Some Procedures for (Bent/Direct) Gregorian Technical Observing with IRTC and AGW

Overview of AGW - Instrument - Telescope Alignment

(JMH - following an IQ Group discussion in Oct 2013)

To get the Instrument, and AGW (bigW=on-axis and littlew=off-axis) and the Telescope all correctly aligned, we have multiple optical axes that must be adjusted.

  1. The chief ray of the telescope travelling from the secondary mirror to the instrument and AGW (sometimes via the tertiary mirror).
  2. The reverse chief ray from the W-unit and dichroic travelling back to the secondary mirror (sometimes via the tertiary mirror).
  3. The reverse chief ray from the off-axis w-sensor travelling back to the secondary mirror (sometimes via the tertiary mirror).
  4. The reverse ray from the instrument travelling back to the secondary mirror (sometimes via the tertiary mirror).

ALL of the above chief rays must be perpendicular to the plane of the instrument rotator, AND they must intersect in the telescope focal plane at the location of the rotator axis for on-axis stars.

We typically adjust the chief rays as follows:

  1. The internal optics of the off-axis guider and the "little w" S-H wavefront sensor are adjusted off the telescope (see engineering alignment procedure).
  2. Once the AGw is mounted on the telescope, we first adjust the guide probe to put the AGw hotspot at the rotator center (one of the next procedures in this document)(This needs seeing <1 arcsec to do a decent job.).
  3. Next we adjust the M3 tip-tilt angle to minimize the pupil wobble on the "little w" S-H wfs sensor for an on-axis guide star (can be done in any seeing).
  4. The instrument optics are adjusted to minimize instrument pupil wobble at different position angles.
  5. Independently, we adjust the AO W-unit position to match the window/dichroic angle (off the telescope?).

Beware that the Tip-Tilt angle of M3 cannot compensate a misalignment of the internal instrument optics (they rotate with respect to each other, except for LBTI). Nor can the Tip-Tilt angle of M3 compensate for a misalignment between the W-unit and the entrance window dichroic. Nor can the Tip-Tilt angle of M3 compensate for a misalignment of the S-H optics.

Beware of position - tilt ambiguities. If the guide probe is not centered on the rotator axis, then the position error can masquerade as pupil wobble.

Locations of Configuration Files

GCS Configuration Files

On the tcs machines the "public" ("public" means updated by astronomers and carried over across TCS builds) config files are in /lbt/data/config/tcs/GCS/.
The "private" files are in the config file directory /lbt/tcs/current/gcs/configuration/GCS/ on the tcs machines, and are not typically modified. The "private" files are distributed with each TCS build.

IDL Configuration Files

The equivalent IDL configuration parameters are in /home/lbto/idl/wfsc/agw/agw_define.pro with the master archive maintained by Doug Miller.

On-Telescope Procedures

Procedure for initial optical alignment after re-installing an M2 hexapod

An overview of steps written by DMiller on 20130513 UT, and transcribed by JHill. This procedure presumes that the previous pointing and collimation model were good, and uses them as the reference for an initial estimate of the alignment to minimize field aberrations. Significant changes to the telescope mechanics and/or pointing errors will ruin this initial estimate.

-1) Be sure to reinstall the nominal (for that secondary) pointing and collimation models (and restart PCS and PSF) if you are switching between rigid and adaptive secondaries. Don't forget the rigid/adaptive flag in psf.conf, and the wavefront models that correct Z6 from the adaptive secondaries on M1.

0) Preset to a pointing star on-axis in ACQUIRE mode

1) Use the original (previously known to be good) pointing model and collimation model.

2) Spiral search to find the pointing star if necessary. If the star is more than 1 arcmin away or is very strongly comatic, that can be a signal that the hexapod legs are connected incorrectly (or something else is mechanically wrong).

3) Use "Coma Free Pointing" corrections on PSF GUI Control applied to M2 to get star back to original pointing model IE and CA (-96, -49.3). (Tip moves with IE, Tilt moves with CA. +Tip moves the star Up in PAM- mode, +Tilt moves the star Left)

4) Use "Pointing Free Coma" corrections on PSF GUI Secondary for zernikes Z7,Z8 applied to M2 to remove coma by eye (looking at an out of focus image).

5) These are now new X, Y, RX, RY values for the M2 collimation model. Add the M2 values for "Active Optics", "Manual Pointing Offsets" and "Global Offsets" to get the new values for "Global Offsets".

