Version 1, 2018-Dec-12

1. Background

The KCRM commissioning plan includes relevant tests from on-sky commissioning plans drafted by Keck Staff and instrument development teams of previous Keck instruments so that the new hardware and software functionality are well tested and characterized. This document is expected to undergo periodic revision up through the commissioning period  for KCRM.

To ensure that the necessary tasks are executed and that the relevant information is reported each task will have an assigned task leader.  Task leaders are responsible for the test plan, execution, reduction, and analysis of the acquired data, and although they may enlist others to complete the task, they will ensure that the tasks are completed and reported on reasonable timescales.

Observers will be at the telescope acquiring data and running the tests. It is the responsibility of the task leader to ensure that task descriptions clearly identify all the necessary steps to acquire the data. Observers will work with task leaders by reviewing the observing plans for accuracy, completeness, and clarity.

Data Reducers will reduce and analyze the data and will contribute relevant information in test reports. The analysis of some tasks is completed during the observations, but the analysis of other tasks (e.g. zero points) is longer term, and for these tasks, it is important to identify who is responsible for analyzing and reporting these results.

This document is based on a spreadsheet available on the Keck KCRM documentation page. On that spreadsheet, each task is assigned a priority and an order of execution. The individual tasks are identified by task ID.
The same task ID appears here.

LIST OF Configuration STATES

2. Engineering Task List

The following list indicates the expected order of testing for CARA-related KCRM tasks.

Seq. Test Priority Sky Time Status
High priority - perform as soon as possible
1 P1. Initial target acquisition H 45
4 R1. Determine rotator zero point H 60
5 F1. Focal plane camera functional verification H 30
2 G1. Guider orientation H 60
3 G2. Guider handedness H 60
6 T1. Focus the telescope (manual and autofocus) H 30
7 F2. FPC: verify handedness and scale H 60
8 P2. Define REF pointing origin H 45
9 G3. Guiding in PA mode H 30
10 G4. Guider plate scale and astrometry H 15
11 R2. Determine rotator linearity H 30
12 S1. Object acquisition H 120
13 P3. Define KCWI/MIRA pointing origin H 60
14 S2. Spectrum acquisition H 180
15 T2. Test MIRA H 20
16 T3. Calibrate MIRA H 60
17 R4. Verify pupil alignment H 60
Polarizer and N&S tasks
1 S6. Rehearsal phase of N&S H 30
2 S7. Execution phase of N&S H 60
3 S9. Polarizer verification L 45
4 S10. Polarizer capabilities for faint objects L 130
Additional science tasks
1

S3. Test spectral throughput
(This is the same as S2 is weather is photometric)

 M 180
2 S4. Spectral throughput for all slices L 240
3 S12. Characterize sky subtraction M 60
4 S5. Characterize the effect of scattered light M

90
5 S13. Characterize object contrast M

60
6 S14. Characterize astrometric accuracy M

90
7 S15. Characterize spectral resolution over full field of view M

180
Additional focal plane camera tasks
1 F3. FOV, vignetting, limiting magnitude L 30
2 F4. Astrometric solution for FPC M 20
Additional guider tasks
1 S8. Verify DAR compensation H 90
2 G5. Guiding in non-sidereal mode L 20
3 G7. Guider performance on large offsets M 20
4 G6. Guider differential flexure L N/A
Additional rotator tasks
1 R3. Rotator performance at high elevation M 60
Additional science tasks
1 S11. Verify direct imaging mode M 20

3. CARA Engineering Task List - Thematic

Introduction

This section provides detailed information on the tests enumerated in the table above. Tests are grouped within major categories. Organization of the information is very similar to that used for the science team's tests, with minor changes (e.g., observers are always assumed to be CARA staff). The following information is provided for each:

Summary

P. Pointing Tests

P1. Initial target acquisition

Purpose: Verify the gross pointing of a target after absolute pointing of the telescope

Overview:

Requirements:

Observing plan:  

Reduction plan: N/A

Deliverables/Completion verification: The star appears near the center of the field of view of the guider

 

P2. Define REF pointing origin

Purpose: Define the fundamental pointing origin REF.

Overview:

Observing plan:  

Reduction plan:

Deliverables/Completion verification: REF pointing origin is determined and saved to the configuration database for TCSU.  A star on the guider ends on the center of the guider if it is “sent to REF”.

 

P3. Define KCRM pointing origins

Purpose: Establish additional pointing origins, including MIRA. The list of pointing origins is:
- REF: Center of the guider (Already defined)
- IFU: Center of the field of view

Overview:

Observing plan:  

Reduction plan:

Deliverables/Completion verification: REF pointing origin is determined and saved to the configuration database for TCSU.  A star on the guider ends on the center of the guider if it is “sent to REF”.

