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Innovative Telescope Engineering Timeline January 13-23

Follow our progress with MMT and AO engineering, imaging, and system adjustments. Overcome challenges, optimize performance, and plan for efficiency enhancements in upcoming runs.

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Innovative Telescope Engineering Timeline January 13-23

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  1. MMT AO run Jan 13 - 23

  2. Timeline: • Night 1: Install hardware during MMT engineering • Nights 2-4: AO engineering with fast-framing H camera (Indigo) • Nights 5-7 (nominally): ARIES commissioning • The good – ARIES mounts just fine and makes focused images. • The bad – Images are badly astigmatic, and the entrance window was cracked while trying to fix this. The detectors are OK, but we still don’t understand where the astigmatism came from. • Night 7: More imaging with Indigo camera • Nights 8-10: Imaging/nulling with BLINC/MIRAC • Night 11: Lost to bad weather and PSU failure

  3. System view • Overall the system runs very sweetly at 550 updates per sec. • Currently we correct the lowest 52 modes of the aberration (sufficient to get the diffraction limit at H in good seeing). • Integration time can be slowed down arbitrarily to give access to fainter guide stars. • Ability to dial static aberration into the WFS to clean up DC errors in the science focal plane.

  4. Secondary mounted and ready to go, November 2002. Takes 1.5 hr and 2 people to mount and dismount (currently requires Francois Wildi and Michael Lloyd-Hart). WFS top box is also straightforward to mount.

  5. Challenges that surfaced • Loss of ARIES was a blow – we need to understand the source of astigmatism before we rebuild the dewar’s front end in case design changes are needed. • Installation of the system is now faster than f/9 although post-installation alignment must still be sped up. • WFS read noise is WAY too high (> 30 e-). Limits us to stars > V ~ 10. • Internal alignment of the WFS must be automated to guard against flexure w/ gravity. • Image jitter is seen at 19 and 38 Hz at the level of 20 mas. This currently limits our Strehl.

  6. Power in one-axis image motion

  7. Current operational constraints • Takes two people (Doug Miller and Guido Brusa) to run the system. • Installation requires a team of ~6 people. • Guide star brightness must be < 10 (we hope this will improve by several magnitudes before our next run). • Still some single point failures that must be addressed (e.g. power supplies).

  8. Future • Most of the hardware has been left at the mountain (it works, so no need to move it). • Problems with WFS sensitivity, optical alignment and image jitter are to be addressed in the next 4 months. • We would like another run in May devoted largely to engineering, demonstrating closed loop on fainter stars and improved robustness/ observing efficiency. • Use PISCES to demonstrate K band diffraction limit (not seen yet).

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