Tuesday, August 9, 2016

DDO 68: Among Galaxies, a Flea, but a Voracious One

Even a dwarf galaxy with very low mass is capable of accreting smaller nearby galaxies, according to an international team of astronomers led by Francesca Annibali of INAF, the Italian National Institute for Astrophysics. This result has been achieved thanks to observations of the region surrounding the dwarf galaxy DDO 68, which has a total stellar mass of only 100 million solar masses, roughly one thousandth of our Milky Way. 

In the new study, Annibali and collaborators took advantage of  the sensitivity and the large field of view of the LBT. The team discovered that DDO 68, a dwarf galaxy located in an isolated region of space defined as a "void," is actually surrounded by a number of smaller satellite galaxies, and is accreting them. 

Follow this link to know more about this discovery!

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.

Friday, January 15, 2016

MODS1+2 first binocular light

At LBTO, first-generation instruments are deployed in pairs. The Multi-Object Double Spectrograph for the Large Binocular Telescope (MODS1 and MODS2) pair is the second one to have been fully installed and commissioned on the telescope. The Large Binocular Cameras have been in binocular mode since 2008.

MODS2 was reunited with MODS1 on Mt Graham in April 2014. Following commissioning, completed by mid-2015, MODS2 was used for science in the second half of 2015, when only one eye of the telescope was available. With the telescope back to two-eye mode at the end of 2015, it was time to move forward and test MODS1 and MODS2 in binocular mode.

Snapshot of the telescope monitoring screen with the two MODS in action (guider and primary mirror active optics wave-front sensor images displayed for each). The red "ADSEC-OFF" on the right side shows that the rigid secondary is used while the right-side adaptive secondary is being serviced.
As a first step, MODS Principal Investigator Richard Pogge (Ohio State University) worked on the interface between the instruments and the telescope to make possible the use of single-MODS scripts for a binocular observation where each MODS is actually doing the same observation, opening the possibility to reduce by nearly a factor of two the time needed for an observing program. While still in early engineering mode, this is an important step toward a more efficient use of MODS telescope time, which is one of the raisons d'être of the binocular nature of LBT!

There is more work ahead to make this mode user-friendly enough to be used by observers. LBTO could offer binocular observations with MODS in shared risk toward the end of the semester. Stay tuned...

The "official" MODS1+2 binocular first-light: a long-slit spectrum of the Seyfert galaxy NGC1068
(3x5mn exposures on each side). 

Monday, November 16, 2015

LINC-NIRVANA is introduced to its new home.

LINC-NIRVANA (LN) is a near infrared imaging instrument for the Large Binocular Telescope (LBT) designed to offer both multi-conjugate adaptive optics (MCAO) and interferometric beam combination for ultra high spatial resolution. LN is a collaboration between the German and Italian partners. Its Principal Investigator is Tom Herbst (MPIA  - Max Planck Institute for Astronomy, Heidelberg).

LN successfully passed its Preliminary Acceptance tests in Heidelberg (Germany) in May 2015. For the following months, the team has been very busy preparing the instrument for shipping, filling up nine 20ft containers and a BIG crate for the LN bench. Before packing the bench itself, a traverse specially built to eventually install the instrument on the LBT was tested in front of the lab at MPIA. It was LN's first flight! (see image on the right)

Bench crate and containers left MPIA in early September and arrived on schedule on Oct 20 and 21 at the MGIO base camp.

Two of the LN containers (left) and the LN bench crate (right) at the MGIO base camp

The bench crate made its way to the mountain on Oct 22, followed by a first set of four containers. They were stored in the high bay, waiting for the arrival of the LN team, eight people from MPIA who started the long reassembly process on Nov 9. The MGIO staff was instrumental in the swift and safe delivery of these heavy loads to the observatory!

Of the many steps in this reassembly process, checking the fit of the LN bench on the telescope is obviously crucial to the whole project. The bench and its traverse were reunited and they both went for a second flight...

Taking off,hanging from the enclosure crane hook 43 meter above the high bay ground.
Reaching the Upper 3 Level where the bogies of the enclosure ride on their track.
Entering the enclosure access well. 
Entering the hatch. The clearance is very small (a fraction of an inch at the narrowest point) 
Nearly done through the narrows...
Finally free to fly in the enclosure!
LN landing pad on the telescope, in front of LBTI (green structure). The two LUCIs (shiny cylinders) are just behind LBTI. The LN bench with its red traverse can be seen through the telescope structure.   