 

G. MAGIQ guider tests

G1. Guider orientation

Purpose: The test determines the angle of the guider image X/Y coordinates relative to the Xim/Yim coordinates.

Overview:

Requirements:

Observing plan:  

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G2. Guider handedness

Purpose: Guider camera flip determines the handiness of the guider camera coordinate system

Overview:

Requirements:
Guider camera orientation, TV angle, defined
Rotator zero point defined or estimated

Observing plan:  

Reduction plan:

Deliverables/Completion verification: TVFLIP and TVANGL are correctly set, and saved on the corresponding configuration files. The star moves in the correct way on the guider when telescope moves are issued.

G3. Guide in sideral mode

Purpose: Main guiding mode. We want to verify that we can guide at different values of the PA

Overview:

Observing plan:  

Reduction plan:
Compare initial and final focal plane images, verify that the star motion is within acceptable tolerance

Deliverables/Completion verification:
The guider can guide at all PA values. The motion is within the acceptable tolerance.

G4. Guider plate scale and astrometry

Purpose: Verify the plate scale of the guider and compare with the expected values

Overview:

Observing plan:  

Reduction plan: Shui has a program to do this, almost in real time.

Deliverables/Completion verification: The guider plate scale and the astrometric solutions are determined.

G5. Guide (non sidereal)

Purpose: Verify that we can guide in non-sidereal mode

Overview:

Observing plan:  
1- Slew to non-sidereal target
2- Set PA=0, start guiding
3- Verify that the target maintains the position

Reduction plan:

Deliverables/Completion verification:
The guider can guide in non-sidereal mode

G6. Measure performance of the guider on large offsets

Purpose: If the high order distortion terms are correct, large offsets are accurate

Overview:

Observing plan:  TBD

Reduction plan:

Deliverables/Completion verification:

G7. Guider differential flexure

Purpose: Not sure this is necessary at this time, as the gravity vector is constant, but here as a place holder in case it becomes necessary

Observing plan:  

Reduction plan:

Deliverables/Completion verification:

 

Rotator tests

R1. Rotator zero point

Purpose: The rotator zero point is the offset of the rotator physical angle such that when rotator physical angle is zero the rotator is aligned with the vertical axis. This procedure should be used only after TV angle is determined

Overview:

Requirements:ROTBASE is estimated

Observing plan:  

Method 1


Method 2

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Update ROTBASE in DCS/TCS configuration and reselect instrument.

Reduction plan:  Software written by S. Kwok

Deliverables/Completion verification:

R2. Determine rotator linearity

Purpose: Verify correct tracking of the rotator

Overview:

Observing plan:  The idea is to acquire star trails at 0, 90, 180, 270 in stationary mode and verify that the stellar tracks are parallel or perpendicular to the CCD reference axis

  1. Point the telescope to (AZ, EL) = (180,70), mount coordinates. Set the rotator to 0°, stationary mode, so that stars trail along the long side of the array.
  2. Reduce rotator angle by 90° increments as many times as allowed by the rotator limits.
  3. Configure FPC for imaging.
  4. Set exposure time to 60 s. The images will thus contain vertical trails of stars exposed as the world turns.
  5. Acquire FPC exposures until at least one good star trail is achieved.
  6. Increase the rotator angle by 90° and acquire more star trail images.
  7. Repeat until no more 90° increments are possible

Reduction plan:

Deliverables/Completion verification:

R3. Determine rotator performance at high elevation

Purpose: Verify and characterize the performance of the rotator at increasing elevations to define the "keyhole"

Overview:

Observing plan:  

  1. Acquire a dense field at elevation > 60 degrees, 10 minutes before transit
  2. Start guiding, and aquire 30 seconds exposures with FPC once per minute
  3. Keep going until 10 minutes past transit
  4. Add 10 degrees to the elevation and repeat

Reduction plan:

Examine the focal plane camera for any smearing of the stellar images

R4. Characterize vignetting/pupil alignment

Purpose: Verify and characterize the possible presence of vignetting and the alignment of the pupil

Overview:

Observing plan:  

  1. Slew to an astrometric field that is at a high elevation (70-85)
  2. Select the KCWI PO and center the object
  3. Apply 500 nm of pmfm and determine if segments are vignetted on the FPC.
  4. Move the telescope to see if there are field points with increased vignetting.
  5. Remove pmfm and defocus secondary instead (25-30mm appears to be possible). This should allow imaging of the pupil. Verify that there is no vignetting and that moving the rotator does not affect pupil image other than rotating it on the detector.  This test would also be possible by using the internal pupil imaging lens.

