1. Water Masers in NGC7538 Region
Osamu KAMEYA　
（Mizusawa VERA Observatory,　NAOJ）,　VERA　team　　　　
VERA stations　
NGC7538 JHK image Ohja et al 2004

2. VERA:VLBI Exploration of Radio Astrometry
1. VERA system and status
VERA:VLBI Exploration of Radio Astrometry
Stations: four
Baseline: km
Diameter：20m
Obs bands: 2, 8,
22, 43GHz
VERA stations and baseline length by geodetic obs on Dec. 17, 2004
Mizu-
sawa
Iriki
41mm/yr
Ogasawara
Ishigaki-
jima
66mm/yr
Unit: mm

3. >> Cancel out the fluctuation of the atmosphere
1. VERA system and status
Dual beam system　
>>　Cancel out the fluctuation
of the atmosphere
>> 10μarcsec accuracy (target)
for position relative to
reference sources
　Maser　　　　　　　Maser QSO

4. VERA can measure parallax of masers In the whole Galaxy. Maser VERA
1AU
Galactic Center
10% accuracy
@10kpc
10% accuracy
0.1% accuracy
@100pc
Sun

5. Maser
Test observations for several years
>> succeeded in measuring parallaxes
for some maser sources （e.g.　 Next talk by Honma ）
>> open the common use observation
for everyone in the world (from this winter)
Details : Next talk by Honma
VERA
1AU
Galactic Center
10% accuracy
10% accuracy
@10kpc
0.1% accuracy
@100pc
Sun

6. 2. Activity of NGC7538 Region CasA－NGC7538 Molecular Cloud Complex
Distance=2.7kpc　（OB　association）
NGC7538（S158)
S159
100pc
@3kpc
S156
S157
CasA
CO　J=1-0　（Kameya et al.1990）
Bell Labo　6m

7. Activity of NGC7538 Region
NGC7538 JHK image Ohja et al 2004

8. Activity of NGC7538 Region NGC7538 IRS1-3 IRS9 IRS11
NGC7538 JHK image Ohja et al 2004
NGC7538
IRS1-3
IRS9
IRS11

9. Ultra compact HII regions VLA 15cm Kameya et al. 1990
Sandel et al JCMT 850μ
Ultra compact HII regions
VLA 15cm Kameya et al. 1990
Kameya et al CO outflow

10. NGC7538 IRS1, 9, 11 Methanol 6.7GHz methanol maser IRS9 & S
1. MERLIN & EVN 2004 Nov
2. EVN Dec
Pestalozzi etal A&A 448, L57-L60
NGC7538
IRS1, 9, 11
Methanol

11. H2O maser IRS1(N) IRS9(E) IRS11(S) Molecular Outflow
NGC7538 H2O Masers （Kameya et al. 1990）
NMA（1987.5）
IRS1(N)
IRS9(E)
Molecular Outflow
IRS11(S)

12. H2O maser IRS11(S) Molecular Outflow
NGC7538 H2O Masers （Kameya et al. 1990）
NMA（1987.5）
IRS11(S)
Molecular Outflow

13. H2O maser IRS11(S) H2O 1977 Feb27-28 Only one VLBI map for IRS11
Genzel et al. 1978
H2O　1977 Feb27-28
Only one VLBI map for IRS11
IRS11(S)

14. 3.VERA observation of H2O masers of NGC 7538
yr103d ( April 13th )　19h-6hUT
Recording mode: GEO1D mode 16MHz-2bit-2ch
Recorder　1000　（256Mbps）　
CepA VS J
CepA VS NGC7538N＆S
　　　2 beam separation: ~2degree
yr 208d　(July 27th) 13h-22hUT
Recording mode: VERA7MM mode 16MHz-2bit-16ch
Recorder　2000　（1Gbps）
　　CepA VS J

15. Results of VERA S(IRS11) NGC7538 N&S water masers
Kameya et al. 1990
　　　　Vlsr=-67km/s component is disappeared.
NGC7538 N&S　 water masers 　
Cross powser spectrum
NGC7538S　H2O maser cross power spectrum　　
CepA　water masers
Cross powser spectrum

