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NIKA2 Re-Commissioning (2nd. part) - First shift

June 10th-12th + 16th-18th, 2025

NIKA2 run 73, Cryo run 85

Infos about the PIIC DAFs for the PIIC monitor

SB has produced some temporary DAFs to be used for run 73 Ar2. They are already copied at Pico.

The idea is to use two different sets of DAFs for Ar1+3 and for Ar2:

• for Ar1 and Ar3, use the DAFs that were produced with the run 72 data. These DAFs work with the new Arrays 1 and 3, but their reference KID is not the central one (because of the bix C issue), and therefore they's a bit of an offset.
• for Ar2, use the older DAFs (run 68). The SWEEP has not changed since then. These DAFs do include the correct (central) reference KID. Use these for pointing, such that the data will all be properly centered.

I cannot mix the two sets of DAFs, because Ar1 and Ar3 use Ar2 as reference and were built with the non-centra reference KID.

As soon as we have beam maps, I will build (temporary) DAFs for all three arrays, referred to the central KID, and we'll be fine.

Ho to proceed in practice:

• Ar2
  • open a terminal, go to the QL directory
  • gagpiic
  • export MOPSIC_DAFS=/local/users/flexible/reduce/dafs_bck/dafs_local_tmp_run73_ar2
  • start the Ar2 monitor (pf)
  • repeat in another terminal for the Ar2 monitor (m)
• Ar1 and Ar3
  • open a new terminal, go to the QL directory
  • gagpiic

  • echo $MOPSIC_DAFS -> check that it says /sw/gildas/mopsic/dafs

  • if not, then set it to that directory
  • proceed normally with the Ar1 and Ar3 monitors
• if Ar2 does not work, please let SB know, and meanwhile use the standard DAFs (i.e. the same as for Ar1 and Ar3)

At this point, use Ar2 for pointing, such that all data are well centered. As soon as there's a decent beam map available, SB will produce new (maybe temporary) DAFs for all three Arrays, referred to the good old (central) reference KID and will install them at Pico, to be used with the next observations.

ADDITIONAL NOTE (2025/06/10 @22:55): using this double setup, you will see an offset betwween Ar2 and Ar13. It is on purpose. Please ignore it and use Ar2 for pointing/focus, until new DAFs with the central as reference will be produced for all three arrays.

First shift

Tuesday, June 10th, 2025

Mónica, Ioannis, Dave, Angel at the telescope. Starting DAQ at the beginning of the maintenance slot.

@11:00: All amplifiers are switched on. T_MC = 0.173 K. Noise traces at this time (ar2, ar1, ar3) are given below.

Traces of ar2 look qualitatively better than those in force during the campaign of March (for a comparison, see the Daily Report of Sunday, March 23rd, 2025 at https://publicwiki.iram.es/DailyReportsNika2Run72).

@15:30: Dave, Mónica, Angel. Cloudy. Rain intervals. Trying to catch a sky hole for a decent resonance work. Configuring NIKA2 at Rx cabin. Restarting DAQ. Impossible to have a reasonably good tuning with the current weather conditions. Waiting for a while.

@17:00: Still being unstable. Taking advantage for testing mppsync/server & HWP. It was necessary to restart the Arduino server. Check: OK.

@18:30: We tried our best for getting good resonances under (very) poor conditions. With 17/6/110 bad KIDS in a1/a2/a3, we tried a quick & dirty (specially the latter) pointing on Mars when wind speed dropped a bit. The good news: the QL-reduction indicates that the amplifier replacement has been successful. Congratulations!

@20:28 Weather still unstable. We did a pointing and see a big offset between a2 and a1/a3 so we changed to the latest DAF's for all arrays. After that there is not offset anymore. We continued with pointing and focus.

@21:00 Stopped. light rain.

