Data analysis of KaVA Astrometric Test observations
For 22 GHz Water Maser Source in W3(OH) Region
Daisuke Sakai (NAOJ), KaVA-GA subWG members
KaVA Galactic astrometry sub-working group is evaluating and establishing an astrometric mode of KaVA array by conducting test observations for Maser-QSO pair andQSO-QSO pair observations. To evaluate the astrometric accuracy obtained by KaVA astrometric mode, we have to compare the phase solutions as well as astrometricpositions between VERA array and KaVA array. Also, we have to confirm the consistency between datasets correlated by Mizusawa SW correlator and KJCC.
By analysing two datasets of test observations for 22 GHz water maser source in W3(OH) region, we found phase differences between Mizusawa SW correlated data
and KJCC correlated data. These differences appear to have a diurnal variation and is similar between two different observational epochs. As a result, these phasedifferences make position differences of about 0.1 milli-arcsecond by conducting phase referencing. In this poster, I will present detailed plots of delay and phasesolutions obtained through data reduction process of test observations.

Results Fringe fitting results for R17352B

Motivations

Fringe fitting solutions of Reference QSO (Delay)
KJCC

Mizusawa Soft. corr.

Plot file version 17 created 08-AUG-2018 21:40:07
Delay vs time for K17352B_B.MSORT.1
SN 5 Lpol IF 9

Plot file version 18 created 08-AUG-2018 18:56:53
Delay vs UTC time for R17352B_B.MSORT.1
SN 5 Lpol IF 9

-0.8
-1.0
-1.2
-1.4
-1.6-1.80.001

1L MIZNAO20-1.0-1.5-2.00.001

0.000

13L OGA4L ISG

3215L KYS

05L KVNYONSE-1-1-2-2
6L KUS-0.5

6L KVNULSAN-0.5KJCC

Nano Seconds

Nano Seconds

20Mizusawa Soft. corr.

-0.001
0.0-0.5-1.0

3L OGASA20

4L ISHIGAKI

32L IRK

2L IRIKI

0.000-0.001
0.0-0.5-1.0

1L MIZ-1.0-1.0-1.5
0.0-1.5
0.0

7L KTN

7L KVNTAMNA-0.5-0.5-1.0-1.0
10111213Time (hours)

14151016

111213Time (hours)

1415

16

The difference of fitting results between Miz and KJCC relative to Iriki station
R17352B Diﬀerences of Fringe solutions (MIZ - KJCC)
MIZ

OGA

111

11

10.5

0.5

0.5

0.5

0.5

0.5

00

-0.5

-0.5

-1-1

-1-1

-1

-1.5

-1.5

-1.5

-1.5

-1.5

0.4

Rate (MilliHz)

Rate (MilliHz)

Rate (MilliHz)
0.4

0.6

0.8

0-10

1

0.2

0.4

0.6

0.8

1150

150

50

50

50

00.2

0.4

0.2

0.6

0.8

100.2

0.4

0.4

0.6

0.8

0.6

0.8

01

0.2

0.4

110.2

0.4

0.6

0.8

00.20.4

0.60.8-10

10.20.4300

250

250200150

1005050500.8

10000.2

0.4

0.60.8100.2

DAY0.4

0.6
DAY24 hours

Delay and rate solutions are well consistent with each other correlators.
- Δdelay < 0.2 nsec, Δrate < 1 MilliHz

KJCC

Mizusawa Soft. corr.

description

CONT: J0244+62 IPOL 22221.875 MHz J0244+6228.ICL001.5

CONT: J0244+62 IPOL 22221.750 MHz J0244+6228.ICL001.4

1010



Image and position
comparisons could not be
conducted
Same a priori parameters
Same a priori parameters(Problem for maser
data for VERAstation)


55
MilliArc seconds

ISG not joined
Not same a priori parametersMilliArc seconds00-5-5-10-101010

50-5
MilliArc seconds
Center at RA 02 44 57.69673300 DEC 62 28 06.5155800
Cont peak flux = 4.7855E-01 JY/BEAM
Levs = 2.644E-03 * (-3, 3, 6, 12, 24, 48, 96, 192)

0-5
MilliArc seconds
Center at RA 02 44 57.69673300 DEC 62 28 06.5155800
Cont peak flux = 4.8904E-01 JY/BEAM
Levs = 2.644E-03 * (-3, 3, 6, 12, 24, 48, 96, 192)

-10

5-10

The rms noise level of KJCC data is slightly larger than Miz soft data

Visibility Phase Plot

Parallax fitting
We conducted parallax fitting for a water maser spot at Vlsr=-51.44 km/s
by using observational data of VERA project observations(c) Parallax

