Version 1, 2002-Apr-22
1. Background
The purpose of this document is to describe the
observatory-specific tasks to be carried out during the DEIMOS
commissioning period. The commissioning of DEIMOS is a
collaborative effort between the instrument team and the
observatory team. Generally speaking, the instrument team will
take responsibility for tests which involve instrument
characterization, such as astrometric tests, sensitivity tests,
etc. This document describes those additional tests which
involve the interface between the instrument and the telescope.
The remainder of this document is divided into two main
sections. The first, a sequential
list, serves as a summary list and notes the order in
which the tests are expected to be carried out. It also
indicates the estimated time requirements and the priority.
The second section is a thematic list
gives details on the individual tests. The document concludes
with an appendix with sections discussing SKYPA definitions and Considerations Regarding Rotator
Calibrations.
2. CARA Engineering Task List - Sequential
The following list indicates the expected order of testing for
CARA-related DEIMOS tasks.
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:
- Overview
- Goal: Statement of goals, why needed
-
Priority: Task priority code; where:
- Priority 1 = Highest priority; should
be done during early June commissioning run
- Priority 1b = High priority; should
be done during June commissioning runs
- Priority 2 = Medium priority; perform no later
than July engineering run
- Priority 3 = Lower priority; can be completed
later, if needed
- Product: Results to be provided
- Data: On-sky data that will be taken and analyzed
- Observing script
- Target: Target IDs, coordinates, finding
charts if needed
- Observing log: number of images, instrument settings,
exposure times
- Procedure: Observing instructions; sequence
of operations
-
Sky time: Estimated time needed to execute
this program, in HH:MM format.
- Requirements: Observing prerequisites: e.g.,
sky conditions, seeing, rotator mode, any parts of the
instrument that DON'T need to be working,
airmass/atmospheric dispersion constraints
- Calibrations: Associated instrument
calibration data and instructions for taking them
(flats, wavelength calibrations, twilights, etc.)
- Notes: Any other information needed by the observers
- Analysis
- Timescale: Timescale for data reduction
- Procedure: Steps in the data reduction
- Software: Software tools needed, including
- Existing packages
- New tools that need to be written
- End products: Lists reports and stuff to be produced
-
Status: Gives the completion status of the test.
Typical stages will be include:
- To be scheduled
- Scheduled
- Observing in progress
- Observing completed
- Analysis in progress
- Analysis completed
- Results posted
Summary
- E. Pointing Tests
- F. Guide Camera Tests
- G. Autoguider Tests
- H. DCS Tests
- I. Rotator Tests
- J. Focusing Tests
E. Pointing Tests
E1. Initial target acquisition
- Overview
- Goal: Verify initial pointing by putting a target
onto the center of the guider
- Priority: 1
- Product: Rough coordinates of REF pointing origin
in the telescope focal plane
- Data: None
- Observing script
- Target: Any prominent Galactic globular
cluster or other extended object with a well-defined
gradient to lead us toward the center, OR a bright (V=3)
star with PMFM=1000
- Observing log: None (no exposures required)
- Procedure:
- Set the instrument rotator to PA mode at 0°.
- Bring up the DCS GUI pointing origin window and
enter the approximate coordinates of the REF pointing
origin.
- For rough pointing check, select and point to a
globular cluster OR bright star, and send to REF
pointing origin.
- If using a bright star, put 1000nm of PMFM into
primary.
- Set handle paddle to "Adjust Pointing Origin"
mode and use it to adjust the position of the REF
pointing origin until object is centered on the guider
pickoff mirror.
- Have OA set pointing.
- Change the rotator angle by 90° and verify
that the object remains in the same position (roughly
--- we expect some movement because REF is still
defined only roughly).
- For fine alignment, select and point to any
reasonably bright star send to the nominal REF
pointing origin for DEIMOS (center of the pickoff
mirror).
- If necessary, center using the hand paddle.
- Have OA set pointing.
- Check pointing using 2-3 nearby GSC target stars.
- Sky time: 0:30
- Requirements: Partially clear skies;
approximate coordinates of REF from Vern Wallace
- Calibrations: None
- Notes: A globular makes a good target; it's
easier to tweak up pointing on than bright stars or other
types of fields -- you hopefully can distinguish a
gradient in the star density. Also possible is to use a
bright star with the segments splayed out using PMFM=1000.
