Back to the NIKA2 Run 80 main page
Contents
-
Run80 data processing
- Focus difference between the three arrays
- Beam maps analysis
- Study of the Ar1 and Ar2 beams at different focus values
- New Study of the Ar1, Ar3 and Ar2 beams at different Z focus values
- Third (and last attempt to study of the Ar1, Ar3 and Ar2 beams at different Z focus values
- Test of focus difference between the three arrays after cryostat total warm-up and cool-down cycle (April 24, 2026)
- Testing focus difference between the arrays: May 19, 2026
- Testing focus difference between the arrays: May 20, 2026
- Testing focus difference between the arrays: May 21, 2026
- Cross-talking of Ar3
- Testing focus difference between the arrays: June 5, 2026
- Testing focus difference between the arrays: June 9, 2026
- Testing focus difference between the arrays: July 8, 2026
- Testing focus difference between the arrays: July 9, 2026
- Testing focus difference between the arrays: July 28, 2026
- Testing focus difference between the arrays: July 29, 2026
- Testing focus difference between the arrays: July 30, 2026
- Testing focus difference between the arrays: July 31, 2026
- Testing focus difference between the arrays: August 4, 2026
- NIKA2 test time: August 5, 2026
- Summary of focus offset tests (mean values) - Run 80
Run80 data processing
Contributions by: Stefano Berta, Kaiyi Du.
Here we include the preliminary data reduction results of the re-commissioning NIKA2 run 80, as obtained at the telescope during this week (2026/03/24-31).
Focus difference between the three arrays
As of 2026/03/25 @01:25 UT.
The focus difference Ar1-Ar2 is roughly +1.00 mm.
The focus difference Ar3-Ar1 is roughly -0.05 mm.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260324s153-157
Uranus
0.27
1.25
1.2
no
Started at 1.0 mm; tadadada; Ar2 good fit; Ar1 and Ar3 fit is marginal
158-162
Uranus
out
1.3
1.25
no
Started at 1.5 mm; Ar1 perfect fit; Ar2 out of range
163-167
Uranus
0.28
out
out
no
Started at 0.5 mm; Ar2 perfect fit; Ar1 out of range
171-175
Uranus
out
1.22
1.18
no
started at 1.5 mm; Ar1 perfect fit; Ar2 out of range
206-210
0851+202
out
1.36
1.31
no
Started at 1.4 mm; Ar1 and Ar3 perfect fit; Ar2 out of range
Beam maps analysis
We have a new Ar3 and we need to characterize its geometry and its flat field. To this aim, on 2026/03/24 we took two beam maps focused on Ar1 (scans 20260324s169 and 177). The idea and hope is that the focus of Ar3 is roughly the same of that of Ar1, thanks to the March 10 intervention, and these beam maps will be good for our purpose.
We reduce the beam maps during the night between 2026/03/24 and 25.
Ar2 is out of focus and in order to be able to reduce it, we need to relax completely the constraints on its beam size and shape.
Ar1 is well on focus. The best beam map is 177. The other (169) has some problems at the lower edge for unknown reasons.
The Ar3 focus is decent. The array is missing Box S, as already known, and also several KIDs in Boxes M, N O (supposedly).
Below here you can see the geometry of the three Arrays as derived from the average of these two beam maps.
Study of the Ar1 and Ar2 beams at different focus values
On 2026/03/25, we carried out a series of calib_1scan with different focus values, starting from the Ar1 optimal focus to the Ar2 optimal focus, in steps of 0.2 mm. The aim was to study the change of MB flux (because the CAL is based on main beams), % of flux in the side lobes of the beam, and FWHM of the minor/major axes of the beam, as a function of focus (distance from the optimal position). Below here you find a table that summarizes our measurements and a series of plots produced by the PIIC monitors for Ar1 and Ar2.
Note, however that polarimetry observations would at best be carried out at the Ar1+3 optimal focus (rather than at a compromise focus) because of the criticality of the IP correction.
Studying this table, we have the suspicion that we need to perform a new lateral focus (XY). We are considering to postpone it to Sep-Oct, after a possible new NIKA2 hardware intervention.
Study of the NIKA2 beams (TP, point-like target)
General
Ar1
Ar2
Scan nr
El. [deg]
Target
Z Focus [mm]
Notes
MB flux [mJy]
Side lobes %
FWHM min [arcsec]
FWHM max [arcsec]
MB flux [mJy]
Side lobes %
FWHM min [arcsec]
FWHM max [arcsec]
243
48.8
3C273
1.35
Ar1 focus
4.85
7.4%
11.40
11.86
6.96
8.5%
17.72
20.47
245
50.1
3C273
1.15
Ar1-0.2 mm
4.32
9.5%
11.43
12.84
7.19
7.7%
17.54
19.49
247
51.8
3C273
0.95
Ar1-0.4 mm
4.07
11.2%
11.61
13.06
7.21
7.8%
17.24
19.60
249
52.9
3C273
0.75
Ar1-0.6 mm
3.77
16.0%
12.44
15.67
7.51
7.2%
17.19
18.84
251
53.7
3C273
0.55
Ar1-0.8 mm
3.62
19.8%
14.78
21.86
7.47
7.3%
17.34
18.56
253
54.3
3C273
0.35
+/- Ar2 focus
3.64
28.1%
17.40
29.17
7.34
8.0%
17.59
18.59
NOTE: the focus values listed here do already include the -0.2 adjustment for the curved focal surfaces
New Study of the Ar1, Ar3 and Ar2 beams at different Z focus values
2026/03/28-29 Following the request by Carsten, we repeat the experiment. Carsten noted that the best Ar2 beam is not at the best Ar2 focus, but a bit far from it. Several factors might be causing this:
- first of all this seems to be an indication of the need of a new lateral (XY) focus. We have discussed it here and we have decided to wait for October, because a) there won;t be any science observations meanwhile; b) there will hopefully be another NIKA2 hardare intervention to fix the difference of focus between Ar13 and Ar2, that seems to be caused again by the dichroic that is bending (a lot).
