ShaneAO Second Workshop, 2016

Announcement

Shane Adaptive Optics Workshop #2

Hello fellow AO users

We are currently evaluating how the Shane adaptive optics / ShARCS instrument can be upgraded to improve scientific productivity and overall scientific impact.

In order to compete in today's observational astronomy environment this AO system must excel in superb image quality and rapidity with which it performs science observations. This allows it to be competitive with a 3 meter aperture in an era of 5-10 meter telescopes.

We are identifying a list of high-payoff items that we can work on, and we are enthusiastically asking for your inputs. Your experience using the instrument is a very valuable in this regard. Here are a few examples of what we thought could have significant general benefit: (LGS=Laser Guide Star, NGS=Natural Guide Star):

1. NGS: Increase NGS off-axis field of view with improvements to the wavefront sensors
2. NGS & LGS: Improve and automate the guide star acquisition and AO tuning process so that operators spend less time adjusting, aligning, and AO tuning on sky.
3. NGS & LGS: Develop a set of software tools for the astronomers use: observing planing tools, exposure calculator, quick-and-dirty online data reduction & display, PSF estimation and image analysis, spectrum reduction.
4. LGS: Commissioning the new fiber laser is somewhat delayed unfortunately,  but we are making progress! For the interim we can repair and restore the present laser back to its original output power so that the AO system will correct better with it.

There are certainly a lot more possibilities, and your experience with the system will help us to vet where to concentrate the upcoming efforts.

To facilitate, we are arranging to convene a workshop, something akin to the workshop we had in December 2014, where AO users can describe their research and discuss instrument issues and plans forward with the ShaneAO community. 

A target time frame for this workshop is November or December 2016.

The workshop will be one-day face-to-face, with video chat enabled, dinner included.  It's been suggest we can have a second workshop a few months subsequent at a different campus location so more people total can participate in person.

In addition, we will set up an interactive web site that provides the info, space for presentations and discussion.

Start here (http://labforao.blogspot.com) and give us your comments, or email me at gavel at ucolick dot org.

Please also visit the ShaneAO website.

1st ShaneAO Workshop

We had a very successful User Workshop on Dec 17 at UC Santa Cruz.

All the users, the instrument developers, and others interested were invited. Many came, and we had a lively discussion of ShaneAO capabilities, science uses, and plans for future upgrades.

Link to the presentations

Attending the workshop were:
Mark Ammons LLNL, Will Deich UCO, Gaspard Duchene UCB, Sandy Faber UCO, Ellie Gates, UCO, Don Gavel UCO, Lea Hirsch UCB, Kyle Lanclos UCO, Paul Lynam UCO (by video), Geoff Marcy UCB, Claire Max UCO, Rosalie McGurk UCSC, Mike Rich UCLA (by phone),  Connie Rockosi UCO, Angie Wolfgang UCSC (by Skype)

ShaneAO Status Report

Compiled for the UCOAC meeting at UCLA on Wednesday 5/21

Present Status

• ShaneAO has completed two engineering runs (one in April, one in May) 
• Now in the midst of the first shared-risk observing nights.
• We have commissioned both natural guide star (NGS) and laser guidestar (LGS) modes for observing. Most systems are checked out and working well: 

ShARCS

• ShARCS cold stop aligned to telescope pupil - much improvement in background over IRCAL's emissivity 

AO Natural Guide Star Mode

• Bright star NGS AO @ 1.5kHz correction - high Strehl (~0.8 ish, as expected in K) 
• Dim NGS down to 12'th mag - M92 picture was taken  with an 11'th mag NGS 

AO Laser Guide Star Mode

• LGS locked in 16x and 8x modes (16x, 8x = wavefront sensing at 16, 8 samples across the aperture respectively) - Laser is dim this time of year, so not much correction, but it locked and is stable 
• Laser uplink tilt correction working 
• Dim tip/tilt star in LGS mode, worked down to 15th mag., goal is 16th 
• LGS mode field steer to tip/tilt star >50 arcsec off-axis and lock

Observing Scripts

• Nod along spectrograph slit - done, but cumbersome, needs some work 
• NGS mode field steer - not very accurate and needs work - automatic nodding scripts close, but not quite finished. 
• Still needs to be done: 
• flexure compensation models for long exposures - needs data collection and implementation 
• field rotation (align along slit via Cass tub rotation) - needs checkout 

More info and pictures: http://lao.ucolick.org/ShaneAO/material/index.html 

Closed-loop PSF - J,H,K bands on-sky

From 5/15

Shared-risk science observer Tucker Jones was kind enough to let us collect point-spread function data at wavelengths across the near IR coverage of ShARCS.

Here's AO-corrected images on-sky in K, H, and J bands:

Point-Spread functions in 3 science bands, compared to open-loop seeing.
ShARCS pixels are 0.035 arc seconds.

