Software Correlation at JIVE & Real-time e-VLBI in the EVN
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Transcript of Software Correlation at JIVE & Real-time e-VLBI in the EVN
Software Correlation at JIVE & Real-time e-VLBI in the EVN
Operations and PI Interaction Astronomy Gains from SFXC Real-time e-EVN status Proposal Tool: recent modifications
Bob Campbell, JIVE
EVN Symposium #12, Cagliari . . . . . . . . . . . . . . . . . . . . . . . . . . 2456940.576 (9/x/2014)
Ops Flowchart (≤ Correlation)
MkIV SFXC: Astronomy Gains
Nsta limited only by available input devices (was 16)
Arbitrary total bit-rate & BWSB (was 1 Gbps & 16 MHz)
~arbitrarily large number of frequency points (was 2048)
Velocity resolution improvements w/o cont. sensitivity penalty
Selectable spectral windowing (Hanning, Hamming, cosine, tophat)
~arbitrarily small integration times (was ¼s)
Large Nfrq & small tint together wider-field mapping
Improvements in correlated data Pure station-based fringe rotation to center of earth
Decoupled correlation/delay-tracking FFT sizes
Consistent cross-polarization handling
MkIV SFXC: as seen by userNsta
2 . Nsb . Npol . Nfrq ≤ 131072 . R
Nsta = (4,8,12,16); Npol = (1,2,4); Nchan ≤ 16; Nfrqmax = 2048
Recirculation: R ≤ 16MHz/BWsb ; Nfrqmax still 2048
(if 8 MHz SB) 9—16 Sta 1 SB 2 Pol 512 Frq (R = 2)
(if 2 MHz SB) 9—16 Sta 1 SB 2 Pol 2048 Frq (R = 8)
Maximal velocity spacings (Nfrq=2048, Δv in [m/s])
Specify desired velocity spacing & required continuum sensitivity (set BWsb, then Nfrq)
BWsb [MHz] Δ [Hz] Δ1420 Δ1665 Δ6668 Δ22235
16 7813 1651 1408 351 1052 977 206 176 44 13
MkIV
SFXC
SFXC: Completely New Astronomy
Multiple output phase centers within a wider field
Pulsar Gating/Binning Both incoherent and (new) coherent de-dispersion
Space VLBI (cf. Duev poster, Molera talk) Near-field correlation (solar-system, GNSS targets) Orbiting antenna (RadioAstron)
“Phasing up” the EVN
Mixed-bandwidth, mismatched-sideband correlation (enables inclusion of wider set of heterogeneous back-
ends)
SFXC: Pulsar Gating/Binning Gating = arbitrary start/stop interval within PSR period
Binning = arbitrary number of bins within the gate Each bin separate correlation / output IDI-FITS file
0329+541.4 GHz
Pulse profile (1 gate, 100 bins)
Sieber et al 1974
SFXC: Wide-Field Mapping Essentially unlimited max-Nfrq, min-tint: can map area
on the sky ~single-dish beam w/ minimal smearing Price = huge output data sets (record soon ~5.5TB FITS files)
Multiple phase-center correlation: outputs only subsets
of the full area (user exps. up to ~200-300 phs.ctrs)
Typical 1st-correlation Nfrq ~16k; tint ~ 4—15 msFurther processing-factor “penalty” small
Example validation run: same source correlated at two positions 1.4’ apart; |Δφ|Ef-Hh = 0.3o pk-to-pk.
Ef-Hh
6cm
SFXC: “Phasing up” the EVN Most applicable to pulsar observations
Correlate phase-reference obs. “normally”
Obtain fringe solutions for as many sources as
possible
Apply fringe solutions back into model for each station
Re-correlate with new model
Output as single (CoE) station in PSR-FITS
a.k.a. filter-bank data
run through PRESTO to fit for pulsar P, Pdot, etc.
SFXC: “Phasing up” the EVN
ms-PSR M15A
in Glob.Clust.
M15
Ar,Ef,Gb,Jb,
On,Tr,Wb
~100 min
Real-time e-EVN Science Proposal-driven e-EVN science observations
1st observation = 16 Mar 2006 (6 stations at 128 Mb/s) Nowadays, a network of 9-10 stations at Gbps is routine Typically ~25-30% of EVN observing time e-EVN network still misses KVAZAR stations & Urumqi
Evolution of e-EVN procedures ~monthly 24-hour runs (+4hr prelim. test) on fixed dates
e-EVN also in regular disk sessions (longer runs)
Proposals now within standard proposal-submission cycles Proposal Class for “triggered” observations (10 since Apr’08) Proposal Class for “short” observations (35 since May’08) Any EVN or GLOBAL proposal may contain e-VLBI observation(s)
Target of Opportunity Observations (49 since Sep’07)
The EVN / e-EVN
e-EVN Operational Bandwidth
Station ConnectionEffelsberg 1024 Mbps (4x in tests)
Westerbork 1024 Mbps
Jodrell Bank 1024 Mbps
Medicina 1024 Mbps
Noto 1024 Mbps
Onsala 1024 Mbps (4x in tests)
Torun 1024 Mbps
Yebes 1024 Mbps (4x in tests)
Sheshan 1024 Mbps
HartRAO 1024 Mbps
Arecibo 512 Mbps
Metsahovi 1024 Mbps
ATNF: 1 Gbps (At,Mp,Pa)
SRT expected soon
Robledo to start tests
Irbene connection in place
Observing Request Tab (Array)
e-EVN now per observation; controls array, correlation parameter choices
Observing Request Tab (Changes to Array Selection)
New category: “special” EVN stations (per band)
New category-specific help
Observing Request Tab (New Help for Array Selection )
Observing Request Tab (Out-of-Session Obs)
Any observation can contain one or more out-of-session segments; new dialog box for describing criteria for
minimally-required array
Obs. Rqst Tab (Format & Correlation)
Some impossibilities pass undetected
Updated for SFXC
capabilities; e-EVN
selection
Solar Activity
Remaining in solar-medium
range since the
previous EVN symp.
Moderate uptick near the start of
2014
Predictions for this Solar Cycle
Sep’10 & ’12 predictions: solar max. in mid-2013 at
140 sfu.
Sep’14 pred: solar max.
just passed.
ref: Space Weather
Prediction Center, via
www.sec.noaa.gov
Summary Pre-/Post-correlation PI Support
Help available — don’t have to wait until last minute Archive: FITS, pipeline, standard plots, feedback RadioNet3 EVN Trans-National Access program
EVN Software Correlator at JIVE (SFXC) Astronomical applications beyond the MkIV correlator More straightforward capacity limitations
e-VLBI now standard/indispensable facet of EVN Proposal Tool “Observation Request Tab”
continually tweaked to reflect new capabilities