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AO4ELT7 Days -5 to -2: The CDI Prologue, AO-istas in France

First stop after the plane, because how else will the people know we’re in Paris?

This is the prologue to the long sweaty conference the XWCL team will be spending in Avignon, in which some of us spend a shorter but just as sweaty time at a workshop in Paris. (There is a heatwave here, and it’s humid, and the desert kid in me is struggling to adapt.). Last year Sebastian, having good ideas as he does, collaborated with other high contrast imaging folks to think up a workshop on Coherence Differential Imaging, or CDI. As the whole point was to entice the next generation of instrumentalists with the siren song of coherent starlight subtraction in control and post processing, I was an easy target to convince to attend. Jared, having never been to Paris before, was also more than willing to spend a few days in the discussion. So here we are, tourists in a world-dominant optics hub.

Day -4: What is CDI again?

“The Castle” – Observatory de Paris, Muedon

The first day of our CDI journey gave us a late start and a delightful Uber driver, who not only saved us from walking up a long hill to the conference location, but also regaled us with a deep dive into just how bad the drivers there really are.

We found that big tower again from the suburbs.

The Observatory itself was nestled overlooking over the city from it’s Parisian suburb, magnificent among the larger park and woods that presumably came with the original estate.

Overview talks included the Self Coherent Camera (SCC) design.

We started the day with a series of very helpful overview talks, in which I rapidly went from not even really knowing what CDI stood for to appreciating cutting edge efforts to use the coherent properties of starlight with our high contrast systems. Barnaby Norris, Sarah Stieger, Axel Potier, and William Thompson should be commended on how much effort they put into the breadth and depths of their review talks. If you had listened closely, over the birds and the beatific breeze, you would have heard my brain expand three sizes in just an hour.

Pastries for thought.

Almost as helpful as the actual programming were our extended coffee breaks, catching up and floating ideas with some of the leading experts in the field amid delicious pastries. It’s a good reminder that no matter how deep in the trenches I am with my little calibration codes, plenty of my colleagues in the field are right there beside me, banging their heads against similar walls.

Gratuitous pictures of snack tarts and our struggles with slicing them.

At the end of the day we snuck in a little solar observing in an H-alpha filter. What a welcome sight to see the small saguaro on the solar telescope, designed and built by Lunt Solar Aystems in Tucson Arizona! With that petite piece of home, this place started to feel familiar.

With just this little guy we saw stellar prominences in great detail.

Day -3: Discussions and downpour

We did ask Sebastiaan if he wanted an umbrella…

Our second day was focused on hands-on teamwork exercises, which the MagAO-X team prepped for with the team exercise of figuring out how to get on the train, in the rain, from the wrong end of the station. It made us miss our chatty uber driver, especially with the quarter-mile hill treck from the train station to the workshop. Sweaty and drenched and a little dazed, we quickly got into our day of working through simulations and practical implementations of CDI algorithms and architectures.

a quick look into the wavefront correction on THD2 – To the left, the pupil, and to the center the PSF

One of our hands-on notebook experiences allowed us to play with the test bench right here in Paris. Their team has done great work to show a possible use case for AO telemetry, and in some of them we were even able to use their complex coronographic phase mask to pull out the planet!

Using a model of the THD2 test bench and well-calibrated telemetry to reconstruct a PSF, and a planet!

After the day wrapped up, and to much nicer weather, Vincent Deo, a Paris local, walked us through the Meudon streets to a delightful sidewalk restaurant. There, discussions continued, though perhaps on much sillier topics, over wine and Belgian Beers and Charcuterie.

Cheers to charcuterie

Meanwhile… word has reached us that the Space Force AO4ELT contingent has arrived on the other side of France …

I spy an XWCL alumni!
Sunsets look better on the harbor

Day -2: Reflect, Revise, Repeat (in 2-3 years?)