- during the whole campaign the best Z focus might have slightly changed, because of a change of Elevation and of other conditions such as temperature etc., although such change is surely not as big at 0.6 mm.
Check the table below: the Ar1 and Ar3 MB fluxes increase when they should be decreasing! Are we seeing the QSO that is bursting? Or is it the wind? Or the change of Elevation (I hope not!)
Study of the NIKA2 beams (TP, point-like target) using calib_1scan
General
Ar2
Ar1
Ar3
Extras
Scan nr
El. [deg]
Target
Z Focus [mm]
Notes
MB flux [mJy]
Side lobes %
FWHM min [arcsec]
FWHM max [arcsec]
MB flux [mJy]
Side lobes %
FWHM min [arcsec]
FWHM max [arcsec]
MB flux [mJy]
Side lobes %
FWHM min [arcsec]
FWHM max [arcsec]
windy records
20260328s165
38.9
3C279
1.59
Ar1 focus
12.34
9.4%
17.35
24.72
8.51
6.3%
11.52
12.10
11.32
7.5%
11.37
12.29
--
167
40.6
3C279
1.49
Ar1-0.1 mm windy
12.32
9.8%
17.25
25.01
8.17
6.5%
11.82
13.64
10.79
7.8%
11.78
13.23
5.5%
169
41.9
3C279
1.39
Ar1-0.2 mm windy
12.77
9.5%
17.03
25.02
8.39
7.1%
11.85
13.44
10.96
7.9%
11.73
13.07
8.9%
171
43.1
3C279
1.39 !
Ar1-0.3 mm windy
14.78
9.6%
16.81
25.82
10.98 (?)
7.8%
11.80
14.06
14.23 (?)
8.2%
11.84
13.52
9.0%
173
44.2
3C279
1.29
Ar1-0.4 mm windy
16.27
10.8%
17.71
26.68 (?)
14.18
9.2%
12.61
17.07
17.56
9.2%
12.63
16.49
7.5%
175
45.2
3C279
1.19
Ar1-0.5 mm
17.18
9.3%
17.31
24.85
14.83
8.4%
11.62
17.56
18.45
8.8%
11.80
16.16
--
177
45.9
3C279
1.59 !
Ar1 focus !
16.7
11.2%
17.05
29.45
15.56
9.1%
12.82
13.64
18.75
8.4%
12.31
13.55
--
20260329s2
46.4
3C279
1.09
Ar1-0.6 mm
18.12
10.3%
17.85
25.41
17.26
10.7%
11.86
21.65
20.12
10.4%
11.96
18.95
--
4
3C279
1.59 !
Ar1 focus ! windy
17.50
13.6%
17.46
34.04
17.19
13.2%
13.92
15.56
19.85
11.9%
12.90
15.72
14.7%
This last scan would have been on ar1 focus! We stop. Too much wind. We will have to repeat this exercise on a calm night, possibly wher the source is culminating, so to minimize the changes of Elevation between scans.
6 n/a
3C279
0.99
Ar1-0.7 mm
8 n/a
3C279
0.89
Ar1-0.8 mm
10 n/a
3C279
0.79
Ar1-0.9 mm
12 n/a
3C279
0.69
Ar2 focus
14 n/a
3C279
0.59
Ar2 focus
16 n/a
3C279
0.59
Ar2 focus
NOTE 1: the focus values listed here do already include the -0.2 adjustment for the curved focal surfaces
NOTE 2: the Ar3 absolute flux calibration is incorrect because no DAFs CAL are available yet
NOTE 3: focus performed in scans 159-163, Ar1=1.59; Ar3=1.54; Ar2=0.59
NOTE 4: windy records = percenteage of records rejected because of too large tracking deviations
Third (and last attempt to study of the Ar1, Ar3 and Ar2 beams at different Z focus values
2026/03/30 I try again. The wind has decreased significantly. This time I use 3C273 (much more stable than 3C279). I do it close to culmination, such that the change of Elevation is minimized. I also monitor the P100 information, i.e. the behaviour of the main dish / back structure temperature sensors. In fact, it is known that these sensors suffer humidity and condensation of the water that accumulates into the back structure. When they "get wet", the temperature difference in the back structure has some peaks and the temperature compensation of the focus goes bananas.
