Poster - 12

VERAユーザーズ・ミーティング 2008 10/9-10

大学ＶＬＢＩ連携観測事業
藤沢健太（山口大学）
NetworkResults

Methanol Maser
Sugiyama et al. (2008) accepted to PASJ
A Synchronized Variation of the 6.7 GHz Methanol Maser inCepheus A
A spatial distribution of the 6.7 GHz methanol maser spots(filled circle) of Cep A. The spot size and color indicates its
peak intensity in logarithmic scale and its radial velocity(see color index at the right), respectively. The contours
indicate the VLA 22 GHz continuum observed by Torrelleset al. (1998) and re-reduced by Gallimore et al. (2003). Astar indicates the peak of 43 GHz continuum emission withthe positional uncertainty of about 10 mas.

Nagayama et al. (2008) accepted to PASJ
H2O Maser Outflow from the Red Supergiant Star NML Cygni observedwith Japanese VLBI Network
Distributions and proper motion vectors of H2O masers in NML Cyg. The
color index denotes the LSR velocity range from -22.2 to 15.5 kms-1, where
22 features are located. The map origin is located at the position of thereference maser feature at vLSR = 5.6 km s-1. The displayed proper motion
vector is that subtraced by a velocity bias (μx,μy) = (0.19,-0.28) [mas yr-1]
from the original vector to cancel out the average motions of all features.

Japanese VLBI Network
The Japanese VLBI Network consists of ten antennas that are
owned and operated by four research institutes (NAOJ, JAXA,NICT, GSI) and four universities (Hokkaido, Gifu, Yamaguchi,Kagoshima University).
These antennas form 50 - 2560 km baselines across the Japaneseislands and provide very dense UV-coverages. Three observing
bands are now available (6.7, 8.4, and 22 GHz). The subarrayoffive telescopes (Usuda 64m, Kashima 34m, Tsukuba 32m,Yamaguchi 32m, and Gifu 11m) are connected with information
networks at 2.4 Gbps for real-time VLBI observation.

Water Maser
Motogi et al. (2008) accepted to MNRAS
Microstructure and kinematics of H2O masers in the massive star forming region IRAS 06061+2151

UV-coverage example.
Left : δ= +60deg
Right : δ= -20 deg

Each point denotes each maser feature. Colour of the maser features indicates a detection epoch,epoch1 (blue), 2 (light blue), 3 (green), 4 (light green), 5 (yellow) and 6 (red). The kink area containing
the brightest features is indicated by dashed circle.

Narrow-Line Seyfert 1and AGNs

Tsuboi et al. (2008) PASJ, 60, 465

In near future…

The 2006 Radio Outbursts of a Microquasar Cygnus X-3: Observations and Data
Upper panel : VLBI image of Cyg X-3 obtained by JVN.
Lower panels : Evolution of the source structure of Cyg X-3 obtained with VLBI. A series ofmeasurements was performed by a visibility based model-fitting using an elliptical-Gaussian profile
model with free parameters of the flux density, the FWHMs along the major and minor axes, and theposition angle of the major axis (see text in detail).
(a) Flux densities of the VLBI component (filled circles). The open circles represent measurements
using a circular-Gaussian model, rather than an elliptical one, due to poor data quality. (b) Angularsizes of fitted source structure. The filled circles and open squares represent the FWHMs along themajor and minor axes, respectively. The solid and dashed lines represent the major and minor axes ofHPBWs of a synthesized beam in uniform-weighting, for a comparison. (c) Position angles of themajor axis of the fitted source structure (open circles). The solid line represents the position angle ofthe major axis of synthesized beam, for a comparison.

Micro-Quasars
East-Asian VLBI Network
The JVN will extend to the East-Asian VLBI Network (EAVN)
in near future, collaborating with the Chinese VLBI Network(CVN) and the Korean VLBI Network (KVN). EAVN has large
aperture and long baselines up to 5000 km; it is one of thelargest VLBI networks in the world.
EAVN is expected to be a ground array for VSOP-2 as well as
the VLBA and EVN. We have started VLBI experiments withChinese/Korean colleagues for constructing EAVN.

Doi et al. (2007) , PASJ, 59, 703
Japanese VLBI Network Observations of Radio-Loud NarrowLine Seyfert 1 Galaxies
JVN images of a radio-loud NLS1 (RXS J08066+7248) and 4other sources at 8.4 GHz. The images were synthesized in naturalweighting. RMS of the image noise was 0.54 mJy beam-1. Halfpower beam sizes are shown in the lower left corners.