Reduction plan:

Examine the focal plane camera for any vignetting of the segments images

Focal plane camera tests

F1. Focal plane camera verification and preliminary characterization

Purpose: Acquire image of near-overhead star on the focal plane camera to verify functionality and image display.  Get an on-sky handle of the camera response with and without the CAL ND filter in the beam. 
*Note:  This task, along with task 25 might be useful to perform before determining the pointing origin for the slicers (Task 4) or general pointing acquisition (Task 10).  A live feedback of telescope moves should be more efficient than waiting on science CCD readout. We will have a fairly good idea of the relative location of the center of the FPC and the slicers from calibration activities (Task 27)

Overview:

Observing plan:  

  1. Telescope in PA mode, Image de-rotator at PA=0°
  2. Slew to a high elevation star (B=TBD) near the slicer PO, use this star for guiding
    (If doing this before KCWI POs are established, may need to manually command offsets to land the star on the focal plane camera. Record this offset, once done)
  3. Make sure CAL ND filter is retracted
  4. Take a short exposures (t = TBD)
  5. Verify that the images are being displayed properly on the ds9 window
  6. Make sure images are not saturated, slew to a dimmer nearby star if so, repeat
  7. Take a series of images and a stack of images
  8.  Insert CAL ND filter, verify telescope does not lose tracking
  9. Take a longer exposure (t=TBD)
  10. Take a series of images and a stack of images
  11. Verify image display in ds9 and approximate reduction in flux
  12. Retract CAL ND filter

Reduction plan:  Inspect saved images offline, verify ND filter acts as expected. Compute rough sensitivity.


Deliverables/Completion verification:  A first pass estimate of the camera throughput and refined (but still not final) B-mag to exposure time calculator for FPC with and without the ND filter. 

F2. Focal plane camera handedness and plate scale

Purpose: Measure the plate scale and handedness of the focal plane camera

Overview:

Requirements:

Observing plan:  

 

Reduction plan: Analyze the images offline (S. Kwok’s software)  Centroid the star in each image compute plate scale and refine tkrose.

Deliverables/Completion verification: Refined tkrose and FPC plate scale

Focal Plane Camera Tests

F3. FPC limiting magnitude

Purpose: Determine the limiting B magnitude of the Focal Plane Camera for a SNR of 5 in 30 seconds.  The FPC field of view is small 18 x 16 arc seconds unvignetted

Overview:

Observing plan:  
Option 1:

  1. Telescope in PA mode with suitable PA angle
  2. Slew to a dense star field (TBD)
  3. Take a short (1 s) exposure to estimate time T to saturation
  4. Take a series of T length exposures to add up to 30 s, repeat. Save all images

Option 2:

  1. Telescope in PA mode with PA=0°
  2. Slew to a series of high elevation stars from B=18 in dB ~ 1 increments, preferably of the same or very similar spectral type
    1. Take a series of t = 1 s images for each star, save images
    2. With a single star in view, use a script to quickly determine the acquired SNR. Script could (should?) generate exposure times for dimmer stars
    3. Be flexible in magnitude increments, skip steps if SNR high to converge on limiting magnitude as quickly as possible
    4. Once limiting magnitude found, confirm with object of similar brightness

Reduction plan:
Option 1:
Reduce offline using standard astronomical tools (SExtractor) and a deep star catalog (e.g., USNO B 2.0). 
Option 2:
            Use script to compute magnitudes (verify later offline).  Need to write script.

Deliverables/Completion verification:

Limiting magnitude of the FPC for a point source in a 30 s exposure. Exposure T calculator?

F4. FPC astrometric solution

Purpose: Find the astrometric solution for the focal plane camera.  Note, that the focal plane camera has a very small field of view (comparable to the medium KCWI slicer, or 15 x 20 arc seconds).   As such, the expected distortions are not anticipated to be particularly large. 

Overview:

Observing plan:  

  1. Telescope in PA mode with suitable PA angle
  2. Ensure FPC images are being saved
  3. Slew to desired dense star field with 10 -20 stars in the FOV and start guiding
  4. Take a short FPC image to establish suitable exposure time, t
  5. Take a series of longer exposure times to build up good SNR (>5) in the majority of visible stars

Reduction plan: Reduce data offline using standard astronomical tools or Shui's software

Deliverables/Completion verification: Astrometric solution for FPC (quaternion? WCS?)

