MODS2 Commissioning Night 1 - 20140430 UT

Observers: DMiller, RPogge, OKuhn (LBTO), JHill, MWagner (Tucson)
Telescope Operator: SAllanson (LBTO)
AO Support: DMiller (LBTO)
Telescope Support: (LBTO)
Software Support: TGolota, KSummers (Tucson)
Instrument Support: JPower (LBTO)
Engineering Support: DAshby (Tucson)



  • Initial checkout of on-axis guiding and active optics.
  • Calibration of RIGHTZEROPOINT aligned to the MODS2 longslit.
  • Adjusted MODS2 stage to put 0,0 on the rotator center
  • Took guider photometric images (in poor seeing)

Anomalies that we have NOT solved:

  • Invalid rotator polynomials - see Issue 4611. This is only a minor impediment to progress.

  • Guide cam loses the star image (and light from the sky) when the guide probe moves off-axis. Feels like an electrical connection problem. This is a major impediment to further progress (see Issue 5166 for a description and resolution).

*Z11/Z22 problems with the wfs - Not stopping work right now, but could be a serious problem. It appears that the MODS2 wfs is not correctly focussed on the pupil at the secondary. Speculation connects that defocus of the outer edge to problems measuring Z4/Z11/Z22.


Running GCS.2014A.Ver-


Sky is photometric, but seeing is poor. Wind is surprising light given how breezy it is in Tucson.

Initial Rotation Alignment

02:30 Adjust RIGHTZEROPOINT to be 57 deg less than LEFTZEROPOINT which is close.

WFSC Lenslet Data

02:30 We collected several WFS images pointing at Zenith with the chamber open. Image right_wfsc000017.fits was used to set the position of the lenslet array. The values of 263, 110 were put into MODS_R.cfg
  • WFS lenslet postion:

Initial Guiding Tests

02:35 GUIDE preset - acquisition offsets did not put the star on the hotspot (even though the present hotspot is not correct for WFS). The guiding corrections are OK as far as we can tell in 3 arcsec seeing.

Correcting Acquisition Offset

Acquisition Offset is wrong. It offsets to the lower left between the 2 acquisition images. The probem was that guidecam_center_x/y was not set to the same value as guidecam_hotspot_x/y. This is a necessary condition for MODS2 (and MODS1 when its modfied). For MODS, the acquisition offset moves the star to guidecam_center_x/y rather than guidecam_hotspot_x/y.

03:05 Acquisition Offset is corrected

Initial Active Optics Check

03:00 Doug proceeding with Active Optics work while John understands the acq offset.

03:15 ACQUIRE preset to allow eyeball collimation. Steve applies -1500 Z7

Why are we having trouble adjusting the hotspot for the wfs? Could it be something more than 3+ arcsec seeing?

03:55 MODS2.cfg was reading the wrong rotator angle. We corrected it to:
WFS_rotatorAngle     mcs.rotatorSide[1].rotators[5].actualPositionASec 

04:10 Now using the same wfs signs as MODS1 (not LUCI2) and the active optics is converging for Z4-Z11.

04:15 ACTIVE preset off-axis - but no star...... The on-axis pointing is OK.

Off-axis guiding tests

04:25 AO857 ACQUIRE gs=1

04:27 AO857 ACQUIRE gs=0 same PA ??? but didn't move to the other star.

04:32 IDL AO857 gs=0, but he sent the wrong PA

04:35 IDL AO857 gs=1

Authorize MODS on both sides, Pseudomono on RIGHT

04:47 ACQUIRE gs=0 PA=280 - orientation looks the same but we can't rule out 180 deg rotation on this equal intensity binary.

04:49 ACQUIRE to adjust pointing on nearby star - SX IE=-47 CA=-35 DX IE=+9 CA=-195

04:52 ACQUIRE on-axis PA=280

04:53 ACQUIRE gs=1 PA=280 (but right side didn't get any stars!)

04:55 ACQUIRE on-axis PA=280 - Rick moving probe to Y=-5, and star disappears. ???????

05:00 Home the MODS probe on both sides. Both probes came back to the same position, but now the strange behaviour is gone momentarily.

05:05 ACQUIRE gs=1 PA=280 - success

05:06 ACQUIRE gs=2 PA=280 (but now acquire readout looks peculiar on MODS2 - did it miss?)

05:16 ACQUIRE AO857 TS=3 (fainter) on-axis - 1 mm of motion is enough (-5 to -6) is enough to make the star disappear.

05:24 ACTIVE gs=0 PA=280 - guide image drops out with a 0.1 mm move of the stage, but wfs image is still there and not obviously vignetted. It seems to drop out at Y=-3.9 mm. Is it repeatable ??

readGuideCam images in /home/dlmiller/data/20140430/

05:47 changing ROI back to 512x512 image. See right_guider000006.fits with star, and 000007 w/o star AND without mask.

05:49 dIE +20 0009 to 0011

Preliminary conclusion is that the problem is off an electrical nature (i.e. not vignetting), but only weak evidence to support that.

05:55 stop and restart the MODS2Cam machine - 0012

06:00 Cycle power on the CCD controller, then restart GCSR (which parked the probe)

06:06 restore IE to bring back the star

0019 is with probe at home position

0020 0021 are before/after hatch closed

06:12 IDL ACTIVE preset on-axis PA=280

06:14 IDL ACTIVE preset gs=1 PA=280 (acq image was OK, at y=-11 mm)

IDL ACTIVE preset gs=2 PA=229

Rotator polynomials are below the minimum limit.

