Thursday, March 24, 2016

First AO light on LUCI1

Exciting times for LUCI1!   After receiving its first light corrected by the Ground Layer Adaptive Optics ARGOS system (see our previous post), LUCI1 was again on the spot for a few nights of commissioning in Adaptive Optics (AO) mode, this time with a full AO correction not limited to low atmospheric layers of the atmosphere.

Much work was done by the LUCI team to reach this important step. LUCI1 was retrofitted with a new detector (the same as in LUCI2) in the Fall of 2015. A new camera (N30) was also installed, designed to provide the image quality and sampling required to exploit the exquisite resolution delivered by the LBT adaptive secondary mirrors. LUCI1 looks much alike LUCI2, though its N30 camera is made of glass mirrors instead of metal mirrors for the LUCI2 N30 camera.

The LBT adaptive secondaries were unavailable for most of the last semester and came back on the telescope late in 2015 (left side - SX) and in early February (right side - DX). Thanks to the combined efforts of LBTO staff and the Arcetri AO team, the SX secondary was back in service and a first set of LUCI1 NCPA (non common path aberrations) measurements was determined just before the LUCI1-AO commissioning run. The commissioning was therefore a mix of AO checkout and LUCI1-AO observations.

Composite image of the planetary nebula NGC 6543 composed of Ks (2.75min), Brγ (16min) and H2 (8min) observations. The Ks-image has been line-subtracted with the Brγ image. Field of view is 30”x30” (0.015”/pixel). The data were taken on March 20 and 21.

The image of M5 above was taken with LUCI1 and FLAO in Ks-band on March 21 2016. Integration time is 11min. The brightest star in the field, with an R+I magnitude of 10.4, was used as reference star for the AO correction. The AO correction was obtained with 153 modes. Ambient seeing was around 0.9”. The images close to the reference star have a FWHM of around 66mas.

Interestingly enough, as seen in the above graph, the image quality is pretty constant over a ~17" radius from the AO reference star.

The next LUCI1 commissioning run is scheduled for April 2016. Stay tuned...

The following step will be to return to LUCI2, which saw first AO light in early 2015 (see here),  for commissioning of its AO spectroscopic mode.

With the addition of AO and ARGOS modes, coupled with routine binocular observations, we expect that the LUCIs will be heavily in use by early 2017, and will be a major contributor  to the scientific productivity of the Observatory.

Congratulations go to the LUCI team for an excellent work in the midst of the adaptive secondaries struggles of these past months, and to the LBTO and Arcetri AO teams for their support!

Tuesday, March 22, 2016

First spectroscopic observations with ARGOS and LUCI1

Two posts were already published on ARGOS in this blog, the first one at the end of 2013 (where you will find more information on the ARGOS project) and the second one  at the end of 2014. In short, ARGOS is a Ground Layer Adaptive Optics (GLAO) system which permits correction of the image blurring seen by the telescope due to low atmospheric layers of the atmosphere. This improves the image quality by a factor of two to three over a large field (minutes of arc). ARGOS is used at the LBTO with the LUCI instruments, a pair of near-infrared imagers and Multi-Object Spectrographs (MOS). 

The ARGOS team, led by Sebastian Rabien, had a very successful commissioning run this March, with five intense days of preparation work followed by five nights with mostly clear skies. Much progress was made towards bringing ARGOS closer to routine operation. The focus of this run was the left side (SX) of ARGOS using LUCI1, though some work was also done on the right side (DX).  

ARGOS launching its lasers, seen from ~20 miles South of the LBT on 12 March 2016 at ~21:00 local time. The gray short beam left of the LBT is not a laser launched by the SMT! It is only a satellite trail... Photography by Dean Ketelesen.

The previous commissioning run, back in December 2015, had been a good opportunity to define and test the many steps required to conduct an ARGOS-assisted LUCI observation. This last run was an excellent opportunity to repeatedly exercise the whole process from telescope pointing and collimation, Adaptive Optics preset, laser launch, laser acquisition, guide star acquisition, loop closure, up to LUCI observations run from a LUCI script.

With low winds and good seeing, the systems turned out to run stably. To check the performance on sky, several imaging targets, were observed, from star clusters, to nearby galaxies and gravitational lenses.

NGC5921 - JHK - 1.5" DIMM seeing - 0.4"..0.5" J..Ks with ARGOS

Under good weather conditions, many targets show a PSF size is of around 0.2'' in Ks and around 0.3'' in J, fairly homogeneous over the LUCI field.

SDSS J1038+4849 (The cat) - main arcs at z=0.97, 2.19 (J-band image)

The team obtained, for the first time, a multi-object spectrum using LUCI with the ARGOS loop closed. While proper data reduction is pending - as for all the observations during this commissioning run - an initial look shows that nearly all of the ~33 immediately visible spectra have a spatial resolution around 0.2-0.3'', with an increased spectral resolution due to the 0.25'' slit width and the N3.75 Camera.

NGC 5466 MOS observation. Spatial resolution ~0.2" in K - 0.25" slit width - N3.75 camera

For a second multi-object spectroscopy test, the target was the arc of a gravitationally lensed high-z galaxy at z=2.49, combining the unique capabillities af LUCI plus ARGOS. The mask contained a curved slit matching the arc's location on sky and had a 0.5'' slit width. While being one of the most challenging applications of the LUCI MOS plus ARGOS, Halpha is detected over the whole extent of the arc with a 30-minute integration time. The clumpy structure of the arc can be seen at the 0.2-0.3''scale.

There is obviously much more work ahead to make ARGOS a reliable and solid facility instrument which will be both efficient and user friendly. The path towards a general use will be challenging, but these exciting results are definitely a great incentive (if any should be needed) for the ARGOS team, LBTO, and the LBT partnership to devote the level of resources to the project that will be required for a swift move to full operation.

Congratulations go to the ARGOS team for their great work. Many thanks to the LBTO staff for their support.

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