The bright-star Strehl ratio performance looks remarkable. Looking at the H band star PSF and comparing it to the image-sharpened internal source, we can make a rough calculation of on-sky relative Strehl:

Strehl in H is around 78%*
*relative to internal calibrator

"Second Light" Engineering Run for ShaneAO

First night saw light overhead cirrus and reasonably normal seeing; about 1 arc second. The goals of the first night were to finish a few NGS mode engineering tasks and start on the LGS ones, then to continue on with deeper exposures of the science targets we started on the first light run. In particular we were able to take another exposure of the open cluster M92, using an 11'th magnitude natural guide star. The guide star appeared dimmer than last time, probably due to the cloudiness. This gave us a chance to tune up on dim star AO performance:

AO with a dim guide star. This was after adjusting settings for low signal-to-noise. 

The second night was beset by clouds and bad seeing, and we were barely able to get even the brightest star to have any signal on the wavefront sensor. The third night was heavy fog and rain and we didn't even open the dome.

Tonight, Friday looks hopeful for clouds clearing by evening. The laser is turned on for the next three nights and the LGS mode AO controller is in place, so we hope to get our first LGS guided images by the end of the run (through Sunday night). Several LGS mode operations and systems need to be tested for the first time on sky, so we hope to get a jump on that starting tonight.


Engineering tasks completed:

• Connected and verified operation of the high-voltage driver for the laser uplink fast steering mirror
• Calibrated 22 more field-steering positions for the wavefront sensor, adding to the set of 4 cardinal points we got on the first light run. We're going to fit a model to these in order to enable arbitrary position offsetting of the natural guidestar.
• We unveiled the GUI for image sharpening. Image sharpening is a calibration process that peaks the PSF on the science image by adjusting the wavefront sensor's definition of "flat wavefront." This cancels the internal aberrations in the science camera. We tested the theory that the image-shapening offsets need to have a scale factor of d/r0 to account for the difference of starlight and internal source size as seen by the wavefront sensor, and this works. We verified with improved on-sky PSFs over no offsets and over not applying the scale factor.

Results of image sharpening

• Validated the dim guidestar AO tuning parameters and closed down to signal-to-noise = 2 on the wavefront sensor. This is an about 11'th magnitude star. Noise is completely dominated by "sky background" noise. We need to investigate now whether some of this "sky background" is in fact caused by glowing lights from electronics boxes and other powered items on the AO bench! If this accounts for say a factor of 2 in background it could make a really big difference in terms of sky coverage in NGS mode - almost a factor of 10 improvement in sky coverage per additional magnitude deeper on a statistical star count basis.

ShaneAO First Light On Sky!

Within an hour of opening the Shane mirror cover on April 12, we had the telescope aligned into the AO system and closed the loop on a bright star, Phi Geminorum.

First, the background sky is used to align the telescope pupil with the AO pupil. Reni is happy about it.

This is "on-sky" closed-loop. Lots of Airy rings on Phi Geminorum!

See the first light photo album for pictures and movies of the events, which include mounting to the telescope, videos of the telescope pointing and instrument rotating, first light activity in the control room.

First light images and tests included

• closed loop images of a bright star
• offload of tip/tilt to telescope guiding (worked like a charm, the Alpao woofer tilt range is adequate between offloads)
• a closely spaced binary star pair - overlapping Airy rings!
• a spectrum of a star, and another after accurate nodding along the slit
• closed loop PSFs with a succession of dimmer magnitude guide stars (in NGS mode)
• closed loop PSF performance at several science wavelengths from 1 to 2.2 microns wavelength
• image of a star cluster (M92), nodded around the field - testing field of view and camera distortion - this is a beautiful demonstration of resolution change from AO off to AO on
• a planetary nebula (IC 4593) - testing imaging of diffuse structure
• the minor planet Ceres - test of resolution and low contrast detail
• closed loop on the laser guide star (but no science images yet; we still need to commission the tip/tilt sensor's closed-loop software, which will happen in our next engineering run)
• outgoing laser wavefront control experiments with prototype high power coated MEMS DMs from IrisAO

The ShaneAO commissioning team in the 120" control room

Stars in the M92 globular cluster

Link for further information, pictures, and presentations on ShaneAO:

http://lao.ucolick.org/ShaneAO

AO Control with turbulence plates!

This is from Tuesday afternoon.

We closed the adaptive optics control loop in simulated atmospheric conditions (created by a spinning phase plate in the telescope beam simulator). The AO system is correcting aberrations using both the woofer and the tweeter deformable mirror in closed loop at a 1500 Hz control update rate.

Click on either of the bottom two images to see a video.

Here is a video of the diagnostic screens. Notice how the "wind" blows from upper right to lower left on the DM screens (bottom two).