The big news of today is that our favorite Viscacha made an appearance at the clean room wall today. We’ve been missing him!
We hadn’t seen the old man, Grumpy Viscacha, Vizzy himself, for a long time. We were getting worried. Yes, he’s still grumpy looking.
After a few days of Engineering and Arizona science, we welcomed Subo Dong from Peking University to the Clay telescope. Jennifer Yee (Harvard), who is observing in a few nights, was also here to help out and see how things work.
Jared, Subo, Jennifer, and Katie set a record for most Sagan fellows (current or past) using MagAO at one time.
We continue to make progress in improving the quality of MagAO operations.
This blog gets results! Here we see logs being taken by the AO operator.
The MagAO team is thoroughly nocturnal now. But that means our food is eaten in the wrong order by all standards of civilization.
Katie’s breakfast. Which was really her supper. Or whatever you call the meal before you go to bed.Just some flowers cuz I saw them today.
Finally, we have a clarification from Katie’s post about all of our control loops. Though not specifically annotated, the VisAO Gimbal was shown on the diagram, and you just have to know where to look for our X-Y-Z stages.
The board GUI (code by Alfio), with extra annotations to show where everything is. Today’s free-sticker-question: what’s wrong with our X-Y-Z coordinate system?
Listen close to this song, and you’ll hear an entire verse about adaptive optics. Plus, once you’ve been on a month long MagAO run you’ll know what Bono is saying, though maybe not in spanish.
A closed feedback loop is when you are monitoring some output so that you can control some input. How many closed loops does MagAO run? Here we present: The Loops of MagAO.
The top-level loop: The AO loop.
1. The AO System’s Pyramid WFS and ASM
The top-level loop is the adaptive optics (AO) loop. This is the loop that all the others are here to serve. We are making flat wavefronts so that our science cameras can take sharp images, and it is a serious business.
How a closed-loop AO system works: Your flat wavefront in space is distorted by turbulence in the atmosphere. The distorted wavefront encounters the deformable mirror at the telescope (the ASM), and a beam splitter sends the bluer light to the wavefront sensor (WFS), where a control system calculates the shape of the wavefront, then applies the opposite shape to the ASM. The corrected, flat wavefront is then sent to the science camera (Clio2 or VisAO).The AO system in controlMe running the AO system a few nights ago. Dear Laird: Do you notice how I’m taking logs?And when everything is running smoothly, this is the AO Interface that the AO operator can use to close the loop
2. The Camera Lens
This loop is my favorite, because it’s one of the subtle calibrations we do that keeps our AO system one of the best in the world. The camera lens loop keeps the positions of the Pyramid pupils aligned to the pixels on the WFS CCD to a tenth of a pixel. This means our AO system is always calibrated, in the way that it measures brightness and on the CCD and converts it to slopes to send to the ASM.
The camera lens loop is my favorite. (Well of course, besides the AO loop). Left: The light falls in these 4 pupils after it hits the pyramid, one for each facet. Center: We measure the position of the pupils in software (red cross-hairs and thin circles). Right: We compare the measured positions to where the software is expecting the light (blue and red lit-up pixels), and the camera lens loop moves the camera lens to line up the pupils with the pixels we want them to fall on.
3. The 585 ASM Sensors
The ASM has 585 actuators to control its shape at 1000 times per second, and they have sensors to control their current and check their temperatures.
The control electronics for the MagAO ASMThe ASM housekeeper tracks the temperatures, currents, and forces of the 585 ASM actuators
4. Telescope Off-loading
We send some of the wavefront correction to the telescope — we call this off-loading. For example, if the ASM has to tilt too far to the side and starts to use up all its “throw” or stroke, then we just send a little nudge to the telescope and re-point the whole telescope, flattening out the ASM. We do this once per second, and we off-load focus once every minute.
5. VisAO Coronagraph Guider
Jared wrote a little opto-mechanical loop for VisAO in coronagraph mode. He nudges the VisAO gimbal mirror to keep the star aligned precisely behind the coronagraph. The loop runs once every few to tens of seconds.
Jared running the coronagraph guider loop on VisAOHere we see the offsets scrolling by, and finally a gimbal command at the endThe coronagraph guider in action
6. Clio Temperature Controller
The Clio2 optics are kept at 77K via the outer dewar, by the LCO staff who refill its liquid nitrogen dewar every morning. The Clio2 detector is kept at 55K by a pump that lowers the pressure of the liquid nitrogen and makes it solid inside the inner dewar. However, the pump could keep lowering the pressure and thus the temperature even more, but it’s important to keep the temperature stable. Therefore, we have a heater that senses the current temperature, and turns on a bit when the temperature is below 55 K, and keeps it always at 55K. This is a closed feedback loop.
