Andrew Yee[_1_]
July 11th 07, 05:36 PM
ESO Education and Public Relations Dept.
----------------------------------------------------------------------------
Text with all links and the photos are available on the ESO Website at URL:
http://www.eso.org/public/outreach/press-rel/pr-2007/pr-30-07.html
----------------------------------------------------------------------------
Contacts:
Jochen Greiner
MPI f. extraterrestrical Physics, Garching, Germany
Phone: +49-89-30000-3847
Michael Sterzik
ESO, Chile
Email: msterzik (at) eso.org
For Immediate Release: 6 July 2007
ESO Science Release 30/07
GROND Takes Off
First Light for Gamma-Ray Burst Chaser at La Silla
A new instrument has seen First Light at the ESO La Silla Observatory.
Equipping the 2.2-m MPI/ESO telescope, GROND takes images simultaneously in
seven colours. It will be mostly used to determine distances of gamma-ray
bursts.
Taking images in different filters simultaneously is important for the study
of many astrophysical sources, and in particular of variable sources, such
as close binaries or active galactic nuclei. But it is most crucial in the
follow-up of gamma-ray bursts. Gamma-ray bursts (GRBs) are short flashes of
energetic gamma-rays lasting from less than a second to several minutes.
They release a tremendous quantity of energy in this short time making them
the most powerful events since the Big Bang.
Gamma-ray bursts, which are invisible to our eyes, are discovered by
telescopes in space. After releasing their intense burst of high-energy
radiation, they become detectable for a fleeting moment in the optical and
in the near-infrared. This 'afterglow' fades very rapidly, making detailed
analysis possible for only a few hours after the gamma-ray detection. This
analysis is important in particular in order to determine the GRB's distance
and, hence, intrinsic brightness.
A first determination of the distance can be done by taking images through
different filters, using the so-called photometric redshift [1]. Because a
typical GRB afterglow becomes 15 times fainter after just 10 minutes, and
over 200 times fainter after an hour, it is important to observe the object
in as many filters as possible simultaneously.
"To make the determination of distance of far-away objects as accurate as
possible, we decided to use four different filters in the optical and three
different filters in the near-infrared," says Jochen Greiner, who led the
development of the GROND instrument. GROND stands for Gamma-Ray burst
Optical/Near-Infrared Detector.
GROND takes thus images of the same region of the sky in 7 different
filters. The field of view in the near-infrared is 10 times 10 arcminutes,
or 1/7th the area of the Full Moon. It is smaller in the visible, slightly
above 5 x 5 arcmin.
GROND is presently in its commissioning phase and its first science
demonstration has been achieved, showing that all technical systems work
properly. In particular, GROND observed a quasar located more than 12
billion light-years away.
As for many instruments specialising in the follow-up of gamma-ray bursts
(see e.g. ESO 17/07 and 26/07), GROND can also be activated with a Rapid
Response Mode (RRM): GRB alerts will be automatically fed into the system
thus minimising the delay between the gamma-ray burst detection by a
satellite and its observation by GROND.
"The implementation of the RRM at the 2.2-m telescope is done in exactly the
same way as for the VLT, and boosts ESO's leadership to offer observing
systems with ultra fast response time towards GRB follow-up," says Michael
Sterzik, Head of Science Operations Department at ESO La Silla.
A dedicated data analysis pipeline is also being tested which will provide
the distance of the burst a few minutes after the first observations.
"Ultimately, the goal is to trigger ESO's VLT to perform spectroscopy of the
source with fine-tuned settings, thereby maximising the scientific return of
GRB follow-up observations of the VLT," says Greiner.
GROND has been built by the Max-Planck Institute for Extraterrestrial
Physics in collaboration with the Thinger Landessternwarte Tautenburg.
Note
[1] The photometric redshift method makes it possible to judge the distance
to a remote celestial object (a galaxy, a quasar, a gamma-ray burst
afterglow) from its measured colours. It is based on the proportionality
between the distance and the velocity along the line of sight (Hubble's law)
that reflects the expansion of the Universe. The larger the distance of an
object is, the larger is its velocity and, due to the Doppler effect, the
spectral shift of its emission towards longer (redder) wavelengths. Thus,
the measured colour provides a rough indication of the distance.
National contacts for the media:
Belgium: Dr. Rodrigo Alvarez, +32-2-474 70 50
Czech Republic: Pavel Suchan, +420 267 103 040
Finland: Ms. Tiina Raivo, +358 9 7748 8369
Denmark: Dr. Michael Linden-Vornle, +45-33-18 19 97
France: Dr. Daniel Kunth, +33-1-44 32 80 85
Germany: Dr. Jakob Staude, +49-6221-528229
Italy: Dr. Leopoldo Benacchio, +39-347-230 26 51
The Netherlands: Ms. Marieke Baan, +31-20-525 74 80
Portugal: Prof. Teresa Lago, +351-22-089 833
Spain: Dr. Miguel Mas-Hesse, +34918131196
Sweden: Dr. Jesper Sollerman, +46-8-55 37 85 54
Switzerland: Dr. Martin Steinacher, +41-31-324 23 82
United Kingdom: Mr. Peter Barratt, +44-1793-44 20 25
----------------------------------------------------------------------------
ESO Press Information is available on Receive email notification
the WWW at about important news from
http://www.eso.org/outreach/press-rel/ ESO - subscribe to the
ESO-NEWS Mailing List.
