As was stated in the Mary Poppins Movie “Winds in the east, mist coming in, /Like somethin’ is brewin’ and bout to begin. /Can’t put me finger on what lies in store, /But I fear what’s to happen all happened before.”
For us it has been out of the South with max of 60 mph. Which means that winter is coming and it is the only change we have in the difference between winter and summer and summer and winter.
“Winds in the south, cold coming in, /Like turbulence brewin’ and about to begin. /Can’t put me finger on what lies in store, /But I fear that AO will soon happen again.”
Was it a green flash? To began the night we started with beautiful clear skies and 30 mph winds
Wind is the worse when it comes to observing. Snow, Rain, Clouds I understand, but wind and with skies like this it seems a waste.
An advantage to having intermediate wind you have the ability to work on code and test it out when you are able to get back on sky. So there has been a lot of debugging going on and improvements the the overall MMTO AO experience when it comes to interfacing with the system.
Latency test. 1.35 frames at 500 Hz
The hints of a MMTAO GUI to control all the inner workings of this system. AO systems are like a mechanical watch the majority of people only see the face of it and never see all the gears and inner workings. We build items in the other direction we have all the inner workings first and then we add the fancy face.
MAPS WFS BoardMechanical Watch
Sleeping accommodations working at the MMTO while waiting for winds to die down.
Well that is all folks. A lot of coding, a lot of friendships being made. So all in all a great night and but looking for clear skies and no wind.
Tonight is our first *official* night on the telescope schedule, as last night was originally scheduled as an MMTO M&E night (maintenance and engineering) that the telescope ended up not needing more than we did, so they let us have an extra night to focus on our alignment. Thank you MMTO!
Craig and Dan came back up to help out at the start of the night with PISCES and the Top Box, respectively. Craig trained ASU grad student Krishna and me on PISCES operations including filling the dewar to keep it at a chilly 77 Kelvin. Fun fact: PISCES has been on 4 professional telescopes on several mountains around southern Arizona!
[Image description: Three photos showing two astronomers adjusting the instrument PISCES mounted to the telescope, and filling it with liquid nitrogen.]
Unfortunately we had to close the dome because of high winds around midnight.
Luckily the software crew were able to continue debugging by our old MagAO trick of closing the loop with tiny gains on WFS noise!
So I thought I would take some time tonight to lay out all the different systems we are controlling on this run, and the operating stations. Our T.O. Ben took for this great pic at sunset: He is standing outside the dome on the ground and the telescope is tipped over looking at horizon and we are all standing on the dome floor near the dome slit. You can see some of the primary mirror (the big glass behind us) and the back of the ASM and its structure.
[Image description: 9 astro-engineers stand in a metal building that is seen from the outside. The building has a large opening and behind that can be seen a round mirror. Metal beams are in front of the mirror holding out another smaller round mirror. The faint blue twilight sky is seen in back. One of the astro-engineers is jumping for joy, the others are smiling and/or looking wind-blown.]
First we have the big picture of our AO system on the telescope. The ASM is at the top, suspended far above the primary mirror. The Top Box (labelled W-unit here) is mounted directly beneath the primary mirror, and PISCES (labelled ARIES/MMTPol here, because any of our science cameras will go in this spot) is mounted just below the Top Box. The ASM power supply and the AO reconstructor computers are off telescope in the equipment room.
[Image description: A line drawing of the MMT telescope, pointed at zenith. It is a Cassegrain alt-az telescope with a fast primary and a small, agile mount. Colored shapes and lines show how the MAPS components fit onto the MMT telescope.]
Let’s follow a wavefront as it enters the MMT. The first surface it encounters is the primary mirror which is controlled by the telescope operator (this week we have the pleasure of working with Ben):
[Image description: Several monitors at the Telescope Operator’s station showing the status of the telescope and guis for controlling its various components, web cams for viewing dome safety, star finding tools, thermal control, weather prediction and status, and astronomical and geometrical status.]
After the primary mirror it goes to the secondary mirror. The ASM is currently operated by Jess and/or Amali who use the original engineering gui written by Elwood to control the coil currents, monitor the temperatures, and apply their best lab flat:
[Image description: Jess sits in front of two monitors full of guis to control the ASM, view its actuators’ health and safety, and log his observations.]
Next let’s look at the Top Box. Here is its layout: After our wavefront encounters our secondary mirror, it goes through the primary’s central hole to the dichroic just above PISCES, and the bluer portion is passed by the dichroic in reflection onto the optical breadboard in the Top Box. Then it travels (in this picture starting from the left) through the periscope (Oli’s elegant design to give us nodding without the heavy Bayside Stages used for this purpose in LBTI and MagAO). Along this beampath we have the option to insert a calibration laser source used for pupil illumination tests. Next comes the input triplet lens and ADC (atmospheric dispersion compensator). Along this beampath some of the light is sent to the acquisition (ACQ) camera (a Basler) with a selectable beamsplitter wheel. Next are the fast-steering mirror (FSM) that we use to modulate the beam (modulator) and K-mirror (which adjusts for the parallactic angle), then we have a flip mirror which gives the option of either the visible-wavelength wavefront sensor (WFS) or the infrared WFS. Just before this flip mirror is a fairly new addition, a pupil imaging lens (with Lyot stop placed just before the FSM) can be inserted here and a pellicle to a ZWO camera to image the pupil. On this run we are primarily focusing on the visible WFS, the acquistion camera, and the pupil imager.