6) IE and CA in ptmodel should remain the same original pt and col at this point.

7) collect field aberration data with IDL task field_collect (detailed instructions are elsewhere)

8) analyze field aberration data (Doug)

9) make binodal astigmatism corrections if needed. These corrections involve changes to IE/CA and Tip/Tilt on M2.

10) collect a small field data set for confirmation

11) test with MODS image with collimation for several guide star positions

Procedure for measuring the X-Y motion versus focus offset

(drafted 5 April 2009)

This X-Y is usually covered by lab measurements, so we rarely do this procedure on-sky.

  • Send an active preset to an on-axis star, pointto BS9152 gs=0 TelM="ACTIVE" PA=180

  • After the telescope is collimated, press "stop guiding" on GCS GUI, so that telescope is tracking open-loop, but with the guide probe still in the center of the field.

  • Start taking 100 full frame guider images with the GCS command line interface, gcsclient readGuideCam [right/left] -e 1000 100 (I like to leave them running but you can start and stop the images at different focus positions if you prefer.) Note that these images do NOT have your modified focus positions in the headers.

  • Read the current focus position (nominally near 31) with the agw software (oacontrol), getfocus -u [#]

  • Set the focus promptly (because you are fighting open loop tracking drift) to different values (in steps of 5-10 mm), setfocus -u [#] -p 41 , setfocus -u [#] -p 21

  • Return to the original value at the end to baseline any drift, "setfocus -u [#] -p 31*

Procedure for adjusting the guiding hotspot so the light from the star goes into the S-H wfs

(drafted 20151025)

In this procedure, we want to set the guiding hotspot position in GCS so that the star images are centered in the wfs field stops (lenslet images), adjust the pupil position parameters in GCS, and use active optics to collimate the telescope. All of these need to be done simultaneously, so an iterative solution is required. The goal is to get the guiding hotspot adjusted within 1 pixel (1/20 arcsec). This procedure assumes that the parameters of the lenslet grid on the CCD have been set correctly in advance with both IDL and GCS.

  • Set GCS parameters (maxOffsetToHotspot and maxHotspotFromProbe in LUCI_L.cfg) for a loose position tolerance on the hotspot (2.54 arcsec rather than the normal 0.54 arcsec radius).

  • Use the lab-determined hotspot as the starting point for guidecam_hotspot_x and guidecam_hotspot_y if you are starting from scratch. In the lab (Aug 2020) we have used * ObserverSupport/agw_spiral.py* to make a spiral search for the hotspot.

  • Stop/start GCS subsystem for these parameters to take effect.

  • Send an ACTIVE preset to an on-axis star, use the GCSGUI Guide Control window to block Zernikes from going to PSF. A star about 11 mag is good, so you can take short wfs exposures and get rapid feedback.

  • Stop sending Zernikes from GCS to PSF until the S-H spots are well illuminated (the hotspot value is close) in order to avoid sending garbage.

  • Use gcsclient setHotspot left -x XXX.X -y YYY.Y to get the guidestar into the wfs aperture. (This can also be done from the GCSGUI Guide Control Window.) Take small steps of ~5 pixels so the guider can follow without violating the hotspot position tolerance. If you violate the tolerance, the WFS loop will either pause or hang and stop taking wfs images (that is why we increased the tolerance above).
For MODS1 nominal agw cameras: Guide+X is is right, Guide+Y is up, WFS+X is down, WFS+Y is right (from Olga's hand-drawn diagram).Increasing guiding_hotspot_y moves star left.

For AGW4@LFBG or AGW4@RDG: Increasing guiding_hotspot_y moves star down in lenslet. Increasing guiding_hotspot_x moves star left in lenslet. (also for RFBG). AGW4 has an X-flip from alternate amplifier in the wfs camera.

For AGW3@RFBG or AGW3@LDG: Increasing guiding_hotspot_y moves star down in lenslet. Increasing guiding_hotspot_x moves star right in lenslet (-x moves left). AGW3 has an X-flip from alternate amplifier in both guide camera and wfs camera.

For AGW1@LFBG: Decreasing guiding_hotspot_y moves star up in lenslet.

  • Allow active optics to collimate, and update the pupil position (wfs hotspot) in LUCI_L.cfg. Note: this process is much easier if you display the pupils with IDL (gcs_wfsc_display) or collimate directly with IDL (collimate_multiple).

