Monday, November 25, 2013

LUCI2 and Pathfinder see the sky for the first time!


A few weeks after LUCI2 met LUCI1 on the telescope and quite a few closed-dome (I should write enclosure) tests, it was time for the second of our near infrared imagers and spectrographs to see first light. Six days of commissioning and a reasonable weather made for a very successful run.

Luci2 on its derotator at the front bent focus of the right side of LBT.

LUCI1 (left) and LUCI2 (right) are seen on the instrument platform behind LBTI 

If LUCI2 is mostly a twin of LUCI1, it comes with a brand new software which was checked, improved and optimized in real observing conditions. The usual commissioning observations to characterize the instrument on sky (astrometric and photometric tests in imaging mode, spectrophotometric zero-point determination for grating 200H+K, ...) were carried successfully. As the new software can handle both LUCI2 and LUCI1, an imaging script in binocular mode was sent and correctly executed. All on-sky tasks foreseen for this run have been successfully performed and the basic functionality and performance of the instrument could be demonstrated.

Two more runs scheduled in December and January should conclude the first phase of the LUCI2 commissioning in seeing-limited mode. 


Pathfinder is an effort to bring a substantial portion of the LINC-NIRVANA instrument to the telescope in advance. Specifically, one Ground-Layer Wavefront Sensor (GWS) and its associated drive electronics and software are implemented at the right, rear, bent focus of the LBT. The main goal is to demonstrate ground layer correction of turbulence, as well as establish the needed infrastructure for telescope and adaptive secondary communications. It will also allow the team to perfect the techniques of star acquisition and tracking. 

Working on the instrument at the rear bent focus of the right side of the LBT. The middle focus station is LBTI and the front is LUCI2 (on the right of the picture). 

Three nights following the LUCI2 commissioning run were scheduled for Pathfinder and LBT engineering. Weather has been unfortunately poor, but Pathfinder was lucky enough to have a couple of openings in the clouds sufficient to catch a couple of bright stars! In spite of a 2.3" seeing, loop was closed with 50 Zernike modes on Epsilon Auriga

There is still a long way to go - this was, after all, only a single star on axis. It is however an important step for the whole team, which left Mt Graham very tired, but happy! In coming campaigns, Pathfinder will be operated with multiple stars in ground-layer adaptive optics mode.

More images on the Pathfinder run here.

Wednesday, November 6, 2013

ARGOS first laser propagation!

ARGOS (Advanced Rayleigh guided Ground layer adaptive Optics System) will eventually bring Ground Layer Adaptive Optics (GLAO) capabilities to LBT.  ARGOS is dedicated to observations with LUCI1 and LUCI2, LBTO's pair of near-IR imagers and multi-object spectrographs.

ARGOS is projecting three beams per LBT's eye, creating a constellation of three artificial stars on a circle of 2' in radius. This constellation will allow a significant improvement of the image quality over the 4' field of view of the LUCIs. Each of the six Nd:YAG lasers sends a beam of green (532nm) pulses at a rate of 10kHz with a power of 14W to 18W. Three beams are launched to the sky on-axis from a mirror on the back of each of the two LBT secondary mirrors.

On the night of Nov5, 2013, the lasers were propagated on the sky for the first time. 

 The beams with the Pleiades and the Hyades 
(photo courtesy of  Julian Ziegleder) 

The beams seen from inside the enclosure under the right side shutter door
(photo courtesy of  Julian Ziegleder)  

 The beams seen from the back of the enclosure (with the left back door half open)
(photo courtesy of Kai Polsterer)

The picture above shows the first acquisition of the six beams (three per LBT main mirror) on the detector of the Mount Alignment Telescope System. For the rest of this first night and during the next three, precise alignment of the beams will be performed and checked with the elevation of the telescope down to 45 degrees, the limit under which no propagation is allowed. Focus range and brightness of the beams will be estimated and all the internal cameras of the ARGOS system will be checked out...

There is still much work left to bring ARGOS to an operational state, but tonight marks a very important step in the whole commissioning process. Following completion of this initial run on Saturday morning, the  next on-sky work is expected to continue in early spring 2014 for first light on the laser guide stars wavefront sensors...

Congratulations go to the ARGOS team for the amazing amount of work done since the Preliminary Design Review back in February 2009, and to LBTO staff for their support of ARGOS since the first hardware showed up at the telescope three years ago. Coordination with FAA and Space Command went very smoothly and the help of Safford Discovery Park docents turned plane spotters is much appreciated for these first four nights of on-sky laser propagation.

More information on the ARGOS project is available on its website here