, no afternoon effect so far! Opacity at ~ 0.14 and atmospheric variations at +/- 0.5 Jy/beam.
• 1 repetition (5/6) on W3IRS4.
• calib_1scan (s20260223s158) on 0316+413 (3C84). Opacity at ~ 0.13 and atmospheric variations haven't picked up much. Beams of both Ar1 and Ar3 are perfectly circular (11"x11") without refocusing so apparently we prevented, for the most part, beam dilution and distortion because of sunlight.
• 1 repetition (6/6) on W3IRS4.
• calib_1scan (20260223s169) on 0316+413 (3C84) to close the bracket for IP.
• calib_1scan (20260223s172) on Uranus to cross-calibrate.
• calib_1scan (20260223s188) on Uranus after refocusing.
• Now switching to pool project for some flux calibrations. Opacity at ~ 0.13.
• @skydip shortly after 19:00 UT.
• calib_1scan (20260223s197) on ALFORI.
• Now switching to project 015-17, targeting OMC-2-S. Opacity is ~ 0.14, well below the requested threshold.
• calib_1scan (20260223s205) on Uranus for IP.
• 1 repetition on OMC-2-S.

21:00-03:00 Sunayana: Starting off with very stable sky conditions; atmospheric fluctuations are of the order 0.1 Jy/beam. Opacity remains around ~0.15.

• Calib_1scan on Uranus to bracket the observations started during the previous shift (20260223s213, for IP). Post-focus calib_1scan on Uranus (20260223s229, for IP).
• One repetition on OMC-2-S.
• Calib_1scan on Uranus to bracket the observations (20260223s237 for IP).
• A second repetition of OMC-2-S is not possible as it is already at an elevation of 31 degrees after the first sequence.
• Switching to project 128-25.
• Calib_1scan on 0316+413 (20260223s240 for IP), followed by b2b calib_1scan on 1226+023 (20260223s245 for IP).
• One repetition on L1482 (starting at 34 deg elevation, 00:17 LT). The elevation of the target becomes very low by the end of the sequence (20.6 deg). Please check the data. A note has been added to the README for this repetition.
• Calib_1scan on 1226+023 (20260224s8 for IP). Focus sequences performed followed by a second calib_1scan done on 1226+023 (20260224s20).
• Moving to nikaw-25 pool account.
• Skydip calibrations (20260224s21)
• Beam map on 3C279 using focus optimised for Ar1 (1.56mm, 20260224s24).

Tuesday, 24th February 2026

03:00-09:00 Albrecht: Stable conditions. Opacity below 0.15 throughout the shift.

• 3x beam maps in POL mode, optimized for focus of Ar1 (20260224s24), Ar3 (20260224s32) and Ar2 (20260224s38)
• observed project 137-25: 2 repetitions of L1241

09:00-10:30 Andres:

• TP: Performed one scan (out of two) on GC1 with the alternative script (project 166-25) - There were some issues with subscans not starting.

IM: End of pool week #6. Thanks to operators - Joaquín and Sergio - and all the participating observers - Sunayana, Vito, Andrés, Miren and Albrecht - for their support and great work!