The procedure is as in the two previous attempts:
- pointing, focus, to determine the best focus values
- pointing, calib_1sca
- starting at the Ar1 focus and decresing to the Ar2 focus, in steps of 0.2 mm (as on 2026/03/25; instead of 0.1 mm as yesterday)
Study of the NIKA2 beams (TP, point-like target) using calib_1scan
General
Ar2
Ar1
Ar3
Scan nr
Tapas El. [deg]
Target
Z Focus [mm]
Notes
windy records
T diff bck struc [C]
T diff quadripod [C]
Z axis corr by T [um]
MB flux [mJy]
Side lobes %
FWHM min [arcsec]
FWHM max [arcsec]
MB flux [mJy]
Side lobes %
FWHM min [arcsec]
FWHM max [arcsec]
MB flux [mJy]
Side lobes %
FWHM min [arcsec]
FWHM max [arcsec]
20260330s11
54.01
3C273
1.05
Ar1 focus
--
-1.35
-0.41
-1063
7.02
12.8%
18.07
26.48
5.38
7.0%
11.50
12.32
6.33
8.5%
11.48
12.50
13
53.37
3C273
0.85
Ar1-0.2
--
-0.94
-0.36
-740
7.05
13.4%
18.17
28.56
5.43
6.9
11.69
12.26
6.3
8.3%
11.25
12.57
15
52.45
3C273
0.65
Ar1-0.4
--
-0.98
-0.36
-759
7.49
10.5%
17.53
23.03
5.44
7.6%
11.29
12.67
6.39
9.0%
11.18
12.58
17
51.44
3C273
0.45
Ar1-0.6
--
-0.86
1.14
-966
7.82
9.3%
17.54
21.00
5.00
10.8%
11.28
14.51
5.95
11.4%
11.31
13.69
19
50.30
3C273
0.25
Ar1-0.8
--
-1.42
-0.18
-1170
8.06
7.6%
17.78
19.17
4.50
16.8%
12.47
18.93
5.15
16.6%
12.37
17.13
21
48.88
3C273
0.05
Ar1-1.0 = Ar2 focus
--
-1.50
-0.23
-1228
8.12
6.7%
17.71
18.79
4.43
21.9%
15.50
24.61
5.04
21.1%
14.66
22.37
23
47.49
3C273
-0.15
Ar1-1.2
--
-1.53
-0.27
-1245
7.99
7.7%
17.53
10.12
4.66
22.0%
19.57
29.36
5.17
24.7%
18.30
26.48
25
45.97
3C273
1.05
Ar1 focus
--
-1.47
-0.15
-1219
7.11
8.4%
17.96
21.77
5.48
6.5%
11.24
11.74
6.46
6.5%
11.02
12.09
NOTE 1: the focus values listed here do already include the -0.2 adjustment for the curved focal surfaces
NOTE 2: the Ar3 absolute flux calibration is incorrect because no DAFs CAL are available yet
NOTE 3: focus performed in scans 4-8, Ar1=1.05; Ar3=1.05; Ar2=out of range
NOTE 3b: focus checked again at the end of the exercise, in scans 26-30, Ar1=1.05; Ar3=1.03; Ar2=out of range; good; the focus kept stable along the whole test.
NOTE 4: windy records = percentage of records rejected because of too large tracking deviations
NOTE 5: the Temperatures of the back structure etc. are recorded at the start of the calib_1scan
Test of focus difference between the three arrays after cryostat total warm-up and cool-down cycle (April 24, 2026)
AoD: Ioannis
Outline of test slot T21-25:
- Started with the test on-time (21:00 LT)
- Tuning instrument with cryostat window closed (run92.ini). Bad kids 12/5/11 for Ar1/Ar2/Ar3. No bumps in DAQ traces for all arrays, instrument looks in very good condition.
- Tuning instrument with cryostat window open. Bad kids 47/13/28 for Ar1/Ar2/Ar3. No bumps in DAQ traces for all arrays, instrument looks in very good condition.
- Pointing and several focus sequences on 3C273. Stability at the beginning at +/- 3 Jy/beam at 2mm.
- Going to 3C279 for another focus test. Stability gets worse at +/- 7-10 Jy/beam. Opt focus for Ar2 and beam is 16.98x18.42
- Later stability improved again at +/- 2-3 Jy/beam
- Back to 3C273 for the calib_1scan series test at different focus positions. Results listed below. Consecutive scans showed strangely a pointing disagreement between the arrays with 2-3 arcsec differences in both Az and El.
- Conditions get much poorer at the end with +/- 20 Jy/beam (2mm)
As of 2026/04/25 @22:00 UT.
The focus difference Ar1-Ar2 is roughly +1.20 mm.
The focus difference Ar3-Ar1 is roughly -0.05 mm.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260425s35-39
3C273
0.81
out
out
no
Started at 1.0 mm; Ar2 good fit; Ar1 and Ar3 fit is out
40-44
3C273
out
1.97
1.93
no
Started at 2.0 mm; Ar1 and Ar3 good fit; Ar2 out of range
45-49
3C273
0.91
out
out
no
Started at 1.4 mm to catch all 3 focus positions but just missed Ar1 and Ar3
51-55
3C279
out
out
out
no
started at 1.6 mm to catch all 3 focus positions but all arrays out of range
56-60
3C279
0.79
out
out
no
Started at 1.0 mm; Ar2 perfect fit; Ar1 and Ar3 out of range
61-65
3C279
out
2.03
1.97
no
Started at 2.0 mm; Ar1 and Ar3 good fit; Ar2 out of range
Study of the NIKA2 beams (TP, point-like target) using calib_1scan
General
Ar2
Ar1
Ar3
Scan nr
Tapas El. [deg]
Target
Z Focus [mm]
Notes
windy records
T diff bck struc [C]
T diff quadripod [C]
Z axis corr by T [um]
MB flux [Jy]
Side lobes %
FWHM min [arcsec]
FWHM max [arcsec]
MB flux [Jy]
Side lobes %
FWHM min [arcsec]
FWHM max [arcsec]
MB flux [Jy]
Side lobes %
FWHM min [arcsec]
FWHM max [arcsec]
20260425s67
49.58
3C273
2.03
Ar1 focus
--
-2.38
+0.33
-2091
7.74
11.6%
18.24
23.26
4.26
11.4%
11.53
11.68
4.35
12.3%
11.10
12.68
69
50.49
3C273
1.63
Ar1-0.4
--
-2.39
+0.29
-2091
8.30
9.2%
17.66
20.77
3.79
14.6%
11.96
12.84
3.99
14.3%
11.13
14.28
71
51.26
3C273
1.23
Ar1-0.8
--
-2.28
+0.39
-2018
8.31
8.1%
17.65
19.76
3.13
20.4%
13.68
17.29
3.35
20.9%
12.47
18.40
73
52.08
3C273
0.83
Ar1-1.2 ~ Ar2 focus
--
-2.32
+0.34
-2042
8.47
8.6%
17.77
19.11
2.93
32.3%
17.11
22.32
3.26
29.0%
16.20
22.54
NOTE 1: the focus values listed here do already include the -0.2 adjustment for the curved focal surfaces
NOTE 2: windy records = percentage of records rejected because of too large tracking deviations
NOTE 3: the Temperatures of the back structure etc. are recorded at the start of the calib_1scan
Testing focus difference between the arrays: May 19, 2026
- AB: thanks to Brisa Mancillas and the current Team of the heterodyne pool week for this opportunity.