The bench is now as high as possible above the telescope. The telescope has to be lowered to give enough vertical space for the bench to come to the rear of the enclosure before approaching its landing.
Getting closer... 
With the telescope back to zenith, the bench is lowered down toward its platform.
On the telescope!

A video of the whole operation, compiled by T. Herbst, is available on the LBTO video web page.

For a few days (Nov 16-20), the LN bench will stay on the telescope, moving around during night-time as regular observing takes place with the LBTO facility instruments. During day-time, the various platforms and covers, which will eventually be added permanently to support LN operations, will be fit-tested. 

Friday, June 5, 2015

In 2015B, LUCI1 out and LUCI2 in!

LUCI2 on its way to its right bent Cassegrain focal station 
After slightly more than 5 years of operation, LUCI1, the first in the pair of LBT's near infrared imager/multi-object spectrograph instruments, will leave the telescope at the end of the semester to be upgraded (new software, new detector, additional camera to enable diffraction limited imaging and spectroscopy).

Therefore, LUCI2 will be offered for science in seeing limited mode in 2015B. While LUCI2 has a different user interface and a different scripting tool from LUCI1, its detector has a 60% higher quantum efficiency: a huge improvement well worth the pain of learning for PIs and observers!

The AO commissioning of LUCI2 has also made good progress, though hampered by bad weather earlier in the semester and the priority given during the last commissioning run to seeing limited mode checkout, thus ensuring that LUCI2 will be ready for science for 15B. We should be able to commission LUCI2 in AO mode before the end of 2015B.

Stay tuned for more news on LUCI2 as we prepare documentation on observing and scripting over the summer. 

LUCI1 (right) and LUCI2 (left) on the telescope

A LUCI2 seeing-limited image of Westerhout 3, a star forming region 6200 light-years away - K band - FWHM: 0.54” 

Thursday, May 7, 2015

LINC-NIRVANA Lean-MCAO successfully passed its Preliminary Acceptance in Europe

LINC-NIRVANA (LN) is a near infrared imaging instrument for the Large Binocular Telescope (LBT) designed to offer both multi-conjugate adaptive optics (MCAO) and interferometric beam combination for ultra high spatial resolution. LN is a collaboration between the German and Italian partners. Its Principal Investigator is Tom Herbst (MPIA  - Max Planck Institute for Astronomy, Heidelberg).

LINC-NIRVANA in the lab ready for inspection (credit: D. Ashby)

LINC-NIRVANA is a large instrument: roughly 5 x 4 x 4.5 meters and weighing 10 tonnes! There are a total of 40 pyramid wavefront sensors on the optical bench, more than 250 lenses and mirrors, 133 motors, and 966 cables...

LN bench hanging on the stand which simulates the telescope platform  (credit: D. Ashby)
On the picture above, the red structure on the left of the bench replaces (same mass and center of gravity) the ground layer wavefront sensor unit already on the telescope as the PATHFINDER experiment, which allowed to validate on-sky some of the capabilities of the MCAO unit.

The LN team will first deploy LINC-NIRVANA on the telescope in its "Lean-MCAO" configuration: each arm of the instrument will be independently capable to deliver an MCAO corrected 10 arc-second field view. Two MCAO systems on each arm will remove the blurring of the atmosphere coming from its ground layer for one, and its high layers for the other.

"Lean-MCAO" went this week through its Preliminary Acceptance in Europe (PAE) at MPIA. Two days of review and two more for splinter meetings in small groups made for fruitful exchanges between the LN team and seven LBTO staff. The instrument passed the review successfully, with no showstopper and only a few actions to be taken care of!

Happy LINC-NIRVANA team and LBTO reviewers (credit: T. Herbst)

It is now countdown time up to the arrival at the Observatory. Nine 20' containers and a HUGE box housing the bench and its supporting structure will travel by boat from the North Sea shores to California Coast (with a Panama Canal passage on the way). LN will then go on the road and ultimately reach the base camp in November of this year. After a full integration in the mountain lab, the installation of LN on the telescope is currently scheduled for the summer of 2016. The Early Science program in the "Lean-MCAO" configuration should start in 2017, once the commissioning  of the instrument is completed.

Twelve busy years went by since the Preliminary Design Review of the instrument. The success of this PAE is a tribute to those who contributed with much energy and creativity to the project in Germany and Italy.      
Congratulations are in order to all involved!