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Introduction to and methods of SPACE-based observational astronomy

Introduction to and methods of SPACE-based observational astronomy. 1 st MAGPOP School (Budapest, Aug 23-25 2006). Armando Gil de Paz (Universidad Complutense de Madrid). Current Space Observatories with GO/GI programs: (Guest Observer/Guest Investigator). Scheme.

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Introduction to and methods of SPACE-based observational astronomy

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  1. Introduction to and methods of SPACE-based observational astronomy 1st MAGPOP School(Budapest, Aug 23-25 2006) Armando Gil de Paz (Universidad Complutense de Madrid)

  2. Current Space Observatories with GO/GI programs: (Guest Observer/Guest Investigator) Scheme 1st MAGPOP School(Budapest, Aug 23-25 2006) HST GALEX Spitzer MAGPOP’s favorites!

  3. Other current Space Observatories with GO/GI programs: Scheme Chandra Akari (Astro-F) FUSE 1st MAGPOP School(Budapest, Aug 23-25 2006) XMM-Newton Integral

  4. Past/Present/ Future Space Observatories: 1st MAGPOP School(Budapest, Aug 23-25 2006)

  5. Today’s lecture Scheme Covering the basics: • Why observing from Space? Image quality, low background, transparency VS. Costs & risks HST 1st MAGPOP School(Budapest, Aug 23-25 2006) • Description of the Observatory • Preparing a HST proposal: • Constraints, APT, etc. • Using Archival Data: MAST

  6. tomorrow Scheme GALEX • Description of the Observatory • Preparing a GALEX proposal • Bright-star and background limitations • Using Archival Data 1st MAGPOP School(Budapest, Aug 23-25 2006) Spitzer • Description of the Observatory • Preparing a Spitzer proposal: Using Spot • Observing constraints, pipeline, & latents • Using Archival Data: Using Leopard

  7. friday Scheme Past: • Using IUE, IRAS, ISO data Future: • James Webb Space Telescope (JWST) 1st MAGPOP School(Budapest, Aug 23-25 2006) Space-based Astronomy Tools and Science: • Use of Space-based data • Synergy with ground-based data (e.g. HST-Keck/VLT, JWST-ALMA)

  8. Ups Space Astronomy: Why? No atmosphere • Better image quality (no atmospheric seeing) FWHMseeing~-0.2 ; Diffraction limit = /D Mauna Kea (average) 1st MAGPOP School(Budapest, Aug 23-25 2006) Antarctica (average) Antarctica (best 25%) Diff.Lim 2m Diff.Lim 8m

  9. Antarctica Ups Space Astronomy: Why? No atmosphere • Better transparency & no cloudy nights 1st MAGPOP School(Budapest, Aug 23-25 2006)

  10. Antarctica Ups Space Astronomy: Why? No atmosphere • Less (scattered and thermal) background 1st MAGPOP School(Budapest, Aug 23-25 2006)

  11. In high orbits (Earth-trailing, L2) • Longer lasting (& fixed) CVZ • Lower thermal background from Earth • No South Atlantic Anomaly passages Ups Space Astronomy: Why? Existence of Continuous Viewing Zones (CVZ) 1st MAGPOP School(Budapest, Aug 23-25 2006) HST HDF observations in CVZ

  12. Downs Higher risks Space Astronomy: Why? • Not 100% launch and deploy successful rates (e.g. HETE, Abrixas, ASTRO-E, WIRE) • Telescope & instruments never tested under exact working conditions (e.g. HST). • Difficult to repair if something fails. Impossible for satellites in high orbits. 1st MAGPOP School(Budapest, Aug 23-25 2006) Limited lifetime • Instrument consumables (cooling: NICMOS, ISO, Spitzer) • Propellant (to compensate for atmospheric drag -Compton GRO- or angular momentum build up -JWST) • Gyros (despite redundant systems).