- Cryostat has been cold since April 24, 2026. During the morning maintenance slot, Dave noticed a relatively wide bump at ~1.4 Hz in the noise traces of array 1, with the window closed.
- Starting the preparation for the focus test at 21:00 (LT); anomalous refraction/unstable atmosphere during the preceding hours; tau_225GHz~0.25; pretty clear sky, no wind. DAQ started at 21:15 just after finishing an EMIR scan; window closed, bad KIDs (ar1, 2, 3): 10/1000, 7/574, 9/749. Noise traces:
- DAQ restarted at 21:25; window open, blank sky, bad KIDs (ar1, 2, 3): 17/1000, 7/574, 17/749. Noise traces:
First pointing on 1226+023 (3C273) @21:33, El. ~51.5 deg.; stability: p2p var. ~5 Jy/beam (2 mm); superb tracking. Five focus sequences. Not so stable in the middle of the session (p2p var. up to ~15 Jy/beam, 2 mm). Switched to 3C279 in the last part. Coming back to EMIR at ~22:35. Ideally, the next test -maybe a repetition of this one for confirming results, before the planned partial warm-up (TBD)- should be carried out just before midnight, so that the telescope is more relaxed. Focus offsets: Ar1-Ar2 = 1.01 mm, Ar3-Ar1 = -0.03 mm.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260519s234-238
3C273
0.23
(1.41)
(1.43)
no
Started at 1.0 mm; Ar2 good fit; Ar1 and Ar3 fit from (FWHM's only), peak fits are bad
239-243
3C273
(0.58)
1.53
1.54
no
Started at 1.45 mm; Ar2 fit from (FWHM's only), peak fits are bad; Ar1 and Ar3 good fit
244-248
3C273
0.56
out
out
no
Instabilities increasing; started at 0.3 mm; Ar2 good fit; Ar1 and Ar3 very bad
250-254
3C279
out
1.59
1.53
no
Started at 1.7 mm; Ar2 fit from FWHM is bad; Ar1 and Ar3 good fit
255-259
3C279
0.55
out
out
no
Started at 0.6 mm; Ar2 good fit; Ar1 and Ar3 very bad
- Selected best-fit plots:
Testing focus difference between the arrays: May 20, 2026
- AB: Cryostat cold since April 24, 2026. As a side note, Dave changed to the 2nd trap in the afternoon. Checking yesterday's results just after midnight, hopefully with a more relaxed telescope and stable atmosphere.
DAQ started at 22:55 (LT), bad KIDs (ar1, 2, 3): 21/1000, 7/574, 13/749. Mild wind (~8 m/s max.). Pointing on 3C279, El. ~47 deg. Excellent tracking and stability throughout the session (~2 mJy/beam 2mm): ended at ~00:10. Focus offsets: Ar1-Ar2 = 1.15 mm, Ar3-Ar1 = -0.02 mm.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260520s186-190
3C279
0.72
out
out
no
Started at 0.5 mm; Ar2 good fit; Ar1 and Ar3 bad
191-195
3C279
(0.89)
1.87
1.83
no
Started at 1.7 mm; Ar2 fit from (FWHM's only), peak fits are bad; Ar1 and Ar3 good
196-200
3C279
0.64
out
out
no
Started at 0.85 mm; Ar2 good fit; Ar1 and Ar3 bad
201-205
3C279
(0.96)
1.82
1.81
no
Started at 1.9 mm; Ar2 fit from (FWHM's only), peak fits are bad; Ar1 and Ar3 good
206-210
3C279
0.6
out
out
no
Started at 0.7 mm; Ar2 good fit; Ar1 and Ar3 bad
211-215
3C279
(0.89)
1.71
1.69
no
Started at 1.8 mm; Ar2 fit from (FWHM's only), peak fits are bad; Ar1 and Ar3 good
- Selected best-fit plots:
Testing focus difference between the arrays: May 21, 2026
- DAQ started at 22:40 (LT), window closed, bad KIDs (ar1, 2, 3): 16/1000, 9/574, 11/749. Noise traces:
DAQ restarted at 23:00 (LT), window open, bad KIDs (ar1, 2, 3): 14/1000, 7/574, 14/749. Low wind speed (<3 m/s max.), tau_225GHZ ~0.2. Noise traces:
First pointing on 3C279, clear sky, excellent tracking, stable (<1-4 mJy/beam throughout the shift). Starting focus sequences. Ended at 00:25 (LT). Focus offsets: Ar1-Ar2 = 1.17 mm, Ar3-Ar1 = -0.05 mm.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260521s290-294
3C279
0.71
out
out
no
Started at 0.5 mm; Ar2 good fit; Ar1 and Ar3 bad
295-299
3C279
(0.92)
1.81
1.78
no
Started at 1.8 mm; Ar2 fit from (FWHM's only), peak fits are bad; Ar1 and Ar3 good
301-305
3C273
0.72
out
out
no
Started at 0.7; Ar2 good fit; Ar1 and Ar3 bad
306-310
3C273
0.79
1.99
1.94
no
Started at 1.6; reasonable fits
311-315
3C273
out
1.79
1.77
no
Started at 1.9; Ar2 marginal, Ar1 and Ar3 good; very stable
316-320
3C273
0.6
out
out
no
Started at 0.8; Ar2 good fit; Ar1 and Ar3 bad; very stable
321-325
3C273
out
1.87
1.83
no
Started at 1.9; Ar1 and Ar3 good
- Selected best-fit plots:
Cross-talking of Ar3
2026/05 Kaiyi started the cross-talk analysis of run 80. It seems that the new Ar3 has quite a number of cross-talking KIDs. Here follows an example of 42 KIDs, showing that several are affected (at least 16/42 in this case). The analysis is ongoing and the list of cross-talking KIDs will be updated in the PIIC DAFs as soon as we have converged on the final identification.