The Clio temperatures
7. Mechanical Loops with Encoders:
We also control a lot of mechanical components using encoders. On the WFS/VisAO board, called the “W-unit”, we have the Bayside stages X, Y, Z; the PI piezo Tip/Tilt mirror X, Y; the camera lens X, Y; the two atmospheric dispersion compensators (ADCs) and the re-rotator (K-mirror); the beamsplitter and the two VisAO filter wheels; and the gimbal motors X, Y. That’s 15 encoders:
All the things on the wavefront sensor and VisAO that move mechanically and with encoders
8. Finally, the telescope itself has several mechanical loops: Elevation; Azimuth; the Dome; and Active Optics (the primary mirror M1 has ~150 actuators controlled via a closed-loop Shack-Hartmann (plus the 5-d vane ends (x,y,z, theta, phi))
The Shack-Hartmann guider loopThe back of the primary mirror, where there are actuators controlling the active optics
Well, I lost count, but that’s a lot of control loops! And when it’s all working, this is what we get:
60 milli-arc-second PSF at H-band on a 7th-magnitude guide star. That’s really good! Also it has a faint companion…
Well, that’s it for tonight, suffice it to say we had a good busy night on sky.
The moon to the west, at sunrise, from ClayThe moon setting as the sun was rising, the morning after the lunar eclipse
The song of the day has an astronomical theme, is by a top South American artist, and it came out on Vevo the day we left Tucson for this trip:
Here’s another good one by Shakira, from when the World Cup was in South Africa, it’s in the top ten most viewed Youtube music videos of all time:
Speaking of the World Cup, I’m happy to report that there is a soccer field at LCO! But it’s near the gate and we never go by there, so I’ve never seen anyone playing soccer here.
Vanessa arrived safely today after boarding 6 planes (but only traveling on 3) to get here. We are happy to see her! She is helping with Clio2 engineering as well as AO operations. We also had 2 of our observers arrive today; their run is in a couple days but they wanted to get up to speed on the system. Unfortunately, we couldn’t show them much at the start of the night, because while closing the loop on the first star, we had a hardware failure that got us pretty worried for a few hours. The ethernet module on our slope computer failed. Luckily, we had a spare, and Jared and Laird put it together without any help from our Italian friends who were all sound asleep in Tuscany.
Two photos of the spare BCU 39 slope computerThe failed ethernet module (top) was swapped out for the spare (bottom)
After they got that fixed (in the mean time, Vanessa and I were working on the CLio computer backup), we got on sky. We had amazing seeing tonight.
I know there’s a reason we picked this site.
And we got some amazing data.
A bright star behind the coronagraph on VisAO at i’ (770 nm) with very high Strehl
We also took some spectral-differential imaging (SDI) data with the Wollaston beamsplitter in to divide the light into the narrow-band and continuum beams. Here is Laird inserting the Wollaston, which he has to go up to the instrument in the telescope to do:
Here is Laird inserting the Wollaston by feel and sound
It was a beautiful night.
The ASM by moonlight. Photo courtesy Prof. Laird M. Close.The Clay telescope by moonlight. Photo courtesy Prof. Laird M. Close.
We’re all quite tired.
The P.I. with his Fanta
But seeing Raphael and Pele dance it up on Xai //na gomasen is quite energizing!
And you can see their dancing much better in this video, I love the Namibian dance style!
T.J., Alycia, and Kate left us yesterday. Vanessa was supposed to be here, but her flight was delayed. So, it was down to Laird, Katie, and Jared to carry on the MagAO mission tonight.
Our day started early. We had to get up before dinner to do some maintenance on our shell wind monitor. This is a little anemometer attached right at the edge of the secondary mirror to tell us if the winds get too high. One flaw with our current device is that it is battery powered and the batteries only last about 10 days. So the crew tipped the telescope over for us, and Laird and Katie climbed up to replace the batteries.
Laird and Katie replacing the batteries on the wind monitor.
After that bit of periodic maintenance was taken care of, we headed back down the hill for our usual breakfast.
We have a nice steak dinner just about every evening — for breakfast.
After that we headed right back up, and closed the loop. Our minimum number of planets detected tonight is 1 (100% confidence). The maximum number is 4, with a most likely value of 2. Stay tuned.
How the AO system looks when it’s running well.
Tonight was a little bit more interesting than usual, since we got to enjoy a total lunar eclipse. We knew we were in for a special night when we saw the moon rise over the Andes on our walk up to the telescope after dinner
The moon looked almost shy.Let the show begin!
With only 3 of us to operate MagAO, Clio2, and VisAO, plus Ernan our telescope operator, we had to watch the eclipse in shifts, leaving one person inside the control room to come holler if something went wrong.
Laird worked hard to get some nice shots of the dark moon.
The eclipse as seen from just outside the Clay control room.Laird might have had too much caffeine before taking this shot. He might also be over-driving tip and tilt.
