Tag: MAPS

I’m going to write nightly updates like last run, even though this time I’m observing remotely from the SPIE Astronomical Telescopes & Instrumentation conference in Yokohama, Japan! Luckily Manny, Jenny, Craig, Grant, Dan, Amali, Bianca, Lauren, and Jorge are there to run things locally.

(Night 1 was 2024/06/14-15th but I’m writing this a little late, during Night 2.)

On Day 1 we installed the Top Box, ASM, and … ARIES! Welcome back to the MMT, Arizona infraRed Imager and Echelle Spectrograph!

We finished installing and setting up ARIES around 11pm. Then we checked the alignment — we couldn’t find the star at first, so Grant went up with an index card into the Top Box and saw that the star was off the dichroic. He and Brian worked to add mount offsets until they had the star on ARIES and the Acquisition Camera. They were quite large, 68” in az and 14” in el, but they did the job and the old hexapod positions successfully kept the star rotationaly centered on the ARIES imager channel. Manny thinks the mounting pin may be adding friction and causing the ASM to go on cock-eyed so perhaps the hexapod is good but the ASM install still needs some work.

Periscope 1 was only moving 1 direction in one of its axes (TY). Luckily we had a spare controller so Grant swapped that out and got it working again!

We tried to check the IR WFS alignment but the camera seemed to be behaving strangely, at least there were some noisy channels. So at the end of the night we went on to the Vis WFS and did a few tests to analyze whether the raggedy edges of the pupils are due to either pupil misconjugation, chromatic bandpass effects, or chromatic ADC effects.

For this run we will have a word/phrase of the night. The word/phrase of the night is “Arigatou gozaimasu” or “Thank you very much [formal]”! It is very useful to say to pretty much all conbini, hotel, and wait staff in Japan.

Tonight was our last night this run. I’m really happy with all the progress we made! It was definitely helped by the fact that this is our best-weather run ever, with the highest percentage of useable time: We were open for 5.6/6 nights, or 93% efficiency!

We solved many problems this run (don’t worry, we also discovered new ones). Jarron fixed his BLINC issues to get a good pupil on MIRAC and he and Jared even got its display on the AO computer so we successfully fulfilled our dream of using MIRAC as a high-speed PSF viewer for AO. MMTO’s Ben and Tim got us aligned to the optical axis (again) but this time we worked hard to all understand each others’ terminology and tolerances so that when we do it again we do it right. Brian kept us safe by monitoring the wind limits. Grant (in-person), Oli (remotely), Bianca, and Manny got the dichroic and periscope re-aligned so we had good AO pupils. Amali poked the edge actuators until they listened better. Amali, Jared, Olivier, Andrew, and I got CACAO working with both the Vis and IR WFS’s. Bianca, Lauren, and Orlando learned more about the Top Box. Jacob and Suresh got DO-CRIMES working with 20 modes and optimized gains. Manny supervised us all and provided insight about all our hardware issues. Dan and Ruby installed (with the help of MMTO day crew) and connected MAPS and I got to see that side of the operations. And the MMTO staff provided a clean and cozy lifestyle. Thanks to all!

On this last night we focused on the IR WFS and trying to understand our hardware problems that we’ll need to fix for next run, as well as to try and get a 20 modes comparison between CACAO and DO-CRIMES. Unfortunately the MIRAC dataset we took with the CACAO loop was pointing into the wind and just when we realized we had to close, and we weren’t able to get a better one. The DO-CRIMES dataset was in better conditions, but they may not be identically comparable. As far as the hardware problems go, we rotated the instrument rotator by 60 degrees and saw that the raggedy edges of the pupil rotated too, therefore (at least in the IR WFS) they are more due to the ASM than to pupil misconjugation. We didn’t have time to switch back to Vis WFS and try the same test, so we should do that next run. The contamination has definitely been a problem and will have to be removed before the next run.

The best 15 minutes of today were around 3am after we saw that the wind was steady below our limits and we got to re-open. This was a first for Jacob and very much need as it enabled him to get that last bit of DO-CRIMES testing and data!

