Technical Observing - Verification of AGw Non-Vignetting 20140227 UT

Observers: JHill (Tucson - remote room)
Telescope Operator: SAllanson (LBTO)


These were measurements to confirm the vignetting or non-vignetting of the ARGOS dichroic mount on AGW2 by looking at the twilight sky with the off-axis S-H wavefront sensor.

The result of these measurements is that we see the shadow of the dichroic mechanism on the lenslet array at the extreme outer corners of the AGW2 guide probe range, however this shadow is outside of the pupil image used for wavefront sensing. We see no significant vignetting of the wfs pupil by the ARGOS dichroic mechanism.

We have not measured AGW1, but we assume that the result is the same since both AGW and dichroic mechanics are identical.

Thanks to DMiller for his assistance in the interpretation of these images.


wfs 0001 - 1 sec dark

We are not authorized, and MODS1 is working on the other side.

selectAGW right LUCI_R.cfg to get the correct configuration in GCSR

Data is in /home/lbto/data/20140227_rfbg/

Rotator 146 deg

Set RFBG rotator angle to 146 degrees (one of two computed angles that would put the AGw probe at the bottom)

Set M3 selector angle to -25.8 deg for RFBG

Using setGSsfp right -x XX.X -y YY.Y to move the probe. The outer corners of the guide patrol field are SFP x=130 y=180 ==> AGw x=-127 y=430; and SFP x=-130 y=180 ==> AGw x=+133 y=433 (where the 3 mm asymmetries are from a peculiar transformation presently installed). Using readWFSCam right -e 1000 to take the images.

01:39 wfs 0002 - 1 sec on-sky w/ probe on-axis at SFP 0,0

wfs 0003 1 sec at SFP -130,180

wfs 0004 1 sec at SFP +130,180

Rotator 156 deg

wfs 0005 1 sec at SFP +130,180

Rotator 136 deg

wfs 0006 1 sec at SFP +130,180

Rotator 200 deg

(200 deg is the other likely position where the probe would be down if I got the sign of the rotation wrong)

wfs 0007 2 sec at SFP +130,180

wfs 0008 2 sec at SFP 0,180

wfs 0009 2 sec at SFP -130,180

Rotator back to 146 deg

wfs 0010 4 sec at SFP -130,180

wfs 0011 4 sec at SFP 0,180

wfs 0012 4 sec at SFP +130,180

wfs 0013 4 sec at SFP 0,0

wfs 0014 8 sec at SFP 0,0

wfs 0015 16 sec at SFP 0,0

wfs 0016 16 sec at SFP -130,180

RPC Communication Error on AGW2 (Steve will deal with this later.)

Twilight ends and MODS1 observing begins.

  • Off-axis positions at rotangle 146 and 200: The upper row of images are from the extreme outer edge of the guide patrol field using images 0007, 0008, 0009 with the RFBG rotator at 146 deg. The lower row of images are from the same probe positions with the rotator at 200 degrees using images 0010, 0011, 0012.

  • On-axis position at rotangle 146: This is a reference view without any vignetting. The brackets to hold the Retroreflector are still in place and visible as shadows against the bright sky.

-- %USERSIG{JohnHill - 2014-02-27}%
Topic attachments
I Attachment Action Size Date Who Comment
7-8-9-10-11-12.jpgjpg 7-8-9-10-11-12.jpg manage 1 MB 27 Feb 2014 - 19:10 JohnHill Off-axis positions at rotangle 146 and 200
on-axis-2.jpgjpg on-axis-2.jpg manage 156 K 27 Feb 2014 - 19:11 JohnHill On-axis position at rotangle 146
Topic revision: r2 - 27 Feb 2014, JohnHill
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