VLBI/eVLBI with the 305-m VLBI/eVLBI with the 305-m Arecibo Radio TelescopeArecibo Radio Telescope

Chris SalterChris SalterTapasi GhoshTapasi Ghosh

Emmanuel MomjianEmmanuel MomjianArun VenkataramanArun Venkataraman

Jon HagenJon Hagen

TimelineTimeline

The post-upgrade 305 m Arecibo radio telescope became a part of the VLBI network in late 1990s for the HALCA mission of the Japanese VSOP project (S2 recorder).

In 2001, Arecibo acquired its hybrid tape-based VLBA-Mark IV (VLBA4) recording system.

In 2004, the Observatory procured its Mark 5A disk-based recording system, enabling the largest telescope in the world to become electronically connected to other radio telescopes in the world in real time via eVLBI observations.

First-ever Transatlantic eVLBIFirst-ever Transatlantic eVLBIThe first eVLBI test observations took place on Sept. 10, 2004. The source, 0528+134, was observed at 1.6 GHz using an array consisting of Arecibo, Cambridge (UK), Torun (Poland) and Westerbork (Netherlands).

The observations resulted in the FIRST transatlantic eVLBI image. Arecibo-Torun is believed to be the LONGEST real-time interferometer baseline yet created.

(Top) The 1.6 GHz continuum image of 0528+134 at 80 mas resolution.

(Below) Visibility amplitude and phase plots between Arecibo and other EVN stations.

Science Demo: 3C 166Science Demo: 3C 166

The first scientific eVLBI observations took place on September 22, 2004. Arecibo, Torun, Westerbork, and Onsala (Sweden) participated. The ULIRG IRAS 06487+2208 and radio galaxy, 3C166, were observed.

1.4 GHz continuum image of 3C166 at 32 x 19 mas resolution. The peak flux density is 318 mJy beam-1. The contour levels are at 4, 8, 16, 32, 64, 128 times 1 (1.8 mJy beam-1).

Data Path to JIVEData Path to JIVE

PRISANET (PR) of the Arecibo Obs./UPR.

AMPATH (US) of Florida Intl. Univ.

Abilene (US) of Internet 2.

SURFnet (NL) of SURFnet BV.

Data rate: 32 Mbps sustained 80 Mbps.

DAR/Formatter

MK5

JIVE

in2net

eVLBIeVLBI

AdvantagesAdvantages No need for disks/tapes.No need for disks/tapes. Speed at which results are Speed at which results are

obtained.obtained. Target of Opportunity.Target of Opportunity. Real-time monitor of Real-time monitor of

Station reliability.Station reliability. Reduced manpower at Reduced manpower at

VLBI station.VLBI station. No longer observing blind.No longer observing blind.

DisadvantagesDisadvantages Fear of single point failure.Fear of single point failure. No multi-pass correlation.No multi-pass correlation. Loss of low bandwidth Loss of low bandwidth

stations.stations. Presently lower max bit rate Presently lower max bit rate

than disks.than disks. Capital and recurring costs Capital and recurring costs

of links.of links.

Current & Near Future ActivitiesCurrent & Near Future Activities

From Sept. 2004, disk-based Mark-5 operations with From Sept. 2004, disk-based Mark-5 operations with EVN. EVN.

From Dec. 2004, regular observing as part of the High From Dec. 2004, regular observing as part of the High Sensitivity Array (HSA; VLBA,Y27, GBT, EB, AR).Sensitivity Array (HSA; VLBA,Y27, GBT, EB, AR).

February 27, 2005: First scientific 1 Gbps disk February 27, 2005: First scientific 1 Gbps disk recording was made. recording was made.

March 11, 2005: Continuum Science Demo. Up to 128 March 11, 2005: Continuum Science Demo. Up to 128 Mbps for 4 hours total.Mbps for 4 hours total.

Mid Summer 2005: Ultra wide-band VLBI test Mid Summer 2005: Ultra wide-band VLBI test (Haystack initiative) with 2 Gbps disk recording.(Haystack initiative) with 2 Gbps disk recording.