WAJIMA, Kiyoaki ( 輪 島 清 昭, KASI)

Transcription

1 The East Asian VLBI Network: Current Status and Action Plan Contents Overview of EAVN Expected Specifications, Current Activities Results and Problems of Fringe Test Observations Action Plan and Timeline Summary WAJIMA, Kiyoaki ( 輪 島 清 昭, KASI) (on behalf of the EAVN Tiger Team) 2015 年 7 月 8 日 东 亚 VLBI 会 议

2 The East Asian VLBI Network (EAVN) In 2005, East Asian Core Observatories Association (EACOA) was established and several WGs were arranged under EACOA, one of which is East Asian VLBI Consortium. At the KaVA Science WG meeting held on June 2013 at Jeju Island, a small task force, the EAVN Tiger Team, was organized. To promote VLBI test observations To proceed data reduction of test observations To clarify the problems for future regular operation and open use A group photo of the EAVN Tiger Team Meeting held on 29 July 2014 at Shanghai Astronomical Observatory. 2/16

3 The EAVN Tiger Team China (7) SHAO (Shanghai): TaoAN ( 安 涛 ), Willem A. BAAN, WuJIANG ( 江 悟 ), Bo XIA ( 夏 博 ) XAO (Ürümqi, Xinjiang):MingZHANG ( 张 明 ) YAO (Kunming, Yunnan):LongfeiHAO ( 郝 龙 飞 ), Min WANG ( 汪 敏 ) Japan (5) NAOJ: NoriyukiKAWAGUCHI ( 川 口 則 幸 ), Hideyuki KOBAYASHI ( 小 林 秀 行 ), Yuanwei WU ( 吴 元 伟 ) Toyo University: Yoshiaki HAGIWARA ( 萩 原 喜 昭,Chair) Yamaguchi University:KentaFUJISAWA ( 藤 澤 健 太 ) Korea (5) KASI: TaehyunJUNG ( 鄭 太 現 ), Jongsoo KIM ( 金 鍾 秀 ), Se Jin OH ( 吳 世 珍 ), Duk Gyoo ROH ( 盧 德 圭 ), Kiyoaki WAJIMA ( 輪 島 清 昭, Secretary) 3/16

4 EAVN: Specifications Number of (potential) telescopes:21 Korea: 4, China: 5, Japan: 12 (Possible) frequency coverage: 6.7GHz (12 stations), 8GHz(16), 22 GHz (18), 43 GHz (10) (2, 86, 129 GHz) (Expected) angular resolution: 1.5 mas (8 GHz; Ogasawara Nanshan (Urumqi)) 0.6 mas (22 GHz; Ogasawara Nanshan) 0.7mas(43GHz;Ogasawara Tianma(Shanghai)) (Expected) recording rate: 1 Gbps (= 256 MHz BW) (Currently used) correlator: KJCC (Korea): KJJVC and DiFX SHAO (China): DiFX

5 Current Activities of the EAVN Tiger Team Execution of fringetests Eight time fringe tests at 8/22 GHz Correlation and data analyses for performance evaluation Comparison of correlation results between SHAO DiFX/KJJVC Thrashing out existing problems for future EAVN open use Tiger team regular meeting (once or twice per month; via Skype) Face to face meeting (once per year; 1st face to face meeting was held on 2014 July 29 at SHAO) 5/16

6 EAVN: Recent Updates SHAO DiFX Refer to Jiang san s presentation (July 9 AM) System upgrade at Tian Ma 65 m Refer to Shen san s presentation (July 8 AM) Telescope renovation at Urumqi Main reflector 25 m 26 m Test observations will start from this autumn 6/16

7 EAVN: Test Observations Fringe test status 8 times to date: 2013 (2), 2014 (5), 2015 (1) Stations participated in: 4 (2014 Sep) 11 (2013 Sep), 16 stations in total (CN: 4, KR: 4, JP: 8) Observing frequency: 8and22GHz Observing mode: 256 MHz bandwidth (16 MHz 16 ch), sampling rate of 1 Gbps Polarization: RHCP (8 GHz), LHCP (22 GHz) Correlator: KJJVC at KASI,and DiFX at KASI/SHAO 7/16

