Category: MAPS

Tonight we worked more on alignment of the WFS pupils (both WFS’s). At the start of the night we attached a cardboard “knife edge” to the ASM so that we could compare the primary mirror and secondary mirror images.

Here’s the resulting image on the ZWO:

And here’s the result on ARIES:

And here are the Vis pyramid pupils:

Checking optics/focus: double knife edge test using primary mirror cover partially lowered and cardboard over ASM (mounted on posts). VIS: – Expectation: one edge would be sharper if said edge was closer to point of focus. – Observation: neither edge is sharp. Fall off on both edges is about 3 pixels on viswfs_pupils. – Assessment: Focal point is near primary, pupil plane inside topbox is somewhat correct.

Next we worked on the IR WFS. We could see the IR source on the SAPHIRA, but only just barely could see the white-light source, and when we went to a really bright and red star (Arcturus) we couldn’t see it. The dark counts were around 30,000 and looked normal (the full well depth is around 100,000), but when Suresh did an up-the-ramp test (which usually saturates after ~20 steps) it saturated after ~5 steps, and wasn’t enough steps to see if it was linear. So now we think either there is a thermal short or some thermal problem, or perhaps a readout/reset problem. TBD.

So we went back to Vis WFS alignment. Oli and Grant did some experiments changing the negative lens (first adjusting it, then removing it completely). Here is one result:

We were closed for high winds from around 1:50am-3:30. During this time we put the negative lens back in. When we opened again we checked it out:

We also tested going to a fainter (almost 7th mag) star and saw that we have plenty of photons on the CCID-75. Now with the winds close to our limit and having completed our engineering tests, the next thing is to get back to working on AO calibrations, but it was too close to dawn to get anywhere especially fighting the almost-limits-winds, so we called it a night.

Meanwhile at the conference there were great talks by Robin, Eden, and Jacob:

Word of the day: “Sumimasen” — excuse me.

Today was the first day of the conference and my talk: “Commissioning MAPS, the MMT AO exoPlanet characterization System.” It went pretty well and it’s also nice to be done with that right at the start of the week! There were a few MAPS-ers in the audience and here’s a photo by one of them, Suresh:

Meanwhile back at MMTO, Brian had a message from Tim that it would be better to take the large tens-of-arcseconds mount offsets and offload them to the hexapod with zero-coma offsets. After he did that the team tested whether the star was still on the chief ray by rotating the instrument and watching it on ARIES — and it was good!

Oli came up tonight and he and Grant put in the ZWO pupil-imaging camera and did the same test we did yesterday to check if offsetting the star shifted the pupils, meaning they are mis-conjugated. However, they only saw a quarter of a pixel shift, or about 5um, which is about 2um out of tolerance (3um tolerance) and still close enough.

Suresh is also observing remotely from Japan and was in communication with the team about the IR camera weirdness from yesterday — the pressure seems high (or the reading is off), and/or the camera isn’t cool enough — so we turned it off for now and will pump on it all day while sleeping. Before that Grant/Oli/Manny went up to check the seating of the fibers in the Top Box.

Finally we tried to do some CACAO and began working our way through a few software bugs. We realized we needed Jared’s help with the pseudo inverse but he was at the conference reception.

We also started looking at our pupils more and decided to explore the alignment and pupil conjugation further. Oli and Grant tried adjusting the negative lens between the pellicle and pyramid. But even with 3 turns and almost all the way off, there was no noticeable difference in the pupil images:

But isn’t it strange that they still look so raggedy, and we can’t even see the spiders? We were wondering about this. So we decided to try and make something even more obvious to see. Some kind of a sharp edge. Shall we say a knife edge.

So we asked Brian to partially obscure the pupil by putting the primary mirror cover tarp about 1/3 of the way across. And here are the pupil images after this. First the ZWO:

Which looks a lot like ARIES in K-band:

And finally the Vis WFS pupils:

They all have a sharp knife edge from the primary mirror cover tarp. But the central obscuration is fuzzy on the Vis, whereas it is sharp in both ZWO and ARIES. And another curious thing is that the IR pupils have a sharper central obscuration.

It was about dawn and our brains were tired, so we will explore this a bit more tomorrow night. But it is curious that we can get a sharp knife edge on the Vis pupils but not a sharp central obscuration. Furthermore it is curious that the IR pupils did have a sharper central obscuration (last run).

The word of the night is Santoku. “Santoku means ‘Three Virtues’ or ‘To solve Three Problems’. The three virtues are meat, fish and vegetables, or slicing, dicing and mincing depending on your interpretation. This means that the Santoku is an all-around knife, suitable for the amateur home cook and the professional chef alike.” [source]

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