Sebastiaan and I finally made our train, and made it to the workshop mostly on time

And before you know it its over. We wrapped up our discussions on the final day, summarizing our progress, thoughts, and future projects to the rest of the attendees. It was required that the students do the talking, and because of that the final presentations had much fresher face than the introductory ones. It did feel like

Thank you to our LOC and SOC for being such wonderful hosts!

Of course, for all we’re learned, it was also a treat to be able to see another world center for astronomy, and another old telescope. Though this site is mostly for solar observing in the modern day, it has a history of observing that you can feel wandering the halls.

The original Lyot Coronograph
The old reflector at the top of the dome
Talk about a distracting view

Finally, we finished this productive and educational tour de force with a very french dinner. More cheese, duck, and good friends from California and Australia.

Everyone but XWCL looks good in this picture, so I guess we’ll use it.

See you all soon in Avignon!

Song of the Day(s):

Blog Rules for the french trip: Every post should use at least one french word, have a song of the day, and be tied to a memory of the trip.

Summer Breeze by The Main Ingredient

The streets of Meudon were perfumed by the many jasmine bushes, wafting along a puff of breeze. I can understand why they’d want to host a workshop out there.

A Toast to Warren, MSc, for the Miles Travelled

Cheers to mastery, mate!

On Thursday last week, Warren Byrum Foster of house XWCL, first of his name, Tzar of tubeless designs and the first picomotors, protector of PIAA lenses, cultivar of pineapple, breaker of linear shift-invariance, the unphased, and (most recently) Master of Science defended his thesis and restored peace and order to the 8th floor of the Optical Sciences building.

Here we go!
Room atmosphere during Warren’s talk.
Great introduction by Jared.

The public portion of the presentation detailed the many intricacies of the Phase-Induced Amplitude Apodization (PIAA) component of MagAO-X and I’m pretty sure I speak for more than just myself when I say that I learned a lot about the importance of this project for pushing the limits of the Magellan Clay telescope. Warren also had the foresight and kindness to distract us with tasty Mexican pastries and fizzy drinks while we awaited the good news during the “grilling” portion of the defense. We would all like to thank him for his work towards shrinking our inner working angle and furthering our long term science goals of becoming the best AO system in the world!

No windows were left with a cork-shaped hole, this clearly isn’t his first time…

Congratulations to Warren! Starting your grad school journey at the apex of the pandemic (Aug. 2020) and completing many of your core classes remotely and mostly solo was no easy feat (source: same cohort as me!) so extra kudos to you for sticking it out and finishing with a bang. We’ll definitely miss you and the positive vibes you bring; whether we’re on observing runs or just experiencing daily life on the UArizona campus. Here’s to the road ahead; may your hunts be fruitful and your arrows fly swift.

For now, Warren is continuing with the refinement of the PIAA setup with some fancy picomotors for finer control during operation. Further into summer, he is pursuing collaboration with the Roger Angel group to demonstrate his talents on the LFAST project.

A nice sunny day in the Summer of 1998 2023 provides the perfect backdrop for celebrating a successful Master’s defense on the 8th floor in Meinel.

For proper celebration shenanigans we found ourselves at 1912 Brewing Co. where we presented Warren with a super cool tee which he promptly and eagerly put on. (Thanks to Joseph for facilitating this!)

Song of the Day

The song of the day is an absolute classic and a known favorite of Warren. I chose this rendition because Ray Chen’s facial expressions while playing the violin more than make up for the lack of vocals here…!

MAPS 2023A Day 5: Sunset on the ASM run

Manny caught an unsuspecting grad student sunset-watching.

Well, the fun had to end sometime. This post marks the official end of the MAPS 2023A run, after a weather-ful last two nights.

One of the big perks of mountain observing in AZ, especially in June, is replacing the 100ºF highs of the valley with mountain temperatures of 40-60º. The first night, as we braved the bitter winds of civilian twilight for the MAPS team photo next to our colleagues with parkas and patagonias, Joseph and and I had the sinking thought that maybe our office-AC outer layers wouldn’t measure up. For the first few nights, we shivered through the few minutes we had to be outside and remembered the summer heat wistfully.