  • Iterate the above steps using IDL program to display the pupils and to measure the mean offsets of the S-H spots. If the guiding hotspot is correct, the value of X,Y Average Removed in the output of gcs_wfsc_display will be less than 0.1 (units of 0.4 lenslet?). A 20 pixel change of hotspot will shift the X,Y Average Removed by 0.5.

  • Check the lenslet rotation angle (rotation of the lenslet grid wrt CCD columns) if this is a new wfs camera.

  • Enter the final hotspot positions in the configuration file (e.g. LUCI_L.cfg). Also note them for IDL (agw_define.pro) and for the next procedure. Put the hotspot position tolerances back to normal. Stop/start GCS to reread the new hotspot from the configuration file.

Procedure for measuring the alignment of the guiding hotspot to the rotator center

(14 Sep 2010, 22 Jan 2013, 02 Sep 2013 JMH)

  • This procedure assumes that the guiding hotspot on the guider CCD has been previously measured (the location on the guider that delivers the light into the WFS), and that the telescope can be collimated. See above.

AIP-style AGw alignment to rotator center

This procedure is for an AIP-style AGw Unit on the left side. See next section for a MODS AGw Unit.

  • Send an ACTIVE preset to an on-axis star, newpoint BS9152 gs=0 TelM="ACTIVE" PA=180, and wait for decent collimation.

  • Press "stop guiding" on GCSGUI left (so that you can take guidecam images from the command line via gcsclient).

  • Send LFBG rotator to either 0 or 360 degrees for a starting position, Use MCSGUI rotator subGUI or rslewtohold lfbg 0 on MCSPU. (This rotator motion cancels the preset state in IIF, but that is OK.)

  • Offset the telescope pointing by 3-5 arcsec to set the diameter of the circle (by deliberate mispointing), ptincrement 0 CA -5

  • Set the AGw probe position to the nominal center (oacontrol), setxy -u [#] -x 0 -y 612.5 (not the nearby refracted position that the preset sent it to).

  • Set the AGw probe focus position to the nominal value for the center (oacontrol), setfocus -u [#] -p 31.0 (The probe is already there if you sent an on-axis ACTIVE preset.) This step is not needed for MODS.

  • Take a full frame guider image with the GCS command line interface, gcsclient readGuideCam left -e 90000
Warning: The first image after stopping the GCS guiding thread has taken an image usually fails, so it is prudent to take a 1 sec test image beforehand. GCS writes the image in /lbt/data/share/tcs/user.yyyymmdd/ or /lbt/tcs_data/user.yyymmdd/

  • About 2 sec after starting the guider image slew the rotator to 360 degrees, Use MCSGUI rotator subGUI or rslewtohold lfbg 360

  • Measure the center of the ring in the image to determine the position of the rotator center relative to the guider hotspot (using a circular region in ds9).
    • start with the ds9 measured x,y center of the circular region that matches the ring.
    • correct for binning : (multiply x,y by 2)
    • correct for limited acq image readout to get CCD coordinates (see FITS header) : if DETSEC is 16:536,40:508, add 15 to x, add 39 to y
    • compare this measured rotator center in physical pixels to the guiding hotspot position - gcsclient getHotspot left
    • convert the desired correction from pixels to arcsec to mm (1 pixel = 1/20 arcsec for Potsdam AGw; and 0.600 mm per arcsec)

  • Calculate the new encoder zeropoints homeoffset for the AGw probe (Jesper Storm was the original specialist of this activity.) and update the configuration file for the oacserver/UMAC. The file is /lbt/oacontrol/current/etc/oacontrol.conf . That filesystem is only accessible from the agw-control class of machines -- ssh into that machine as oac@oac.
    • The parameters to adjust are homeoffset (units are counts) for the ROT and ooffset (units are microns) for the RAD axes of the AGw.
    • The ROT axis has approximately 68 counts/mm at full extension. The RAD axis has 5200 counts/mm (but you are adjusting in microns).
    • Decreasing ROT homeoffset moves the star image (center of rotation) toward larger X pixel values (unless you have an X-flip in your guide camera like AGw3).
    • Decreasing RAD ooffset moves the star image (center of rotation) toward larger Y pixel values.

  • Issue the AGw command to implement the new parameters in the UMAC: rdwrconfig -u [#] NOTE: You must stop and restart the appropriate GCS subsystem for the changes to take effect (although maybe not these particular changes?).

  • Optionally resend the active preset - Repeat process as needed from moving the guide probe on-axis.

