4. Pointing

4.1. Blind all-sky pointing

4.1.1. Specification

Better than 10 arcsec (maximum), after thermal correction.

4.1.2. Verification

After correcting for thermal offset in the pointing kernel on one star, point to 30+ stars with a similar sampling of azimuth and elevation that would be used to produce a pointing model. Record departure of centroid from axis for each case and determine pointing statistics.

4.1.3. Results:

4.2. Blind offset pointing

4.2.1. Specification

 Better than 100 milli-arcsec RMS [RD2]

4.2.2. Verification

Select field with well-known astrometric standards such as stars in Messier 67 of Hipparcos stars. Offset between stars with well known separations, and determine error in centroid position from the expected position. Repeat test for offsets ranging from 20” to 1’ and determine RMS errors.

4.2.3. Results:

5. Tracking

5.1. Tracking open-loop

5.1.1. Specification

 Better than 100 milli-arcsec RMS for 30 seconds under low to moderate wind conditions

5.1.2. Verification

Start tracking, log the (not applied) guide corrections from GCS over a 30 second period.

5.1.3. Results:

5.2. Tracking closed-loop

5.2.1. Specification

 Better than 100 milli-arcsec RMS for 1200 seconds and low to moderate wind conditions

5.2.2. Verification

Start guiding on off-axis guide star. Once guiding has started and has converged log the guide corrections sent to PCS from GCS over a 20 minute period. Ensure that collimation look-up corrections are frequently applied so that collimation drift does not affect pointing. To achieve this one could run the active optics routine for closed-loop active correction, ensuring collimation and pointing updates every ~ 32 seconds.

5.2.3. Results:

6. Delivered Image Quality

6.1. Plate scale stability

6.1.1. Specification

 Platescale at the F/15 focal plane entering LUCIFER should be stable to 0.02%.

6.1.2. Verification

Verify on Lucifer images.

6.1.3. Results:

6.2. Active Optics Acquisition range

6.2.1. Specification

 The collimation model must provide a wavefront within the capture range of the SHWFS at the start of each observing session for seeing conditions better than 2.5 arcsec.

6.2.2. Verification

Deliberately pre-aberrate the wavefront with aberrations driven into the system using the PSF GUI, and test for convergence of active collimation and M1 deformation adjustments. Combinations of low-order aberrations adding up to 6000 nm RMS WFE should be used as a starting point.

6.2.3. Results:

6.3. Active Optics Convergence iterations

6.3.1. Specification

 The active optics system shall converge to < 400nm RMS WFE in < 5 iterations after initial collimation at start-up.

6.3.2. Verification

Deliberately pre-aberrate the wavefront with aberrations driven into the system using the PSF GUI, and test for convergence of active collimation and M1 deformation adjustments. Combinations of low-order aberrations adding up to 6000 nm RMS WFE should be used as a starting point.

6.3.3. Results:

6.4. Active Optics Stability

6.4.1. Specification

 The active optics RMS WFE should not exceed 400 nm during closed loop iterations once the system has converged.

6.4.2. Verification

Leave closed loop active optics running on a near zenith transiting star for 30 minutes and record RMS WFE for each cycle. In the long term data on variation of this performance with seeing can be determined.

6.4.3. Results:

6.5. Wavefront Correction

6.5.1. Specification

 The active optics RMS WFE should not exceed 400 nm or natural seeing +10% during closed loop iterations once the system has converged.

6.5.2. Verification

Select a zenith-transiting star (or close to it) to maximize the change in elevation over the 20 minute test, and measure the WFE with the SHWFS without sending closed-loop corrections for 20 minutes. Repeat at several starting elevations, sampling the range of elevation from near zenith to 20 degrees elevation. Note that corrections will be sent to one or more of the primary, secondary and tertiary during open-loop testing from the collimation models.

6.5.3. Results:

6.6. AGw coordinate system alignment

6.6.1. Specification

 Better than 0.05 degrees and < 1 arcsec.

6.6.2. Verification

TBD.

6.6.3. Results:

6.7. Actual Image Quality

6.7.1. Specification

 Specification: Better than sqrt(0.42 + seeing2) arcsec FWHM  Goal: Seeing + 20% arcsec FWHM

6.7.2. Verification

TBD.

6.7.3. Results:

7. System Reliability and System Performance

7.1. Technical downtime

7.1.1. Specification

 Less than 20% telescope technical downtime over duration of commissioning run

7.1.2. Verification

TBD.

7.1.3. Results:

7.2. Observing efficiency

7.2.1. Specification

For SDT: Better than 25% shutter open time

7.2.2. Verification

Seifert proposal:
It has to be demonstrated that 3-4 hours science observation/night is feasible. The observing program for those nights should ressemble a typical science run program, implying both imaging and spectroscopy. We propose here four observing blocks, each with 1 hour on source integration:

(1) Imaging: 2sec DIT (+ 2 sec read out) (+ imaging acquisition (inclusive preset) ~ 5min)
(2) Imaging: 300sec (+ 2 sec read out) (+ imaging acquisition (inclusive preset) ~ 5min)
(3) Longslit spectroscopy: 300 sec (+10 sec read out) (+ spectroscopic acquisition ~ 15 min)
(4) Longslit spectroscopy: 900 sec (+10 sec read out) (+ spectroscopic acquisition ~ 15 min)
On-sky calibration to be added:
(1)(2): Photometric standard: 2 sec DIT (+2 sec read out) - 5 positions (1min/position)
(3)(4) Telluric standard: 2 sec DIT (+2 sec read out) / 30 sec (+2 sec read out) - 2 positions

7.2.3. Results:

7.3. Preset Stability

7.3.1. Specification

 Preset commands from Lucifer shall either return success or legitimate error code for >95% of sent preset commands.

7.3.2. Verification

During Bent Gregorian Commissioning log the number of presets sent and the number of failed presets. Document system failures.

7.3.3. Results:

-- JoarBrynnel - 03 Mar 2009
Topic revision: r2 - 05 Mar 2009, JoarBrynnel
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