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The Herschel Space Observatory

The Herschel Space Observatory. James Di Francesco Herzberg Institute of Astrophysics. Whee!. 1738-1822. What is Herschel?!. 3.5 m diameter space telescope covers ~57 - 670 m m to be launched by ESA in 2008 4th ESA “cornerstone” missions from Horizon 2000 plan.

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The Herschel Space Observatory

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  1. The Herschel Space Observatory James Di Francesco Herzberg Institute of Astrophysics Whee! 1738-1822

  2. 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

  3. Payload Module Mirror Assembly Service Module Sunshield/shade Herschel Space Observatory

  4. Why go into space? Whee!

  5. Why go into space? submillimetre wavelengths transparent 350 mm 1 2 5 10 4 8 9 mm opaque longer wavelength shorter wavelength No atmospheric absorption!!

  6. Herschel Primary Science Goals • The cool universe: formation of galaxies and stars, • ISM physics/chemistry, solar system objects • Herschel’s large aperture, low background and no atmospheric attenuation = high sensitivity

  7. 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

  8. Herschel in Context: the Present JCMT (1987 - ?); 15 m aperture - photometry at 450 & 850 mm (SCUBA2) - spectr’py at 1300, 850, 650, 450 mm Spitzer (2003 - 2008?); 0.85 m aperture - photo’ry 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/spectr’py at 1.8-26 mm (IRC)

  9. Herschel Factoids • primary diameter = 3.5 m (large!) • primary material = SiC with a thin reflective Al layer + plasil layer • primary WFE < 6% • telescope temperature < 90 K • telescope emissivity < 4% • abs/rel pointing (68%) < 3.7” / 0.3” • science instruments = 3 • cryostat lifetime > 3.5 years • height / width ~ 7.5 m / 4 m • launch mass = 3200 kg • power ~ 1500 W cold side hot side

  10. 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!

  11. Herschel located in large Lissajous orbit around L2

  12. 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)

  13. 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

  14. PACS SPIRE HIFI 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

  15. Confusion Limitations • Photometric Confusion: Zod- iacal dust inter stellar dust inter gal’tic 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

  16. Confusion Limitations • Spectroscopic Confusion: Schilke et al. (2001) - “U” lines problematic (but not like OMC1 everywhere)

  17. 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 (>100 hrs), GT & OT - two for regular programs, GT & OT - in every cycle, GT before OT observations } 6 mos.

  18. 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

  19. 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”

  20. 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!

  21. 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”

  22. 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/herschel Whee! Whee! Whee! The end???

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