Differences between revisions 1 and 3 (spanning 2 versions)
⇤ ← Revision 1 as of 2015-11-09 15:04:56 →
Size: 1860
Editor: CarstenKramer
Comment:
← Revision 3 as of 2015-11-09 15:05:32 → ⇥
Size: 1857
Editor: CarstenKramer
Comment:
Deletions are marked like this. Additions are marked like this.
Line 1: Line 1:
Line 23: Line 22:
 {{attachment:AntennaFast20151105t185327-1.png||height=250}}  {{attachment:AntennaFast20151105t185327-1.png||width=550}}

Telescope oscillations

This page has been created by CK on 9-Nov-2015.

During the 1st NIKA-2 run in October/November 2015, the telescope ocasionally showed strong and fast oscillations. Here, we collect all available information.

Summary of findings so far:

  • It seems that the oscillations are not repeatable.
  • They only occur with NIKA-2 and its 8Hz slow loop.
  • They manifest themselves with strong Azimuth oscillations of 3arcmin peak-to-peak in Azimuth, while Elevation at the same time shows much weaker oscillations. (AS)
  • Oscillations show-up when doing fast OTF maps with scanning speeds between 40"s and 55"/s.
  • These OTF maps are done with very short subscan lengths of between 7.5sec and 11sec, only.
  • Elevations are normal, 24 to 41deg.
  • The period of the oscillations is about 1sec. (AS)
  • Motor encoder readings are OK. (JP 9-Nov-2015)
  • Often the wind was high (10-15m/s) coming from the North.
  • Oscillations occur after one or more successful OTF scans on the same source.

Tracking

  • AntennaFast20151105t185327-1.png

Scans (CM)

scan          UT start  Az/El   wind(max)    observing mode/script
              OTF parameters: x/ystart/x/yend/x/ystep/totf/notf/scan speed

20151105s152  18:53:19  110/34  3.9m/s       otf (beammap.pako 2nd part)
              -300"/-112"/300"/-112"/0"/3.5"/11s/65/54.5" per s

20151105s156  19:22:58  116/39  5.8          otf (beammap.pako 2nd part)
              -300/-112/300/-112/0/3.5/11s/65/54.5" per s

20151105s158  19:35:19  118/41  5.2          otf (beammap.pako 2nd part)
              -300/-112/300/-112/0/3.5/11s/65/54.5" per s

20151108s43   01:36:53  338/24  14.2         otf (nkotf.pako 5 5 90 0 20 40 radec)
              150/150/150/-150/-20/0/7.5s/16/40" per s

OffProcNika2Run1TelescopeOscillations (last edited 2016-01-18 08:30:48 by CarstenKramer)