2013A – Page 2 – Extreme Wavefront Control Lab

Comm2 Day 17: Calibrating Clio while clouded out

We were clouded out tonight:

Also, a truck on the highway had an accident, which closed the highway, so the new turno couldn’t get here so the day crew had to also be the TO’s at night. We’ve been away from home for ~3 weeks and everyone is tired, but we stayed up all night in the control room working.

So, instead, I’ve been working on reducing my data, which includes determining various necessary calibrations for Clio. One important correction needed for high-contrast photometry is calibrating the linearity of the detector. To do this calibration, I took a set of measurements of increasing integration time, and determined the counts per itime:

I then fit various functional forms to the data until I found the best calibration of the linearity is a third-order polynomial that must be applied to pixels with counts above ~27,000 DN in the raw images, giving the result here:

The result of applying the linearity correction to the raw data. The linearity calibration must be applied to pixels with values above ~27,000 DN, and is not valid for pixels with values above ~45,000 DN for high-contrast photometry (there is margin up to ~52,000 DN for low-dynamic-range photometry).

Note that the data cannot be well-corrected above ~45,000–52,000 DN (depending on your tolerance for photometric error), and these values should be considered saturated in the raw images. I apply the calibration through an IDL function I wrote called “linearize_clio2.pro”. This is going onto the Clio observer’s manual.

Jared and I are working on astrometry, comparing Clio and VisAO measurements and exploiting our capabilities for boot-strapping: Clio has a wider field (up to ~30”) and can get a longer lever-arm on astrometric measurements, but VisAO has a finer pixel scale (~8mas) and a tighter PSF and can get precision astrometry on close companions. We are starting by verifying that we both get the same measurements for the locations of stars in the Trapezium cluster. To do this, I look at our Trapezium images and identify which star is which, then I compare the positions I measure to the positions measured by an earlier author. Here’s an illustration:

Measuring astrometry using Trapezium stars. (Left) Trapezium as imaged at the LBT/PISCES in the IR a year or so ago by Laird. (Right) Trapezium as imaged with MagAO/Clio here at LCO by me. — Measuring astrometry using Trapezium stars. (Left) Trapezium as imaged at the LBT/PISCES in the IR a year or so ago. (Right) Trapezium as imaged with MagAO/Clio here at LCO. Can you identify the stars in the picture on the right? (Ignore the black splotches which are negative star images, from the sky subtraction.)

I’ve measured the plate scale in both cameras and various filters, as well as the rotation offset to orient the images with north-up, which I’ve written in the IDL function “derot_clio.pro”. We’re working on a code repository for these data-reduction utilities that we’re calibrating on these commissioning runs.

In fact, Clio has two cameras, a wide and a narrow camera. Here is a comparison of the fields of view, including an illustration of the overlap:

The narrow field is shown within the wide field. — The narrow field (16” x 8”) is shown within the wide field (28” x 14”).

VisAO’s field of view is similar to Clio’s narrow camera along the short direction (8” by 8”).

Finally, I’ve been having a bit of fun experimenting with the APP coronagraphs that I want to use for following up GPI planets:

Well, it’s been a long night, good morning!

Comm2 Interlude: Announcing MagAO’s new Sagan Fellow

We are pleased to announce that our very own Jared Males (VisAO instrument scientist and software engineer) has been awarded a 3-year NASA Sagan Postdoctoral Fellowship by the NASA Exoplanet Science Institute to bring his PhD work to the next level.

They will look just like this. — Jared’s Sagan Fellowship is awarded to continue his work on MagAO, and use the system to look for exoplanets in the habitable zones of nearby stars.

MagAO will be a 2-Sagan project! — MagAO’s and VisAO’s own Jared Males will begin his Sagan Fellowship next year.

During Jared’s fellowship, he will design and implement sophisticated techniques for imaging exoplanets in the habitable zone of nearby stars, using both MagAO/Clio, MagAO/VisAO, and LBT instrumentation. Read the press release here and here.

Jared will continue at the University of Arizona where he has access to the telescopes and instrumentation he needs for this work. Here is further information about Jared’s project:
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It is wonderful for the MagAO project to continue getting this recognition for the great strides our instrument is making in exoplanet research. Congratulations, Jared, and welcome to the Sagan Fellows family!

Comm2 Day 16: Bad Horrible No Good Seeing

Alycia says I’m spoiled. Fine. But when you’re used to half arcsecond seeing, one arcsecond seeing is a “disaster” (Alfio’s word, not mine).

No JRFAve A. Not even B! — Seeing blew up right before it was time to do my favorite star.

We did do some good science tonight. The AO system is running fantastically well now that we replaced the troublesome switch BCU, and our two cameras are catching all sorts of diffraction limited circumstellar photons.

On my way up tonight I had to negotiate a Burro herd.

The herd was waiting for me. — Just standing around, slowing traffic.

Not so cute when they open their mouths. — The babies were making all sorts of noise. They sound just like you’d expect: hee-haw.

She actually seemed pretty tame — Mom. She made sure I didn’t get too close.

Vizzy was in his usual spot:

We had a surprise visitor in the control room tonight:

that was big — This little dude was hiding under Katie’s bag. Fun.

Tonights quote:

“When it’s good, it’s very good. The problem is when.” — Alfio, talking about a nameless telescope, somewhere else.

