Japanese VLBI programs, East Asian VLBI Network and Space VLBI;VSOP-2 H.Kobayashi(NAOJ) 2011, Jan., 27 Future of VLBA

First VLBI experiments between Korea and Japan( ) VY CMa VY CMa SiO(J=2->1) 86 GHz SiO(J=2->1) 86 GHz Shibata et al, 2003

VSOP ( ) HALCA(8m), Launched in 1997, Elliptical Orbit with the apogee 21,000km & perigee 560km HALCA(8m), Launched in 1997, Elliptical Orbit with the apogee 21,000km & perigee 560km 18cm(1.6GHz), 6cm(5GHz) & 13mm(22GHz) 18cm(1.6GHz), 6cm(5GHz) & 13mm(22GHz) Shanghai,Urumqi,Usuda,Kashima stations were involved as ground stations Shanghai,Urumqi,Usuda,Kashima stations were involved as ground stations

East Asian VLBI Network array

Current working VLBI stations in Eastern Asia Japan(13) Japan(13) VERA(4), Kashima, Tsukuba, Yamaguchi, Nobeyama, Usuda, Tomakomai, Gifu, Uchinoura, Takahagi, HitachiVERA(4), Kashima, Tsukuba, Yamaguchi, Nobeyama, Usuda, Tomakomai, Gifu, Uchinoura, Takahagi, Hitachi Korea(3) Korea(3) KVN (3) Yonsei, Ulsan, TamnaKVN (3) Yonsei, Ulsan, Tamna China(4) China(4) Shanghai, Urumqi, Beijin, KummingShanghai, Urumqi, Beijin, Kumming Shanghai 65mShanghai 65m

Feature of East Asia VLBI network Largest number of VLBI stations Largest number of VLBI stations 8GHz 13 stations8GHz 13 stations 22GHz 19 stations22GHz 19 stations 43GHz 8 stations43GHz 8 stations S/X geodesy 13 stationsS/X geodesy 13 stations Phase referencing Phase referencing VERA 2 beam systemVERA 2 beam system KVN multi-frequency + fast noddingKVN multi-frequency + fast nodding Good UV coverage Good UV coverage Minimum baseline length ; 50 kmMinimum baseline length ; 50 km Maximum baseline length ; 5000 kmMaximum baseline length ; 5000 km

Observation features Phase referencing observations Phase referencing observations VERA 2 beamVERA 2 beam KVN multi-frequencyKVN multi-frequency NoddingNodding -> high sensitivity observations for low Tb objects (RQQ, SNR, Galactic objects) -> high sensitivity observations for low Tb objects (RQQ, SNR, Galactic objects) ->astrometry for maser sources ->astrometry for maser sources (H 2 O,SiO,CH 3 OH..) (H 2 O,SiO,CH 3 OH..) High dynamic range observations High dynamic range observations Ground array of VSOP-2 Ground array of VSOP-2

Total effective aperture and baseline length VLBI arrayEAVNVLBAEVN No. of Stations ２０１０１２ Baseline length 5,000km8,000km2,000km- 8,000km Effective Aperture ８ GH ｚ 9,000m 2 3,700m 2 9,800m 2 Effective Aperture 22GHz 4,900m 2 3,200m 2 4,900m 2 Effective Aperture 43GHz 1,400m 2 2,900m 2 1,800m 2

Science (Dec. 5,2008)

Current status of astrometry with VERA

Kaguya (RISE) lunar mission Precise gravity field of moon -> cooling time differences between farside and nearside

Japanese VLBI Network (JVN) Collaboration Collaboration NAOJ (VERA)NAOJ (VERA) Hokkaido, Ibaraki, Tsukuba, Gifu, Osaka-Pref, Yamaguchi, Kagoshima universityHokkaido, Ibaraki, Tsukuba, Gifu, Osaka-Pref, Yamaguchi, Kagoshima university JAXA, NICT, GSIJAXA, NICT, GSI 13 telescopes (11m ~ 64m)13 telescopes (11m ~ 64m) Purpose Purpose A new, characteristic VLBI arrayA new, characteristic VLBI array A Base of East-Asian VLBIA Base of East-Asian VLBI Progress Progress Started in 2004Started in 2004 Steady Observation in 2005Steady Observation in 2005 First Paper published in 2006First Paper published in 2006 Observing time ~200 hr/yr Observing time ~200 hr/yr EAVN test observationEAVN test observation

Simultaneous Multi-Frequency Obs. - Phase Compensation, mm-VLBI Constructions of three stations were completed on Dec !

* 86, 129 GHz Receivers will be installed. Prototype 43 GHz Receiver Receiver

First fringe between Seoul and

Seoul VLBI correlator center Opened on May 13 th, Gbps x 16 station Largest VLBI correlator

VERA/Tape terminal Korea/China (Mark-5b) VERA/Disk (VOA) Optical fiber (VSI-E) ＶＬＢ Ｉ data server Wideband correlator 8Gbps 16 stations Data processing and archive Operation System New Correlator at Seoul -Joint development with Korea and Japan – Software correlator 1Gbpsx4 stations

Schedule ２０１０ ２０１０ Test Observations with VERA+KVNTest Observations with VERA+KVN Start of science observations with Japan (VERA,JVN) /Korea (KVN), and Japan(JVN)/China(CVN).Start of science observations with Japan (VERA,JVN) /Korea (KVN), and Japan(JVN)/China(CVN) Start of science observations with Japan, Korea and ChinaStart of science observations with Japan, Korea and China

Target Life Time is 3 years. Dual 8, 22, 43 GHz Phase-referencing capability Switching Maneuver 10 cm Orbit Determination 9.3 m Antenna with high surface accuracy (0.4mm rms) precision pointing (0.005deg) 1 Gbps Data Downlink ASTRO-G Mission

Cancellation of Astro-G PDR PDR Uncertainty of deployment antenna repeatabilityUncertainty of deployment antenna repeatability Problems of surface accuracy (thermal conditions, radiation conditions) Problems of surface accuracy (thermal conditions, radiation conditions) Tiger team activity Tiger team activity Only 1mm rms is achievable.Only 1mm rms is achievable. Cost will overrun more than 50% of initial cost.Cost will overrun more than 50% of initial cost ISAS Science council recommended the cancellation ISAS Science council recommended the cancellation ISAS advisory council also recommended it ISAS advisory council also recommended it.

Conclusion East Asian VLBI Network is organizing with Japan, Korea and China. East Asian VLBI Network is organizing with Japan, Korea and China. Science targets are precise astrometry and high sensitivity imaging with high spatial resolution. Science targets are precise astrometry and high sensitivity imaging with high spatial resolution. From 2012, full array observation with Japan, Korea, and China is expected. From 2012, full array observation with Japan, Korea, and China is expected. VSOP-2 will be cancelled. VSOP-2 will be cancelled.