16. Results of VERA Mapping of S (IRS11） 2005 105day
-53.3 ,-53.9
-53.3
-53.9
-49.3,-61.7,-65.1
-56.0
-61.4 　-61.6　-61.7
　-56.7　-56.9 　
(0,0)の座標（1950.0）=（23h11m36. s03±0.05s、
　　　　　　　　　　　　　　61°10’30“.35±0.35”）
V_lsr(km/s)
Jy/Beam
RA offset (mas)
DEC offset (mas)
-4.93E+01
7.40E+00
1.61E+03
-1.52E+03
-5.31E+01
1.25E+01
-9.66E-02
-7.06E-02
-5.33E+01
3.98E+01
-6.06E-02
-5.26E-02
-5.35E+01
7.47E+01
-3.00E-02
-2.82E-02
-5.37E+01
1.03E+00
-9.20E-03
-8.40E-03
-5.39E+01
1.12E+02
0.00E+00
-5.41E+01
9.17E+01
-2.10E-01
1.82E-02
-5.43E+01
5.27E+01
5.82E-02
4.90E-02
-5.56E+01
4.03E+00
7.04E+01
5.08E+01
-5.58E+01
3.88E+00
5.09E+01
-5.60E+01
1.96E+00
-6.15E+01
1.93E+01
1.51E+03
-1.49E+03
-6.17E+01
2.09E+01
-6.51E+01
1.31E+01
1.62E+03
4.19E+00
2.75E+00
2.02E+00
2.95E+00
2.71E+00
1.94E+00
2.18E+01
2.80E+03
-1.90E+03
-5.62E+01
2.8954
1.52E+03
-1.50E+03
3.26E+00
-65.1
--61.7
-61.7
-49.3,

17. Results of VERA Mapping of S (IRS11） 2006 208day -52.3 -54.3 -64.8
-56.3
-61.4 　-61.6　-61.7
(0,0)の座標（1950.0）=（23h11m36. s03±0.05s、
　　　　　　　　　　　　　　61°10’30“.35±0.35”）
-64.8
-64.8

18. Results of VERA (S) Molecular Outflow Results （Mapping） Y
-53.3 ,-53.9
-54.3
-65.1
　 　-54.9
　 　-55.5
　　　　Y
-61.7
-56.0
-56.3
-49.3,
-64.8
-61.4 　-61.6　-61.7
　-56.7　-56.9 　
Kameya et al. 1990
NMA　H2O　1987 May 9
Kameya et al. 1990b
VLA　1989 April
Ultra compact HII region
Genzel et al. 1978
VLBI H2O　1977 Feb27-28
Molecular Outflow

19. Results of VERA N(IRS1) NGC7538N H2O maser cross power spectrum
Kameya et al. 1990
　Vlsr=-82、-48km/s components are　disappeared.
NGC7538N　H2O maser cross power spectrum　　

20. Results of VERA (N) Molecular Outflow Results （Mapping） X
-60.4 S？ X
-59.8
-70.9、-71.18、-72.4
--57.7
Molecular Outflow
Kameya et al. 1990
NMA　H2O　1987 May 9

21. 4. Summary and Conclusion
VERA status
VERA will open the common use observations for astronomers in the world from this winter.
Details : Next talk by Honma
NGC7538 Region
Most detailed H2O maser distribution of N(IRS1-3) and S(IRS11) of NGC7538 region has been obtained by two- epoch VLBI observations by VERA.
The global distributions of masers are not changed for 30years.
Each region associate with the high dense cores, IR source, Outflow, Ultra-compact HII region, H2O, OH, methanol, and the other masers.
Future Works
VLBI Observations of NGC7538 Region can make clear the dynamics of each star forming region (N&S).
Distance measurement for Cep A H2O maser using VERA.
Distance measurement for NGC7538 using VERA.