Testing focus difference between the arrays: June 5, 2026
- First focus test after the partial warm-up of May 22nd. Cryostat in good shape, DAQ started earlier, window closed, bad KIDs (ar1, 2, 3): 14/1000, 9/574, 7/749. Nice noise traces.
DAQ re-started at 23:55 (LT), window open, bad KIDs (ar1, 2, 3): 28/1000, 4/574, 14/749. Mild wind (~7-8 m/s max.), tau_225GHz ~0.4-0.5. Pointing on 3C273, El. ~43 deg. Excellent tracking and stability along the session (<2 mJy/beam, 2mm): ended at 01:20. Focus offsets: Ar1-Ar2 = 1.13 mm, Ar3-Ar1 = -0.05 mm.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260605s300-304
3C273
0.55
(1.49)
--
no
Started at 1.0 mm; Ar2 good fit; Ar1 fit from (FWHM's only); Ar3 bad (4/5 scans only)
20260605s305-309
3C273
(0.68)
1.65
1.61
no
Started at 1.6 mm; Ar2 fit from (FWHM's only, marginal), peak fits are bad; Ar1 and Ar3 good
20260605s310-314
3C273
(0.89)
1.7
1.64
no
Started at 1.8 mm; Ar2 fit from (FWHM's only, marginal), peak fits are bad; Ar1 and Ar3 good
20260605s315-319
3C273
0.54
(1.47)
out
no
Started at 1.0 mm; Ar2 good fit; Ar1 fit from (FWHM's only, marginal); Ar3 bad
20260605s320-324
3C273
out
1.66
1.61
no
Started at 1.9 mm; Ar2 bad; Ar1 and Ar3 good
20260605s325-329
3C273
0.38
out
out
no
Started at 0.8 mm; Ar2 good fit; Ar1 and Ar3 bad
20260605s330-334
3C273
out
1.52
1.46
no
Started at 1.8 mm; Ar2 bad; Ar1 and Ar3 good
Testing focus difference between the arrays: June 9, 2026
- Second focus test after the partial warm-up of May 22nd.
- Test started late, after 22:15 local time due to strong atmospheric instabilities earlier.
- Cryostat in good shape, DAQ started with window closed, bad KIDs (ar1, 2, 3): 15/5/9. Nice noise traces. Then retuned with window open, bad KIDs (ar1, 2, 3): 17/4/13. Noise traces still nice. See screenshots below.
Low wind (~1-3 m/s max.), tau_225GHz ~0.25-0.32. Pointing on 3C279, El. ~50 deg. Excellent tracking and good stability along the session (~2-5 Jy/beam @ 2mm): ended at 23:40 local time. Focus offsets: Ar1-Ar2 = 1.17 mm, Ar3-Ar1 = -0.05 mm.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260609s205-209
3C279
0.24
1.41
1.38
no
Started at 1.0 mm; Ar2, Ar1 and Ar3 just acceptable fits, a bit on the edge
20260609s210-214
3C279
0.22
out
out
no
Started at 0.5 mm; Ar2 good fit; Ar1 and Ar3 bad
20260609s215-219
3C279
out
1.41
1.36
no
Started at 1.6 mm; Ar2 fit bad; Ar1 and Ar3 good
20260609s220-224
3C279
0.20
out
out
no
Started at 0.3 mm; Ar2 good fit; Ar1 and Ar3 bad
20260609s225-229
3C279
out
1.36
1.30
no
Started at 1.4 mm; Ar2 bad; Ar1 and Ar3 good
- DAQ started at 22:15 (LT), window closed, bad KIDs (ar1, 2, 3): 15/1000, 5/574, 9/749. Noise traces:
DAQ restarted at 22:45 (LT), window open, bad KIDs (ar1, 2, 3): 17/1000, 4/574, 13/749. Low wind speed (<3 m/s max.), tau_225GHZ ~0.27. Noise traces:
Testing focus difference between the arrays: July 8, 2026
- First focus test after the total warm-up of June 12th. Cryostat is cold since July 2nd (telescope's heavy maintenance in the middle).
At the beginning, tau_225GHz ~0.3; ambient temperature: 18.5 C. Homology corrections went crazy with the first scan. Frédéric fixed it. Pointing on 3C273, El. ~50 deg. Excellent tracking and good stability along the session (~1-4 Jy/beam @ 2mm): ended at ~21h (sunset: 21:38). Focus offsets: Ar1-Ar2 = 1.27 mm, Ar3-Ar1 = -0.03 mm.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260708s253-257
3C273
--
0.89
0.86
no
Started at 1.0 mm; Ar2 marginal fit, Ar1 and Ar3 good
20260708s258-262
3C273
-0.37
out
out
no
Started at 0.2 mm; Ar2 good, Ar1 and Ar3 out; repointing on Ar2 again (s263) after setting focus
20260708s265-268
3C273
-0.38
out
out
no
Started at 0. mm; confirming focus for Ar2; Ar1 and Ar3 out, Ar2 good
20260708s269-273
3C273
out
0.89
0.85
no
Started at 1.1 mm; Ar2 quite marginal, Ar1 and Ar3 good; even more stable in the l.o.s.