Lady bugs huddling in the outside cracks of MMT for warmth.

Careful what you wish for. After the chilly 50s of the first few nights, our second to last night we got hit with an uncharacteristically balmy and breeze-less front. Lovely for humans, but very bad for ASMs who need weather-based cooling. So yesterday, we spent a crystal clear night waiting on and off for a hot, crabby ASM with no wind to soothe it.

Tonight, however, the chilly breeze was back, and with it the clouds. We got a sunset so spectacular that the whole control room ran out to see it. Did I miss a green flash? Yes. Yes I did. Apparently I haven’t learned the proper technique even with weeks of observing at LCO.

Even Joseph, perched at the ever-rotating window, had to admit the sunset was worth going out to see.

Though astronomers might love a good sunset, astronomy doesn’t like the clouds they can bring. We ended up being clouded out for a good portion of our final night, an anticlimactic way to end a week of speed-learning a CACAO system. As it became clear that the clouds weren’t going to clear out anytime soon, person by person the crew took off to bed, prepping for mountain-top departure in the morning. What was left by 3am was the skeleton crew, the bare minimum to keep everything running. Brian for the telescope, Jaren for the science camera, Manny for the ASM, Me for CACAO, and Joseph for morale.

Skeleton crew selfie right before closing.

Though Joseph and I were last minute additions to MAPS and the learning curve was steep, it was such a privilege to be able to help with an AO system on such a historical telescope. One that has been on the forefront of segmented mirror alignment and Infrared science. Hope to see you soon MMT!

The last sunrise.

Song of the Day

Sleepy Eyes – Eerie Wanda

MAPS 2023A Day 4: What’s a couple of shmims between friends?

After the previous night’s untimely clouds, we were fortunate to have clear skies and moderate-to-good seeing all night. The MIRAC-5 team continued work on their instrument, which the adaptive optics operator Eden found extremely useful for its fast video feed showing how (and if) our adaptive optics experiments were improving their images.

I, however, mostly spent the night shmim-wrangling.

MAPS (like its cousins MagAO-X and SCExAO), uses shared memory images—shmims—to relay data at high speed from a wavefront sensor, through an adaptive optics loop, to the point where commands are handed off to the adaptive secondary mirror.

There it is! Way high up off the ground!

Of course, a shared memory image is just a hunk of memory with a hint about the type of data it contains (floating-point numbers, integers of various sizes, etc.). One could just as easily use a shmim to store a vector, or a single number, or a data cube.

One such vector was my target yesterday: the vector of “modal gains.” Each entry in the vector scales the system’s correction for that mode by the factor you provide, allowing you to correct low-order modes more strongly while easing off the high-order modes that you may not be able to control as effectively. It’s sort of like the EQ sliders on a stereo.

What’s he listening to?

Still, one may ask, what is a “mode” in an AO system? The answer: something too abstruse, dear reader, to bother this blog with.

That won’t stop me, though! You know how the optometrist fiddles around with their equipment to find the best focus for your eyes, and only then starts in with the next level: correcting for astigmatism? Well, AO systems fiddle around many times per second to get the best focus for the telescope, and the best astigmatism correction, and a few more besides. It turns out there are “levels” beyond astigmatism, accounting for even more subtle changes to the image. We need to correct those for the sharpest image possible.

That’s the short version, anyway. The long one involves math. If you’re looking for a low-stress beach read this summer, I can recommend Adaptive Optics for Astronomical Telescopes by Hardy (1998).

In MagAO-X we divide the gain controls into blocks of modes and use buttons to bump them up or down to improve our correction. MAPS does not use all the same MagAO-X software, and the two of us from the MagAO-X team were missing the fun of clicking a lot of buttons really fast. So, while Andrew develops the real, production-grade, network-enabled button-pushing infrastructure for MAPS, I brought a little bit of MagAO-X from home.

