eVLBI at Arecibo
Arun Venkataraman (on a phone-in)
&
Ganesan Rajagopalan
Arecibo Observatory
NAIC/ Cornell
US VLBI Technical Meeting,
Haystack, May 29 – 30, 2008
AO is an EXPReS partner
• Express Production Real-time e-VLBI Service (EXPReS,
www.expres-eu.org) is a three-year project funded by the
European Commission
• Goal is to create a real-time distributed astronomical
instrument of intercontinental dimensions. This electronic
Very Long Baseline Interferometer (e-VLBI) is achieved
using high-speed (up to 1 Gbps) communication
networks and connecting together some of the largest
and most sensitive radio telescopes on the planet.
• EXPReS is a collaboration of 19 radio astronomy
institutes and national research networks in 14 countries
and is coordinated by the Joint Institute for VLBI in
Europe (JIVE). Arecibo is the sole member of the
EXPReS consortium from the US.
US VLBI Technical Meeting,
Haystack, May 29 – 30, 2008
Connectivity enhancement since
the last meeting
• The gigabit connection between AO and UPR
was finally established in December 2007
• From Asynchronous Transfer Mode (ATM) 155Mbits/s to the 1-Gbits/s ethernet link; provided
by Centennial PR.
• Uplink to FIU became available only in March
2008
• With the new capability the AO can transfer data
out at up to 512-Mbits/s.
US VLBI Technical Meeting,
Haystack, May 29 – 30, 2008
Some constraints
• 512 Mbps is available only by prior
arrangement with UPR from midnight – 6
am
• Only 155 Mbps is guarantied at all times
via a dedicated link from AO to UPR
• Protocol used UDP and not TCP/IP. Jive
seems happy with UDP.
US VLBI Technical Meeting,
Haystack, May 29 – 30, 2008
Recent Success stories
• Press releases from JIVE on recent eVLBI
success.
• http://www.expreseu.org/TERENA08_science.html
– EXPReS conducts first real-time e-VLBI observation
with telescopes in Africa, Europe, North America and
South America
• http://www.expreseu.org/TERENA08_networking.html
– Networks create 11,000km real-time virtual telescope
US VLBI Technical Meeting,
Haystack, May 29 – 30, 2008
The recent additions of Arecibo (Puerto Rico), Effelsberg (Germany),
Hartebeesthoek (South Africa) and TIGO (Chile) telescopes to e VLBI
capabilities of the European VLBI Network means a tremendous
improvement in sensitivity for detecting the faintest cosmological
sources. Image: JIVE
US VLBI Technical Meeting,
Haystack, May 29 – 30, 2008
First-ever four-continent fringes
•
The first-ever simultaneous four-continent fringes were obtained.
The telescopes involved were;
–
–
–
–
North America: Arecibo
South America: TIGO, Concepcion, Chile
Africa: Hartebeesthoek, South Africa
Europe: Effelsberg (Germany), Westerbork (Netherlands), Medicina
(Italy) & Onsala (Sweden)
•
The Arecibo data rate was solid at the required 256 Mbps.
•
Also used as a demo at the annual meeting of TERENA (TransEuropean Research and Education Networking Association), a
forum to develop and share knowledge on Internet technology,
infrastructure and services to be used by the research and
education community.
US VLBI Technical Meeting,
Haystack, May 29 – 30, 2008
Plot showing throughput from all telescopes. Data was streamed
at 256 Mbps from five stations and 64 Mbps from two stations for
a total of 1.44 Gbps. Image: JIVE
US VLBI Technical Meeting,
Haystack, May 29 – 30, 2008
Fringes from the 4 continent run on
May 22, 2008
US VLBI Technical Meeting,
Haystack, May 29 – 30, 2008
What next?
1Gbps is the current "state of the art" for
AO given bandwidth limitations to the
island of PR. 10Gbps will probably take a
long time to come..
Try and negotiate to open a longer time
window from the current 12 – 6am
schedule
US VLBI Technical Meeting,
Haystack, May 29 – 30, 2008