SB @22:55 LT: the offset between Ar2 (special DAFs, run 68, see above) and Ar13 (run 72 DAFs) is normal because the Ar2 is referred to the central KID while the Ar13 are not. So basically this offset is on purpose. It will disappear once I produce the new DAFs with new beam maps. Please keep using the run 68 DAFs for Ar2 (special instructions above), and use Ar2 for pointing/focus, ignoring Ar13, so that all data are referred to the central KID and I can produce the new DAFs for Ar13 with the proper reference KID. Otherwise everything will be shifted and we will need to re-do it once again. Thanks.

Wednesday, June 11th, 2025

@00:15: Rolling back to the run 68 DAFs for Ar2 in PIIC. Still windy. Opacity about 0.7 and rising. Telescope parked.

@02:15: Weakly-polarized (<1%) and polarized (>1%) sources from SMA-Pol added by Ioannis to the current commissioning catalogues (see /pako/202503 at t22). It's raining again. Wind peak speed >15 m/s.

@04:00: Stormy weather.

@09:00: Opacity going down (tau_225 ~ 0.9), max. wind speed >18 m/s.

@16:00: Wind goes down and we try to start the antenna.

@16:20: wind speed below 10 m/s and Tau ~ 0.5. We start the acquisition with better conditions than yesterday. Bad kids 10, 6, and 90 in ar1, ar2 and ar3 respectively. Continue with pointing, focus in Mars. The first sequences of focus show that the beam is distorted (a bit elliptical FWHM ~ 20" x upt to 25"). Mars's size is 5.3". We expect the antenna behaves better after the sunset.

@17:40 After several focus sequences specially the last one (scans 23 to 29) the peak to peak variations were from 15 to 30 Jy/beam at 2mm. Atmosphere is unstable. So we will wait for better conditions.

@17:45 SB: Hi! Thanks for starting the observations. I've taken a look to the PIIC monitor plots. Yep, I agree it's better to wait a bit. Is the homology fine, and the table in "level attente"? Thanks. Cheers. I'll check later tonight again. Monica-Ioannis: the homology is fine (we have not get any alarm) and the option is set to level_attente.

@19:50 Starting observations again, tau is decreasing. Checking pointing and focus in Mars. The pointing sequences show that the beam is still a bit elongated (scan 50 FWHM ~ 19.1" x 24.6"). We will try later in 30 min.

@21:00: Acquisition restart to recover more dead pixels. Results now look much better with 9/3/45 bad kids for ar1/2/3. Pointing and focus on Mars to check beam and conditions.

@21:28: Wind increased (some alarms for high gusts). Antenna parked.

Thursday, June 12th, 2025

@00:30: Wind speed dropped a bit on average, last gusts: 13-20 m/s; tau_225 ~ 0.35.

@02:10: Gusts about 10 m/s. Wind blowing from South direction. DAQ restarted, 9/6/40 bad kids for ar1/2/3. No planets/bright QSOs at ~40 < El. < 75 deg. right now for a beam map.

• First pointing 1741-038 (Az. ~175). Moderately good tracking; one focus scan lost due to high tracking deviations (38.6%). No focus fitting. P2P variations of timelines: 10-20 Jy/beam (2 mm).
• Moving to 3C286 (Az. ~283). First pointing and one focus scan lost due to tracking deviations (25-29%). Guess focus correction: 1.8 mm
• Moving the telescope backing to the wind: 1928+738 (Az. ~370). Tracking deviations remained below 20%. Best focus: 1.4 mm.; FWHM 17.4" x 19" (2mm) after pointing. Estimated MB flux (2 mm): 1.6 mJy/beam. Looks more stable in the l.o.s.
• One round on G2 field launched before reaching El. 30 deg. Motor torque and wind alarms activated almost simultaneously when the third scan (out of four) of the round was finishing. Despite this, no significant tracking deviations appear in the first two scans gathered. Telescope parked at 03:40 (LT).

@04:00: The upward trend in wind speed is confirmed. Waiting for better conditions.

@10:00: Wind mean speed has continued to increase since early morning.

