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