The Herschel Space Observatory

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The Herschel Space Observatory
Whee!

• James Di Francesco
• Herzberg Institute of Astrophysics

1738-1822
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What is Herschel?!

• 3.5 m diameter space
• telescope
• covers 57 - 670 mm
• to be launched by ESA
• in 2008
• 4th ESA cornerstone
• missions from Horizon
• 2000 plan

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Payload Module
Mirror Assembly
Service Module
Sunshield/shade
Herschel Space Observatory
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Why go into space?
Whee!
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Why go into space?
submillimetre wavelengths
transparent
350 mm
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2
5
10
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9 mm
opaque
longer wavelength
shorter wavelength
No atmospheric absorption!!
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Herschel Primary Science Goals

• The cool universe formation of galaxies and
  stars,
• ISM physics/chemistry, solar system objects

• Herschels large aperture, low background and no
• atmospheric attenuation high sensitivity

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Herschel in Context the Past
IRAS (1983) o.57 m aperture - all sky survey at
12, 25, 60, 100 mm - low-res spectroscopy at 7.5
- 23 mm
ISO (1995-1998) o.60 m aperture - photometry at
2.5 - 240 mm - spectroscopy at 2.4 - 197 mm
KAO (1974-1995) o.91 m aperture - photometry
and spectroscopy from ll 20 mm to 500 mm
many instruments
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Herschel in Context the Present
JCMT (1987 - ?) 15 m aperture - photometry at
450 850 mm (SCUBA2) - spectrpy at 1300, 850,
650, 450 mm
Spitzer (2003 - 2008?) 0.85 m aperture -
photory at 3.6, 4.5, 5.8, 8.0 mm (IRAC), 24,
70, 160 mm (MIPS) - spectroscopy at 5-38 mm (IRS)
ASTRO-F Akari (2006 - ?) 0.685 m - 4-band
all-sky survey at 50-200 mm (FIS) -
imaging/spectrpy at 1.8-26 mm (IRC)
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Herschel Factoids

• primary diameter 3.5 m (large!)
• primary material SiC with a thin
• reflective Al layer plasil layer
• primary WFE lt 6
• telescope temperature lt 90 K
• telescope emissivity lt 4
• abs/rel pointing (68) lt 3.7 / 0.3
• science instruments 3
• cryostat lifetime gt 3.5 years
• height / width 7.5 m / 4 m
• launch mass 3200 kg
• power 1500 W

cold side
hot side
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Herschel Science Team at ESTEC on 2006 Feb
1 Spacecraft in structural thermal test
configuration Flight cryostat parts of flight
service module and sunshade installed
Whee!
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Herschel located in large Lissajous orbit around
L2
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Herschel Instruments

• PACS (Photodetector Array Camera and
  Spectrometer)
• SPIRE (Spectral and Photometric Imaging
  REceiver)
• HIFI (Heterodyne Instrument for the Far-Infrared)

HIFI
SPIRE
PACS
(EQMs)
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Herschel Instruments

• Photometry/Imaging 6 bands at 75-500 mm
• - PACS 1.7 x 3.5 FOV at 75/110 mm and 170
  mm
• - SPIRE 4 x 8 FOV at 250, 363 and 517 mm
• - sensitivity 1 mJy - 1 s - 1 hour
  (confusion!)
• - no chopping! (no spatial filtering of
  emission)
• - angular resolution 15 x (l/250 mm)

PACS
SPIRE
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Herschel Instruments

• Spectroscopy 57 - 670 mm range, R 20 - 107
• - PACS (grating) 0.8 FOV at 57 - 210 mm,
• R 1500 - 4000, 5 x 5 spatial x 16
  spectral pixels
• - SPIRE (FTS) 2.6 FOV at 200 - 670 mm,
• R 20 - 100
• - HIFI (heterodyne) 1-pixel FOV at 157 - 212
  mm and
• 240 - 625 mm (no gaps), 4000 channels, R
  107

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Confusion Limitations

• Photometric Confusion

Zod- iacal dust
inter stellar dust
inter galtic dust
exgal bkgrd
CMB
- extragalactic confusion 1 source / 20
beams - interstellar dust cirrus w. powerlaw
fluctuations - both improve w. instrumental
resolution - Herschel Confusion Noise Model
made by scaling COBE/ISO data, etc. to
PACS/SPIRE bands - determining actual
confusion will be major PV activity
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Confusion Limitations

• Spectroscopic Confusion

Schilke et al. (2001)
- U lines problematic (but not like OMC1
everywhere)
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Herschel Timeline Telescope

• 2008 August - LAUNCH
• travel to L2, cooldown
• commissioning performance verification
• science demonstration workshop
• routine science operations (36 months)
• - 1000 days of available time (2009-2011)
• - 1/3 share is Guaranteed Time (GT) to
  instrument teams
• - 2/3 share is Open Time (OT) to world
  community
• three Calls for Proposals (Cycles) foreseen
• - one for Key Projects (gt100 hrs), GT OT
• - two for regular programs, GT OT
• - in every cycle, GT before OT observations

6 mos.
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Herschel Timeline Data

• issue AO as late as possible, to maximize
  timeliness of
• scientific programmes and knowledge of
  instruments
• 2007 Feb 1 AO for KP proposals issued
• 2007 Apr 5 deadline for GT KP proposals
• 2007 Jul 5 selection/announcement of GT KP
  projects
• 2007 Nov 1 deadline for OT KP proposals
• 2008 Feb 28 selection/announcement of OT KP
  projects
• 2008 Feb 28 AO for regular GT proposals
• 2008 Apr 3 deadline for GT1 proposals
• 2008 Jun 5 selection/announcement for GT1
  projects
• 2008 August LAUNCH

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Space Astronomy Proposals

• given limited time (and maybe the promise of
  extra
• ), space astronomy observing time is often
  heavily
• oversubscribed (e.g., HST 10!)
• also, relatively few proposal opportunities
  available
• during lifetime of any given satellite
• need to have the highest quality proposals
  possible, with
• very little room for largesse (in words or in
  time!)

Google image search for working hard
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Herschel Pre-Observations
Google image search for waiting

• space observations require careful planning and
  program
• optimization (mission costs 1o6 euros/day!)
• use Astronomical Observing Templates (AOTs)
  to script a series of Astronomical
  Observing Requests
• (AORs) to execute a program, minimize overheads
• For this, Herschel will use HSPOT, a variant of
  the Spitzer
• Observing Tool (SPOT) extremely easy and fun
  to use!

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Herschel Post-Observations

• data reduced using single, coherent package
  HCSS-DP
• Java-based, platform independent - no licences
  to buy
• toolbox to aid interactive analysis (IA) of data
• generation of standard data products and
  relevant quality
• information (SPG QC pipelines)
• up to GT groups to provide extra tools
• extensive, online context sensitive
  documentation
• data will be in FITS format and VO-compliant

Google image search for data reduction
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Summary

• Herschel will probe a relatively unexplored
  regime of
• the EM spectrum at high sensitivities
• data will be very complementary to JCMT, ALMA
• 2/3 observing time is available to the world
  community,
• 2009-2011
• For more info see http//www.rssd.esa.int/hersche
  l

Whee!
Whee!
Whee!
The end???