Recent Activities of the KVN
Do-Young Byun and KVN Group

Korea Astronomy and Space science
Institute2014. Sep. 24
VERA User’s Meeting, Mitaka

KVN YonseiObservatory

KVN Ulsan
Observatory

θHBPW ~ 6 mas @ 22
~ 1 mas @ 129

KVN Tamna
Observatory

Multi-Frequency Receiving System• Simultaneous Multi-frequency Observation– @ 22/43/86/129GHz– Multi-Frequency Phase Referencing enable us to overcome
limitation of mm-VLBI• Rapid phase variation due to water vapor in troposphere• Typical coherence time scale ~30sec @ 100GHz22GHz43GHz129GHz86GHz

Source : 1308+326
Phase Referencing(前)(後)Weak Source Detection
at High Frequency by MultiFrequency Phase Referencing(Taehyun Jung+ in prep)

Ф129, referenced = Ф129,m – Ф22,m x (𝝂𝟏𝟐𝟗)
𝝂𝟐𝟐• Flux1308+326 : 300~420 mJy
NRAO512 : 160~250 mJy
The FIRST detections at 129GHz.
Successful evaluation of MFPR.

Visibility Phase @ 129GHz[-180° ~ 180°]• Short term variation of visibility
phase at 22GHz traces
tropospheric phase variation• Trop. phase variation ∝ νTN - USTN- YSUS - YS

1 hour

1 hourSource Frequency Phase Referencing
for AGN core shift• Maria J. Rioja+, 2014, AJ accepted• SFPR– Multifreq Phase Transfer + Ionospheric / instrumental phasecalibration using bright calibrator– Relative astrometric position at high freq wrt low freq

• KVN Simultaneous 22/43GHz / VLBA Frequency Switching– 0854+213 w/ reference OJ287 (1.2deg away)• Core shift accuracy of KVN ~ 40 μas @ 43GHz– Consistent with VLBA within 1σ-error• Structure blending effectshould be considered• Flux recovery ~ 94%using KVN SFPR

Source Frequency Phase Referencingof Stellar Maser Lines• Richard Dodson + , 2014, PASJ accepted• H2O and 43GHz SiO (v=1,v=2) of R LMi– Reference : 4C39.25 ~ 6 deg away
• H2O position accuracy< 3x5 mas• mas-level astrometric alignment of SiO maser wrt H2Omaser

KVN Key Science Projects• Early Phase Key Science Projects will be launched
2015– Total KSP time ~1000 hr/yr for 3 years• Evolved Star– Simultaneous Monitoring of KVN 4 bands toward EvolvedStars (H2O & SiO masers using SFPR)• AGN– Origin of Gamma-ray flares in AGN (iMOGABA)– MF AGN Survey– MF Polarization Survey• Star Forming Region– 22/44(/95GHz) maser study– 22/44GHz maser polarization

Common Use of KVN and KaVA
• KVN

– 2013B semester : Open to Korean community– 2014A/B semester : Open to East Asian community– 2015A semester : Open to East Asian community• Deadline: early Nov. (http://kvn.kasi.re.kr)• Open Use Time : ~300h• 22, 43, 86GHz : normal / 129GHz : risk shared– 2015B semester : Open to World community• KVN+VERA (KaVA) Common Use– 2015A semester : Open to East Asian community• Deadline: early Nov.
• Open Use Time : ~ 250h
• single frequency observations at 22GHz or 43GHz• Risk shared, Imaging only

Upgrade Activities• 8Gbps operation– 2Gbps x 4 streams(Mark5B : 1Gbps recording)– Mark6 (16Gbps max)
+ Fila10G(VSI – Opticalconverter)– First fringe test in next week

• Network Speed Upgrade– 10Gbps to Yonsei– 5Gbps to Ulsan, Tamna

Quasi Optics for K/Q SimultaneousObservation at VERA Mizusawa• Quasi opitcs for K/Q simultaneous observation atMizusawa was installed on 5 Dec 2013.
(Dr. Han, Mr. Kang (KASI), Dr. Kameya)

First KVN-MIZ K/Q Simultaneous Fringes!!
observation : 2014-06-16
correlation : KJCC

Source : OJ287

K-bandQ-bandSummary• KVN is in steady operation phase and there will
be common use call for 2015.
• KVN is producing early science results– Weak source detection using MFPR capability– SFPR techniques applied to KVN observations• Early Phase KVN Key Science will start from2015• 8Gpbs mode will be available from 2015