Redetermining the IHMP zero points

Every time the ACAM or the IHMP are moved then this test needs to be conducted to determine what changes might be needed to best ACAM setup positions, shuffle positions, offset from B->R, etc..

Procedure:

Determine the Center of the BIB:

• Select a 14th mag star in a reasonably rich field with shuffle for the BIB
• Setup on the very center of the BIB field of view (NOTE: this may not match the wiki value, if not then correct the wiki value) and save an image.
• Guide on one of the guide probes
• Put in the ACAM and save an shallow image with the target star not saturated.
• Report on the position of the BIB in the night report and on NightOperations/Commissioning/Results
• Save a deeper image which should show more than a dozen stars.

Determine the Center of LRS2-B

• Select a 14th mag star in a reasonably rich field with shuffle for the LRS2-B
• Setup on LRS2-B and start guiding on one of the guiders
• Take LRS2-B spectrum, probably 60 seconds.
• Adjust the position so that the star is at the center of LRS2-B IFU using lmap until the offsets are less than 0.3"

syscmd -T 'Guider1_offset_fiducial ( dx_asec=-0.01,dy_asec=0.55,compensate="false")'

• Confirm the star is at the center of the IFU by taking a spectrum.
• Once it is as the center of the IFU put in the ACAM and take a shallow image so that the star is not saturated.
• Report on the position of the LRS2-B in the night report and on NightOperations/Commissioning/Results
• Take a deeper image so that there are large number of stars.

Determine the Center of LRS2-R

• Select a 14th mag=== Testing of the ACAM position === star in a reasonably rich field with shuffle for the LRS2-R
• Setup on LRS2-R and start guiding on one of the guiders
• Take LRS2-R spectrum, probably 60 seconds.
• Adjust the position so that the star is at the center of LRS2-R IFU using lmap until the offsets are less than 0.3"
• Confirm the star is at the center of the IFU by taking a spectrum.
• Once it is as the center of the IFU put in the ACAM and take a shallow image so that the star is not saturated.
• Report on the position of the LRS2-R in the night report and on NightOperations/Commissioning/Results
• Take a deeper image so that there are large number of stars.

Look at the new positions of the LRS2-B and LRS2-R compared to the old values. Determine if there is simply a linear translation or a translation and rotation.

If there is simply a translation follow this procedure:

• In the shuffle.cfg file adjust the acam_x_origin and acam_y_origin based on the differences between the new and old LRS2 positions
• Rerun shuffle for the LRS2-B and LRS2-R same star used above and compare the fake ACAM with the real ACAM to confirm that no rotation is needed for blind setups.
• Update the markers wiki page with the new LRS2-B, LRS2-R, IHMP positions as a new dated entry.
• E-mail the new shuffle values to Greg Zeimann to get that updated.

If there is a translation and rotation then try the following:

• In the shuffle.cfg file adjust the acam parameter by the amount of rotation needed. For example if you need +1.2 degrees then change it from acam = 1.07 to acam = 2.27
• Run shuffle for the fields taken earlier with the correct position for the stars for LRS2-B and LRS2-R.
• From the fake ACAM images determine if the rotation sign was correct.
• If the rotation is now correct then use the procedure above for the simple translation case comparing the Fake ACAM positions to the real ACAM positions.
• When done you will need to make a judgment call if the TCS zero point angle needs to be update to make the TCS ACAM offsets. This will depend if you think just the IHMP wave moved or if the ACAM was moved.
• If the IHMP has rotated (as opposed to the ACAM) take a few dither sets on a rich globular cluster so that the HETDEX team can determine if new dither values are needed.