 

T. Telescope tests

T1. Focus the telescope (manual, Autofocus)

Purpose: Focus the secondary mirror

Overview:


Requirements:

Observing Plan:

Reduction Plan:

T2. Acquire images for MIRA calibration

Purpose: Take images with FPC at different PMFM modes to determine rotation and handedness of images for MIRA analysis.  

Overview:

Observing plan:  

  1. Slew to MIRA star at an elevation of 70 and hour angle 2 hours east
  2. Center the star on the FPC
  3. Apply 250 nm of PMFM
  4. Acquire FPC image, verify exposure
  5. Kick out a segment, acquire second image

Reduction plan: Shui to analyze in real time and make corrections to MIRA script if necessary. This is an update done in real time.

Deliverables/Completion verification: MIRA images are characterized in position and rotation angle.

T3. Verify execution of MIRA script and calibrate MIRA

Purpose: Run the MIRA script and verify it correctly measures focus and tilt (Optional)  

Overview:

Observing plan:  

  1. Slew to MIRA star at an elevation of 70 and hour angle 2 hours east
  2. Center the star on the FPC
  3. Focus the telescope using alternate method (Autofocus)
  4. Run MIRA script
  5. Verify that MIRA requires no focus correction
  6. Apply piston offset
  7. Verify that MIRA predicts the piston correction
  8. Repeat for different values of piston

Reduction plan:

Deliverables/Completion verification: MIRA correctly corrects for piston offsets.

 

Science tasks

S1. Object acquisition

Purpose: Show that target objects can be positioned in the science field of view.  Determine the focus offsets of the FPC and the three image slicers in zero order.

Overview:

Observing plan:  This task is complementary to Task 11, KCWI Pointing Origins.

  1. Insert the focal plane camera (FPC) in the field
  2. Align the science camera for zero order imaging
  3. Remove the N&S mask
  4. Insert the red blocking filter
  5. Remove the grating
  6. Verify the spectrograph is in focus with a flat field calibration arc lamp image
  7. Acquire a star (within 1 hour of zenith) in the guider
  8. Center the star in the guider
  9. Focus the guider
  10. Begin guiding
  11. Download a FPC image, verify properly exposed star image
  12. Capture FPC images at different telescope focus positions
  13. Refocus the guider at the FPC focus position
  14. Verify star image is in a location that will be captured by all 3 slicers
  15. Offset star in guider field if necessary
  16. Insert the large IFU slicer
  17. Download an image, verify properly exposed star image
  18. Focus the telescope of the large slicer
  19. Repeat for the medium and small slicers.

Reduction plan: Offline? The reduction plan would be to use a modified form of CWI_Center_Star on the raw KCWI images to determine offsets from the slicer origins.  Images can be examined in ds9 to determine best focus.

Deliverables/Completion verification: The guider images, pointing offsets, focus offsets  and science images should all be captured.  If a star on the guider can be successfully offset and focused for each IFU and the Focal Plane Camera, then the task is complete

S2. Spectrum acquisition

Purpose: The purpose of this task is show that the instrument properly acquires seeing-limited spectra.  It is complementary to Task 18 (S2)

Overview:

Observing plan:

To the extent that standard stars can be observed, this task overlaps Task 34 (S12)

  1. Insert the large slicer in the field
  2. Remove the N&S mask
  3. Insert the red blocking filter
  4. Insert the RH3 grating
  5. Configure for observations
  6. Verify the spectrograph is in focus with a flat field calibration arc lamp image
  7. Acquire a star (within 1 hour of zenith) in the guider
  8. Center the star in the guider (presuming no offset is required for any slicer)
  9. Focus the guider
  10. Begin guiding
  11. Download an image, verify properly exposed star image
  12. Focus the telescope on the large slicer
  13. Repeat 11-12 for the medium and small slicers.
  14. Reconfigure for RM grating with the large slicer
  15. Acquire a flat field calibration arc lamp image to verify spectrograph focus
  16. Determine best telescope focus for the RM grating
  17. Repeat 14-16 for the medium and small slicers
  18. Reconfigure for BRL grating with the large slicer
  19. Acquire a flat field calibration arc lamp image to verify spectrograph focus
  20. Determine best telescope focus for the BL grating
  21. Repeat 18-20 for the medium and small slicers

Reduction plan: We will be able to determine best focus from visual analysis of the data at the telescope, but more detailed analysis offline may be desired for the final result.  It should be possible to use the focus offsets determined in Task 33 rather than refocusing each slicer/grating combination.  It depends on how stable to telescope focus is and whether there is a benefit to refocusing to provide confidence in the measured spatial resolution.