- Analysis
- Timescale: Immediate
- Procedure: N/A
- Software: None
- End products: TBD
- Status: To be scheduled
E2. Define REF pointing origin (T667b)
- Overview
- Goal: Define the position at which target
stars should appear on the guider
- Priority: 1
- Product: Accurate coordinates of REF
pointing origin in the telescope focal plane
- Data: None
- Observing script
- Target: Any moderately bright star
- Conditions: Partially clear skies
- Prerequisites: Determine TV guider pixel
position at which stars should be centered (nominally the
pixel center of the pickoff mirror region?)
- Observing log: N/A
- Procedure:
- [OA] Acquire GSC star and send to REF pointing
origin. It should be nearly centered on the guider.
Begin guiding.
- Bring up the DCS GUI pointing origin window.
- [OA] On XGUIDE, set "Adjust pnt origin using ADJ
PNT/GOTO" to "no".
- [OA] Adjust collimation by pressing the "Adjust
Pointing" button on Xguide.
- Note the current REF X and Y coordinates.
- [OA] Halt guiding. Immediately drive the rotator
through plus or minus 180° and wait until it is
once again tracking. Resume guiding.
- [OA] On XGUIDE, set "Adjust pnt origin using ADJ
PNT/GOTO" to "yes".
- [OA] Immediately adjust pointing origin.
- Note the current REF X and Y.
- Calculate the average of the (X,Y) readings from
steps 5 and 9. Type the resulting position into the DCS
GUI pointing origin window under REF and click "Define".
- Repeat steps 3-10 time permitting, until you have
made four adjustments to the pointing origin
(i.e. until you have, in total, driven from 0 ->
-180 -> 0 -> -180 -> 0). Even a single
iteration is useful though.
- Adjust collimation and save pointing origins and
mark and save collimations.
- On XGUIDE, set "Adjust pnt origin using ADJ
PNT/GOTO" to "no".
- Sky time: 0:30
- Calibrations: None
- Notes:
- Analysis
- Timescale: Immediate
- Procedure: See above
- Software: None
- End products: TBD
- Status: To be scheduled
E3. Define SLIT/DEIMOS/FOCUS pointing origins
- Overview
- Goal: Define the focal plane positions of
the longslit center, imaging FOV center, and telescope
focus (Mira) position relative to the REF pointing origin.
- Priority: 1
- Product: Accurate focal plane coordinates
of the specified pointing origins
- Data: None
- Observing script
- Target: Any moderately bright star
- Conditions: Partially clear skies
- Prerequisites:
- Define the REF pointing origin (Test E2).
- Determine DEIMOS imaging pixel positions
corresponding to longslit center, imaging center, focus
position.
- Algorithm to convert from pixel offsets to focal
plane offsets.
- Observing log: N/A
- Procedure:
- Point to a sparse star field at which the ROTPPOSN
will be changing very slowly while in PA (position angle)
rotator mode. For example, try near dec=+50 and at least
1 hour AWAY from the meridian.
- Put the rotator into PA mode. Do not guide.
- Rough Alignment:
- Find a relatively bright and isolated star
(mag < 13)
and center it on REF.
- Select the pointing origin of interest (SLIT, DEIMOS,
FOCUS).
- Bring up the handpaddle in "pointing origin"
adjustment mode. Use this to offset the star onto the
imaging field of view.
- Take a DEIMOS image and locate the star.
- If star is more then 100 px from the desired
pixel position, use the handpaddle to make an
appropriate offset in the pointing origin and
return to previous step.
- Fine Alignment:
- Acquire a DEIMOS image
- Locate the alignment star and measure a
centroid (x1, y1)
- Rotate the instrument by 180°
- Acquire a DEIMOS image
- Locate the alignment star and measure a
centroid (x2, y2)
- Compute the averages xc=0.5*(x1+x2) and
yc=0.5*(y1+y2)
- Compute the error dx=x-xc and dy=y-yc, where
(x,y) is the desired pixel position
- Convert the error to a change in focal plane
position using the appropriate algorithm
- Compute the new pointing origin coordinates
based on these errors
- Have the OA enter these values into the DCS
GUI and verify that the telescope moves
appropriately.
- Repeat loop until convergence is achieved.