20260708s274-278
3C273
-0.38
out
out
no
Started at -0.15 mm; Ar2 good, Ar1 and Ar3 out
20260708s279-283
3C273
out
0.95
0.93
no
Started at 1.2 mm; Ar2 out, Ar1 and Ar3 good
20260708s284-288
3C273
-0.34
out
out
no
Started at -0.2 mm; Ar2 good, Ar1 and Ar3 out
20260708s289-293
3C273
out
0.92
0.89
no
Started at 1.25 mm; Ar2 out, Ar1 and Ar3 good
- Selected focus fit plots:
- DAQ started at 20:50 (LT), window (tightly) closed, telescope stopped, mild wind, bad KIDs (ar1, 2, 3): 14/4/7. Some correlated noise is observed below ~1 Hz:
- DAQ restarted at ~21:10, window open, bad KIDs (ar1, 2, 3): 24/6/20. Sampled spectra, El. ~70 deg.:
Testing focus difference between the arrays: July 9, 2026
At the beginning (19:05 LT), tau_225GHz ~0.35 (80% R.H); ambient temperature: ~16 C. Wind speed (max.) ~9 m/s. Pointing on 3C273, El. ~50 deg. Good tracking, p2p ~3-10 Jy/beam @ 2mm over the shift: ended at 21:00 (sunset: 21:37). Focus offsets: Ar1-Ar2 = 1.14 mm, Ar3-Ar1 = -0.04 mm.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260709s261-265
3C273
(0.19)
1.22
1.18
no
Started at 1.0 mm; Ar2 fit from (FWHM's only), peak fits are bad; Ar1 and Ar3 are reasonably good
20260709s266-270
3C273
(0.44)
1.16
1.12
no
Started at 1.35 mm; Ar2 fit from (FWHM's only), peak fits are bad; Ar1 and Ar3 are good
20260709s271-275
3C273
0.04
out
out
no
Started at 0.3 mm; s273 corrupted; even so, Ar2 has a confident fit, Ar1 and Ar3 out
20260709s276-280
3C273
0.08
out
out
no
Started at 0.1 mm; Ar2 good, Ar1 and Ar3 out
20260709s282-286
3C273
(0.23)
1.17
1.15
no
Started at 1.2 mm; Ar2 fit from (FWHM's only), marginal; Ar1 and Ar3 good
20260709s287-291
3C273
(0.37)
1.24
1.20
no
Started at 1.4 mm; Ar2 fit from (FWHM's only), Ar1 and Ar3 good
20260709s292-296
3C273
0.04
out
out
no
Started at 0.2 mm; Ar2 fit good; Ar1 and Ar3 out
20260709s297-301
3C273
(0.42)
1.18
1.15
no
Started at 1.4 mm; Ar2 fit from (FWHM's only), Ar1 and Ar3 good
- Selected focus fit plots:
- DAQ started at 20:55 (LT), window closed, telescope stopped, wind speed (max) ~10 m/s, bad KIDs (ar1, 2, 3): 10/5/8. The ladder above the cryostat and other possible sources of mechanical vibrations were checked: ok.
- DAQ restarted at ~21:15, window open, bad KIDs (ar1, 2, 3): 28/6/20. Sampled spectra, El. ~70 deg.:
Testing focus difference between the arrays: July 28, 2026
* First focus tests after the NIKA2 DAQ problem.
* Starting at 16h30 LT, under very poor weather conditions. Opacity ~ 1 (~ 0.8 towards the end of the session). However, not very unstable: +/- 5 to 7 Jy/beam peak-to-peak at 2 mm.
* Low wind (~ 2.5 m/s); ambient temperature ~ 20 C.
* 3C279: El. ~ 45 deg; 3C273: El. ~ 50 deg.
* Given the very high opacity, today's focus tests should be taken with a pinch of salt. Note also the large number of bad KIDs.
* Bad KIDs Ar1/Ar2/Ar3: 74/8/154
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260728s170-174
3C273
-0.06
0.8
0.74
no
Started at 0.8 mm; Ar2 fit from FWHM's only
20260728s175-179
3C273
-0.12
0.8
0.8
no
Started at 0.8 mm; Ar2 fit from FWHM's only
20260728s182-186
3C273
-0.06
0.86
--
no
Started at 0.8 mm; Ar2 fit from FWHM's only
20260728s192-196
3C273
out
1.18
0.95
no
Started at 0.6 mm; Ar1 and Ar3 from gFit peak, but not nice
20260728s197-201
3C273
-0.4
1.15
out
no
Started at 0.4 mm
20260728s202-206
3C273
-0.52
out
out
no
Started at 0.4 mm
20260728s209-213
3C279
-0.4
0.7
0.63
no
Started at 0.4 mm; Ar2 fit from FWHM's only
20260728s214-218
3C279
-0.6
0.72
0.68
no
Started at 0.4mm; Ar1 and Ar2 fits from FWHM's only
* We try to recover more KIDs with a new tuning. Bad KIDs Ar1/Ar2/Ar3: 71/9/38.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260728s227-231
3C279
-0.5
0.78
0.81
no
Started at 0.2 mm; Ar1 and Ar3 fits from FWHM's only
20260728s232-236
3C279
-0.34
0.85
0.74
no
Started at 0.4 mm; Ar2 and Ar3 fits from FWHM's only
20260728s237-241
3C279
-0.39
0.92
0.81
no
Started at 0.4 mm; all based on FWHM, but not good fits
20260728s242-246
3C279
-0.2
0.84
0.77
no
Started at 0.6 mm; all based on FWHM; Ar3 fit bad
20260728s247-251
3C279
-0.22
0.8
0.76
no
Started at 0.6 mm; Ar2 fit from FWHM's only
20260728s252-256
3C279
-0.37
0.9
0.87
no
Started at 0.5 mm; all based on FWHM
20260728s257-261
3C279
-0.34
0.85
0.7
no
Started at 0.5 mm; Ar2 fit from FWHM's only
* Focus offsets: Ar1-Ar2 = 1.16 mm, Ar3-Ar1 = -0.07 mm.
* Window open and low wind speed (~2.5 m/s), tau_225GHz ~ 1. Noise traces:
Testing focus difference between the arrays: July 29, 2026
* Starting at 15 LT, under very poor weather conditions. Opacity ~ 1 most of the time, but ~ 0.6 towards the end of the session. Ambient temperature 19.9 C.