Deliverables/Completion verification: The Hbeta spectrograph focus should be recorded for each grating and slicer combination.  Assuming 10 images are required for each focus curve, there will be 90 images and 9 instrument configurations required to complete this task.  The task is complete when seeing-limited spectra have been acquired in all modes.

S3. Spectral throughput

Purpose: Spectrophotometric standards will be used to determine the total throughput of the instrument (and telescope and sky).

Overview:

Observing plan:

  1. Insert the large slicer in the field
  2. Remove the N&S mask
  3. Insert the red blocking filter
  4. Insert the RH3 grating
  5. Acquire a standard star (within 1 hour of zenith) in the guider
  6. Center the star in the guider (presuming no offset is required for any slicer)
  7. Focus the guider (presuming the guider focus has been chosen to be confocal with the science focal plane)
  8. Begin guiding
  9. Configure for observations
  10. Verify the spectrograph is in focus with a flat field calibration arc lamp image
  11. Download an image, verify properly exposed star image
  12. Repeat 10-11 for the medium and small slicers.
  13. Reconfigure for RM grating with the large slicer
  14. Acquire a flat field calibration arc lamp image to verify spectrograph focus
  15. Repeat 13-14 for the medium and small slicers
  16. Reconfigure for RL grating with the large slicer
  17. Acquire a flat field calibration arc lamp image to verify spectrograph focus
  18. Repeat 16-17 for the medium and small slicers
  19. As time permits, the camera/grating may be configured to other wavelengths to capture the full range of BL, BM and BH with at least one slicer.

Reduction plan: Reduction will be offline using the pipeline and probably one independent method for verification.

Deliverables/Completion verification: The effective area of the system in each mode should be documented in a report with an attempt to back out the efficiency of the instrument alone.


S4. Spectral throughput for all slices

Purpose: Measure the relative throughput across the science field of view

Overview:

Observing plan:  The plan is to measure the flat field of the instrument using illumination from the sky, and to scale this to the measured standard star efficiency.  For the purposes of generating a high signal-to-noise flat field, twilight illumination will be useful.

  1. Insert the large slicer in the field
  2. Remove the N&S mask
  3. Insert the red blocking filter
  4. Insert the RH3 grating
  5. Point telescope to the zenith during twilight
  6. Configure for observations
  7. Verify the spectrograph is in focus with a flat field calibration arc lamp image
  8. Download an image, verify properly exposed star image
  9. Record enough images to create a high S/N flat (~1%)
  10. Repeat 6-9 for the medium and small slicers.
  11. Reconfigure for RM grating with the large slicer
  12. Acquire a flat field calibration arc lamp image to verify spectrograph focus
  13. Record enough images to create a high S/N flat (~1%)
  14. Repeat 11-13 for the medium and small slicers
  15. Reconfigure for RL grating with the large slicer
  16. Acquire a flat field calibration arc lamp image to verify spectrograph focus
  17. Record enough images to create a high S/N flat (~1%)
  18. Repeat 15-17 for the medium and small slicers
  19. As time permits, the camera/grating may be configured to other wavelengths to capture the full range of BL, BM and BH with at least one slicer.

Reduction plan: Data will be reduced offline using a combination of the pipeline and custom software.

Deliverables/Completion verification: The absolute throughput as a function of wavelength for each configuration and position (flat field vs wavelength) should be available to observers to aid in the reduction of their data.

S5. Measure the effect of scattered light

Purpose: Measure the effect of moon light contamination

Overview:

Observing plan:  

  1. Slew to selected position near the moon
  2. Acquire spectrum
  3. Slew to next position (repeat at 5,10,15,20, 30 degrees away)
  4. Acquire spectrum

Reduction plan: Full pipeline reduction

Deliverables/Completion verification: The produce is a table of sky background contribution as a function of moon distance, and a recommendation to the users as to how close to observe to the moon.

S6. Rehearsing phase of N&S

Purpose: Verify the correct functioning of the S&N rehearsal phase.

Overview:

Pre-observing plan:

  1. Pick a nearby galaxy with obvious emission features.
  2. Set exposure time such that observation will produce high S/N imaging.
  3. Pick a blank background field with no point sources.
  4. Generate finder charts for two fields for verification.
  5. Generate script with N&S planning tool or by hand.

Observing plan:

  1. Run N&S execution tool.
  2. Load script and set to rehearsal mode in GUI.
  3. Acquire science field
  4. Verify science field and guide star coordinates.
  5. Begin guiding.
  6. Initiate rehearsal move to background.
  7. Verify background field and guide star coordinates.
  8. Save script with guide star adjustments.
  9. Complete rehearsal mode.
  10. Verify return to science field with guiding on.
  11. Verify updates to script.