  13. Downs Space Astronomy: Why? Higher costs • For both telescope & instruments plus launch cost. • Example: All four VLTs cost ~1/7 HST. 1st MAGPOP School(Budapest, Aug 23-25 2006) Source: Federation of American Scientists

  14. Downs Space Astronomy: Why? Higher rates of high-energy particles: • Cosmic-rays events in HST detectors are several times higher than in the ground (1.5-3% ACS/WFC pixels affected in 1000s). • This situation is worse in high orbits (5%-10% pixels expected to be affected in a JWST 1000s exposure) where there is no protection by the Van Allen belts. 1st MAGPOP School(Budapest, Aug 23-25 2006) Single 600s-long HST ACS/WFC raw image

  15. Space Astronomy: Specifics These Ups and downs determine the specifics of the analysis methods used in Space Astronomy: • High-spatial res. & Diff.Lim. images: PSF phot. (HST, Spitzer) • Low background: Highly Poissonian statistics (HST & GALEX) • High cosmic-rays rates: (HST CR-SPLIT) 1st MAGPOP School(Budapest, Aug 23-25 2006) Specifics of the instrumentation used in Space Observatories exploring new windows (UV, FIR): • Count-rate, color, and position-dependent PSF (GALEX & MIPS) • Multiple time constant response (MIPS 70 & 160um) • Confusion limits (GALEX & MIPS)

  16. 2.5-m telescope in a low orbit (600 km) deployed in 1990. • Current functioning instruments: ACS, NICMOS, WFPC2 • Replaced or non-functioning (“legacy”) instruments: FOC, FOS, GHRS, HST, WF/PC, STIS • New service mission (SM4) has not yet been decided. Hubble Space Telescope 1st MAGPOP School(Budapest, Aug 23-25 2006)

  17. Imaging: HST Instruments 1st MAGPOP School(Budapest, Aug 23-25 2006)

  18. Choosing the right imaging instrument: HST Instruments 1st MAGPOP School(Budapest, Aug 23-25 2006)

  19. Slitless spectroscopy: (no long-slit spectroscopy since STIS failure in 2004) HST Instruments 1st MAGPOP School(Budapest, Aug 23-25 2006)

  20. Feasibility: Proposing for HST • Reasonable number of orbits (compared with the expected scientific return and number of people involved). Use ETC. • The assumptions for determining the number of orbits are well justified and the overheads are properly accounted for. • Also address: 2-gyros mode impact, parallel observations. 1st MAGPOP School(Budapest, Aug 23-25 2006) Need for HST: • HST (and only HST) can address this particular science topic. • Available in the MAST archive? If so, justify additional time. Flexibility: • Long & frequent visibility windows and no unnecessary timing or orientation constraints.

  21. Orbit: 96 min long. Most objects partially occulted by the Earth (up to 44 min/orbit). CVZ within 24o the orbital poles. • (Note: CVZ should not be requested for background-limited broad-band imaging or observations with timing constraints, special orientation requirements, or ToO) • SAA: Although precession cycle is 56 days (so objects can be in the CVZ for many days in a row), the SAA limits the longest continuous observation to 5-6 orbits. • Pointing constraints: Within 60o of the Sun, 20o of the Earth and 9.5o of the Moon. Additional constraints for the ACS/SBC MAMA detector apply. • Other constraints: Since Aug 2005, HST is observing in two-gyros mode. Proposing for HST: Constraints 1st MAGPOP School(Budapest, Aug 23-25 2006)

  22. HST Phase I: APT First steps: • Documentation: Call for Proposals, HST Primer, and relevant instrument (ACS, NICMOS, WFPC2) handbook. • Get Scientific Justification LaTeX/Word/PDF template • Software: Proposer Tool (APT) & Visualizer (VTT, Aladin) • (See APT training materials!) 1st MAGPOP School(Budapest, Aug 23-25 2006)

  23. HST Phase I: APT 1st MAGPOP School(Budapest, Aug 23-25 2006)

  24. Images can be retrieved using starview and visualized using VTT (included in APT) or directly from MAST. • Data formats (see the instruments data handbooks): Multiextension FITS: Science, data quality and error arrays • Extensions:RAW, FIT, CRJ, DRZ (ACS & STIS), _raw, _ima, _cal, _mos (NICMOS), _d0f, _c0f (WFPC2) • WFPC2 associations: 15000 combined WFPC2 images created from associations of 50000 individual WFPC2 frames. • Images are VO complaint. HST archive: MAST 1st MAGPOP School(Budapest, Aug 23-25 2006)

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