Arecibo’s Existing VLBI Capability Arecibo’s Existing VLBI Capability DAR - VLBA4 MK5A Max 1-GHz IF The Big Dish (Gain~10k/Jy,SEFD~3-5 Jy)‏ Correlator Internet FedEx Receivers Max. IF bandwidth/Rx # of BBCs & Max ∆ν/BBC Total single-pol RF Bandwidth Total data rate 327, L, S,S-High, C, C-High, X.05,.5 (#1,2 Rxs), 1 GHz 2 x 8, 16 MHz 256 MHz (max)‏1024 Mbps Co-Observing Networks: 1.VLBA + Ar & the HSA (HSA, includes the phased-VLA, GBT, EF)‏ 2. European VLBI Network + Ar 3. Global - Network 4. eVLBI (Real-time VLBI via internet as yet with EVN only)‏

A continuum observation, =18-cm, data-rate=512 Mbps, i.e. 128 MHz of RF bandwidth, dual-polarization,  = 120 minutes on source: Arecibo’s Contribution to the Arrays A spectral-line observation, =18-cm, 64 channels over 1-MHz, 2 pol, 120 min mJy/beam/ch mJy/beam/ch VLBA+Y27+Gb+ARVLBA+Y27+GBVLBAEVN+AREVN HSA (VLBA+Y27+EF+GB+Ar)‏ -Ar 1σ Image noise = 3.3 μJy/beam 7.1 μJy/beam EVN+Ar -Ar 1σ Image noise = 3.8 μJy/beam 9 μJy/beam Global (EVN+VLBA+Y27+Gb)+Ar -Ar 1σ Image noise = 2.5 μJy/beam 4.7 μJy/beam

eVLBI : Test run at 512-Mbit/sec First trans-Atlantic eVLBI fringes at a data rate of 512 Mbits/sec on 9 September Data arriving at JIVE Arecibo Fringes with EVN Telescopes  PRISANET (PR) of the Arecibo Obs./UPR.  AMPATH (US) of Florida Intl. Univ.  Abilene (US) of Internet 2.  SURFnet (NL) of SURFnet BV. Arecibo has a dedicated 200 Mbit/sec, Internet-2 connection. In addition, for eVLBI run it borrows ~300 Mbps from the University of PR’s commodity internet, allowing data to be transferred at a rate of 512 Mbps. Data leaving Arecibo

Scientific Results: Compact Cores in radio-quiet Seyfert galaxies: Giroletti et al. “These are observations of parsec scale radio cores in Seyfert galaxies at 1.6 and 5 GHz. These galaxies are thought to be radio quiet, but it seems that the presence of a compact radio core is actually quite ubiquitous when the sources are observed with the proper sensitivity. Arecibo, of course, is essential for this goal, as it provides great sensitivity and long baselines (=high angular resolution) at the same time”.

Scientific Results contd. Scientific Results contd.: Supernovae & AGN(?) in the Western Nucleus of Arp220 - Conway, Lonsdale, et al.

eVLBI : Monitoring the Jet in M87 during a Tev Outburst (Giroletti et.al.) Optical HST image of M87Jet & a knot of hot gas, HST-1, seen to be brightening in 2005 Superluminal motion in HST-1 during a TeV outburst The inner Jet (collimated for ~200 mas) and the weaker complex, HST-1 (at 800 mas from the core), imaged at 5-GHz, with resolution 7 x 3 mas, and map noise of 0.12 mJy/beam. Nov19 Jan27 Feb10 Nov1 9 Mar02 Mar30

VLBI Sensitivity Upgrade Increasing the US VLBI data recording rate to at least 4 Gbps by 2010: Goal set by the Taylor Committee. Increasing the Bandwidth : Arecibo is in the process of: (a) replacing the analog DAR with a Digital Back End (RDBE). - The Digital Down Conversion (DDC) personality consists of four independently tunable sub-bands per IF, with bandwidths MHz and 1–8 bit output sample precision. There is also a Polyphase Filter Bank (PFB) personality with 32 sub-bands spanning the 500-MHz wide IF. Output is via 10-Gbit Ethernet transporting individual sub-band packet streams. Maximum data rate of 8 Gbps. Arecibo has ordered two RDEs from NRAO. (b) upgrading to the Mark5C recording system developed by Haystack & Conduant Corp. Control software is still under development at Haystack. Arecibo has purchased and received two Mark5C units.

Increasing the Integration Time VLBI is severely limited by ionospheric and tropospheric phase fluctuations, leading to a loss of coherence. As a solution, many VLBI observations these days are taken in “Phase referenced” mode. The most commonly used form of this mode needs slewing between the target and a strong, compact calibration source (generally within a few degrees of the target) every 3-4 min. Phase, derived from the calibrator, is then applied to the target data. The low slew rate of 305-m antenna can lead to over 50% loss of integration time in phase-referenced VLBI.

The 12-m Antenna Problem for the Big Dish - The low slew rate of 305-m antenna can lead to over 50% loss of integration time in phase-referenced VLBI. Solution - A nearby antenna tracks the calibrator continually, while the 305-m tracks just the target, with occasional visits to the calibrator. Phase derived from the small antenna will be applied to the 305-m data under the assumption that the same ionospheric correction applies to both data sets. How Big? - To provide a baseline sensitivity within a factor of 2 of an intra-VLBA baseline, the small antenna should be at least about 12-m. With this, sources brighter than ~110 mJy can be used as phase referencing calibrators. Freq. Coverage - L, S, C & X bands are required for astronomy; S/X bands will be initially available. Eventually, 1 – 12 GHz will be covered. Single Dish Uses - Education and research applications with Puerto-Rican universities and other educational establishments Other Uses - (a) Possible participation in regular VLBA operations, and/or (b) VLBI2010; (c) The L-band, voltage beamwidth of a 12-m antenna contains all 7 ALFA beams, opening up the possibility of multi-beam interferometric applications..

Operational block diagram (evolving)

The 12-m Site The AUT Patriot 12-m Antenna Timeline : 1. June 2010 – construction complete 2. Acceptance test using temporary backends, integrate RDBE+MK5C 3. Jan 2011 – test observations in VLBI mode at S/X 4. Wide band receivers by 2012 Science Areas: Astronomical VLBI with 305-m, Stand-alone VLBI for astronomy, astrometry & Geodesy, Single dish uses, and UG-teaching aid