Reduction plan: None.

Deliverables/Completion verification: Verification of correct functioning of N&S rehearsal mode, initial estimate of rehearsal overhead (time).

S7. Execution phase of N&S

Purpose: Verify the correct functioning of the S&N rehearsal phase.

Overview:

Observing plan:

  1. After completion of N&S rehearsal phase, initiate execution phase.
  2. Verify nods with guider display.
  3. Verify completion of execution and readout of image.
  4. Verify correct shuffling of charge by display of science image in ds9.
  5. If time permits, verify pausing and aborting the execution phase.

Reduction plan: Reduce data offline with KDERP.  Verify N&S subtraction.

Deliverables/Completion verification: Verification of correct functioning of N&S execution mode and operational procedure for operating the N&S execution script, initial estimate of N&S overhead (time).

S8. Verify and Characterize DAR compensation

Purpose: The MAGIQ guider in the KCWI Blue Channel instrument guides in I band, whereas the instrument observes in U, B, and V.  Differential atmospheric refraction will lead to smearing of objects on the science detector.  The purpose of this task is to verify that the magnitude and direction of the DAR compensation built into guiding is correct. This can easily be done in bright time and can (probably) be done in nautical twilight or dimmer sky.

Overview:

Observing plan:  


Sequence 1:

  1. Telescope in PA mode
  2. Slew to a bright (U = TBD) blue star at high airmass (setting z = 2 or rising z = 3 ) with Dec close to 19.8°
  3. Set PA to align the dispersion direction (elevation) with the long axis of a slice
  4. Offset star to the center of slice 10, configure the DAR tool/software to compensate and track at 380 nm
  5. Take science exposures of a few seconds to and adjust exposure time t to get good SNR
  6. Take a cadence of exposures as the object rises (sets?) for 40 minutes
  7. Record MAGIQ guider generated offsets and guider images during this time

May need a second sequence to verify compensation angles, or at another slicer orientation?  These tests can be quite time consuming, though.

Reduction plan:
Reduce data through KCWI pipeline offline.  Determine shift of object at different wavelengths within the BM range – making sure that the configured wavelength (380 nm) remains fixed.  Do this by looking at narrowband images from the cube around 380 nm.  Verify other wavelengths shifting in appropriate fashion

Deliverables/Completion verification: Verification that the DAR compensation is valid


S9. Verify Polarizer Capability

Purpose: KCWI is equipped with a linear polarizer that can be inserted into the beam and rotated to an arbitrary angle.  Three images of an object, with the polarizer set to 3 different angles, allow for the determination of the amount and direction of the linear polarization of the source.  The purpose of this test is to verify this capability and to refine the polarizer offset angle.

Overview:

Observing plan:  

  1. Telescope in PA mode with PA=0°
  2. Instrument configured as follows:

  3. Slicer

    FPC

    Grating

    BL

    Filter

    FPC-ND?

    Mask

    No

    Polarizer

    Out

     
  4. Slew to a polarimetric standard (LRIS documentation is a good resource:
    http://www2.keck.hawaii.edu/inst/lris/polarimeter/pol_quickref.html)
  5. Offset to slicer pointing origin, begin guiding
  6. Take a series focal plane image of the object (determine exposure time and save all FPC images)
  7. Insert polarizer into the beam with and take a series of images with polarizer at angle P=0°, 120°, 240°. Instrument setting:

  8. Slicer

    FPC

    Grating

    BL

    Filter

    FPC-ND?

    Mask

    No

    Polarizer

    Yes (0°, 120°, 240°)

     

    Other requirements

    Guiding

     
  9. Repeat steps 2 to 6 for another standard
  10. Turn off focal plane camera, insert large slicer:

  11. Slicer

    Large

    Grating

    BL

    Filter

    Red-Blocking

    Mask

    No

    Polarizer

    Yes (0°, 120°, 240°)

     

    Other requirements

    Guiding

     
  12. Offset object to center on slice 11
  13. Rotate polarizer to P=0°, 120°, 240° and acquire science image with good SNR at each setting
  14. Remember to take a full set of calibrations, including polarizer flats in the afternoon/morning

Reduction plan:  Reduce science data offline through the KDERP.  Analyze FPC images offline. Determine fluxes for the three polarization images and combine to deduce the degree of linear polarization and direction. Compare with and calibrate against tabulated values.

Deliverables/Completion verification: Verification of polarizer capability and refinement of polarizer 0 angle.

S10. Verify Polarizer Capability for Faint Objects

Purpose: Explore the sensitivity of the KCWI polarimeter to faint diffuse sources.  This could be part of the science verification, though in that case the target selected will be dimmer, and required time longer (200 minutes, min).