This tool replicates the UI we have for MagAO-X gain tuning, with the additional trick of a parametric gain curve. Rather than tuning the modes by blocks, one can type in some parameters to define that pink curve with a different gain value for every single mode. Clicking “Apply” then fires the numbers off into the appropriate shmim, where they are applied to the AO loop.

Of course, all the software in the world can’t change the laws of physics. Summer seems to have finally made it to Mt. Hopkins, and with it the need for active ASM cooling has become acute. It turns out that bending glass mirrors takes a lot of power, and some of that power escapes as heat. That heat, in turn, makes the whole system (red-faced and panting) call for a time-out while it collects itself.

It’s not often I wish a mountaintop were colder and windier. Tomorrow’s our last night, and we’ll have to see if we can keep our cool when it’s a balmy 54ºF at 1 A.M.

Song of the Day

“Que Sera” by Wax Tailor. It’s a groove, trust me.

MAPS 2023A Day 3: MIRAC-5 has entered the chat

After some berating from @jlong, here is my inaugural post! First, an obligatory observatory picture.

The MMT at sunrise with the full moon on the horizon

The MIRAC-5 team arrived Friday, June 2nd to prepare for installation of the latest iteration of the instrument. Originally conceived in 1988 by Bill Hoffmann at the University of Arizona, MIRAC (Mid-Infrared Array Camera) is an ever-evolving mid-IR camera built for observing between 1 and 18 microns. It has a long and illustrious career of testing out mid-IR technologies, including various detectors and nulling interferometry (test bed for LBTI nulling). As the name suggests, we are on the 5th iteration after almost a 10-year dormancy period!

MIRAC was pulled out of retirement and refurbished to house a new mid-IR detector: the 2k x 2k GeoSnap-18 array manufactured by Teledyne. This GeoSnap is an engineering grade device with a wavelength cut-off of 13 microns. Designed for high-background applications this array is perfect for ground-based mid-IR astronomy! The primary features are wavelength sensitivity at H, K, L, M, and N-Bands (science-grade arrays will extend down to 0.7 microns), well depths of 1.3 million e– (twice that for science-grade), and continuous frame rates of >85 Hz without any reset or data acquisition overheads! After commissioning of MAPS and MIRAC, we plan to use these instruments to characterize exoplanet and brown dwarf atmospheres in the mid-IR, complementing the capabilities of JWST MIRI.

The GeoSnap engineering array in its storage contain. Of the full 2048 x 2048 pixels, only one quadrant is bonded with photosensitive material (HgCdTe).

Anyway, off came the PISCES camera and on went MIRAC. Comparatively, MIRAC is a bit of a beast.

U. Michigan graduate student Rory Bowens (right) and U. Arizona PI Jarron Leisenring (front left) and U. Michigan PI Michael Meyer (back left) posing next to MIRAC-5 mounted to the MAPS top box.

Upon hooking up the bazillion cables, we realized that the fiber extender used to transfer the data from the GeoSnap detector to the computer (located in an adjacent rack) wasn’t working as expected. The only solution was to keep the original (short) cables attached and strap the computer to the instrument cart on the telescope. It didn’t seem to complain about the free ride.

After bringing the detector temperature to a cool 40K, we were able to get the acquisition software working on the first try thanks to the diligent efforts of our software engineer Dennis Hart and successful implementation of the @jrmales’s rtimv visualization software.

Early image of a controlled PSF at K-Band running with a frame rate of 5 Hz. Hot pixels have not been masked out.

Throughout the evening, we successfully acquired a number of stars, co-aligned with MAPS, performing continuous PSF display at high frame rates, tested internal pupil chopping operations, measured background levels, and a whole host of other commissioning activities. While a few challenges inevitably arose, which we will address during the summer, it has been a pretty successful and rewarding “pre-commissioning” run so far!

Additional Random Photos

Sunset over Kitt Peak
MMT Primary
Michigan PI Michael Meyer

Song of the Day