MAPS-2024A – Page 3 – Extreme Wavefront Control Lab

MAPS May 2024A Night 3: Alignment Crimes

Cell phone photo (!) by Suresh of the Milky Way over the MMTO last night. [Image description: a star-filled sky, and a cloudy-looking galaxy band, over a telescope dome on top of a pine-forested mountain.]

The nice thing about observing at the MMT rather than Magellan (even though they don’t haul food, meal prep, cook, nor clean dishes for us here) is that when you have an urgent need for one of your engineers to come up, it’s only a 2-hour drive (rather than a 2-day flight/drive) from Tucson! Tonight Grant kindly came up and got us aligned.

Why did we need to do alignment again? Well between the telescope and the AO bench we have so many degrees of freedom, and the telescope staff that we work with have different ideas about what to do, and our team has different ideas about what to do, that we had gotten very misaligned and had to start all over again. As I mentioned yesterday, Tim and Ben got us aligned to the chief ray of the telescope. Tonight Grant, Oli (remotely), Bianca, Manny, et al then went back to our first upstream optic: the dichroic — and starting there did a beautiful iterative alignment (even having to move the MOUNT of periscope 1 because it had run out of range) and got us filled pupils! (Especially after Amali also encouraged some of the edge actuators to do a better job holding up their edges.)

Yes we are still a bit unclear as to why the dichroic was so far off (since we hadn’t touched it and we THOUGHT we were on the chief ray in January when we installed/aligned it), and why periscope 1 had wandered so far. But I think it’s just a complex system with many parts controlled by different teams and we have different staff (both from MMTO and MAPS) at different times so we never quite know if we are doing things the same way every time, no matter how hard we try, especially since the system is still so new and we are constanly making adjustments and working out kinks anyway.

So we will continue to learn more about the situation, but thanks to Grant for coming up and Oli for being on the phone and to everyone for filling our pupils once again!

Grant looking at pyramid pupils on a laptop at the Cass of MMT in the dark. [Image description: Grant is peering at the pupil image, and about to reach in and adjust another optic and watch the change.]

After this we went on-sky and Andrew got the IR CTL pupil tracking working! And then Jacob and Suresh took Do-Crimes interaction matrices and closed the loop with a 20-modes loop! We were debugging this at dawn when some patchy clouds suddenly showed up (after a beautiful clear night with 0.8-1” seeing) and so it was time to call it a night (It’s a night!).

Amali’s completed Tunisian crochet project! [Image description: A scarf is draped across 2 chairs. The scarf has a geometric pattern that morphs into the word “MAPS” and has colors of dark blue, reddish-orange, and whitish-cream.]

The best 15 minutes of the day were one of my trips up to see the alignment in the dome.

Song of the night: “I’m a Slave 4 U” by Britney Spears (2001)

MAPS May 2024A Night 2: MIRAC

Conditions were great tonight — clear, not too windy, and seeing around 0.8” (definitely usable).

Also I updated yesterday’s post with some pictures and a song of the day.

Tonight was the second MIRAC night and the instrument had finished cooling and was nice and cold, so Jarron got to taking data! Unfortunately he had a vignetted pupil again (but differently from last time) but he still got a lot of good throughput and sensitivity measurements.

Meanwhile on the AO side we worked on trying to align our vignetted pupil with the periscope, and also tested the IR camera lens, and took data to calibrate the IR camera lens loop.

Here’s our vignetted AO pupil. [Image description: Two monitors with instrument displays and GUIs. Top left camera display shows the ZWO image. A crescent pupil can be seen. It should look like the telescope pupil.]

This one is a little better. The pupil image looks mostly like the telescope pupil! [Image description: Same monitors, GUIs, and image displays. The top left display shows a mostly-filled pupil image. To the right of it is a bright blob which is the star in the focal plane. Peeking in on the right is a third monitor where you can just see the pyramid pupils — 4 pupil images instead of just 1.]

Also we spent some time with MMTO staff (Ben and Tim) in the first half working on getting the hexapod offsets to point to the rotational center of the telescope. This involved rotating the instrument rotator, measuring the arc on MIRAC, and shifting the hexapod to point there.

By the way, I forgot to mention that we also found ASM contamination yesterday. It was a hard blockage about 160 microns tall. After the contamination removal procedure by Manny, Amali, and Dan, it got down to 60-80 microns, which was workable.

ASM display, after Amali flipped it so that it matches the coordinates when you’re up on the scissor lift facing the ASM. Contamination is at 5:00. [Image description: 3 circles (the ASM at different measurements) with 336 little circles (the actuators) of different colors to represent the actuator currents, heights, and temperatures. A slight raised color table in an almost pie-shaped wedge at 5:00 is the contamination.]

Manny, Dan, and Amali removing contamination in the ASM yesterday.

The best 15 minutes of the day were when, after I woke up early (around 7am), I was reading and grew sleepy again, and realized I was about to get my second sleep! Very important for successfully shifting to a night schedule!