When the moon is full here, the mountain top is really really bright.
Clay, containing the MagAO system, by the partially eclipsed light of the moon.
MagAO also obtained world-wide coverage of the eclipse. Well-planned, I say.
The departing members of the MagAO team saw the eclipse from the Miami airport this morning.
On our walk up at sunset, the Moon and Sun were 180 degrees apart in the sky. On our walk down at sunrise, they had nearly exactly swapped positions. Mornings here can be stunningly beautiful.
The moon, now opposite the sunrise. Free MagAO sticker to the first person who emails me the name of the pink band on the horizon (hint, the answer is in a blog post from last April).
You might remember that this isn’t the first time we’ve observed an eclipse at LCO.
Have you ever heard that pigeons are the rats of the sky? Well, tonight we were contemplating that binaries are the vermin of the sky. The binaries we are talking about are “stars” that are actually two stars, only they are so close together that they weren’t discovered to be 2 stars by the early astronomy surveys. But when you have AO on a large telescope like we do, you find out that a lot of stars you thought were single are in fact binary. And then you are disappointed if you were looking for something else when you chose to look at that star.
Laird discovered a binary with the pyramid wavefront sensor tonight. The pyramid pupils were lit up diagonally, and he correctly predicted its properties (about an arcsecond separation, about equal brightness) before we even saw it on one of our cameras VisAO or Clio2. Here it is: Laird discovered a binary star with the pyramid wavefront sensor (left) before we even had a chance to look at it in the focal plane with VisAO (right)!
We have been looking at disks around stars recently. Here is a Clio2 image by T.J. of a star that was supposed to have a disk… but instead it was a binary star: A binary imaged with Clio2. The ring around the primary star is the control radius of the AO.
Kate, Alycia, and T.J. are heading down tomorrow, and our mean tiredness is going to go way up. Thanks for all your hard work, guys! Here is the disk team hard at work.
Tonight we got on sky about half an hour earlier than normal, to get some narrow-camera K-band flats, which have proved to be difficult to get enough light. I’ve made a new page with all the Clio2 calibrations, and I’m posting the flats as we get them. They are still not ideal due to an in-focus pupil glow that we think may be related to a slight pupil misalignment. Here we are opening up the dome the previous night: The Clay telescope opening at dusk
And from the inside: The ASM hanging over the Clay primary, from inside the dome, at dusk.
The pyramid pupils taking sky flats. On the left, you can see a pretty cool diffraction pattern around the tip of the pyramid
We miss Alfio, but things have been running pretty smoothly, which is a testament to the amazing software he left for us. The team on Alfio’s last night. From left to right: Kate Follette, Katie Morzinski, Jared Males, Alfio Puglisi, Alycia Weinberger, Laird Close, and T.J. Rodigas.
The Clay and Baade at sunsetAlycia took this picture of Quadritos cereal with braille on the box
Although this post says day 18, we started the 2014A blog on “day 0” (the PI arrived on “day 1”) and it took 2 days to travel here …. so Jared, T.J., and I left our homes 3 weeks ago now, and it’s been 20 days for Laird. In honor of that milestone, here are some pictures from the run that haven’t made it onto the blog yet:
In the first week we were here, Laird put some new filters in the VisAO filter wheel. It took a while because one of the filters wasn’t sized correctly for the slot, so he put a helpful “Stay away” note.The “village” at LCO where we live this month. Down there you can see the dorms and the kitchen.Laird taking a picture of the ASM with his fiducial tape on the cap. He taped the crosshair on pretty much by eye and it worked perfectly!T.J. and I opening up Clio2 in the clean room, back on the first few daysJared is dismantling the earlier part of his PhD project. It was a high-speed shutter he built to do Strehl selection because everyone said visible-light AO wouldn’t work. However, thrillingly, MagAO works great in the visible wavelengths, and we never used the high-speed capabilities of the shutter.Alfio and me after attaching the wind monitor to the ASM with LairdThe small telescope next to the Clay that measures seeing. It is a Differential Image Motion Monitor and is called a DIMM.Panorama around the back side of Clay where the DIMM is. This is where I go hunting for vizzies at dawn.Vizzy resting on the wall, looking out over the LCO villageA wild vizzy at dawn (foreground, lower left), looking out over the smaller telescopes at LCO
And here’s a bird, but not a vermin of the sky: The LCO Whistler at dawn
Here’s a movie Jared took of the LCO whistler, watch/listen to the video and you’ll know why. Note how it tips it’s head back when it whistles!
My brother gave me some mp3’s of him playing some peaceful songs on piano, which has been nice to listen to when I need to focus on reducing data in the control room. One of them is Prelude Op 28-15 “Raindrop” and here’s a version of the song from Youtube:
