Wednesday 27 June 2012

Pending Professional Observatory Visits

I'm getting very excited about my pending visits to various professional observatories here in Chile. Over the next 2 weeks I'll be visiting Gemini, ALMA and Paranal.

This coming Friday I will visit the Gemini Observatory, which is situated on Cerro Pachón, at 2700m. As the name would suggest, Gemini is one of a pair of telescopes, the other situated on Mauna Kea, Hawaii, at 4200m. Each telescope has an 8.1m diameter mirror and are optical/infrared telescopes. With their respective locations, they can collectively observe the entire sky.

You can find out more about the Gemini Observatories here: Introduction to Gemini

Both of the Gemini telescopes have an instrument called GMOS, which scientists and engineers at the UK Astronomy Technology Centre helped to build. GMOS is a multi-object spectrograph and camera. The multi-object mode of GMOS allows astronomers to obtain spectra of hundreds of objects simultaneously.
GMOS being installed at Gemini S (copyright UK ATC)
During the commissioning of GMOS-S, this image of the Hickson Compact Group 87 (HCG87) was obtained - previously only seen from space. HCG87 is a diverse group of galaxies located about 400 million light years away in the direction of the constellation Capricornus.
The Hickson Compact Group as taken with GMOS-S
Another multi-object spectrograph which the UK Astronomy Technology Centre have been heavily involved with is KMOS, which is heading to Paranal later this year - another place I'll be visiting soon. The Paranal Observatory is managed by ESO, a research organisation for astronomy, supported by fifteen countries. Paranal is at an altitude of 2635m and is home to various telescopes. The most well-known of these is the VLT or Very Large Telescope. The VLT consists of four 8.2m telescopes, each given names of object in the sky in the Mapuche language - Antu, Kueyen, Melipal and Yepun.

Sadly I'll be at Paranal before KMOS, as it would have been great to see it installed having seen it for all these past months seeing it being built and tested in the labs in Edinburgh. KMOS will be installed on the telescope called ANTU (The Sun in Mapuche) at the VLT.

KMOS has 24 robotic arms, which means it can obtain spectra for 24 different objects in one observation.
KMOS and its 24 arms
The capability of KMOS will allow astronomers to further investigate star and galaxy formation and evolution. 

As well as seeing the Very Large Telescope, I'm also hopeful I'll get to see VISTA at Paranal - a 4m wide field survey telescope, the project management of the design and construction of which, the UK ATC was responsible for. Not long after I started work at the Royal Observatory Edinburgh, VISTA was being shipped out to Chile, so it would be amazing to see it in its home.

Being a survey telescope means that VISTA maps the sky systematically, sometimes studying small patches of sky for long periods to detect extremely faint objects and at other times surveying the entire southern sky. One such survey VISTA has been doing is that of the Magellanic Clouds - our neighbouring galaxies. The results obtained from this survey are allowing astronomers (including Dr Chris Evans, based at the UK Astronomy Technology Centre) to study not only the inner regions of the Tarantula nebula (within the Large Magellanic Cloud) but also to study the multitude of smaller stellar nurseries nearby. These studies will allow astronomers to look into the regions where massive stars are still forming and look at the interactions between these and the older stars in the wider region.

VISTA Magellanic Cloud Survey view of the Tarantula Nebula (credit ESO)

One thing I really hope to see in action during my overnight stay at Paranal is the laser guide star of the VLT's adaptive optics system. This would be absolutely amazing to see.
VLT Laser Guide Star in Action (credit ESO)
Adaptive Optics is a technology used on telescopes to help remove the distortions caused by turbulence in the atmosphere. This turbulence is what causes the stars to 'twinkle' and, for astronomers, causes blurring of images. By using a laser guide star and a deformable mirror, corrections can be made for the atmospheric distortions.

Between my visits to Gemini and Paranal, I'll be visiting ALMA - a different sort of telescope altogether. ALMA is an array of radio telescopes, which work at millimetre and submillimeter wavelengths, and is the current largest ground-based astronomical installation in the world. When complete, it will consist of 66 dishes acting as a single giant telescope, using interferometry. Because it is an array, it will have greater sensitivity and higher resolution than existing submillimetre telescopes, like the James Clark Maxwell Telescope in Hawaii (on which SCUBA 2 is installed - another instrument built by the UK ATC). The ALMA site is on the Chajnantor Plain in the Atacama Desert at an altitude of 5000m.

Interferometry works on the basis of two or more separate telescopes combining their signals, offering a resolution equivalent to that of a telescope of diameter equal to the largest separation between its individual elements. It requires high precision engineering as all 66 antennae must work in complete synchrony with a precision of one millionth of a millionth of a second. Also, the path followed by the signal from each antennae to the central computer must be known with an accuracy equivalent to the width of a human hair - not much room for error.

These 66 antennae will be able to be moved to span an area of 10 miles at its largest, creating nearly 71,000 square feet of radio light collecting area.

Currently there are 34 antennae in position and already the Early Science phase has produced some fantastic results. One such result is the observation of some of the dust ring around Formalhaut - a star around which there are planets - which has led to some exciting developments. Astronomers had already obtained direct images of this system, but the new observations by ALMA, along with computer simulations, have helped to determine that the 2 planets orbiting the star are actually much smaller than it was originally thought. This observation was done when only a quarter of ALMA's antennae were in place...just imagine what it will help to discover in the coming years!
ALMA's observations of dust ring around Formalhaut. Blue image shows earlier image obtained by Hubble (credit ESO)
I look forward to blogging about my visits to these magnificent observatories!!

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