* Again: given the very high opacity, today's focus tests should be taken with a pinch of salt. Note also the large number of bad KIDs when NIKA2 window is open (tried retuning several times, but getting always similar results).
* Not able to get a calib_1scan on Mars (bad pointing and focus + low elevation) and similar situation at the end of the session on MWC349.
* Checking noise traces.
NIKA2 windows closed, vertex closed, mirrors pointing EMIR. Antenna at 70 deg in elevation. DAQ started at 15h16LT. Bad KIDS Ar1/Ar2/Ar3: 15/4/8.
NIKA2 windows open, vertex open. Antenna at 70 deg in elevation. DAQ started at 16LT. Bad KIDS Ar1/Ar2/Ar3: 53/13/27.
* Stopped for an hour waiting for the weather to improve and resumed observations at 18 LT. Bad KIDs Ar1/Ar2/Ar3: 56/8/30.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260729s201-205
3C279
-0.34
0.98
0.91
no
Started at 0.67 mm; all based on FWHM
20260729s206-210
3C279
-0.03
1.07
1.07
no
Started at 0.9 mm; Ar2 fit from FWHM's only
20260729s211-215
3C279
out
1.07
1.01
no
Started at 1.1 mm
20260729s221-225
3C279
-0.01
1.06
1
no
Started at 1.1 mm; Ar2 fit from FWHM's only
20260729s226-230
3C279
-0.3
0.89
0.92
no
Started at 0.5 mm; Ar1 and Ar3 fits from FWHM's only
20260729s231-235
3C279
-0.35
0.85
0.8
no
Started at 0.5 mm; Ar1 and Ar3 fits from FWHM's only
20260729s236-240
3C279
-0.23
out
out
no
Started at 0.3 mm
20260729s243-247
3C279
-0.06
1
0.95
no
Started at 0.9 mm; Ar2 fit from FWHM's only
* Focus offsets: Ar1-Ar2 = 1.16 mm, Ar3-Ar1 = -0.04 mm.
Testing focus difference between the arrays: July 30, 2026
* Starting with opacity ~ 0.8 and finishing with opacity ~ 0.5.
* Wind ~ 3 m/s; ambient temperature 19 C.
* Checking noise traces.
NIKA2 windows closed, vertex closed, mirrors pointing EMIR. Antenna at 70 deg in elevation. DAQ started at 15h08 LT. Bad KIDS Ar1/Ar2/Ar3: 24/6/9.
NIKA2 windows open, vertex open. Antenna at 70 deg in elevation. DAQ started at 15h30 LT. Bad KIDS Ar1/Ar2/Ar3: 34/10/20.
* Two calib_1scan on Mars (20260730s202 and 20260730s203), under pretty bad conditions; with focus correction from Ar1 and pointing correction from Ar2.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260730s207-211
3C273
-0.40
0.98
0.74
no
Started at 0.5 mm; Ar2 fit from FWHM's only
20260730s212-216
3C273
-0.50
out
0.45
no
Started at 0.0 mm; Ar3 is missing a scan
20260730s217-221
3C273
-0.58
out
out
no
Started at -0.3 mm
20260730s222-226
3C273
-0.46
1.01
0.96
no
Started at 0.5 mm; Ar2 fit from FWHM's only
20260730s227-231
3C273
out
0.78
0.71
no
Started at 0.9 mm
20260730s246-250
3C279
out
0.80
0.75
no
Started at 1.0 mm
20260730s252-256
3C279
-0.39
out
out
no
Started at -0.6 mm
* Finished the slot with a few test scans for the NIKA2 high-frequency noise analysis, but only for the 60”/sec version, but only checking the vertex status (open/closed). Test scan range: 20260730s257 and 20260730s265.
* Focus offsets: Ar1-Ar2 = 1.28 mm, Ar3-Ar1 = -0.06 mm.
Testing focus difference between the arrays: July 31, 2026
* Opacity at the beginning: ~0.7; increasing up to ~1 at the end of the shift along with atmosphere instabilities. Peak-to-peak variations of the timelines > 10 Jy/beam (2 mm).
* Max. wind speed between 6 and 9 m/s; ambient temperature up to 21C. Enhanced 2mm-beam shape: 20.2" x 20.9" from a pointing scan after the first best focus on Ar2.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260731s190-194
3C273
(-0.16)
0.71
0.68
no
Started at 1 mm; Ar2 marginal (Ar2 fit from FWHM only); Ar1 and 3 good
20260731s195-199
3C273
-0.68
(0.33)
(0.25)
no
Started at -0.3 mm; Ar2 good; Ar1 and Ar3 marginal (fit values from FWHM only)
20260731s201-205
3C273
(-0.22)
0.74
0.65
no
Started at 0.8 mm; Ar2 marginal (Ar2 fit from FWHM only); Ar1 and 3 good
20260731s206-210
3C273
-0.72
out
out
no
Started at -0.1 mm; Ar2 good; Ar1 and Ar3 bad
20260731s212-216
3C273
-0.61
out
out
no
Started at -0.6 mm; Ar2 good; Ar1 and Ar3 bad
20260731s217-221
3C273
(-0.18)
0.73
0.68
no
Started at 0.8 mm; Ar2 marginal (Ar2 fit from FWHM only); Ar1 and Ar3 good
Focus offsets: Ar1-Ar2 = 1.38 mm, Ar3-Ar1 = -0.06 mm.
- Selected focus fit plots:
* After the last focus correction, a series of scans on Arp220 for testing high-frequency noise was launched: (i) on-sky (opacity/instabilities increased substantially in the middle): scans 20260731s231-233 (120 arcsec/s), s234-236 (60 arcsec/s) and (ii) window closed: scans s237-239 (120 arcsec/s), s240-242 (60 arcsec/s). Scans with vertex closed + window open omitted by mistake (AB). Scans s243-248 should not be used.