8 Observation and Data Flow KVN Mark 5B Disk Pack/ 1 min FTP 1 min FTP CVN Mark 5B Correlator VERA OCTADISK KJCC (KJJVC/DiFX) SHAO (DiFX) JVN OCTADISK Digital BBC Data transfer via optical fiber Mitaka 8/16

9 Results of Fringe Tests 8th fringe test on 2015 February 12 at 8 GHz KVN Ulsan, Kunming, Sheshan, Yamaguchi, Tsukuba Correlator: SHAO DiFX Source: 3C 454.3, integration time: 1 minute Fringes were successfully detected for all baselines except Yamaguchi. Kunming Sheshan Kunming Ulsan Multiband delay (top yellow) and delay rate (top blue), single band delay (bottom left), averaged cross power spectrum (bottom right); amplitude (red) and 8 July phase 2015 (blue). 东 亚 VLBI 会 议 9/16

10 Results of Fringe Tests LULULULULULULULU 8th fringe test on 2015 February 12 at 8 GHz Ulsan Shanghai Tsukuba Shanghai Kunming Shanghai Ulsan Tsukuba Ulsan Kunming Tsukuba Kunming Correlator: KJJVC Red: inter CVN/JP KR baselines Yellow: trans CVN baselines LSB channels (odd IF) have 180 deg phase offset with respect to USB channels (even IF) Phase slope can be seen in some of IFs 10/16

11 Results of Fringe Tests 7th fringe test on 2014 November 11 at 22 GHz Fringes were detected for all baselines (source: W49N) Comparison of correlation results (left: SHAO DiFX, right: KJJVC) 16/20

12 Problems to be Solved Different bit assignment between CVN and KVN/JVN VEX file format of VERA, which differs from CVN/KVN Preparing a web based interface to upload station logs, T sys files, and operator reports Sharing the current web based system of KaVA to avoid duplication of effort for development, and to consider convenience for operators Media shipping time from China, Japan to KJCC FTP data transfer 12/16

13 Main Action Items for Future Open Use Further fringe tests and imaging tests Performance evaluation of the array Scheduling issues Preparation of web based observation feedback to upload station logs, T sys files, and operator reports Sharing the current web based system of KaVA to avoid duplication of effort for development, and to consider convenience for operators Study of possible science cases Extension of the current KaVA activity to EAVN? 13/16

14 Proposed Timeline Year Actions 5 time fringe tests done FTP data transfer test Further fringe tests Imaging tests, performance evaluation Imaging tests Science commissioning observations Fringe tests at 43 GHz (Early or late 2017) Risk shared open use at 6.7/8/22 GHz Performance evaluation at 43 GHz Frequency 8, 22 GHz 6.7, 8, 22 GHz 6.7, 8, 22, 43 GHz 6.7, 8, 22, 43 GHz Purposes Fringe detection from some telescopes in EAVN Evaluation of array performance and imaging capability Evaluation of array performance and array operation commissioning Performance evaluation at 43 GHz Initial scientific outputs from EAVN Confirmation of performance at 43 GHz 14/16

15 Small Face to Face Meeting Small Face to Face Meeting of the EAVN Tiger Team When? July 8 (today), 12:45 Where? Meeting room No.3 Main topic? Confirmation of action items for future open use Plan for test observations in the second half of 2015 Roadmap for routine operation 15/16

16 Summary The EAVN Tiger Team has been organized and is carrying out various tasks to evaluate performance and to clarify the problems for future regular operation and open use. We have carried out eight time fringe test observations to date and fringes were successfully detected at both 8 and 22 GHz, although there are several problems to be solved. In 2015, we will continuously carry out test observations to evaluate array performance and to check imaging capability. 16/16