Home of MagAO and MagAO-X.
After our pre-ship review, we had a few things to fix – the only difficult one was a misbehaving actuator in the ASM. These have all been dealt with, and after a final review by the director we today received permission to ship the Magellan AO system to Chile.
LCO here we come!
Some packing pictures courtesy of Carmelo Arcidiacono:
The Magellan AO VisAO camera includes a novel system for performing “frame selection”, which is the technique of using only periods of good seeing and/or AO correction in the final science image. Traditional “lucky imaging” does this by reading short exposures and selecting in post processing. In our system, we use measurements of Strehl ratio in real time and open and close the shutter based on those measurements. This video shows our shutter working with the AO loop closed in the Solar tower in Arcetri, Italy. It was taken during the week after our pre-ship review.
The Strehl time series is derived from our custom wavefront reconstructor (calculations are done on a GPU). During this testing the shutter decisions were based only on the most recent Strehl measurement, meaning that we did not use any predictive algorithms. Note the fleeting moments of a clear Airy pattern as the shutter finds the highest peaks in the Strehl ratio time series.
The real question is: does it do any good? We’re still analyzing all the data we took, but for now this demonstration is an important step showing that our telemetry and hardware systems can do real-time frame selection.
This video demonstrates the MagAO high-level software GUIs used to acquire the star, set up the AO system, and close the loop. The entire process takes about ~3-4 min. at this time.
(Filmed by Alfio, narrated by Laird, cameo by Katie operating the VisAO camera)
Go to https://www.youtube.com/watch?v=wSiFoG8qgKI to view the video in high-def.
Description:
After the telescope slews to a new target, the guider will acquire the star to within 4” on the Technical Viewer (CCD 47 in AO acquisition mode; otherwise CCD 47 is the VisAO array). Next, the MagAO Command GUI controls the AO system and is operated as follows:
The MagAO project hosted our Pre-Ship Review (PSR) last week at Arcetri Observatory in Florence. The purpose of this review was to ensure that lab work on the AO system is complete and that MagAO is ready to move to the telescope for on-sky commissioning.
Six external reviewers (4 in person and 2 by videocon) gave us their time and attention for 2 days in real time, as well as studying up beforehand and writing a report after the fact. The scope of their expertise covered subjects from large telescopes, commissioning AO systems, instrument development, logistical implementation, real-time software, and adaptive secondaries.
The review lasted 2 days and included presentations, discussions, and a demonstration of the AO system in the tower, controlled from the chem. lab. Topics included a description of the Magellan telescope, an overview of the MagAO project and instrument, the scientific justification, detailed technical descriptions of all subsystems, logistical considerations, and our plans for commissioning. The reviewers considered everything in detail and gave us a report in the format of Findings, Comments, and Recommendations.
The review went very well — the reviewers were extremely thorough and helpful. They included three requirements and four recommendations, as well as findings and comments. We are working to address the requirements identified by the panel, before we ship to Chile. Two have been addressed already this week, and the third is waiting for next week.
Here are some photos from the review:
Yesterday we tested closing the loop on a faint R=13 mag star. Ambient light from computer monitors in the test tower was too bright and so we closed the loop from the “control room” in the chem. lab. It’s a good thing we got all the computers, desks, and high-speed ethernet links so that our control room is all set up and we could darken the “dome”!
We closed the loop on this R=13 star with the conservative 75th %ile seeing we’ve been using, 0.8” FWHM (r_0~15cm) and 33 mph winds (~15 m/s). The frame rate was 200 Hz to get enough counts on the WFS with the pixels binned by 2. Our resulting Strehl was 13% in z’-band which is about 200 nm rms wavefront error. (The correction for our simulated turbulence not having high-order modes, and the correction for the double-pass on our DM in the test tower have a negligible contribution at this level). Here is the image in z’-band:
For comparison, typical Keck AO wavefront control on H~7-9 mag NGS is also around 200 nm, or ~50% Strehl in H-band (result from 1000 Keck images from my dissertation). So we are quite happy with this image quality!