- Sky time: 1:30 (0:30 per)
- Calibrations: None
- Notes:
- Analysis
- Timescale: Immediate
- Procedure: None
- Software: Need algorithm to convert pixel
offset to focal plane coordinate offset
- End products: TBD
- Status: To be scheduled
F. Guide Camera Tests
F1. Determine TVFLIP
- Overview
- Goal: Determine the handedness of the
DEIMOS guider FOV
- Priority: 1
- Product: TVFLIP value
- Data: None
- Observing script
- Target: Any reasonably bright star
- Conditions: Partially clear skies
- Prerequisites: None
- Observing log: N/A
- Procedure:
- Note the orientation of the tkrose for the
guider. If the azimuth arrow points 90 degrees
CLOCKWISE from the elevation arrow, this will be
called left-handed. If it is 90 degrees
COUNTERCLOCKWISE this will be called righthanded.
- Move the telescope in elevation by -10 arcsec.
The star will move along the positive elevation
direction.
- Move the telescope in azimuth by -10 arcsec. The
star will move along the positive azimuth direction.
- Compare the observed handedness with the tkrose
handedness. If they differ, use "show -s dcs tvflip"
to check the current handedness, and change it.
- Sky time: 0:10
- Calibrations: None
- Notes: If you have to modify TVFLIP, you
must reselect the instrument, kill and restart the
tkrose.
- Analysis
- Timescale: Immediate
- Procedure: None
- Software: None
- End products: TBD
- Status: To be scheduled
F2. Determine TVANGL
- Overview
- Goal: Determine the sense of rotation for
the TV guider.
- Priority: 1
- Product: TVANGL value
- Data: None
- Observing script
- Target: Any reasonably bright star
- Conditions: Partially clear skies
- Prerequisites: None
- Observing log: None
- Procedure: TBD
- Sky time: 0:15
- Calibrations: None
- Notes: Requires input from Al Conrad
- Analysis
- Timescale: Immediate
- Procedure: N/A
- Software: None
- End products: TBD
- Status: To be scheduled
F3. Determine guider pixel scale
- Overview
- Goal: Measure the approximate pixel scale of
the DEIMOS guider
- Priority: 1
- Product: Number of arcsec/px in guider X and
Y coordinates
- Data: 4 guider frames
- Observing script
- Target: Isolated m=15 star
- Conditions: Partially clear, stable seeing
- Prerequisites: None
- Observing log:
- 1 TV image at +30, +30
- 1 TV image at +30, -30
- 1 TV image at -30, -30
- 1 TV image at -30, +30
- Procedure:
- Acquire isolated star and center on guider
- DISABLE guiding; guider offset require knowledge
of pixel scale, and hence guiding could bias the results
- Set guider binning to 1x1
- Rotate instrument such that north is up (and thus
that RA/Dec offsets will be along columns/rows)
- Save a fullframe guider image and verify that target is
well exposed but not saturated. Modify guider
integration time or select new target as needed.
- Offset telescope to (+30,+30) arcsec and save exposure
- Offset telescope to (+30,-30) arcsec and save exposure
- Offset telescope to (-30,-30) arcsec and save exposure
- Offset telescope to (-30,+30) arcsec and save exposure
- Offset telescope to (+30,+30) arcsec and save exposure
- Sky time: 0:15
- Calibrations: None
- Notes: Because we are unguided, this test is
best done at a location where the rotator is stationary
and the star's movement on the sky is small; for
example, on the meridian at dec=+50°. Need to ask
software folks how this information is incorporated into
the guider software to perform offsets.
- Analysis
- Timescale: 10 minutes
- Procedure:
- Compute the change in guider (X,Y) between
consecutive guider images
- Divide known offset of 60 arcsec by the measured
dX or dY to derive plate scale in arcsec/px
- Average scale_X and scale_Y values to derive results.
