SPIE meeting, Marseille June 23 2008 1

SPIRE

• Scientific goals• Instrument overview• Current status• Performance estimates

Herschel-SPIRE: Design, Ground Test Results, and Predicted

Performance

Matt Griffin for the SPIRE Consortium

SPIE meeting, Marseille June 23 2008 2

SPIRE

• Cardiff University, UK• CEA Service d’Astrophysique, Saclay, France• Institut d’Astrophysique Spatiale, Orsay, France • Imperial College, London, UK• Instituto de Astrofisica de Canarias, Tenerife, Spain• Istituto di Fisica dello Spazio Interplanetario, Rome, Italy • Jet Propulsion Laboratory/Caltech, Pasadena, USA• Laboratoire d’Astronomie Spatiale, Marseille, France• Mullard Space Science Laboratory, Surrey, UK• NAOC, Beijing, China• Observatoire de Paris, Meudon, France• Rutherford Appleton Laboratory, Oxfordshire, UK• Stockholm Observatory, Sweden• UK Astronomy Technology Centre, Edinburgh, UK• University of Colorado, USA• University of Lethbridge, Canada• Università di Padova, Italy

The SPIRE ConsortiumCanada China France Italy Spain Sweden UK USA

SPIE meeting, Marseille June 23 2008 3

SPIRE Herschel/SPIRE Science GoalsνI

νW

m-2

Sr-1

10-9

10-8

10-7

10-6

10-10

10-11

1011 1012 1013 1014 1015 1016

FIR/Submm Visible/UV

ν (Hz)

νIν

W m

-2Sr

-1

10-9

10-8

10-7

10-6

10-10

10-11

1011 1012 1013 1014 1015 1016

FIR/Submm Visible/UV

ν (Hz)

PlanckHerschel

Herschel range

SPIE meeting, Marseille June 23 2008 4

SPIRE

• 3-band imaging photometer

- 250, 350, 500 μm (simultaneous)

- λ/Δλ ~ 3- 4 x 8 arcminute field of view

- Diffraction limited beams (19, 24, 35”)

• Imaging Fourier Transform Spectrometer- 194 - 672 μm

(complete range covered simultaneously)

- 2.6 arcminute field of view

- Spectral resolution up to Δσ = 0.04 cm-1 (λ/Δλ ~ 1000 at 250 μm)

Spectral and Photometric Imaging Receiver

SPIE meeting, Marseille June 23 2008 5

SPIRE SPIRE Block Diagram

FPU

Cryostat Wall

SpacecraftElectronics

FCU

Power

Cooler, Mechanisms, Calibrators, Thermometers Detector Arrays

Commandingand Telemetry

DPU

JFETs

DCU

SPIRE WarmElectronics

SPIE meeting, Marseille June 23 2008 6

SPIRE

Herschel focal

surface

2-Kcoldstop

M3

M4

M5

M6

M7

M8

Beam steering mirror

Relay optics

Dichroics and

arrays

M9

3He cooler

Detector array

modules

Beam steering mirror

SPIRE optical bench (4 K)

2-K box

M3

M4

M5 M7

M6M8

Photometer Layout and Optics

SPIE meeting, Marseille June 23 2008 7

SPIRE FTS Layout and Optics

Telescope input port

Calibrator input portOutput

port

Output port

Intensity beam

dividers

Fore-optics shared with photometer

Mirrormechanism 2nd-port

calibrator

Beam divider

4-Kbox

Baffle

2-Kbox

Detector array

modules

SPIE meeting, Marseille June 23 2008 8

SPIRE SPIRE Subsystems

SPIE meeting, Marseille June 23 2008 9

SPIRE Instrument Assembly and Testing• Instrument assembled in stages and tested in dedicated

facility at RAL, UK• Started February 2005• Finished March 2007 - instrument delivered April 2007• Five cooldowns• Two cold vibrations• All major requirements and most goals are met

SPIE meeting, Marseille June 23 2008 10

SPIRE Photometer Observing Modes

Point source: 7-point

θ

Small map: 4 x 4 arcmin jiggle-map

Large map:Scan-map

SPIE meeting, Marseille June 23 2008 11

SPIRE SPIRE-PACS Parallel Mode

• • Scan map with SPIRE and PACS simultaneously

• • Suitable for large areashallow surveys (~ 20 mJy rms)

• • SPIRE- Three bands; no loss of data

• • PACS- Two bands- Enhanced data compression- Some beam smearing at high

scan speed

SPIE meeting, Marseille June 23 2008 12

SPIRE FTS Observing Modes • Δσ = 0.04 - 2 cm-1 by adjusting scan length

• Continuous scan (nominal mode):- Calibrator in 2nd port nulls telescope background

• Imaging spectroscopy (full spatial sampling)- Beam steering mirror adjusts pointing between scans to

acquire fully-sampled spectral image

• Point source or sparse map spectroscopy/spectrophotometry- Also produces sparse map – background characterised by adjacent pixels

