LBBG Commissioning with AGW1 on December 11-16, 2011 UT

Performance Verification Plan

General Description

John's Email of 10 Nov 2011


While we made good progress on AGW1 commissioning in 2.5 nights on-sky
out of Nov 1-5 2011 UT, there are still a number of issues that need
to be resolved before future adaptive work with IRTC on LBBG can
proceed.  This is a summary of what is NOT yet completed.

See
and the associated night logs
for what was completed.


NEEDED BEFORE NEXT OBSERVING

   - Diagnose and repair the readout problem of the WFS camera. (Issue 3770)
   - Analyze the Field Aberration data (to confirm M3 alignment)
   - Update global offsets to LBBG pointing and collimation

CRITICAL (needed before any AO work can proceed)

   - Verify repaired WFS camera readout on-sky
   - Install and verify updated (8-Nov) AGw probe transformation with another set of Transform data.  (The transformations we tested on-sky 4-Nov were clearly wrong.)

HIGH (would be prudent to complete)

   - Resolve the IDL-GCS discrepancy in the Active Optics calculation.  The problem appears to be on the IDL side - thus not critical.  (Doug might be able to solve this offline.)
   - Remeasure position of rotator center after remounting AGW1.
   - Field Equation Check
   - Complete ~0.5 night of performance verification.

MEDIUM (not very urgent)

   - Measure the platescale on the guider and IRTC on an astrometric field.
   - Measure guider photometric zeropoints other than r'.
   - Pointing model

I estimate that we need two half-nights to complete the critical
priority tasks - really half nights with time for analysis in
between. We would need two full nights to complete the critical and
high priority tasks.

The collection of performance verification data will be the same as the data collect in April for RFBG focal stations, with a few improvements.

Prior to First Night (Dec 10)

DONE Diagnose and repair the readout problem of the WFS camera. (Issue 3770) (John)

WFSC image acquisition worked in the lab and after AGW#1 was reinstalled on the telescope. No changes were made to the camera or AzCam system. The dropping of wfsc frames seems to have "fixed" itself. DLM

ALERT! Analyze the Field Aberration data (to confirm M3 alignment) (Andrew/Doug)

Field data are very noisy, probably due to the pupil wobble problem. In general, Active Optics is having problems with convergence and convergence rate because of this pupil wobble. I may be able to make a fix for the wobble and re-evaluate the Field Data from 20111103.

DONE Update global offsets to LBBG pointing and collimation (John)
DONE Install Jesper's newest transformation (John)
ALERT! Resolve the IDL-GCS discrepancy in the Active Optics calculation. The problem appears to be on the IDL side - thus not critical. (Doug might be able to solve this offline.) (Doug)
DONE Check Lenslet Rotation value (Doug)

Checked it at 1.06 degrees and looks fine

ALERT! Upgrade transformation_collect and transformation_process_set routines (Doug)
DONE Determine better pupil.x, pupil.y from on-axis wfsc data (Doug)

From Field data take on 20111103 at LBBG I found:

  • Pupil_x = 376.7
  • Pupil_y = 199.1

John installed these values in the GCS .config file

Doug installed these values in /home/LBTO/idl/wfsc/agw/agw_set_values.pro

DONE Determine better lenslet_x and lenslet.y values from transform data (Doug)

Determined better values from

  • agw[lbbg].lenslet_edge[0,0] = 358.0
  • agw[lbbg].lenslet_edge[1,0] = 200.0

from the image /Users/dlmiller/lbto/projects/commissioning/focal_station/lbbg/data/wfsc/right_wfsc000001.fits (Note the right_ should be left_)

John installed these values in the GCS .config file

Doug installed this in /home/LBTO/idl/wfsc/agw/agw_set_values.pro

DONE Add AGW_Probe_X and AGW_Probe_Y to DD list in IDL (Doug)

Task List (in order of priority unless poor seeing)

Critical

DONE Verify repaired WFS camera readout on-sky (John, Tina, Jochen)

DONE Measure and install collimation zero points (Steve, John, Dave, Andrew)

DONE Measure and install pointing model offsets specific to LBBG

DONE Realign tertiary to remove WFSC pupil wobble.

From Field Data collected on 20111103 I found one subap wobble as a function of rotator position. See plot of pupil wobble at the bottom of this TWiki page

Does this mean the 1' pointing offset will be removed, as the tertiary position is improved? Should this 1' offset be removed before any pupil wobble analysis?

DONE Measure and install pointing model offsets again post tertiary adjustments.

DONE Remeasure position of Guider rotator center after remounting AGW1. (Needed for transformation data) (John, Tina, Jochen)

See TWiki log 20111211 Log at 02:33

  • guider_x = 220
  • guider_y = 230

ALERT! Remeasure position of IRTC rotator center after remounting AGW1. (Needed for transformation analysis) (John, Tina, Jochen)

Measure with poor seeing.

  • irtc_x = 159
  • irtc_y = 128

We should remeasure this in better seeing.