06:18 Left side is then stuck, when we cancel the right preset. Left says "preset aborting".

06:20 Restart PCS - had to kill it.

06:23 Left says "preset aborting".

Uncheck pseudomono.

06:22 gs=2 Change PA from 229 to 280 - rotator is happy but acquire image is goofy.

06:25 IDL ACTIVE preset gs=1 PA=280 all OK.

06:26 IDL ACTIVE preset gs=1 PA=229 - rotator fails.

John's PCSGUI core dumps (the QT4 problem)

06:30 IDL ACTIVE preset gs=2 PA=280 acquire image is striped.

Off-axis guiding and wfs tests were not completed due to the problems we encountered.

Measuring the Rotator Center (in bad seeing)

back to pseudomono

06:40 ACTIVE preset to fainter target

06:45 clear Forces on DX primary

Active Optics seems to be applying Z11 that it does not need to which is building up crosstalked Z22. This is the 11x11 mask with dynamic reconstructor.

Stop guiding

dIE=5 arcsec

Probe to 0,0

readGuideCam right -e 1000 (dummy)

Move rotator to 0, then slew to 360

07:02 readGuideCam right -e 90000 - 0023 (apparent 224,211.5 ==> 224+84,212+50 ==> physical 308,262) hotspot is at physical 269,234

slew 360 to 0

07:05 readGuideCam right -e 90000 - 0024 (apparent 222, 216)

07:11 ACTIVE preset while calculating

probe -Y makes the star move in +Y guider pixels

stop guiding

Rick adjusts stage -2 mm X, +2.4 mm Y

dIE = +5

slew to rotator 0, then to 360

07:21 readGuideCam right -e 90000 - 0025 (apparent 193,175 ==> 193+84,175+50 ==> physical 277,225)

07:27 ACTIVE preset while calculating

slightly more X, slightly less Y ==> -2.61, +1.73 mm

07:30 readGuideCam right -e 90000 - 0026 (apparent 185.5, 184.1)

Note added later (O Kuhn) Rick adjusted Xcenter, Ycenter, Focus0 in agw.ini file so that gprobe 0 0 will correspond to rotator center.

# Puts GProbe 0 0 at measured rotator center 2014-04-30
XCenter 91.31
YCenter 201.960
Focus0  39.504

07:36 ACTIVE preset briefly

while adjusting config file, and restart the server in MODS. (restart agw server)

07:46 ACQUIRE PA=0 and recenter DX IE=+15 CA=-199

07:49 ACQUIRE PA=90

07:50 ACQUIRE PA=180

07:51 ACQUIRE PA=270

Adjustment of the MODS2 stage relative to the rotator center was completed.


08:00 ACTIVE preset

Clear Active Optics on Primary

John thinks the wfs is not properly focussed on the secondary and that this is the irritant for spherical aberration since the spots at the edge of the pupil are soft. The other possibility is that the wfs collimator lens is too far from the focal plane and we are vignetting on the edge of the lens.

08:25 Rick and Olga are doing offsets in TRACK mode, but these notes aren't well connected with what they are doing. This is the mis-mounted MODS2 orientation, so we'll have to repeat this in the fall.

Olga adding notes to RightZeroPoint20140430



09:25 The RIGHTZEROPOINT value is confirmed within the limits of 2 arcsec seeing.

Convention for determining the sign to apply:
  1. Compute the angle the lines of stars must be rotated to align with the slit image on the CCD detector
  2. If the correction is clockwise, it is subtracted from the initial ZeroPoint
  3. If the correction is counterclockwise, it is added to the initial ZeroPoint

Guide Camera Photometric Performance

Back to pure monocular mode

Doug copied the default flat file to MODS.flat for the adaptive secondary.

09:32 ACQUIRE to Pointing Star near M92 - DX IE=19 CA=-205 : Steve added a note to Issue 4611.

09:43 Changed RIGHTZEROPOINT from -32.45 to +327.45 Note added later by O Kuhn...Actually, RIGHTZEROPOINT in PCSInstrument.conf = 327.55 (= -32.45+360)

09:51 TRACK Preset to M92, then send guide probe to 0,0

09:52 Polycom disconnects (8 hours limit? call time was 08:00:35)

09:58 Unwrap

John is not taking detailed notes about which fields and filters they are working on.

Olga adding her notes on acquiring data for assessing the guide camera photometric performance at GuideCameraPhot

10:49 ACTIVE preset PA=0 for collimation and rotator polynomial test.



Filters for these photometric images are not correct in the header.


11:40 Close for impending dawn

Refine WFSC Pupil Center

Next Day: Fine a reasonable good (collimated and OK seeing ~1.5) WFSC image and determine the pupil to be 417.6, 228.2.
  • By eye circle around WFSC pupil:
  • WFSC pupil with lenslet grid:
Topic attachments
I Attachment Action Size Date Who Comment
lenslet_alignment.jpgjpg lenslet_alignment.jpg manage 239 K 30 Apr 2014 - 19:40 DougMiller WFS lenslet postion
pupil_center_1.jpgjpg pupil_center_1.jpg manage 73 K 30 Apr 2014 - 20:24 DougMiller By eye circle around WFSC pupil
pupil_center_2.jpgjpg pupil_center_2.jpg manage 94 K 30 Apr 2014 - 20:24 DougMiller WFSC pupil with lenslet grid
Topic revision: r9 - 02 May 2014, RichardPogge
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