DiFX at KASI

Jongsoo Kim and Taehyun Jung Korea Astronomy and Space Science Institute

http://jskim.kasi.re.kr/difx

Yonsei Ulsan Tamna

Korean VLBI Network

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3 × 21m Antennas Maximum Baseline : 480 km 4 Channel (22/43/86/129 GHz), LCP/RCP Simultaneous Observing System Multi-Frequency Phase Referencing Correlators: Daejeon(HW), DiFX(SW)

22/43/86/129 GHz Receivers

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Performance tests

East Sea

Korea : KVN antenna Yonsei (Seoul), Ulsan, Tanma (Jeju)Japan : VERA antenna Mizusawa, Ishigaki, Iriki,Ogasawara

1.4 mas@22GHz0.7 mas@43GHz

Improved image (22GHz) of M87 by KVN+VERA

Total flux : 1.18 JyPeak flux : 1.04 Jy/beamImage rms : 4 mJy/beam

Total flux : 1.55 JyPeak flux : 1.08 Jy/beamImage rms : 2 mJy/beam

Daejeon Correlator@KJCC

DiFX system• one difx server: 16

cores (E5-2690), 64GB memory, CentOS 6.3

• Storage: 120TB+80TB RAID 6, direct attached to server

• Mark5 unit: Mark 5B+(SDK8.3), 5C(SDK9.2), direct connection to server with 1GE

Operations• Just started normal operations for

KVN only following standard proce-dure– Fuse or mk5cp – vex2difx– calcif2–mpifxcorr– difx2mark4, fourfit– difx2fits

Example

Performance• mk5cp: ~ 0.51 Gbit/sec• mpifxcorr with 16 cores: ~24 hours

correlation time for a 12 hour 1Gbps observation with 3 KVN antennas

Future Plan• “native” Mark5 correlation• infiniband upgrade• Correlation for KVN+VERA – Require copy of VERA 2000 tape to Mark

5 diskpack or storage