1 / 26

A SkyMapper Update

A SkyMapper Update. Stefan Keller. Who is SkyMapper?. Brian Schmidt (PS) Mike Bessell Peter Conroy Paul Francis Andrew Granlund Stefan Keller Errol Kowald A. Paddy Oates Tony Martin-Jones Tim Preston Patrick Tisserand Annino Vaccarella Mark Waterson.

lamya
Download Presentation

A SkyMapper Update

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A SkyMapper Update Stefan Keller

  2. Who is SkyMapper? Brian Schmidt (PS) Mike Bessell Peter Conroy Paul Francis Andrew Granlund Stefan Keller Errol Kowald A. Paddy Oates Tony Martin-Jones Tim Preston Patrick Tisserand Annino Vaccarella Mark Waterson

  3. 1.35m telescope with a 5.7 sq. degree field of view To conduct the Southern Sky Survey: Five year Multi-colour (6 filters) Multi-epoch (6 exposures, each filter) 2π steradians Limiting mag. g~23 Aiming for regular operations mid 2008 Summary of program: Keller et al. 2007 astro-ph 0702511 What is SkyMapper?

  4. We aim to fill the gap in the coverage of the Southern sky, matched to SDSS but with significant improvements: sky + temporal coverage; sensitivity to stellar parameters The Rapid Imaging Survey Era

  5. Where is the SkyMapper Telescope?

  6. The SkyMapper Telescope

  7. Level 2 Service Level Front Shutter Level 1 Thermally Isolated Equipment Level Rear Shutter Vent Door Level 3 Observing Space The SkyMapper Enclosure 11.5m tall 6m diameter

  8. Lightning Protection • A high incidence of lightning strikes in the vicinity (3/km2/yr) • Four air terminals mounted on the dome to ground plane of copper braid • Commercial lightning detection warning • park telescope in preferred orientation

  9. Telescope – Focal length & f/ ratio. 16224.75mm f/4.78 Telescope Optics 0.75m secondary Modified Cassegrain design 0.6m fused silica asphere 1.3m primary 2 x 0.45m fused silica spherics

  10. Guider Shack-Hartmann Filters Shutter SkyMapper Cassegrain Imager • Being built by RSAA • 16384x16384 pixel array Cooled with Closed-Cycle He system • Off-axis guider • Shack-Hartmann system for collimation, etc. • 6 Filters slots (< 20 second exchange time) • Bonn shutter (2ms accuracy)

  11. 32 E2V CCD44-82 devices: 2048x4096 15 micron pixel CCDs Broadband coated 40 micron (thick) deep depletion devices Reduced fringing, inc. red response 16384x163840.5” pixels Using new Pan Starrs controllers (Onaka) Readout in ~10-20seconds Readnoise ~8e- @ 12 seconds The SkyMapper CCDs

  12. The Design of the Southern Sky Survey

  13. 2π coverage: 4096 fields observed in six filters, six times per filter Cadence: hours, days, weeks, months, years star/galaxy photometry to 3% globally (g<18) astrometry to 50 (15 relative) milliarcsec (absolute) 36 images of each object over 5 years ⇒ proper motions to ±5(2) mas/yr. (i.e. σvtan=25km/s at 2.5 (6)kpc) ⇒ parallax ±5 (2) mas (i.e. 20pc (50) σd=10%) survey complete in 5 years The Southern Sky Survey

  14. SkyMapper Filter Set Ex-atmosphere

  15. u v g r i z 1 epoch 21.5 21.3 21.9 21.6 21.0 20.6 6 epochs 22.9 22.7 22.9 22.6 22.0 21.5 Sloan Digital Sky Survey comparison 22.0 n/a 22.2 22.2 21.3 20.5 Expected Survey Limits AB mag. for signal-to-noise = 5 from 110s exposures

  16. Understanding the illumination correction is fundamental In commissioning construct Illum. Corr. via dithered observations of a field Then rotate instrument and repeat... Develop 6 reference fields spaced in RA at dec~-20 Calibration Plans V+R from ESO 2.2m (Koch+03)

  17. Conduct Five-Second Survey in photometric conditions cover the southern sky w. 3x5 exposures: 8-15th mag During 5-s observe the highest two reference fields every 90 minutes primary standards: Stars in Walraven system with STIS spectrophotometry Anchor the deeper Main Survey to the Five-Second photometry and astrometry Enables the Main Survey to proceed under non-photometric conditions. Calibration Plans

  18. Raw Images, Flatfielded images, combined images Photometry - aperture, PSF, Kron, Petrosian Astrometry - Derived quantity datasbase parallax,proper motion image id (QSO, galaxy, star(type) What is in the Database

  19. Science Programs Utilising the Southern Sky Survey • Extremely Metal-Poor Stars • Galactic Structure • QSOs • Stromlo Missing Satellite Survey • Young Stars • Solar System Keller Da Costa Tisserand Jerjen Bessell Francis MORE WELCOME Science Programs External to the Southern Sky Survey • Planetary Transit Search • GRB + Low-z SNe • MgII of Southern Sky • Ha of Southern Sky • Variable Stars Sackett Schmidt Freeman Bessell Wood

  20. Blue Horizontal Branch Stars MS+BS logg=5 logg=2 ZAHB HBA RRL Teff: 10000K 6000K takes us out to distances >100kpc with low contamination

  21. The SDSS view Use a set of colour and spectroscopic indices to isolate BHBs Extend to 60kpc The SkyMapper View Photometric BHB selection to 130kpc with 5% contamination + RRLs obtained from time series Blue Horizontal Branch Stars From Sirko et al. 2004

  22. Extremely Metal-poor Stars in the Halo • Goal: find the first stars to have formed in the Universe: tell us about the assembly and chemical enrichment of the Galaxy • v-g is dependent on the level of metal line blanketing in the blue continuum • not perturbed dramatically by C-enhancement, chromospheric emission as affects objective-prism surveys F G

  23. Extremely Metal-poor Stars in the Halo Scale HES numbers for increased area, depth ~130 [Fe/H]<-5 Select a sample with photometrically derived [Fe/H]<-4 and g<18 returns this sample of spectroscopic [Fe/H]

  24. Data Release • Deliverables to the Outside User: • Data (epoch, RA, DEC, mags, galaxy shape info,…) to be available through a web-served interface which provides catalogs over a user defined area • Images to be available through a web-served interface which provides images over a user defined area • Data release will occur after extensive data validation: • Five-Second data after closure in RA and trial application to concurrently obtained main-survey data • FDR Main Survey 3 epochs all filters • SDR Main Survey 6 epochs all filters FL+1.5yrs FL+1.5yrs FL+>3yrs

  25. DONE Telescope has had first light in Jul in Tucson Final integration of imager undergoing Filters on track by end of year Dome done Software pipeline finishing up Telescope delivery (Jan?) Imager Delivery (Mar) Progress Regular Observations 2008

More Related