ALERT! Collect full set of Transform data. 20+ points (John, Tina, Jochen, Jesper, Doug)

Data set collected, but seeing was from 0.9" to 1.5". We will see if Jesper can build a better transformation

ALERT! Determine and install new, better transformation (Jesper, Doug)

ALERT! Verify updated AGw probe transformation with another set of Transform data. 10+ points (John, Tina, Jochen, Jesper, Doug)

High

ALERT! Complete 2 nights of performance verification (Tina, Jochen, Doug)
ALERT! Test new Guide Image Astigmatism routine (Andrew, Olga)

Medium

ALERT! Measure the platescale on the guider and IRTC on an astrometric field. (John, Tina, Jochen)
ALERT! Measure guider photometric zeropoints other than r'. (John, Tina, Jochen)
ALERT! Pointing model (John, Tina, Jochen)
ALERT! Investigate collimation problems at low elevation: Differential Refraction (Tina, Jochen, Doug)
ALERT! Collect another Field Data set (Tina, Jochen, Doug)

Task Descriptions

Critical

AGw Transformation Data Collection

See AGw Transform for instructions.

Seeing should be better than 0.9"

*Tina is checking list files and should update this list*
  • StoneO is on the Meridian at 21:47
  • StoneM at 17:51
  • StoneL at 16:00 Sidereal.

High

Performance Verification

In the past we have used a table (see below) to keep track of performance verification data. As data sets are collected for each type of data and at each elevation the directory name where the data are held is placed in the appropriate column. I have placed a few examples in this table.

Elevation Preset Guiding/Collimation Dice5 (1x1) Dice5 (10x10) Large Offsets (1'-3')
30     dice1_30a dice1_30b    
45   col_45a col_45b      
60       dice10_60a  
75         dice_big_75a

Description of Data Set Types

Presets

A presets data set consists of multiple presets at various elevations to the same target and off-axis guide star with the same position angle (PA). The purpose is to check the repeatability of the all the systems needed to preset, in ACTIVE mode, at different elevations and at different times.

Data Set Requirements

It would be best to have four sets of Preset Data sets.

  • 6 to 8 presets in the elevation range from 30 to 75 degrees
  • Same off-axis (off the Y-axis would be best) guide star
  • Same position angle (say PA=0 for a correctly orientated guide star)
  • Offset telescope by 30"
  • Collect background IRTC images with same parameters as above
  • Allow active optics corrections (Note, one correction can be performed during background collection)
  • Collect IRTC for 30 seconds total integration time (cubes 15 images with 2 second integrations)

Each set, with 6 to 8 points, could be all increasing or decreasing in elevation, or could be both increasing and decreasing elevation (ie collect data on a star from 30, through zenith, and back down to 30)

*Note:* Some data points could be drawn from the Guiding and Collimation Data Sets (See below)

Guiding and Collimation

A guiding and collimation data set consists of presetting the telescope to a target, that can be seen on IRTC and using an off-axis guide star, and allowing the telescope to follow the star for at least 15 minutes. These data sets will contain information about:

  • How well is Guiding working
  • How well Active Optics is working
  • Image quality from IRTC (FWHM to compare to guider value, ellipticity)

Data Set Requirements

We should collect 6 to 8 sets with a range of conditions:

  1. Elevation from 30 to 75 degrees
  2. Range of off-axis guide probe positions
  3. Two sets at the same elevation with all parameters the same expect PA=60 and PA=-60
  4. Various guide star magnitudes (10th to 16th magnitude...should be to 18th mag)

Data Set Acquisition

See Guiding and Collimating for instructions.

Offsets (dice5)

A Dice5 data set consists of presetting the telescope to a target that can be seen on IRTC and then offsetting a given amount in a pattern of the five spots on a di. These data will allow us to understand the accuracy and repeatability of the offsets. Plus these data can be used to analyze image quality.

Data Set Requirements

Dice5 data sets should include the following parameters:

  • Offsets should span a range of distances, say 1", 10" and 3'
  • They should span elevations from 30 to 75
  • Persson (BS) or Stone fields are best to use

Data Set Acquisition

See Dice5 for instructions.

Medium

Differential Refraction

Another possible cause of collimation problems at low elevations may be the differential atmospheric refraction between the guider wavelength and the wfsc wavelength displaces the wfsc pupil enough at low elevation to get some vignetting on the pinhole in front of the wfsc.

To test this hypothesis we will change the guider x,y hotspot and see if the vignetting of the wfsc image changes.

  • Preset to a low (~30) elevation star with a bright (<12 mag) guidestar, on-axis
    • Get current guider hotspot: % getHotspot left
    • Set wfsc integration time to 10 seconds
    • Collect two wfcs images
    • Change guide_x_hotspot by 10 pixels (0.5 arcseconds): % setHotspot left "x value + 10" "y_value"
    • Collect two wfsc images
    • Change guide_x_hotspot by -10 pixels (-0.5 arcseconds): % setHotspot left "x value - 10" "y_value"
    • Collect two wfsc images
    • Change guide_y_hotspot by 10 pixels (0.5 arcseconds): % setHotspot left "x value" "y_value + 10"
    • Collect two wfsc images
    • Change guide_y_hotspot by -10 pixels (-0.5 arcseconds): % setHotspot left "x value" "y_value - 10"
    • Collect two wfsc images

  • Preset to a high (~75) elevation star with a bright (<12 mag) guidestar, on-axis
    • Perform same sequence as above to see if same vignetting of wfsc image occurs

Pointing Model

See Pointing Model for instructions.

Can be marginal seeing (~1.0"-1.3")

-- DougMiller - 06 Dec 2011
Topic revision: r15 - 11 Dec 2011, DougMiller
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