  • Adjust the ROT limits for the probe when you are finished (only if a large correction more than 1 mm was applied). If homeoffset is more negative, then both of the limits for that axis must become more positive by the same amount. The two variables for the limits are lim_f and lim_n (far and near respectively) .

MODS-style AGW alignment to rotator center

This procedure is for an MODS-style AGw Unit on the left side. See above for an AIP-style AGw Unit.

  • Send an ACTIVE preset to an on-axis star, newpoint BS9152 gs=0 TelM="ACTIVE" PA=180, and wait for decent collimation.

  • Press "stop guiding" on GCSGUI left (so that you can take guidecam images from the command line).

  • Send LDG rotator to either 0 or 360 degrees, Use MCSGUI or rslewtohold ldg 0 on MCSPU (This cancels the preset state in IIF, but that is OK.)

  • Offset telescope pointing by 5-7 arcsec to set the diameter of the circle (deliberate mispointing), ptincrement 0 CA -5

  • Set the AGw probe position to the nominal center, on the MODS GUI (command window) the command is gprobe 0 0 . (not the refracted position that the preset sent it to)

  • Take a full frame guider image with the GCS command line interface, gcsclient readGuideCam left -e 90000
Warning: the first image after the GCS guiding thread has taken an image usually fails, so it is prudent to take a 1 sec test image. GCS writes the image in /lbt/data/share/tcs/user.yyyymmdd

  • About 2 sec after starting the guider image slew the rotator to 360 degrees, rslewtohold ldg 360

  • Measure the center of the ring in the image to determine the position of the rotator center relative to the guider hotspot (using a circular region in ds9).
    • start with the x,y center of the circular region that matches the ring.
    • correct for binning : (multiply x,y by 2) (not needed for MODS with bin=1)
    • correct for limited acq image readout to get CCD coordinates (see FITS header) : if DETSEC is 16:536,40:508, add 15 to x, add 39 to y
    • compare measured rotator center in physical pixels to guiding hotspot position - gcsclient getHotspot left
    • convert the desired correction from pixels to arcsec to mm (1 pixel = 0.1069 arcsec for MODS AGw; 600 microns per arcsec; gives 0.06414 mm/pix)
Current values for MODS1 (as of October 2016) are: XCenter 89.58 YCenter 204.593
The original on-axis stage position was (xs,ys) = (92,204).   YCenter=204 is the maximum allowed value?
The sw range was +/- 92 about the XCenter, and so this shift in xs limited the range of probe travel to the left of the field center. 
A few months ago the stage hit the hardware limit for a guide star near the left edge of the patrol field.

  • Adjust parameters Xcenter and Ycenter (mm) in MODS configuration file agw.ini by adding your corrections in mm. EXCEPT MODS1 YCenter which you have to subtract. (how can that be? 20180921)

  • On mods1data, mods1 stop agw service / mods1 start agw service to read in the new configuration.

  • Optionally resend the active preset - Repeat process as needed starting from gprobe 0 0.

  • Adjust the travel limits for the probe when you are finished (only if a large correction more than 1 mm was applied). Is this needed for MODS?

Procedure for Measuring Pupil Wobble and Adjusting M3 with Off-Axis Guider

See the detailed instructions in ComTools = https://wiki.lbto.org/Commissioning/ComTools#Pupil_Wobble_Measurement_for_the_Off_45Axis_S_45H_Wavefront_Sensor

AGw Transformation Data

See the detailed instructions in ComTools = https://wiki.lbto.org/Commissioning/ComTools#Guide_Probe_Transformation

Overview of AGW Active Optics Setup and Calibration

(This was drafted by JMH in September 2018 -- a work in progress.)

Off-axis Guider

Adjust telescope pointing

Send an ACQUIRE telescope preset on-axis and adjust telescope pointing (IE/CA) to put the star on the nominal guide hotspot.

Adjust field orientation

Send an ACQUIRE telescope preset off-axis to make sure the AGw is mounted in the way you (and PCS) think it is so that you find an off-axis guide star. (The low-level AGw configuration in oacontrol.conf is beyond the scope of these instructions.) PCS parameters may need to be adjusted here.

Check rotator direction

Fullframe ROI

Set the full frame ROI to get rid of funny features at the edge of the acquisition image. The features can detract from the identification of faint guide stars. guidecam_ROI

Set the acquisition offset direction and the guiding direction

This assumes that you have already adjusted PCS parameters to get the desired science detector orientation with respect to the sky (i.e. North up).