- Software:
- Use IRAF imexamine to derive accurate centroids
- End products: TBD
- Status: To be scheduled
F4. Characterize guider vignetting
- Overview
- Goal: Investigate vignetting in the DEIMOS guider
- Priority: 3
- Product: Diagram of vignetting vs. pixel
position on the guider
- Data: Series of guider images taken in PMFM
mode at various locations on the guider
- Observing script
- Target: Isolated, m=12 star
- Conditions: Partially clear skies
- Prerequisites: None
- Observing log:
- Procedure:
- Acquire isolated star
- Center star on guider
- Set binning to 2x2
- Set PMFM to +500
- Observe whether all 36 segments are visible
- Offset star to corner of pickoff mirror and check
36 segments; save cam image if desired
- Check the other 3 corners to verify no vignetting
- Check other locations only if vignetting is found
- Sky time: 0:15
- Calibrations: None
- Notes:
- Analysis
- Timescale: Immediate
- Procedure: N/A
- Software: None
- End products: TBD
- Status: To be scheduled
G. Autoguider Tests
G1. Verify standard guiding modes
- Overview
- Goal: Check that guiding in the following
common guiding modes works as expected:
- Position-angle mode
- Vertical-angle mode (off slit)
- Stationary mode (off slit)
- Priority: 2
- Product: N/A
- Data: None
- Observing script
- Target: Pair of m=15 stars, well-separated
on DEIMOS guider
- Conditions: Partially clear
- Prerequisites: None
- Observing log: N/A
- Procedure:
- Position-angle mode
- Acquire high-elevation (>80°) m=15
star pair on guider, slightly east of meridian (HA=0:15)
- Set rotator to any angle, position angle mode
- Begin guiding on one of the stars
- Save cam images regularly for 0:30 while target
transits
- Verify that stars do not change pixel
position on guider
- Vertical-angle mode (offset/DIFF mode)
- Acquire high-elevation (>80°) m=18
star on guider, slightly east of meridian (HA=0:15)
- Set rotator to parallactic angle, vertical
angle mode
- Insert longslit
- Send object to slit
- Select object location (on slit) and guide
star (on pickoff mirror); set hfudge parameters
appropriately
- Remove longslit
- Acquire DEIMOS image
- Monitor guider or instrument compass rose and
verify that slit remains parallel to elevation
axis while rotation relative to (N,E)
coordinates
- Take DEIMOS images every 5 minutes for 0:30
- Analyze images to verify that star did not
move during interval
- Stationary mode (offset/DIFF mode)
- Similar to vertical-angle mode procedure,
except set rotator mode to "stationary" and set
hfudge parameters appropriate for stationary mode
- Monitor guider or instrument compass rose and
verify that roses rotate while telescope tracks
through meridian.
- Analyze images to verify that star did not
move during interval
- Sky time: 2:00
- Calibrations: None
- Notes: Pointing origins and rotator must be
calibrated before attempting this test
- Analysis
- Timescale: Next day
- Procedure: See above
- Software:
- IRAF imexamine task to measure star positions
- End products: TBD
- Status: To be scheduled
G2. Verify Reseaux guiding mode
- Overview
- Goal: Check whether Reseaux guiding mode
works as expected
- Priority: 1b
- Product: TBD
- Data: TBD
- Observing script
- Target: TBD
- Conditions: Partially clear skies
- Prerequisites: None
- Observing log: TBD
- Procedure: TBD
- Sky time: TBD
- Calibrations: None
- Notes:
- Analysis
- Timescale: TBD
- Procedure: TBD
- Software: TBD
- End products: TBD
- Status: To be scheduled
H. DCS Tests
H1. Determine INSTFLIP
- Overview
- Goal: Determine handedness of DEIMOS images
- Priority: 1
- Product: INSTFLIP value
- Data: TBD
- Observing script
- Target: Isolated m=15 star
- Conditions: Partially clear skies
- Prerequisites: None
- Observing log: TBD
- Procedure: TBD
- Note the orientation of the tkrose for the
instrument. If the azimuth arrow points 90 degrees
CLOCKWISE from the elevation arrow, this will be
called left-handed. If it is 90 degrees
COUNTERCLOCKWISE this will be called right-handed.
- Acquire star on guider and send to DEIMOS
pointing origin
- Mark base
- Acquire a DEIMOS image
- Move the telescope in elevation by -10 arcsec
- Acquire a DEIMOS image. The star will have moved
along the positive elevation direction. Mark this
vector on the display.
- Go to base
- Move the telescope in azimuth by -10 arcsec.
- Acquire a DEIMOS image. The star will move along
the positive azimuth direction. Mark this vector on
the display
- Compare the observed handedness with the tkrose
handedness. If they differ, use "show -s dcs instflip"
to check the current handedness, and change it.
- If needed, restart the tkrose and verify that the
handedness is now correct.