* Checking noise traces:
NIKA2 window closed, vertex close, mirrors pointing EMIR. Antenna at 70 deg in elevation. DAQ started at 15:05 LT. Bad KIDS Ar1/Ar2/Ar3: 13/6/11.
NIKA2 window open, vertex open. Antenna at 70 deg in elevation. DAQ re-started at ~15:50 LT. Bad KIDS Ar1/Ar2/Ar3: 49/9/25.
Testing focus difference between the arrays: August 4, 2026
- Test was delayed due to problems with EMIR and FTS. Prioritize solving them to make sure that all projects of that week run without problems. Started with NIKA2 test time (T21-26) at 19:00 LT.
- NIKA2 tuning with bad KIDs 77/8/34 (Ar1/Ar2/Ar3). Traces look normal in all three arrays. No prominent bumps (just a broad bump around 1 Hz when NIKA2 window is closed, similar to the one seen in the last test). Opacity at the beginning: ~0.6; increasing up to ~0.8 at the end of the shift along with atmosphere instabilities. Peak-to-peak variations of the timelines cover a wide range, about 2-10 Jy/beam (2 mm). Max. wind speed between 4 and 6 m/s.
ql_new_run92 directory folder imbfitsDir symbolic link changed to the new "August" directory (/mnt/data/NIKAIMBFITS/2026/08) to point to the place with the latest data.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260804s171-175
3C273
(-0.02)
1.07
1.00
no
Started at 1.0 mm; Ar2 marginal (Ar2 fit from FWHM only); Ar1 and 3 good
20260804s176-180
3C273
-0.19
out
out
no
Started at -0.6 mm; Ar2 good; Ar1 and Ar3 out of bounds
20260804s181-185
3C273
(0.26)
0.99
0.98
no
Started at 1.2 mm; Ar2 marginal (Ar2 fit from FWHM only); Ar1 and 3 good
20260804s187-191
3C279
-0.43
out
out
no
Started at -0.4 mm; Ar2 good; Ar1 and Ar3 out of bounds
20260804s187-191
3C279
(-0.19)
0.98
0.87
no
Started at 1.4 mm; Ar2 marginal (Ar2 fit from FWHM only); Ar1 and 3 good
Focus offsets: Ar1-Ar2 = 1.30 mm, Ar3-Ar1 = -0.06 mm.
- Selected focus fit plots:
![/!\](/moin_static1911/modernized/img/alert.png "/!\"){kind=small}
DRAFT TEXT BELOW, TO BE EDITED LATER
NIKA2 test time: August 5, 2026
NIKA2 tuning with bad KIDs 78/15/34 (Ar1/Ar2/Ar3). Traces look normal in all three arrays, no prominent bumps. Opacity at the beginning: ~0.9; stayed high (>0.7) throughout the shift along with atmosphere instabilities. Peak-to-peak variations of the timelines cover a wide range, about 2-10 Jy/beam (2 mm). Max. wind speed between 4 and 9 m/s.
- Enhanced 2mm-beam shape: 20.2" x 20.9" from a pointing scan after the first best focus on Ar2.
Focus sequences
Scan nr
Target
Ar2
Ar1
Ar3
Polarized?
Notes
20260805s158-162
3C273
-0.50
out
out
no
Started at -0.5 mm; Ar2 good; Ar1 and Ar3 out of bounds
20260805s163-167
3C273
(0.01)
0.97
0.92
no
Started at 1.0 mm; Ar2 marginal (Ar2 fit from FWHM only); Ar1 and 3 good
20260805s180-184
3C279
-0.32
out
out
no
Started at -0.7 mm; Ar2 good; Ar1 and Ar3 out of bounds
20260805s190-194
3C279
out
0.75
0.61
no
Started at 0.9 mm; Ar2 out of bounds; Ar1 and 3 good
20260805s195-199
3C279
-0.43
out
out
no
Started at -0.4 mm; Ar2 good; Ar1 and Ar3 out of bounds
20260804s200-204
3C279
(-0.54)
0.75
0.67
no
Started at 0.6 mm; Ar2 marginal (Ar2 fit from FWHM only); Ar1 and 3 good
Focus offsets: Ar1-Ar2 = 1.24 mm, Ar3-Ar1 = -0.09 mm.
- Selected focus fit plots:
For the last part of the slot, the opacity stayed high (>0.7) but the stability was acceptable (4-5 Jy/beam), so decided to take some test scans for the NIKA2 high-frequency noise analysis. First we did the 60"/sec version for all vertex/window open/close combinations, scan range 20260805s210-218. Then, with the closed window version tuning of box "I" was lost so repeat the tuning with bad KIDs 124/17/35 (Ar1/2/3, increased due to bad weather?). Then I continued with the 120"/sec version for all vertex/window open/close combinations, scan range 20260805s223-231.
Summary of focus offset tests (mean values) - Run 80
Please update this table after a new session and keep it at the bottom of the page. FWHM-only individual focus corrections were not taken into account:
- (*) Re-commissioning week.
Session dates
Ar1-Ar2 [mm]
Ar3-Ar1 [mm]
Warm-up starts (full/partial)
Cool-down ends
24/3 - 31/3/2026 (*)
1.08
-0.04
03/3 (full)
18/3
25/3
1.00
-0.05
25/4
1.15
-0.05
09/4 (full)
24/4
19/5
1.01
-0.03
20/5
1.15
-0.02
21/5
1.17
-0.05
05/6
1.13
-0.05
22/5 (partial)
26/5
09/6
1.17
-0.05
08/7
1.27
-0.03
12/6 (full)
02/7
09/7
1.14
-0.04
28/7 (Considering FWHM-only individual focus corrections, otherwise no results)
1.16
-0.07
16/7 (partial)
23/7
29/7 (Considering FWHM-only individual focus corrections, otherwise no results)
1.16
-0.04
30/7
1.28
-0.06
31/7
1.38
-0.06
04/8
1.30
-0.06