Send a GUIDE preset on-axis. In GCS, use pointingCorr_flip_x,y to set the direction of the acquisition offset so the star is placed on the guiding hotspot.

Use guidingCorr_flip_x,y to adjust the guiding directions. An immediate runaway indicates that the signs are incorrect. Spiral guiding indicates that the axes / angles may be wrong.

S-H WFS

Align lenslet analysis boxes to images of field stop in lenslet array.

The lenslet array is glued to the wfs CCD chip, so this step can be done off-sky with any decent uniform illumination. The relevant variable is lenslet_center_x,y in IDL agw_define.pro, but is named differently as WFScam_hotspot_sext_x,y in GCS LUCI_L.cfg. Hint: You might think that lenslet_x_center,lenslet_y_center is the lower left pixel of the lower left lenslet, but Doug moves a full lenslet down and to the left from there (i.e. virtual lenslet 0,0 rather than lenslet 1,1). To be clear, the IDL variable lenslet_x_center specifies the lower left corner lenslet, while the GCS variable WFScam_hotspot_sext specifies the same lower left lenslet.

Note that all of the following steps require a certain level of collimation, so there is some/much iteration required to get the final optimized parameters. The final position of the lenslet array is tweaked by minimizing "X,Y Average Removed" (units are lenslets = 13.3 pixels) in a well-collimated state, but you must have the guiding hotspot well-centered before doing that.

Set the guide hotspot so that starlight is sent through the pinhole into the S-H wfs.

This hotspot position is recorded in lab checkout, but needs to be refined on-sky. A twilight sky behind the guide star is the most convenient situation so that you can see the lenslet (field stop) and the star. See the procedure for aligning the guide hotspot above.

Locate the on-axis pupil position

The central obscuration of the collimated on-axis telescope pupil should land on lenslet 7,7 give or take the fractional lenslet shift of the actual pupil position. Specify this position with pupil_x_on_axis,pupil_y_on_axis in IDL and WFScam_hotspot_x,y in GCS. This parameter adjusts the subimage cutout of the full wfs image. Doug's IDL routines measure the position of the pupil, but there is some scatter from image to image. Thus, it helps to have a number of on-axis wfs images that you can average.

Work out the signs of the Zernikes and the rotation angle

The rotation of the measured Zernikes from wfs space to primary mirror space is controlled by WFS_rotAngleOffs in GCS plus geometrical terms based on the probe position. This parameter is added to the instrument rotator angle to get the angle to rotate the Zernike terms by. Make sure that GCS is reading the correct rotator angle in agwN.cfg. Also beware of direction changes for the rotator between direct and bent Gregorian.

See Doug's routine zernike_collect for a systematic approach once you have decent collimation. Commissioning/ComTools#Zernike_Rotation_Measurements

It is suggested to zero the PSF Active Optics gains for everything beyond Z4-Z8 for the initial collimation.

From 20191181 UT: For those who like geometrical puzzles, I think I've now understood that AGW1 and AGW2 have off-axis wfs cameras that are rotated by 180 degrees.For historical reasons, the resulting inverted pattern of Zernike gains/signs are preserved in the GCS and IDL software.When we moved AGW4 from the left side to the right side, it seemed obvious that we should use the right-side gains from AGW2.That turned out to be a wrong assumption, because the AGW4 camera is not rotated by 180 like AGW2.It turns out that the left-side gains/signs are the ones that work for AGW4@RFBG after you correct for AGW4 using the alternate readout amplifier.

Collimate and iterate the above steps until collimation is good and alignment is consistent.

Particularly note that the hotspot centering is dicey if the collimation is poor and the guidestar is blobby. The poor hotspot alignment will shove the spots into the edge of the lenslet field stops and make the wfs non-linear. (That's why you want Doug helping you.)

Work out the scale/direction/sign/transpose of the off-axis pupil shift

The wfs optics are non-telecentric, so the S-H wfs pupil shifts on the CCD as a function of guide star position in the telescope field. GCS has parameters to predict this shift as a function of guide probe position (WFS_pupil_shift_x,y for sign) (WFS_r_to_pupil_shift for scale) (WFS_pupil_rotoffset for rotation of the wfs camera with respect to guide probe XY). There is also WFS_pupil_dir_x,y which change the signs of the shifts to account for alternate readout amplifiers. The function of WFS_pupil_shift_y is NOT identical to WFS_pupil_dir_y. The central obscuration of the off-axis telescope pupil should land on cutout lenslet 7,7 give or take the fractional lenslet shift of the actual pupil position.