- Sky time: 0:20
- Calibrations: None
- Notes:
- Analysis
- Timescale: Immediate
- Procedure: See above
- Software: None
- End products: TBD
- Status: To be scheduled
H2. Determine INSTANGL
- Overview
- Goal: Calibrate the rotation of the
instrument detector relative to the rotator zeropoint
- Priority: 1
- Product: INSTANGL value
- Data: n/a
- Observing script
- Target: V=15 star
- Conditions: Partially clear
- Prerequisites: Rotator must be properly
zeropointed relative to the slitmask
- Observing log: TBD
- Procedure:
- Set INSTANGL to 90°
- Acquire star and send to DEIMOS pointing origin.
- Acquire a guide star near the field center and
begin guiding
- Mark base coordinates
- Save a DEIMOS image, measure star location (x1,y1)
- Move telescope 60 arcsec in instrument X
coordinates using the command "mx 60"
- Save a DEIMOS image, measure star location (x2,y2)
- If the star "moved" to the left; angle is okay.
If the star moved to the "right", change INSTANGL to
-90° and repeat test. If star moved another
direction, there is a problem...
- Sky time: 0:10
- Calibrations: None
- Notes:
- Analysis
- Timescale: Immediate
- Procedure: See above
- Software: None
- End products:
- Status: To be scheduled
H3. Verify telescope offsetting in instrument coordinates
- Overview
- Goal: Verify that telescope moves performed
in the instrument coordinate system produce the desired
direction and magnitude
- Priority: 1b
- Product: n/a
- Data: DEIMOS direct images
- Observing script
- Target: V=15 star
- Conditions: Partially clear
- Prerequisites: Rotator and INSTANGL must be
calibrated
- Observing log: TBD
- Procedure:
- Acquire star and send to DEIMOS pointing origin.
- Acquire a guide star near the field center and
begin guiding
- Mark base coordinates
- Save a DEIMOS image, measure star location (x1,y1)
- Move 60 arcsec in instrument X coordinates
- Save a DEIMOS image, measure star location (x2,y2)
- Go to base coordinates
- Save a DEIMOS image, measure star location (x1,y1)
- Move 60 arcsec in instrument Y coordinates
- Save a DEIMOS image, measure star location (x2,y2)
- Sky time: 0:15
- Calibrations: None
- Notes:
- Analysis
- Timescale: Immediate
- Procedure:
- Verify that star moves are purely in (x) or (y)
as appropriate.
- Software:
- IRAF imexamine to measure star centers
- End products:
- Status: To be scheduled
I. Rotator Tests
I1. Calibrate Rotator Zeropoint
- Overview
- Goal: Zeropoint the rotator based on the
orientation of the DEIMOS slitmask plane.
- Priority: 1
- Product: ROTBASE value
- Data: Trailed star images
- Observing script
- Target: Equatorial star field on the meridian
- Conditions: Clear skies
- Prerequisites: None
- Observing log:
- 5×100s trailed star images
- 60s image of pinhole grid mask illuminated by sky
- Procedure:
- 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.
- Configure DEIMOS for imaging.
- Set exposure time to 100 s. The images will thus
contain vertical trails of stars exposed as the world
turns.
- Take 5 exposures; examine each image for the
quantity and quality of star trails. We require a few
trails in at least 2 images with signal at least 200
counts above background, separated by about 100 pixels
from neighboring trails of high signal, preferably
located within the central 1000 column region. If
conditions are not clear enough to meet the signal
requirement for even 1 star trail, then abort the test
in favor of clearer conditions later. Note also that
observations made at LST=1:00 or 13:00 will be near
the galactic poles and hence unlikely to contain
sufficient density of stars.
- Insert grid of holes mask. Enable tracking to
prevent trailed stars on pinholes. Take 1 60s exposure
to define the rotation of the detector relative to the
slitmask.
