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
20260219s74-78	1757-240	?	1.58	1.80	N	started focus @ 1.7mm
20260219s89-93	MWC349	?	1.83	2.3	N	started focus @ 1.58mm
20260219s103-107	MWC349	?	1.54	1.76	N	started focus @ 1.83mm
20260219s111-115	MWC349	?	1.39	1.62	N	started focus @ 1.54mm
20260219s118-122	MWC349	?	1.3	1.6	N	started focus @ 1.39mm

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

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

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.