----------------------------------------------------------------------------
Copyright ESO Education & Public Relations Department
Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany
----------------------------------------------------------------------------
----------------------------------------------------------------------------
Text with all links and the photos are available on the ESO Website at URL:
http://www.eso.org/public/outreach/press-rel/pr-2007/pr-30-07.html
----------------------------------------------------------------------------
Contacts:
Jochen Greiner
MPI f. extraterrestrical Physics, Garching, Germany
Phone: +49-89-30000-3847
Michael Sterzik
ESO, Chile
Email: msterzik (at) eso.org
For Immediate Release: 6 July 2007
ESO Science Release 30/07
GROND Takes Off
First Light for Gamma-Ray Burst Chaser at La Silla
A new instrument has seen First Light at the ESO La Silla Observatory.
Equipping the 2.2-m MPI/ESO telescope, GROND takes images simultaneously in
seven colours. It will be mostly used to determine distances of gamma-ray
bursts.
Taking images in different filters simultaneously is important for the study
of many astrophysical sources, and in particular of variable sources, such
as close binaries or active galactic nuclei. But it is most crucial in the
follow-up of gamma-ray bursts. Gamma-ray bursts (GRBs) are short flashes of
energetic gamma-rays lasting from less than a second to several minutes.
They release a tremendous quantity of energy in this short time making them
the most powerful events since the Big Bang.
Gamma-ray bursts, which are invisible to our eyes, are discovered by
telescopes in space. After releasing their intense burst of high-energy
radiation, they become detectable for a fleeting moment in the optical and
in the near-infrared. This 'afterglow' fades very rapidly, making detailed
analysis possible for only a few hours after the gamma-ray detection. This
analysis is important in particular in order to determine the GRB's distance
and, hence, intrinsic brightness.
A first determination of the distance can be done by taking images through
different filters, using the so-called photometric redshift [1]. Because a
typical GRB afterglow becomes 15 times fainter after just 10 minutes, and
over 200 times fainter after an hour, it is important to observe the object
in as many filters as possible simultaneously.
"To make the determination of distance of far-away objects as accurate as
possible, we decided to use four different filters in the optical and three
different filters in the near-infrared," says Jochen Greiner, who led the
development of the GROND instrument. GROND stands for Gamma-Ray burst
Optical/Near-Infrared Detector.
GROND takes thus images of the same region of the sky in 7 different
filters. The field of view in the near-infrared is 10 times 10 arcminutes,
or 1/7th the area of the Full Moon. It is smaller in the visible, slightly
above 5 x 5 arcmin.
GROND is presently in its commissioning phase and its first science
demonstration has been achieved, showing that all technical systems work
properly. In particular, GROND observed a quasar located more than 12
billion light-years away.
As for many instruments specialising in the follow-up of gamma-ray bursts
(see e.g. ESO 17/07 and 26/07), GROND can also be activated with a Rapid
Response Mode (RRM): GRB alerts will be automatically fed into the system
thus minimising the delay between the gamma-ray burst detection by a
satellite and its observation by GROND.
"The implementation of the RRM at the 2.2-m telescope is done in exactly the
same way as for the VLT, and boosts ESO's leadership to offer observing
systems with ultra fast response time towards GRB follow-up," says Michael
Sterzik, Head of Science Operations Department at ESO La Silla.
A dedicated data analysis pipeline is also being tested which will provide
the distance of the burst a few minutes after the first observations.
"Ultimately, the goal is to trigger ESO's VLT to perform spectroscopy of the
source with fine-tuned settings, thereby maximising the scientific return of
GRB follow-up observations of the VLT," says Greiner.
GROND has been built by the Max-Planck Institute for Extraterrestrial
Physics in collaboration with the Thinger Landessternwarte Tautenburg.
Note
[1] The photometric redshift method makes it possible to judge the distance
to a remote celestial object (a galaxy, a quasar, a gamma-ray burst
afterglow) from its measured colours. It is based on the proportionality
between the distance and the velocity along the line of sight (Hubble's law)
that reflects the expansion of the Universe. The larger the distance of an
object is, the larger is its velocity and, due to the Doppler effect, the
spectral shift of its emission towards longer (redder) wavelengths. Thus,
the measured colour provides a rough indication of the distance.
National contacts for the media:
Belgium: Dr. Rodrigo Alvarez, +32-2-474 70 50
Czech Republic: Pavel Suchan, +420 267 103 040
Finland: Ms. Tiina Raivo, +358 9 7748 8369
Denmark: Dr. Michael Linden-Vornle, +45-33-18 19 97
France: Dr. Daniel Kunth, +33-1-44 32 80 85
Germany: Dr. Jakob Staude, +49-6221-528229
Italy: Dr. Leopoldo Benacchio, +39-347-230 26 51
The Netherlands: Ms. Marieke Baan, +31-20-525 74 80
Portugal: Prof. Teresa Lago, +351-22-089 833
Spain: Dr. Miguel Mas-Hesse, +34918131196
Sweden: Dr. Jesper Sollerman, +46-8-55 37 85 54
Switzerland: Dr. Martin Steinacher, +41-31-324 23 82
United Kingdom: Mr. Peter Barratt, +44-1793-44 20 25
----------------------------------------------------------------------------
ESO Press Information is available on Receive email notification
the WWW at about important news from
http://www.eso.org/outreach/press-rel/ ESO - subscribe to the
ESO-NEWS Mailing List.
----------------------------------------------------------------------------
Copyright ESO Education & Public Relations Department
Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany
----------------------------------------------------------------------------