Adjust the AGw stage focus with respect to the instrument

The "z" position of the AGw stage determines where the focussed star is positioned relative to the instrument entrance aperture when the active optics loop is running. The instrument should have been focussed relative to the focal plane sieve mask first (before adjusting the AGw focus position).

WHERE IS THE OLD PROCEDURE FOR THIS FOCUSSING? See our wiki log from 20180913 UT for an improvised approach.

Adjust probe position so the guiding hotspot is on the rotator axis.

See procedure above.

Adjust M3 Tip-Tilt to minimize pupil wobble

See procedure above.

Other

Field Corrections

Field Corrections are Zernike offsets as a function of guide star position in the field to give minimal aberrations on-axis. Use gcs_wfsc_display to compare the IDL and GCS values. Use field_collect to compare the on-axis and off-axis positions. If Field Corrections are set correction and binodal astigmatism is low, then switching from an on-axis star to an off-axis star should make no change in collimation.



Doug's Request for Vibration Data with IRTC (03 April 2009)

Request for fast IRTC data for LBT vibration analysis:

We would appreciate if you could take a few sets of data early in the run so we could analyze the data and possibly modify our request for more data later in the run.

I email me and Guido if you have any questions or comments.

Thanks, Doug

Notes:

1) In order to get a good centroid, we need to make sure the
 star is fairly well centered in the subarray.
2) The subarrays are small so we can read out the IRTC
 quickly (100 to 500 Hz).
3) If the tracking or guiding of the telescope is poor such
 that the star is moving out of, or near the edge of the subarray,
 then the data could still be collected, but may not be very
 useful.
4) The nominal exposure of 1 msec can probably be increased
 to 10 msec depending on the magnitude of the star for the lower
 rate (100Hz) acquistions.
5) Probably M5 stars will be needed so there is enough flux to
 set the exposure time to 1 msec.
6) If Guiding is "to bouncy", guiding could be paused while the fast
IRTC data is collected.  The position of the star on the subarray should
 be checked.
             **Important**
7) **Important** After each set of data is collected, please record the
measured frame rate displayed on the bottom left of the IRTC GUI (see the
 attached image "Gui_with_notes.jpg")
             **Important**
8) Make the directory /Repository/ITRC_Data/090402 and set the
 "Path FITS" to R:/Repository/IRTC_Data/090402 (use correct data)
9) Set the prefix to "vibrate_"
10) Set the Configuration by clicking one of the three images along the
 top of the IRTC Gui.  The box around the selected configuration (image
size) will be lighter grey.  The motion of motors to change the
configuration
take up to several minutes, so be patient.  The square on the upper left
 of the IRTC Gui should change to Green (from yellow I think).  See the
 attached "Gui_Big.jpg" for an example.
11) It would be useful to have 2-3 sets of data at several elevations and
 azimuths relative to the wind
12) Please record wind and azimuth direction ( eg takepic with IRAF and
 copy the resulting image into /Repository/IRTC_Data/090402 and record
 the name)
13) Filter not important
14) Cooling turned on and set to proper value (245)
             **Important**
15) **Important** Collect and record filenames of fast accelerometer data
 at the same time IRTC optical data (Dave Ashby?)
             **Important**
=> seeing <= 0.7"

IRTC Settings:
---------------------
Configuration 2: 6 arcsec FOV, 20 mas/pixel

Subarray: 100x100, 2 arcsec FOV

Exposure: 1 msec

Rate: 200 Hz

Frames: 3000

+++++++++++++++++++++++++++++++++++++++++++

=> 0.7" < seeing <= 1.2"

IRTC Settings:
---------------------
Configuration 2: 6 arcsec FOV, 20 mas/pixel

Subarray: 150x150, 3 arcsec FOV

Exposure: 1 msec

Rate: 100 Hz

Frames: 3000

++++++++++++++++++++++++++++++++++++++++++++

=>  1.2" < seeing  (probably not very useful)

IRTC Settings:
---------------------
Configuration 3: 30 arcsec FOV, 100 mas/pixel

Subarray: 64x64, 6.4 arcsec FOV

Exposure: 1 msec

Rate: 500 Hz

Frames: 3000

-- JohnHill - 18 Apr 2009

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