@11:30: We find a small window with a bit lower wind speed and decide to start the system in case we can take some data. Tried on Uranus and 3C84 but wind is fighting back hard. Many scans are lost due to tracking errors, 25%, 35% 45% ... Shortly before the end of the T21-25 slot this week, we go back to Uranus and we get a pointing. Focus is again not possible due to lots of tracking errors (in elevation. in azimuth tracking looks fine). In the last 20 mins we made the "executive decision" to start a beam map, even if the conditions are far from ideal (manual focus correction, wind on the limit, similar elevation and relatively close to the Sun - 23 degrees ...) but maybe it can be (marginally) useful, at least for a "crude" analysis (e.g. matching the ar1/3 and ar2 geometries etc.).

SB @18:20 LT: Thank you for these heroic days and the final attempt. The beam map is scan 20250612s43. Results of a quick analysis of this beam map: the quality of the beam map (sky, telescope, focus, etc.) is unfortunately not good enough for making new (preliminary) Ar1 and Ar3 DAFs. Below you see the classic FOV beam-map figure. Ar3 is much worse than Ar1 likely because the best focus difference that affects it. Nevertheless, also Ar1 is unusable.

IM : Thanks for the update Stefano. That was expected, the conditions were not very good when we took the data. Let's hope for a better chance in the next re-commissioning slot that starts on Monday.

Second shift

Monday, June 16th, 2025

Mónica, Miguel, Angel at the telescope. Ioannis in remote. Starting time scheduled at 17:00 (LT)

@17:15: Hail & thunder storm. Low wind speed (< 5 m/s). The storm ceased at ~18:30, but mean wind speed is increasing. More, dense clouds towards East.

@20:30: Weather has improved substantially; tau_225GHz ~ 0.6. Enough for checking the whole system. DAQ restarted in total power. Bad KIDs: 22/5/99 (ar1/ar2/ar3).

@22:30: Opacity varied between 0.5 and 1.7 before this time. We checked the stability and beam geometry during the sunset until reasonable values were reached. First good focus: scans 164-167 (see table below). Calib_1scan on Mars with focus optimized to ar2 (s169) and for ar1 (s170). A skydip after that (s171).

@23:10: Beam map in total power, focus optimised to ar2/~1, scan 20250616s179. Unfortunately ~0.6 < tau_225GHz < 1.1 during the scan. After a pointing correction without sensitive variations of the beam sizes, another beam map with focus optimised to ar3 was launched (20250616s181). Opacity still being high, although the atmosphere instabilities seem to be not so high as we can expect with such opacity levels.

Tuesday, June 17th, 2025

@00:30: Pointing on 1144+402 and two rounds in G2 (scans 190 to 197). Tau is stable, weather conditions improving. Mean rms ~ 95 mJy/beam (@2mm in scan 192). Towards the end of the second round the mean rms improved to 85 mJy/beam.

@01:41: Pointing on 1144+402 and two rounds in G2 (scans 199 -206). The mean rms ~ 90.6 mJy/beam (scan 199). Opacity spikes appeared again. According to the weather predictions we are in the best time of the night.

@03:05: Changing to NIKA2-Pol. HPW in the optical path. DAQ restarted. Phasing tried twice but crashed after a few seconds. Mppsync/server & DAQ restarted again: ok. Bad KIDs: 10/3/64 (ar1/ar2/ar3).

@03:22: Pointing/focus (see table below) on MWC349; tau_225GHz ~ 0.5. Launching a first set of calib_1scan maps with two focus optimizations (1.3 mm for Ar2/~1 and 1.75 mm for Ar3): MWC349, NGC7027, CRL2688 (scans 20230617s16 to s21). Quite stable atmosphere.

@04:30: New pointing/focus corrections on MWC349 (el. > 80 deg; tau_225GHz ~ 0.6). Launching a second set of calib_1scan maps with two focus optimizations (1.15 mm for Ar2/~1 and 1.6 mm for Ar3): MWC349, CRL2688, NGC7027 (scans 20230617s29 to s34).