4Offset (mas)Decl. offset (mas)

6

W3OH

Offset (mas)

20

2

0-2
0-2

-4

R.A. offset (mas)

-6

2017

2018

Year

1
0.8
0.6
0.4
0.2
0-0.2
-0.4
-0.6
-0.8
-1-1.2-1.42017

Visibility phase plot of water maser spot at V=-51.44 km/s (Phase-referenced)
R17352B
位相補償後のW3OH water maser のVPLOT出力の位相
黒 ： Mizsoft
オレンジ ： KJCC

Black : Miz soft, Orange : KJCC
100-100100-100100-100

2018

Year100Error

0.562 mas

0.044 mas

IRK-OGA(2-3) (2-3)
IRIKI-OGASA200-100
IRK-ISG(2-4) (2-4)
IRIKI-ISHIGAKI

0-100
100

2.702 mas

MIZ-ISG(1-4)
MIZNAO20-ISHIGAKI(1-4)

0R.A. (17352) Dec. (17352) Parallax-4.377 mas

MIZ-OGA(1-3)
MIZNAO20-OGASA20(1-3)

0100Miz soft

PLot file version 1 created 08-AUG-2018 22:01:58
19:38:00
Phase vs Time for W3OH.CVEL.1 Vect aver. CL # 8
IF 1 CHAN 266 STK LL of W3OH.ICL001.1
MIZ-IRK (1-2)
MIZNAO20-IRIKI(1-2)

0Degrees(a) Positions (R.A.-Dec.) (b) Time-Pos.

OGA-ISG(3-4)
OGASA20-ISHIGAKI
(3-4)

0-100
10KJCC-4.244 mas

2.497 mas

0.549 mas

0.051 mas

We can see that Miz soft results fit well in the direction of Dec.
,while KJCC results relatively fit in the direction of R.A..

111213Time (hours)

1411501000.60.8
KTNsoft-KJCC

200

100DAY0.6DAY300

0.40350

KUSsoft-KJCC

2500.21

MIZsoft-KJCC

DAY1500.8-5350

2000.60300

00.4

50-101

KYSsoft-KJCC

DAY0.210-500DAY

5350

0.80.8MIZsoft-KJCC

DAY0.60.6

The image of the refefence QSO (J0244+6228)

Miz soft KJCC

R17352B

0.410

MIZsoft-KJCC

000.2

However, phase solutions show systematic differences (day scale variation?)
The behavior of this phase difference is almost same for different
observational epochs.

Target – Reference source : W3(OH) – J0244+6228
Line : 22 GHz water maser
Correlation : Miz soft and KJCC

R17293B

1

ISGsoft-KJCC

DAYDAY-20DAY0-100150

100

1-52001000.8

5250

200

0.6

10300

10000.4DAY350

OGAsoft-KJCC

Phase (degree)

Phase (degree)

200

0.2

DAY250250-2010-100300

300

0.8-5350

MIZsoft-KJCC

0.6

MIZsoft-KJCC

DAY35000.4

5-50.20.2105001

MIZsoft-KJCC

DAYPhase (degree)

0.8

DAY10MIZsoft-KJCC

0-100.6
DAYRate (MilliHz)

0.2

Phase (degree)

01

Rate (MilliHz)

0.8

Phase (degree)

0.6

Rate (MilliHz)

0.4

Phase (degree)

0.2-2-2-2
0-5

Observations

R16074A-0.5-0.5

5

1. The fringe fitting results- Delay, rate, and phase solutions from fringe fitting of QSO (J0244+6228)
2. The quality of the image- Peak intensity, rms noise revel, spot structures
3. Positions and parallax

0-0.5-110phase0-0.5DAY To confirm the accuracy of KaVA astorometric mode, we have compared dataset correlatedwith Mizusawa Software Correlator and KJCC from some points of view.

0

Delay (nsec)

1.5

Delay (nsec)

1.5

Delay (nsec)

1.5

Delay (nsec)

1.50

MIZsoft-KJCC

MIZsoft-KJCC

1.5-2

Aim of data reduction

KTN
22
MIZsoft-KJCC

1.5-1.5rate

KUS

KYS
2

MIZsoft-KJCC

MIZsoft-KJCC

MIZsoft-KJCC

Delay (nsec)

Delay (nsec)

ISG
222

delayJ0244+6228

15

In some part, visibility phase of Miz soft and KJCC are different up to ~50 degree. This
phase difference should become a position difference of about 0.2 mas in the left Table.

0.81