- Sky time: 0:30
- Calibrations: None
- Notes:
Analysis
- Timescale: Immediate
- Procedure:
- Process images to remove overscan, trim, convert
to flatspace
- Measure the skew of star trails relative to the CCD
columns
- Measure the skew of slitmask holes relative to the
CCD columns
- Convert the angular offset between star trails and
slitmask angle into a correction to the ROTBASE keyword
- Software:
- IDL routines to debias DEIMOS images
- IDL routine to analyze angle of star trails and
output new ROTBASE value
End products: TBD
Status: To be scheduled
I2. Verify rotator accuracy/repeatability
- Overview
- Goal: Characterize the ability of the DEIMOS
rotator to rotate accurately
- Priority: 2
- Product: Repeatability of rotator angles
- Data: Star trail images at various rotator angles
- Observing script
- Target: Equatorial starfield at meridian
- Conditions: Clear
- Prerequisites: Rotator must be calibrated
- Observing log: TBD
- Procedure:
- 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.
- Reduce rotator angle by 90° increments as
many times as allowed by the rotator limits.
- Configure DEIMOS for imaging.
- Set exposure time to 100 s. The images will thus
contain vertical trails of stars exposed as the world
turns.
- Acquire DEIMOS exposures until at least one good
star trail is achieved.
- Increase the rotator angle by 90° and acquire
more star trail images.
- Repeat until no more 90° increments are possible
- Sky time: 0:30
- Calibrations: None
- Notes:
- Analysis
- Timescale: Few days
- Procedure:
- Measure star trail angles on images and verify
that as the rotator moves by 90°', the star
trails also rotate by 90°
- Software: TBD
- End products: TBD
- Status: To be scheduled
I3. Verify rotator tracking performance
- Overview
- Goal: Characterize the quality of tracking
by the rotator by taking images in position angle mode
during transit
- Priority: 3
- Product: Measurement of rotator tracking accuracy
- Data: Images of rich star field during transit
- Observing script
- Target: A rich star field at declination in
the range 15-17° dec or 23-25°
- Conditions: Clear with good seeing (<1 arcsec)
- Prerequisites: None
- Observing log: TBD
- Procedure:
- Set up DEIMOS for imaging
- Acquire rich star field 20 minutes east of
meridian and send to DEIMOS pointing origin
- Acquire guide star and begin guiding in PA mode
- Take 30s DEIMOS images every minute starting 0:10
before transit and continuing until 0:10 after transit
- Sky time: 0:30
- Calibrations: None
- Notes:
- Analysis
- Timescale: Few days
- Procedure:
Measure the rotational smearing of star images at the
edges of the image and derive limits on telescope
tracking accuracy.
- Software: TBD
- End products: TBD
- Status: To be scheduled
J. Focusing Tests
J1. Verify AUTOFOC operation
- Overview
- Goal: Determine that AUTOFOC works properly
to focus the telescope on the longslit, and compare
results obtained with star on pickoff mirror vs. star on
longslit.
- Priority: 1
- Product: n/a
- Data: Sequence of guider images at various
secondary piston settings
- Observing script
- Target: Isolated V=12 star
- Conditions: Clear and stable
- Prerequisites: REF pointing origin defined
- Observing log: n/a
- Procedure:
- Acquire star in guider and send to REF pointing
origin
- Note the starting value of TELFOC keyword
- Save guider image and measure starting image
quality
- Execute the AUTOFOC procedure to focus star on
guider pickoff mirror
- Note the revised value of TELFOC
- Save guider image and measure ending image
quality
- Send star to the SLIT pointing origin and move it
off the slit
- Increase exposure time as needed to obtain a
usable image of the star
- Execute the AUTOFOC procedure to focus star on
longslit area
- Note the revised value of TELFOC
- Save guider image and measure ending image
quality
- Sky time: 0:30
- Calibrations: None
- Notes:
- Analysis
- Timescale: Immediate
- Procedure: Automated
- Software: AUTOFOC analysis tool
- End products: TBD
- Status: To be scheduled
J2. Calibrate Mira
- Overview
- Goal: Obtain the measurements needed to
program the Mira software for operation with DEIMOS
- Priority: 1b
- Product: Handedness of DEIMOS images and
approximate pixel scale
- Data: Series of direct images taken in PMFM mode
using DEIMOS
- Observing script
- Target: V=12 star
- Conditions: Partially clear
- Prerequisites: DEIMOS pointing origin must
be defined
- Observing log: TBD
- Procedure:
- Acquire star on guider and send to DEIMOS
pointing origin
- Set PMFM to +500
- Configure DEIMOS for direct imaging
- Save a DEIMOS image; note SKYPA and ROTPPOSN
- Rotate DEIMOS by 45°
- Save a DEIMOS image; note SKYPA and ROTPPOSN
- Sky time: 0:10
- Calibrations: None
- Notes:
- Analysis
- Timescale: 1 day
- Procedure: TBD
- Software: TBD
- End products: TBD
- Status: To be scheduled
J3. Verify Mira operation
- Overview
- Goal: Run Mira on DEIMOS to verify and optimize
operation. Vary the initial conditions (secondary tilt,
rotator position) to ascertain whether proper corrections
are achieved.