Comm2 Day 15: Continuous closed loop

Tonight we had great seeing and also fixed a hardware problem, allowing us to practice operating the AO system, VisAO, and Clio under ideal conditions. In fact, Laird ran the AO system, under Alfio’s careful tutelage, and the loop never spontaneously opened the whole night! This is thanks to Runa who replaced the switch BCU earlier in the evening:

Keep calm & close the loop — Runa tests the fiber connection to the new switch BCU.

We miss Vanessa, who left yesterday, but now Alycia is here and she is able to help TJ run Clio on their targets, while I was running it with Laird on our targets. This is great and enabled me to get a bit of a break from observing at the beginning of the night, to work on other things. We are still engineering all our various modes — below is a photo of “waffle mode” that creates a cross pattern due to uncorrectable modes — and we are making great progress!

One of the Clio modes we’ve been excited to test, for imaging faint companions, is the APP coronagraph. Here’s a pupil image of the APP with a bright star:

JRfave — The APP illuminated by a bright star in pupil imaging mode — you can actually see the phase aberrations that make the dark hole on one side!

Our shipment of hard drives and hard hats finally arrived.

A(R) — Our shipment finally arrived! Laird, Jared, and I show off our Arizona hard hats.

Vanessa had to leave because her skills are also in demand at the LBTI. But here’s one last picture of her and Jared, two graduates of Brookings High School, South Dakota, doing awesome work to bring the sharpest images in the darkest skies. Thanks for all your hard work, Vanessa!

Go bobcats — Vanessa had a big impact on improving the performance of Clio. Here she is posing with Jared (whose impact is in developing and implementing VisAO) by Clio, VisAO, the WFS, and the Nas.

This is good work but exhausting. It’s nice to have something beautiful to see when we step out of the dome in the morning, to head down to a breakfast of fresh-squeezed orange juice and oatmeal and yogurt:

Maybe we didn't. — The colors at dawn to the east are just beautiful. When we’re walking down to breakfast at the end of the night, we have tried looking for the morning green flash — maybe we saw it!

Quotes:
“Call it Laird… dot tickle” (aka .tcl) — Katie to TJ, writing a TCL script to observe Laird’s target.
“Be motivated.” — Runa
“It’s like driving a rover on Mars.” — Alycia, watching TJ align Clio’s pupil, which is a very tricky business.
“It’s like a 6.5-meter space telescope!” –Laird, marveling at how well VisAO is working.

Comm2 Day 14: An outsider arrives

I get to give an outsider’s perspective on the AO system as a guest blogger
tonight. It’s incredibly exciting to be here and see the AO working.

As best I can tell, the team was not intentionally showing off when just after
sunset, Alfio flattened the secondary, Gabriel our TO brought up the primary
mirror, TJ aligned CLIO’s masks and Katie was off and running for some CLIO
phase plate orientation tests on the Trapezium.

I spent the first part of the night trying to absorb how the three components
(secondary, visAO and Clio) all play nicely together. That’s 8 monitors of
information going at once. It’s mesmorizing to watch the pyramid wavefront
sensor, even if it’s just a slowed-down version of the real-time loop.

I have to admit to some dismay when I saw the bad cosmetics of the Clio
detector. Really, we’re working with that? I preserve it here so we can
reminisce about how ugly it was after it’s replaced next fall.

We all have some blemishes, it's true, but Clio has more than its share. — We all have some blemishes, it’s true, but Clio has more than its share.

Katie and TJ quickly showed me that most of the centrally located blemishes
subtracted out well. And really, once I saw that lovely diffraction limited
image on it, I (mainly) forgave it its cracks, holes and delamination.

Look at that Airy ring. You could marry someone with that.

I’m enjoying watching TJ’s scripting efforts and his insouscience in the face
of guff from the VisAO/secondary crowd. Readout and usage of the detector is
pretty efficient, and getting better with every script that TJ writes. Maybe
if I can get up to speed on running Clio, I can provide a bit of a break to
the overworked commissioning team here who have been concentrating without a
break for over a week.

The optimism in the room is delightful. The weather helps; apparently the
commissioning team believes that Las Campanas is the Lake Wobegon of observing
sites. The telescope is strong, the skies are good looking, and all the seeing
is below average.

Yes, it's warm and comfy and the wind is low, but look at the next figure. — Yes, it’s warm and comfy and the wind is low, but look at the next figure to appreciate Las Campanas / Magellan fully.

Look at that better than median seeing. — Love that seeing.

Oh, and I would be remiss if I didn’t note that we made awesome images of one of my favorite disks at not one, not two, but three wavelengths while running VisAO and Clio simultaneously. That jazzed me awake for several hours, but I have to admit that the travel fatigue finally caught up with me, and I had to head back for some sleep at about 3:15 AM. I walked down to the Lodge under a moonless clear sky, with the Milky way from horizon to horizon. The Galactic Center was rising. I actually had to look hard for Scorpius because there were so many stars that even Antares didn’t pop right out. Truly, the skies over Las Campanas are breathtakingly beautiful, so much so I almost woke up again. Almost.

Quotes from the night:

“You’re greedy, aren’t you? No, I see, you’re not greedy, you’re just spoiled” –Alycia to Jared who wanted to wait for the seeing to drop from 0.6 to 0.3″ before he did his favorite target.

“VisAO is going to melt” — Laird (you may have heard about its hot filter)