[Image description: An optical diagram of the Top Box shows optical beams and elements that pass and control the light in the wavefront sensor subsystems.]
Here is a pupil image Grant took last night with the ZWO camera in pupil imaging mode as the dome was closing, to help Oli size the Lyot stop correctly: The bright ring is the sky, the circular shadow is the secondary, supported by the spiders in black, and the white rectangle in the center is the last bit of the primary mirror that can see the dawn sky as the dome was closing.
[Image description: Blurry white ring on a black background. Inside the white ring are four dark diagonal lines making a cross, and a white elongated rectangle with a dark hole in the center.]
The Top Box is currently operated as follows. During initial alignment at the start of the run, a lot of optics must be adjusted manually (often by Oli; this run it was by Grant and Dan). Next we have the movement of remotely-adjustable motors, from filter wheels and the periscope to the modulator (FSM) speed and amplitude. While we have a gui design in progress, these are currently being operated using the original engineering guis of each of the individual COTS components, here is their control station:
[Image description: Photo of a computer screen with several guis for components by Thor Labs and Basler among others.]
The WFS in the Top Box and the ASM above the telescope work together in a closed feedback loop to flatten the wavefront. This is controlled by the AO software CACAO and CHAI currently being written and operated by Andrew, Amali, Eden, Jared, Olivier, Jacob, and Robin. Here are Amali and Andrew closing the loop on WFS noise when the dome is closed due to high winds:
[Image description: Amali sits in front of two monitors and a laptop. The monitors are full of guis, TMUX screens, and displays of the AO system and CACAO. The laptop has Andrew on Zoom.]
Now consider the redder portion of our wavefront. That passed through the dichroic in transmission and went into our science camera PISCES. The PISCES optical path inside the dewar has two cameras (narrow-field 26” f/23 and wide-field 100” f/5), a filter wheel (JHKs and narrow bands 1.113um, H2 2.122um, Br-g 2.166um, FeII 1.64u, and 1.2um), and a Hawaii-1 chip.
[Image description: On the left is a line drawing of the optical diagram of PISCES. On the right is a photo of PISCES mounted to the telescope, which is labeled with PISCES’ components.]
PISCES is operated from our fifth and final computer station in the control room:
[Image description: Photo of the computer screen for running PISCES control software, which consists of a ds9 display of a seeing-limited star at K-band, a terminal, the control gui, and the PDF operations manual.]
It’s 5am (about an hour before dawn) and looking at the weather, we don’t think the wind will clear up in the next hour, so we’re going to bed early. The song of the day is Chilly Winds by the Kingston Trio:
[Media description: Folk group “The Kingston Trio” sings “Chilly Winds” on a stage in the early 60s.]
Hello Extreme Wavefront friends, I’m back! Tonight was the start of our first MAPS run after the summer shutdown and it’s the usual packed control room, multi-tasking team, full moon, and beautiful mountaintop observatory!
[Image description: Gallery of photos showing the MMT Observatory at the top of Mount Hopkins, the telescope overlooking the valley, and the moon and clouds through the dome slit.]
MAPS is the MMT AO exoPlanet characterization System and is an ASM-based third-generation AO system with two pyramid wavefront sensors and a suite of science cameras. Our primary focus is on exoplanet science, although the broader diffraction-limited/enhanced-seeing MMT community will also benefit from the return of AO.
On this run we are starting with general system checkout and alignment, then focusing on AO software tasks such as offloading and pupil real-time alignment, as well as on-sky calibration of our interaction matrices.
It was a fun first night with Grant announcing “Field trip!” everytime we asked him and Dan to go up to the dome and adjust something in the Top Box.
By the end of the night we had nicely aligned PISCES and the pyramid pupils.
[Image description: Gallery of photos showing astro-engineers in the control room operating AO software or looking at the sunset; line drawing of telescope and camera optics; and photos of various guis showing starlight manipulated in various ways to show PSFs, pupil images, and pyramid pupils.]
For the blog rules, we’ll stick with the classic/basics: One post per night, one song of the day.
Tonight’s song of the day is a cover of the Cranberries’ Zombie by Bad Wolves:
[Media description: High-production-value music video of the group “Bad Wolves” performing the song “Zombie” as a cover and tribute to the original by the Cranberries.]
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!
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.
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.