focuses the telescope with DEIMOS
- Priority: 1b
- Product: Varies
- Data: DEIMOS images taken in PMFM mode
- Observing script
- Target: Isolated V=12.5 star
- Conditions: Clear, stable
- Prerequisites: Mira must be calibrated
- Observing log: TBD
- Procedure: TBD
- Sky time: 2:00
- Calibrations: None
- Notes:
- Analysis
- Timescale: 1 day
- Procedure: TBD
- Software: Mira tool
- End products: TBD
- Status: To be scheduled
J4. Calibrate Mira secondary tilt compensations
- Overview
- Goal: Calibrate the telescope secondary
mirror tilt corrections required to put the secondary in
the on-axis position, as a function of the physical
instrument rotator position angle.
- Priority: 1
- Product: Model for Theta_x and Theta_y secondary
mirror corrections vs. ROTPPOSN
- Data: Series of images acquired in PMFM mode
vs. ROTPPOSN
- Observing script
- Target: V=12.5 star at a sky location with
slowly changing parallactic angle (az=270, el=75?)
- Conditions: Clear, stable
- Prerequisites: DEIMOS pointing origin defined
- Observing log: TBD
- Procedure:
- Configure DEIMOS for imaging
- Set instrument rotator to negative limit
- Acquire star and send to DEIMOS pointing origin
- Set PMFM to +500
- Subwindow detector as appropriate
- Acquire 10-second exposure
- Rotate instrument by +30°
- Repeat previous two steps through 540° of rotation
- Sky time: 0:30
- Calibrations: None
- Notes:
- Analysis
- Timescale: 1 week
- Procedure: TBD
- Software:
- Mira
- Custom IDL analysis routines developed for LRIS
- End products: TBD
- Status: To be scheduled
J5. Verify secondary tilt compensations
- Overview
- Goal: Check that the secondary tilt
compensations for DEIMOS correctly place the telescope
secondary on-axis.
- Priority: 3
- Product: Coma vs. ROTPPOSN plot
- Data: DEIMOS images taken in PMFM mode at
various rotator angles
- Observing script
- Target: V=12.5 star at a sky location with
slowly changing parallactic angle (az=270, el=75?)
- Conditions: Clear, stable
- Prerequisites: Secondary corrections
calibrated and put into Mira
- Observing log: TBD
- Procedure:
- Configure DEIMOS for imaging
- Set instrument rotator to negative limit
- Acquire star and send to DEIMOS pointing origin
- Run Mira at least twice, sending rotator coma
corrections (i.e., click "spectroscopic mode" button
on Mira when sending corrections), until solution converges
- Set PMFM to +500
- Subwindow detector as appropriate
- Acquire 10-second exposure
- Rotate instrument by +30°
- Repeat previous two steps through 540° of rotation
- Sky time: 0:30
- Calibrations: None
- Notes: These data can also be analyzed to
measure the secondary mirror decentering.
- Analysis
- Timescale: 1 week
- Procedure:
- Analyze images using Mira; obtain theta_x,
theta_y corrections
- Plot the correction vectors and verify that they
are all near zero
- Software: Mira
- End products: TBD
- Status: To be scheduled
J6. Determine offset from AUTOFOC to Mira
- Overview
- Goal: Measure the difference
between secondary focus measured using Mira and AUTOFOC.