The song of the night is “Hold Me Closer” by Elton John & Britney Spears (2023)

Our science cameras image the star in the focal plane, and our wavefront sensors image the star in the pupil plane. A conjugate plane is where your alignment needs to be in order to get those images in focus. After tonight we are wondering whether our VisWFS pupils are conjugate to the telescope pupil.

Tonight we started with Do-Crime on the IR WFS and MIRAC photometry, then moved on to CACAO on the VisWFS when Jared and Olivier called in on Zoom. We first closed the loop on the 50-modes response matrix from yesterday, and it still worked to the extent that it tightened up the PSF!

We next wanted to explore why the higher-order modes had been unstable and why our pupils still looked raggedy and soft on the edges. Because we had trouble calibrating the edge actuators of the ASM in the lab, we have always blamed the edge weirdness on the imperfect ASM calibration. However, tonight we decided to try a Hadamard matrix diagnostic, which pokes each actuator individually (but efficiently) and measures the result on the WFS. The result was that some parts of the mirror were having no effect whatsoever on the wavefront. One of those regions was where the shell is contaminated, but there were other regions too. Even after Amali put some disabled actuators back in the loop, the result was the same.

Olivier started wondering aloud whether our pyramid image was actually conjugate to the telescope pupil. If it’s out of focus of the pupil plane, then the response would no longer be linear, and you would also get mixing of phase and amplitude of the electric field. This could explain why the pupil images don’t look sharp or round.

We did a test where we translated the star about an arcsecond away from the tip of the pyramid, and saw the pupil image shift by around 4 pixels. The shape of the central obscuration changed too.

So we switched to the IR WFS to see if we could see a similar shift. The IR pupils look sharper than the Vis, and they didn’t shift much if at all.

This was about as far as we got with CACAO before it was time to switch back to Do-Crimes. Tomorrow night we will use the IR WFS and compare CACAO and Do-Crimes corrections.

The song of the night is “Gimme more” by Britney Spears (2007)

The best 15 minutes of the day were flying a kite with Amali, Manny, and Bianca. It’s a homemade kite made by Amali, and the gusts across the peak and around the dome are not very laminar, so it was hard to get a sustained flight, but we did get it to dance and dive in the wind. And we also had fun trying but failing to see the green flash again.

That leads us to the bonus song of the night: “Let’s go fly a kite” from Mary Poppins

We made a lot of AO progress tonight! We switched over to the VisWFS and CACAO, and started with measuring latency (mlat). Jared and Olivier joined us on Zoom and helped debug some settings that were causing us to think our hardware latency was noisy and to suspect timing issues or simlinking the slopes instead of the pupils, but now we think it was actually just a normalization. Here is a nice mlat we got:

After the mlat’s, we closed the loop on the first 3 modes with our best response matrix from March. It worked!! But we couldn’t do higher-order modes — probably because the pupil and alignments had changed. So we moved on to take a new response matrix, but closing on the first 3 modes using the March matrix. We also tested tip/tilt offloading to the mount. And after some investigation of why some of the modes looked noisy or didn’t have much power in them via plotting self response matrices (selfRM), we continued and took a 50-modes calibration. We closed the loop with it and (even though we had to put tiny gains on modes 37-50), it was actually correcting and improved the PSF!

It was cloudy this afternoon and there were a few patchy clouds at sunset, but pretty soon it cleared up and we had a nice night with seeing around 1-1.3”. Earlier in the day Jarron opened the warmed-up BLINC and removed the baffle that was vignetting his pupil, so tonight we all had good pupils for the first time and we were able to get some nice looking PSFs!

When Jared and Olivier went to bed it was time to end our time with CACAO for tonight, and switch to Jacob and Suresh’s project with DO-CRIME and the IR WFS. We finally ended at dawn, a very full and useful night!

The best 15 minutes of the day were trying to watch the green flash at sunset with Amali, Lauren, and Bianca. (We didn’t see it though, but we used the trick Gill taught us.)

The song of the night is “Toxic” by Britney Spears (2004)

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!

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!).

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)