SPIE meeting, Marseille June 23 2008 13

SPIRE FTS Spectral Line Resolving Power(Δσ = 0.04 cm-1)

100 200 300 400 500 600 7000

300

600

900

1200

1500High Res Unapodised Resolving Power

Wavelength (microns)

Res

olvi

ng P

ower

a

FWHM = 0.048 cm-1 = 1.4 GHz

Unapodised

Apodised

SPIE meeting, Marseille June 23 2008 14

SPIRE FTS Spectrophotometry Resolving Power (Δσ = 1 cm-1)

100 200 300 400 500 600 7000

10

20

30

40

50

60Low Res Unapodised Resolving Power

Wavelength (microns)

Res

olvi

ng P

ower

a

SPIE meeting, Marseille June 23 2008 15

SPIRE

Instrument Performance

Estimates

SPIE meeting, Marseille June 23 2008 16

SPIRE Telescope Emissivity and Stray Light Model

• Two reflectors• Stray light component equivalent to10% of a

70-K; 3% emissive telescope

100 200 300 400 500 600 7000

0.20.40.60.8

11.21.41.61.8

2

Wavelength (um)

Em

issi

vity

(%

)

Total (two reflectors + stray light

One reflector

Stray light

SPIE meeting, Marseille June 23 2008 17

SPIRE

150 200 250 300 350 400 450 500 550 600 650 7000

0.10.20.30.40.50.60.70.8

Wavelength (microns)

Filt

er S

tack

Tra

nsm

issi

onPhotometer Filter Bands

PSWλo ≈ 250 μmλo/Δλ = 3.3

PMWλo ≈ 350 μmλo/Δλ = 3.4

PLWλo ≈ 500 μmλo/Δλ = 2.5

Typical

SPIE meeting, Marseille June 23 2008 18

SPIRE FTS Bandsu

100 200 300 400 500 600 700 8000

0.10.20.30.40.50.60.70.8

Wavelength (microns)

Filt

er S

tack

Tra

nsm

issi

on SLW316 – 672 μm

SSW194 – 324 μm

Typical

SPIE meeting, Marseille June 23 2008 19

SPIRE Photometer SensitivityPoint Source 7-Point Observation

• Typical observation- Nod sequence A-B-B-A with 64 s

each on source = 256 s- 8 BSM positions per nod position

(centre observed twice) with 8 sec. each

- Chop freq = 2 Hz → 16 chop cycles per position

- Instrument overheads = 143 s- Slewing overhead = 180 s- Total time = 579 s (44% efficient)

• Predicted 1-σ sensitivities: - (1.4, 1.6, 1.3) mJy at (250, 350, 500) μm- Anticipated 1-σ extragalactic confusion level ~ 7 mJy

θ

SPIE meeting, Marseille June 23 2008 20

SPIRE Photometer SensitivitySmall (4x4 arcmin) Jiggle Map

• Typical observation- 64-point jiggle map with 9” spacing

- Over-sampled at 350, 500 μm - Half-beam sampling at 250 μm

- Nod cycle A-B-B-A-A-B-B-A- 64 s per nod position

→ 512 s integration time - 16 BSM positions per A-B pair

→ 4 sec. per BSM position→ 8 chop cycles per BSM position

• Instrument overheads = 433 s• Slewing overhead = 180 s• Total time = 1135 s (45% efficiency) • Predicted 1-σ sensitivities:

- (3.3, 4.5, 3.8) mJy at (250, 350, 500) μm• Can do it quicker (687 s; 37% efficiency)

- (4.7, 6.3, 5.3) mJy at (250, 350, 500) μm

SPIE meeting, Marseille June 23 2008 21

SPIRE Photometer SensitivityLarge Scan Map

• Typical observation- 30”/s scan speed- 30 x 30 arcmin- Cross-linked with 1 repeat

• 944 s on-source• Instrument overheads = 651 s• Slewing overhead = 180 s• Total time = 1775 s (53% efficiency) • Predicted 1-σ sensitivities:

- (10, 13, 11) mJy at (250, 350, 500) μm• Larger maps are more efficient

SPIE meeting, Marseille June 23 2008 22

SPIRE FTS SensitivityPoint Source; Line Spectroscopy (Δσ = 0.04 cm-1)

(W m-2 x 10-17 5-σ 1 hr)

SPIE meeting, Marseille June 23 2008 23

SPIRE FTS SensitivityPoint source; Spectrophotometery

(Δσ = 1 cm-1; mJy 5-σ 1 hr)

SPIE meeting, Marseille June 23 2008 24

SPIRE Current Status• System-level testing of

Herschel is in progress

• Spacecraft mechanical qualification tests done

• First operation in Herschel at 0.3 K in July- Verification of performance

• Some technical concerns to be evaluated:- Detector temperatures- Microphonic and EMI susceptibility- SMEC friction and microvibration

sensitivity

• Planning for operations in progress

Herschel/SPIRE Science GoalsSPIRE Block DiagramFTS Resolution