Overview:

Slicer

Large

Grating

TBD

Filter

Blue

Mask

IN

Polarizer

In

 

Other requirements

 

 

Observing plan:  

  1. Prepare a nod-and-shuffle observation for the selected extended object
  2. Telescope in PA mode, PA angle set to selected target
  3. Instrument in N+S mode, large slicer, filter, grating TBD
  4. Slew to known polarized extended/diffuse nebula (TBD)
  5. Align on target and rehearse N+S script
  6. Insert polarizer and rotate to P=0°
  7. Rotate polarizer to P=120°
  8. Rotate polarizer to P=240°
  9. Retract polarizer
  10. Remember to take appropriate calibrations in the afternoon/morning

Reduction plan: Offline, using KDERP, same concept as task 32.

Deliverables/Completion verification: Estimate of the sensitivity of polarimetric measurements with KCWI Blue.

S11. Direct Imaging Mode


Purpose: Verify direct imaging data acquisition and image reconstruction

Overview:

Observing plan:  

  1. Telescope in PA mode with PA angle set appropriately for the target (most likely PA=0° is OK)
  2. Slew to target (TBD, open cluster, outskirts of a cluster, dense star field, etc. – want 10 – 20 stars on the large slicer)
  3. Offset target to slicer pointing origin, start guiding
  4. Focal plane camera in
  5. Large slicer in
  6. Medium slicer in
  7. Small slicer in

Reduction plan: Reduce offline with  KDERP. FPC images using standard astronomical image reduction tools.

Deliverables/Completion verification:  Confirm direct imaging works, estimate sensitivity from stars in the field. 

S12. Charterize sky subtraction


Purpose:Characterize the accuracy of sky subtraction using nod-and-shuffle source/background subtraction.  The simplest approach is to first perform a series of shuffle with no nod exposures. The precision can be measured by summing the source and the background spectrum and looking at the subtraction residuals vs. the expected Poisson noise. Then the same experiment can be performed using either a blank field target or science target as “Source”, with an offset “Background” field. Ideally this would be done to the deepest level possible with multiple gratings and slicers. This is not practical during commissioning. More realistically we will select 3 settings, RH2 with Small slicer, RM with medium slicer, and RL with large slicer in order to span the resolution space from R~1000 to R~20,000.

Targets: Blank sky, high latitude. Lyman alpha blob. Lyman break galaxy halo.

Observing plan:  
Sequence 1 (Shuffle/No Nod):

  1. Prepare a nod-and-shuffle observation for the selected extended object
  2. Telescope in PA mode, PA angle set to selected target
  3. Instrument in N+S mode, large slicer, filter, grating BL
  4. Slew to blank sky location (no bright stars, no galactic cirrus, high galactic latitude). Ideally no elevation greater than 90° to eliminate rapid pupil rotation. Align on target. Start guiding
  5. Perform standard NAS script but disable telescope moves. Utilize 2 min integrating time, 10 total source/10 total background exposures
  6. Obtain TBD exposures

Sequence 2 (Nod and Shuffle)

  1. Prepare a nod-and-shuffle observation for the selected extended object
  2. Telescope in PA mode, PA angle set to selected target
  3. Instrument in N+S mode, large slicer, filter, grating BL
  4. Slew to blank sky location (no bright stars, no galactic cirrus, high galactic latitude). Start guiding.
  5. Align on target and rehearse N+S script
  6. Perform standard NAS script. Utilize 2 min integrating time, 10 total source/10 total background exposures
  7. Obtain TBD exposures

Sequence 3 (Shuffle no nod): repeat sequence 1 with BH2, small slicer
Sequence 4 (Nod and shuffle): repeat sequence 2 with BH2, small slicer
Sequence 5 (Shuffle no nod): repeat sequence 1 with BM, medium slicer
Sequence 6 (Nod and shuffle): repeat sequence 2 with BM, medium slicer

Reduction plan: Reduce data through KCWI pipeline offline.  Determine residuals in standard source minus background data cube, compare to expected noise.

Deliverables/Completion verification:   

S13. Charterize object contrast

Purpose:  Characterize the contrast of an object vs positon

Possible targets: Bright blue SAO stars

Observing plan:  

  1. Telescope in PA mode
  2. Instrument large slicer, BL grating
  3. Slew to a bright (U = TBD) blue star at low airmass
  4. Offset star to the center of slice 12
  5. Take science exposures of a few seconds to and adjust exposure time to get maximum DN without saturation
  6. Obtain TBD exposures. Dither ½ slice between exposures
  7. Repeat 2-6 with small slicer, BH2, and medium slicer,BM

Reduction plan:
Reduce data through KCWI pipeline offline.  Co-add data cubes after alignment. Determine PSF distribution out to edge of slicers.

