# AOS rotation: test 2

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#### Details

• Improvement
• Status: Done
• Resolution: Done
• None
• 3
• Telescope and Site

#### Description

• Turn off all perturbations again, but this time use the cmd file to add back 1 Zernike perturbation at a time to M1 only.  I’d suggest an amplitude of maybe 250 nm.
• Single star on the boresight.
• For each Zernike index 4-22 (or some subset if this is too much), make a plot of the estimated Zernike coefficient vs input rotation angle.  You should get sine waves for these, with periods as follows:
• Z4, Z11, Z22 estimated Zernikes are independent of input rotation angle.
• Z7, Z8, Z16, Z17 period is 360 degrees
• Z5, Z6, Z12, Z13 period is 180 degrees
• Z9, Z10, Z18, Z19 period is 120 degrees
• Z14, Z15, period is 90 degrees
• Z20, Z21, period is 72 degrees
• I predict that the above are periodic with rotTelPos, but not rotSkyPos.
• Note that phosim injects circular Zernikes, but ts_wep is estimating annular Zernikes, so we don’t expect to recover 2*250 nm (reflection so path length changes by 500nm!) if we inject a 250 nm perturbation.

#### Attachments

1. image-2022-04-08-12-46-19-723.png
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2. image-2022-04-08-12-42-20-382.png
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3. image-2022-04-08-12-18-32-244.png
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4. image-2022-04-04-14-09-53-568.png
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5. image-2022-04-04-14-07-40-131.png
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6. image-2022-04-04-14-06-25-418.png
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7. image-2022-04-04-14-02-41-345.png
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8. all_zk_comparison_rotSkyPos_vs_rotTelPos.png
1.26 MB

#### Activity

Krzysztof Suberlak added a comment - -

Comparison of donuts given a single zk for a variety of rotSkyPos, keeping rotTelPos=0. The number in each postage stamp is the value of 'rotSkyPos' in that simulation.

Krzysztof Suberlak added a comment - - Comparison of donuts given a single zk for a variety of rotSkyPos, keeping rotTelPos=0. The number in each postage stamp is the value of 'rotSkyPos' in that simulation.

Comparison of donut postage stamps given a single input zk (18) for a variety of rotTelPos, allowing PhoSim to calculate rotSkyPos. As above, the number in each stamp is the value of angle input in the simulation, in that case rotTelPos:

Krzysztof Suberlak added a comment - Comparison of donut postage stamps given a single input zk (18) for a variety of rotTelPos, allowing PhoSim to calculate rotSkyPos. As above, the number in each stamp is the value of angle input in the simulation, in that case rotTelPos:

In summary, as mentioned here https://lsstc.slack.com/archives/C9BEJU1T3/p1649452191399489?thread_ts=1649278238.043959&cid=C9BEJU1T3 , these tests prove that "rotTelPos in phosim_syseng4 is really just rotSpiderPos", i.e. the camera is kept at a fixed angle wrt M1M2, and the only thing that rotates due to changing "rotTelPos" is the spider.

Krzysztof Suberlak added a comment - In summary, as mentioned here https://lsstc.slack.com/archives/C9BEJU1T3/p1649452191399489?thread_ts=1649278238.043959&cid=C9BEJU1T3  , these tests prove that "rotTelPos in phosim_syseng4 is really just rotSpiderPos", i.e. the camera is kept at a fixed angle wrt M1M2, and the only thing that rotates due to changing "rotTelPos" is the spider.

In summary, I think we can say convincingly that this proves that there is no camera rotation imparted by 'rotTelPos', only the spider rotation. The camera is at a fixed angle wrt M1M3 assembly. This is similar to the findings of https://jira.lsstcorp.org/browse/DM-31532

Krzysztof Suberlak added a comment - In summary, I think we can say convincingly that this proves that there is no camera rotation imparted by 'rotTelPos', only the spider rotation. The camera is at a fixed angle wrt M1M3 assembly. This is similar to the findings of https://jira.lsstcorp.org/browse/DM-31532 .

This one looks done.

Joshua Meyers added a comment - This one looks done.

#### People

Krzysztof Suberlak
Krzysztof Suberlak
Joshua Meyers
Joshua Meyers, Krzysztof Suberlak