KVN-VERA test observation

KVN-VERA test observation
Sohn, Bong Won1
Miyazaki, Atsushi Byun, Do-Young Kobayashi, Hideyuki
Je, Do Heung Kanya, Yukitoshi Kurayama, Tomoharu
Lee, Sang Sung Jung, Tae Hyun KVN and VERA team
1 Korea Astronomy and Space Science Institute2009 VERA users’ meetingKVN-VERA test observation

Contents
KVN (and EAVN) sensitivities
KVN-VERA test observation
Detected fringes
Snapshot image of NRAO150
Test observation so farThings to be improved

KVN-VERA test observation
Baseline Sensitivity

Baseline Sensitivity
Point Source Detection Threshold
2κT
SEFD = ηAsysA√√SEF
Di SEF Dj1√∆Sij = ηs2×∆ν×τf f

Continuum Fringe detection limit (10σ) ∼ 80 mJy
Frequency
Tsys
ηA
SEFD (Jy)∆Scont (mJy)∆Sline (Jy)

22 GHz
70
0.7
797
7.9
0.51/0.72

43 GHz
140
0.7
1594
15.9
1.02/1.44

86 GHz
250
0.6
3320
33.1
2.12/3.00

129 GHz
300
0.5
4781
47.6
3.05/4.31

Table: 128MHz and τint 60s, for line sensitivity 31.25, 15.625 KHz used

KVN-VERA test observation
Image Sensitivity of Array

Image Sensitivity of KVN(+VERA) array
Image Plane Noise Limitqbaseline ν×τ
2×Nijint1∆I = ηs Σ( √)−1 Jy/beam
SEF Di ×SEF Dj

comparable to FIRST survey (NRAO VLA) @1.4 GHz
Strong ’in-beam’ or phase ref source necessary
Array
Frequency
SEFD(VERA)∆Simg (mJy)

KVN
22 GHz797
0.59

43 GHz
1594
1.18

EAVN
22 GHz1093 (1500)
0.19

43 GHz2187 (3000)
0.38

Table: Image Sensitivity of KVN and KVN + VERA, τint 60min

KVN-VERA test observationKVN-VERA fringe test
VLBI Test Observation

Description of Observations
KVN-VERA fringe detection test
Image sensitivity test and pilot scientific operation
With DIR-1000 and Mitaka correlator (BW 32 MHz)
Unknown parameters → KVN telescopes

first day of KVN VLBI observation

KVN-VERA test observation
KVN-VERA fringe test
Results

Fringe detections
Fringes detected at all baselines with all observed sources

NRAO150(J0359+5057) BL Lac object at K-band, 3rd Nov. 2008

KVN-VERA test observation
KVN-VERA fringe testResults

Fringe detections
Fringes detected at all baselines with all observed sources

NRAO150(J0359+5057) BL Lac object at K-band, 12th Mar. 2009

KVN-VERA test observation
KVN-VERA fringe test
Results

Fringe detections
Fringes detected at all baselines with all observed sources

NRAO150(J0359+5057) BL Lac object at Q-band, 13th Mar. 2009

KVN-VERA test observation
KVN-VERA fringe test
Results

Fringe detections
Fringes detected at all baselines with all observed sources

November 2008
LL detected at KVN ’RCP’-VERA LCP
due to → odd number of mirrors in KVN quasi-optics
Residual delays are relatively huge, |∆| > 18µsec, at MIZ-YS
Residual delay difference is also huge, KVN problem?

KVN-VERA test observation
KVN-VERA fringe test
Results

Fringe detections
Fringes detected at all baselines with all observed sources

March 2009
Huge Residual delays disappear
Residual delay is also small
Problem in correlation parameter in 1st experiment?
Problem in Ogasawara in 2nd experiments
Fringes are detected at K and Q bands

KVN-VERA test observation
KVN-VERA fringe test
Results

Baseline SNR comparison of March 2009 observation

at K-band KVN better than VERA, but as as good as its SEFD predicts

KVN-VERA test observation
KVN-VERA fringe test
Results

Baseline SNR comparison of March 2009 observation

at Q-band, VERAs are better than KVN

KVN-VERA test observation
KVN-VERA fringe test
Results

Snapshot of NRAO150 on 3rd Nov. 2008

UV coverage of 10 min. observation on NRAO150

KVN-VERA test observation
KVN-VERA fringe testResults

Snapshot of NRAO150 on 3rd Nov. 2008

NRAO150 at K-band (3 Nov. 2008), ∼ 10mJy/Beam RMS noise
Are the structures real? KVN-VERA test Monitoring began

KVN-VERA test observation
KVN-VERA fringe test
Results

Snapshot of NRAO150 on 3rd Nov. 2008

Recent VLBA observation at 15 and 43GHz (Agudo, 2007),
feel better?

KVN-VERA test observation
KVN-VERA fringe test
Summary

Summary of KVN-VERA K-band fringe test
Successful fringe detections at K-band with all observed
sources
Further fringe detection test at K and Q band, 12/13 March2009
RCPLCP

Higher visibility phase noise at KVN baselines
Bright source imaging feasible
Pilot Scientific Operation?
∼ 10 mJy/beam with 5 telescopes and 32MHz bw in 10 min.
No cable calibration at KVN, hard to utilize phase referencing
yet
Monitoring of powerful sources, Image sensitivity study

KVN-VERA test observation
KVN-VERA fringe test
Summary

KVN-VERA K/Q band experiments
1st fringe test at K-band on 1st/3rd of Nov., 2008
Maser: W49N, Ori-KL, Cont: J2148+0657, NRAO150(10 minper scan)
Maser(LCP)-Maser(RCP)-AGN(RCP)-AGN(LCP); VERA LCP
fringes detected from all observed sources; K band2nd fringe test at K/Q band on 12/13th of March, 2009
After re-installation of 22 and 43 GHz receivers
fringes detected from all observed sources; K/Q bands
Sheshan participated on 12th, failed

Image sensitivity experiment on 18th April, 2009
good UV-coverages and 1 hour of observation per source
NRAO150, 4C39.35, J0646+4451, 3C236 at K-band

Image sensitivity experiment on 20/22th May, 2009
good UV-coverages and 1 hour of observation time per source
NRAO150, J0646+4451, 3C236, KV2327+1524, J1502+106
at K-band
Sheshan participated, first EAVN fringe!, bad weather

KVN-VERA test observation
KVN-VERA fringe test

Things to be improved
Higher RMS than estimation
optimistic VERA SEFD in my estimation?
KVN system problem (cable cal., wet Feeds)?

KVN Station log will be improved
DIR-1000 bandwidth limitation 32MHz (MK5B 256MHz)KVN cable cal. system and KJJVC for optimal operation