Deliverables/Completion verification:
Broad wing PSF vs. slicer/grating. Verify intensity of scattering wings is below 1.e-3 beyond 5 arcsec radius in all directions.

S14. Charterize astrometric accuracy

Purpose:  Characterize the accuracy of astrometric solution in reduced data cubes using direct imaging and BL grating and all three slicers.  

Possible Targets: M13, M36, other open clusters

Observing plan:  

  1. Telescope in PA mode
  2. Slew to a open star cluster with >10 stars per small slicer field
  3. Take science exposures of a few seconds to and adjust exposure time to get good SNR
  4. Record FPC prior to each science exposure
  5. Take a series of ~10 guided exposures dithering ¼ slice perpendicular to slices between exposures
  6. Take a series of 10 guided exposures dithering 2 arcsec parallel to slices.
  7. Take a series of 10 guided exposures offsetting rotator PA by 10° between exposures
  8. Store MAGIQ guider and FPC camera images for all exposures

Reduction plan:
Reduce data through KCWI pipeline offline. Determine centroid positions of all stars in data cubes for each dither/PA position. Determine residuals of KCWI and GSC/other astrometric reference catalog, compare to requirement, and determine any systematic trends of residuals vs. star/slice/Position Angle.

Deliverables/Completion verification:
Verification that the astrometry requirement of 0.2 arcsec (rms) knowledge is met.

S15. Charterize spectral resolution over full field of view

Purpose:  Characterize the highest possible spectral resolution using the highest dispersion gratings with the small slicer. Characterize the spectral resolution for point sources using the medium and large slicers and BH2.

Possible Targets: Dwarf elliptical galaxies with velocity dispersion <10 km/s. Bright stars. Globular clusters (many choices). Galactic nebulae (PNe or reflection nebula).

Observing plan:  
Sequence 1: Bright star

  1. Telescope in PA mode
  2. Slew to star
  3. Take science exposures of a few seconds to and adjust exposure time to get good SNR
  4. Take exposure required to obtain good SNR in 1”x1” pixels
  5. Take a grid of exposures 2” x 5” over slicer
  6. Take 2 settings per grating for all 3 gratings to cover full 3500-5600Å bandpass

Sequence 2: Globular cluster (good seeing)

  1. Slew to Globular Cluster
  2. Take science exposures of a few seconds (fast/4amp) and adjust exposure time to get good SNR
  3. Take deep exposure of center of GC.
  4. Take 2 settings per grating for all 3 gratings to cover full 3500-5600Å bandpass

Sequence 3: Galactic nebula

  1. Slew to nebula
  2. Take science exposures of a few seconds (fast/4amp) and adjust exposure time to get good SNR
  3. Take deep exposure of center of GC.
  4. Take 2 settings per grating for all 3 gratings to cover full 3500-5600Å bandpass

Sequence 4: Elliptical Galaxy

  1. Slew to galaxy
  2. Take science exposures of a few seconds (fast/4amp) and adjust exposure time to get good SNR in 2” x 2” voxels
  3. Take deep exposure of center of galaxy.
  4. Take 2 settings per grating for all 3 gratings to cover full 3500-5600Å bandpass

Reduction plan:
Reduce data through KCWI pipeline offline. Measure spatial resolved spectral resolution. Measure spectral resolution in light bucket mode.

Deliverables/Completion verification:
Verification that the on sky spectral resolution is the same as that measured using the Cal system and meets requirements.

4. List of instrument states

Appendix

SKYPA Definitions

Keck instruments generally have multiple sky position angles defined. The fundamental definition of the sky position angle (SKYPA) is the angle between celestial north and the guider YIM axis. Accordingly, the sky position angle which will be saved in the image headers and displayed on FACSUM will not be the fundamental sky position angle as defined in KSD 40.

The following SKYPA options are proposed for KCWI:

Name Description Offset*
[°]
SKYPA0 Perpendicular to slicers 0
SKYPA1 Guider column (YIM)** 0
SKYPA2 FPC column 0

Notes:

Considerations Regarding Rotator Calibrations (TBD!!)

According to KSD 40, guider YIM shall define the rotator angle and hence the fundamental SKYPA, SKYPA1. However, the guider is neither the most stable not the most astronomically important element in the focal plane: the slicer mechanism is of greater utility. This suggests the following plan for achieving rotational alignment of the focal plane systems: This suggests the following order of operations to define DCS parameters: