Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.stsci.edu/jwst/instruments/nirspec/docarchive/NIRSpec-pocket-guide.pdf Дата изменения: Unknown Дата индексирования: Mon Apr 11 20:11:10 2016 Кодировка: Поисковые слова: m 2

James Webb Space Telescope:
At a glance:
Detectors: Two Teledyne Hawaii2RG; HgCdTe arrays with 5.3m cutoff; 2048 в 2048 pixels each Overall field of view: 2.2 в 2.4 arcmin Plate scale: 0.065 arcsec/pixel Dispersers: One prism (R=100) and two sets of gratings (R=1000 and 2700)

Near Infrared Spectrograph (NIRSpec)

NIRSpec in the JWST focal plane. The overall NIRSpec FOV is 3.2 в 3.3 arcmin. Note that the NIRSpec FOV is rotated by 41 degrees relative to the other instruments.
NIRSpec Modes Multi-object spectroscopy ( MSA) Targets Rich fields; ex tended targets Wavelengths Prism: 0.7­ 5.0m Band I: 0.7­1.8m Fixed slits Integral Field Unit ( IF U ) Target Acquistion Single sources; bright stars Up to 10 arcsec ex tended Reference stars (~10) 0.8 ­2.0m Band II: 1.7­3.0m Band III: 2.9 ­ 5.0m Aper ture/FOV 0.2 в 0.46 arcsec 0.2 в 3.3 0.4 в 3.8 1.6 в 1.6 3.0 в 3.0 arcsec Uses MSA mirror 100 1000 2700 Resolving Powers

A detailed simulation of NIRSpec obser v d e t e c to r s a n d t h e g a p b e t w e e n t h e m . A use of three shut ters ver tic ally for each s in the center of the detectors. The input

ation for ~30 0 objects in por tion of the field is enl ource to allow dithering. used physic ally realistic

a ver y dense field, a r g e d o n t h e r ig h t The adjacent shut s p e c t r a o f a v a rie t

using the R~10 0 (PRISM) mode of NIRSpec. Note the t wo to reveal individual spectra with emission lines. Note the ters are recording background, as are the fixed-slit spectra y of likely high-redshif t objects.


NIRSpec Spectrum Resolving Power

Usage notes
· All observations start with an acquisition that uses NIRSpec's MS A and ~10 reference stars. Highly precise astrometr y is required, taken from a NIRCam pre-image or other space-based image.

Resolving Power

G235H G140H G235M PRISM

G395H

· The 1.6 в 1.6 arcsec fixed aperture is intended specifically for observing exoplanet transits of bright stars.

G140M

G395M

Throughput
The NIRSpec PSF at five wavelengths. The rectangle is the size of an MSA shut ter (0.24 в 0.46 arcsec). The grow th and structure of the PSF with wavelength illustrates the need to keep sources within the central areas of the shut ters.

G140H G140H F070LP F100LP

G235H F170LP

G395H F290LP

Continuum ux F (nJy) v

G140M F070LP

G140M F100LP

G235M F170LP

G395M F290LP

0

1

2

Line ux (ergux (erg ) cm ) Line s cm s

Wavelength ( m)

3

4

5

5x10-19
1

Continuum ux F (nJy) v

)

Wavelength ( m)
1 2 3 4 5

5x10-19

200

Line ux (ergux (erg ) cm-2) Line s cm s

1

2

Continuum ux F (nJy) v

-2 -1

500

inuum ux F (nJy) v

2000

10 05s
4

Wavelength ( m)

Wavelength ( m)
Operated for NASA by AURA

AC SP E TELESCOPE SCIENCE INSTITUTE

4.5

5

)
4 4.5 5

)

R=2700 S/N=10 texp=105s

5x10-19

10 05 00s

Wavelength ( m)
1 2 3 4 5

200

1

1.5

2

2.5

3

3.5

4

4.5

5

10-18

300

)00

5x10-19

4

4.5

5

Line ux (erg s-1 cm-2)

400

1000

-1

)

10-18 -19 5x10

4

4.5

5

S/N=10 texp=105s
1 2 3

600

10 05s

R=2700 S/N=10 texp=105 R=2700s

Wavelength ( m)

3

4

5

Continuum ux F (nJy) v

)00 10 05 00 s

4

5

Wavelength ( m)

0

1

2

Wavelength ( m)

R=1000 S/N=10 texp=105s

3 R=2700 S/N=10 texp=105s

4

5

5x10
1

Wavelength ( m)

1500

10-18

4

5

1

1.5

2

2.5

3

Wavelength ( m) S/N=

3.5 4 R=2700 10 texp=105s

4.5

5

1

2

3

4

5

1000

1500

Wavelength ( m)

-19

1

1.5

2

2.5

3

3.5

4

4.5

5

10

4

5

1

2

3

4

5

R=100 S/N=10 texp=104s

Line ux (erg s-1 cm-2)

5x10-19

10-18

400

S/N=10 texp=105s

Line ux (erg 300 cm-2)500 s-1 400 2000 200

10-18 5x10-19

S/N=10 tex =105 R=p1000 s

Continuum ux F (nJy) v

Limiting emission lR=1000 nsitivity ine se
10-18

-2

Point source sensitivities for continuum sources.

200

R=1000 S/N=10 texp=105s R=1000 S/N=10 texp=105s

-2 -1

-1

600

-18

10-18

400

PRISM

R=100 S/N=10 texp=104s

Line ux (erg s-1 cm-2)