@05:22: Coming back to total power. Bad KIDs: 11/4/70 (ar1/ar2/ar3). Very stable in the l.o.s., superb tracking, tau_225GHz ~ 0.5.

@05:55: Beam map on 2251+158 (3C454), focus optimised to ar2/~1, scan 20250617s49.

@06:30: Beam map on 2251+158 (3C454), focus optimised to ar3, scan 20250617s51.

@07:10: Switching to NIKA2-Pol again. Bad KIDs: 9/4/58 (ar1/ar2/ar3).

@08:10: A calib1_scan in Neptune first using a focus correction optimized to ar2 (scan 62) then optimized to ar3 (scan 63). Move to source MWC349 for pointing, focus, pointing, calib_1scan maps with two focus optimisations (s77 and 78). The same for CRL2688 (s91 and 92).

@16:00: Maintenance slot ends successfully; tau_225GHz ~ 1.4. Forecasts announce adverse weather. PT taking the opportunity for VLBI tests as long as the conditions are not favourable.

@17:45: Opacity ~ 0.85 (stable). Acquisition restarted with bad KIDs 16/8/94 for ar2/ar1/ar3 respectively. Go first to Mars for a initial calibration.

@18:35: calib_1 scan optimized for a focus solution of ar2 (0.91, scan 143),calib_1 scan optimized for a focus solution of ar3 (1.4, scan 144).

@18:53: skydip around Mars and tau very unstable (scan 147). Checking pointing a focus in Mars (very bad focus), moving to the north, trying different sources (0851+202, 0716+714) at different azimuth positions expecting better atmosphere, but unsuccessfully since the pointing and focus results are very poor.

@20:10: Poiting and Focus in Mars since the Tau is very unstable.

@20:15: Blank field G2 in total power (two rounds). Previously, pointing and focus on 3C345 and pointing on 0954+658.

@23:00; Ioannis: Pointing and focus on 3C345. Several attempts due to lack of pointing solutions for Ar3. Focus was appearing as out of range for Ar3. Finally, centering at 1.6 the focus sequence worked for all 3 arrays. Then nearby pointing on 0954+658 and one more repetition of G2 field (focus optimized for Ar2).

Wednesday, June 18th, 2025

@01:45; Ioannis: Change to NIKA2-Pol. Several attempts to tune NIKA2 but frequent failures to tune Ar3. After moving to a different position on sky, tuning worked with 17/6/114 bad kids for ar1/2/3, respectively. Then pointing and focus on 3C345 but Ar3 solution again didn't work. Atmospheric stability not too bad despite the high opacity, ~3 Jy/beam at 2mm. Fine-tuning focus to Ar2 and going to secondary calibrators for calib_1scans: NGC7027, CRL2688 and MWC349. Then did a focus sequence on NGC7027 and this time it worked for Ar3 as well (see table below). Fine-tuning on focus of Ar3 (1.75 mm) and repeat the calib_1scan with the same sources (scans 20250618s27, 29, 31).

@04:22; Taking over from Ioannis. Completing the the cycle of calib_1scan maps on MWC349, NGC7027 and CRL2688 after setting focus to ar2 based on the last corrections found (scans s32, 33, 35).

@04:50: Starting a series of calib_1scan maps on bright QSOs & planets with optimizations of ar2/1 and ar3 foci. A summary is given below:

@07:45: Switching to total power. Acquisition restarted with bad KIDs 12/3/79 for ar2/ar1/ar3 respectively. Pointing on 3C454 (2218+451). Focus correction for ar2 looks fine: FWHM 17.2" x 18.2" (2 mm); quite stable despite the opacity level. Launched a beam map on 3C454 (scan 20250618s83), focus optimized to ar2/1.

@09:00: pointing and focus at 3C454 (2218+451). Beam map on 3C454 (scan 20250618s90), focus optimized to ar3.

@9:17: Pointing on 2234+282 and move to Field source.