Song of the night: “Oops I Did It Again” by Britney Spears (2000)

MAPS May 2024A Day 1-Night 1: Installation and Alignment

The first two nights of this run are for MIRAC (PI: Leisenring), while the last 4 are for AO (PI: Morzinski). Therefore I decided this was my chance to come up in the morning to see the installation of MAPS. See, usually I try and sleep in on the morning before a MAPS run, to help me switch to a night schedule. But instead today I got up in the morning as usual, headed up to MMT, and was able to observe the installation of the Top Box and ASM with a full MMTO crew as well as Dan and Ruby from MAPS. This is important to me because we’ve talked a lot about the installation procedure and whether it can be made more repeatable, but I hadn’t actually seen the full procedure yet. Now I have a much better picture of the process and thoughts about repeatability.

Installing the Top Box to the Cass port of the MMT.

So here’s what I saw. When the Top Box is installed there are 4 feet on the lift that can be independently adjusted. However, the actual measurement of how parallel the Top Box plate is to the Cass plate is through hand-held measuring tapes. There are 2 pins that help guide the Top Box up. And in the end the plates were flush. But I was wondering whether there could be any skew on one side or another.

Installing the Top Box: Measuring the gap on all sides to make sure it’s going on straight.

The ASM installation is complex. The ASM is mounted to the hexapod. This is done while the former is hanging from the crane and the latter is supported on a bouncy stand — so could these be misaligned? But then the screws are gronked on until the plates are flush, except for a gap covering about 20deg on one side where the ASM plate is warped, of about 4 thou. Then the hexapod is mounted to the hub. It’s behind a flange, but the 2 pins keep it aligned, one of them is diamond shaped to control angle, and then the screws are gronked on until tight so we assume it is flush too.

Measuring the gap over about a 20-degree wedge due to a slightly twisted ASM mounting plate. It appears to be repeatable, plus all the bolts are flush and the rest of the mounting plates are flush with no gap all the way around.

Craning the ASM+Hexapod structure up to mount it to the Hub.

Also Dan and Ruby connected the rack and all our other cables:

Connecting the cables in the elecronics rack on the third floor.

Then tonight was supposed to be a MIRAC night but they had a chiller problem and weren’t cold enough, so instead we decided to try AO.

Except instead it still took over half the night to complete set-up and alignment. So we continue to explore how to improve these procedures.

Even though this is the MAPS run not the MagAO-X run, I’ll stick with the MagAO-X blog rules for this run. Therefore, the best 15 minutes of the day were seeing the ASM mount to the Hexapod and then the whole assembly mount to the Hub. I have to admit I’ve never quite pictured it correctly when we talk about in our off-mountain meetings, so this helped me visualize what’s happening very well!

Song of the Day/Night: “…Baby One More Time” by Britney Spears (1998)

MAPS/MIRAC Mar. 2024A Nights 5-6: Windy cloudy graupel

Night 5 started out with Manny and Dan cooking a delicious pancake/egg/sausage/bacon breakfast for the whole crew! Dan came up just to help Manny out, and a great time was had by all.

Post-breakfast, pre-sunset game of pool.

At sunset we were closed due to high winds, then the thick clouds rolled in. It looked like the wind was dropping, but actually the anemometer must have frozen because the winds were still very high in real life!

This picture is supposed to illustrate high winds and building-up clouds at sunset on Night 5. It’s hard to depict wind in a still jpeg though. But those pine tree branches were really blowing!

Around the halfway point of the night it started to graupel, and there were thunderstorms 30-50 miles away. So we never opened, and we put the telescope and instruments into lightning shutdown mode. The MAPS and MIRAC teams waited out the weather until around 3am when we and our TO agreed that the weather seemed to be behaving according to the forecast, and the forecast was calling for more snow and wind the next day and night. Therefore, towards the end of night 5 we decided to call off night 6, and the MAPS/MIRAC teams fled the summit and the snow for the balmy Tucson rain.

Some of us left around dawn, others slept a bit longer, but here was my dawn between Nights 5-6:

The song of the nights is the sound of wind-driven graupel striking the side of the metal dome.

MAPS/MIRAC Mar. 2024A Night 4: We fixed it!

Despite the partly cloudy night, we fixed several issues and made a lot of progress!

MIRAC pupil alignment — an errant detent was corrected and the ellipsoidal mirror internal to MIRAC solved the mystery of co-aligning telescope, AO, + MIRAC pupils!

AO camera lens loop — finally got it calibrated, and working beautifully on-sky!

AO calibrations — got a successful 20 modes loop, and discovered that a better SNR is needed for higher-order loops. SNR can be increased by raising the amplitude/stroke (but need to test where the linear range ends), and/or by increasing the number of iterations (we went from 500 to 2000). We also received wisdom on inverting the calibrations and making our own masks.

However, the partially-cloudy conditions made it impossible to actually take a long-enough running calibration to raise the SNR enough to go to 100 modes. So that awaits another night.

The song of the night is the sound of silence.