- Priority: 3
- Product: Delta(TELFOC)
- Data: PMFM and autofoc images
- Observing script
- Target: V=12.5 and V=15 stars at a place
where rotator and elevation are changing slowly
- Conditions: Clear and stable with decent
seeing (1 arcsec or better)
- Prerequisites: Mira calibrated
- Observing log: TBD
- Procedure:
- Configure DEIMOS for R-band imaging
- Disable temperature and elevation corrections to
secondary focus
- Acquire V=12.5 star
- Run MIRA, send moves
- Repeat MIRA to verify solution
- Acquire V=15 star
- Run AUTOFOC, note but do NOT send moves
- Acquire V=12.5 star
- Run MIRA, note but do NOT send moves
- Acquire V=15 star
- Run AUTOFOC, note but do NOT send moves
- Repeat as needed until a well-defined
delta(TELFOC) is determined
- Enable temperature and elevation corrections to
secondary focus
- Sky time: 1:00
- Calibrations: None
- Notes: Want rotator position relative to
secondary mirror nearly constant in
order to prevent confusion due to rotator-dependent
focus and come corrections. Want elevation
slowly-changing in order to prevent confusion with
elevation-dependent corrections.
- Analysis
- Timescale: Immediate
- Procedure: Self-evident
- Software: None
- End products: TBD
- Status: To be scheduled
J7. Test Shack-Hartmann guider focus mask procedure
- Overview
- Goal: Verify feasibility and refine
Shack-Hartmann mask method for focusing telescope
- Priority: 2
- Product: Procedure for focusing telescope
using guider Shack-Hartmann masks
- Data: Guider images acquired with
Shack-Hartmann masks
- Observing script
- Target: TBD
- Conditions: Clear, good and stable seeing
- Prerequisites: TBD
- Observing log: TBD
- Procedure: TBD
- Sky time: TBD
- Calibrations: TBD
- Notes: This method depends on the
stability of the guider focus, which should probably be
tested separately.
- Analysis
- Timescale: TBD
- Procedure: TBD
- Software: TBD
- End products: TBD
- Status: To be scheduled
K. Miscellaneous Tests
K1. Verify operation of facility scripts to offset telescope
- Overview
- Goal: verify proper operation of all scripts which
can't be completely testing during daytime, including
those that:
- Perform offsets in detector arcsec c.s.
- Perform offsets in detector pixel c.s.
- Perform offsets in guider pixel c.s.
- Perform offsets in guider arcsec c.s.
- Perform offsets in RA/DEC c.s.
- Perform offsets in az/el c.s.
- Dither objects along slit
- Priority: 2
- Product: n/a
- Data: n/a
- Observing script
- Target: V=15 star
- Conditions: Partially clear
- Prerequisites: INSTANGL, ROTBASE, TVANGL,
etc., calibrated
- Observing log: TBD
- Procedure:
- Acquire star and send to guider
- Take starting image
- Execute script to move telescope
- Take ending image
- Continue as required until script is completed
- Sky time: 2:00
- Calibrations: None
- Notes:
- Analysis
- Timescale: n/a
- Procedure: n/a
- Software: n/a
- End products: TBD
- Status: To be scheduled
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. As with LRIS, this direction will be approximately
perpendicular to the direction which is of most interest to
observers, that of the slit. 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 DEIMOS:
Name |
Description |
Offset* [°] |
SKYPA0 |
Long slit |
+90 |
SKYPA1 |
Guider column (YIM)** |
0 |
SKYPA2 |
Up on science detector*** |
0 |
Notes:
- *Offsets are approximate and are expressed relative to
the fundamental SKYPA, SKYPA1
- **This is the fundamental SKYPA (i.e., the one displayed
on FACSUM and saved in image headers as keyword ROTPOSN) and
has zero offset by definition
- ***The DEIMOS science detector consists of 8 separate
CCDs with slightly different physical orientations; hence,
we must identify the detector which is to serve as the
reference for this SKYPA. Logically, this should also be the CCD on
which the DEIMOS pointing origin lies.
Considerations Regarding Rotator Calibrations
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 slitmask mechanism is of greater
utility. This suggests the following plan for achieving
rotational alignment of the focal plane systems:
- The longslit orientation shall form the basis of
alignment in the focal plane.
- The CCD dewar (or, more likely, a chosen CCD within the
dewar) shall be adjusted rotationally until it is well
aligned with the slitmask.
- The TV guider detector shall be adjusted rotationally
until it is well aligned with the slitmask.
This suggests the following order of operations to define
DCS parameters:
- Set TVFLIP appropriately for guider image
- Set TVANGL to 0° or 180°
- Set ROTZERO to produce images aligned to TV guider
rows/columns
- Re-init rotator
- Adjust ROTBASE keyword value to produce images aligned
precisely to CCD rows/columns
- Set INSTANGL to +90° or -90° and verify operation
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