The SkyMapper Telescope

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					SkyMapper

         SkyMapper and
 the Stromlo Southern Sky Survey




            Stefan Keller, Brian Schmidt, Paul
                Francis and Mike Bessell
     Research School of Astronomy & Astrophysics   Slide 1
SkyMapper
                   What is SkyMapper?
 • 1.35m with a 5.7 sq.
   degree fov
 • To reside at Siding
   Spring Observatory
 • First light in Dec 2006
 • To conduct a multi
   colour/epoch Stromlo
   Southern Sky Survey
 • Replacement for the 50”
   Great Melbourne
   Telescope




       Research School of Astronomy & Astrophysics   Slide 2
SkyMapper
                   Why a SkyMapper?

 • There is no deep digital optical map of the southern
   sky
 • no instrument is planned that can map the entire
   southern sky in multiple colours and epochs
 • SkyMapper will provide an automated large-scale
   imaging capability that is matched to Australian:
    – Science strengths;
    – Instrumentation (AAOmega, Gemini etc.), and;
    – Conditions – poor seeing a benefit  cover the sky faster!



     Research School of Astronomy & Astrophysics                   Slide 3
SkyMapper
       The Stromlo Southern Sky
              Survey = S4
 • Major component of SkyMapper telescope will be
   providing a survey of the southern sky
    – Multi-colour, multi-epoch of southerly 2 steradian
    – Star and Galaxy photometry (3% global accuracy)
    – Astrometry (better than 50 mas )
    – Cadence: hours, days, months and years.
    – Five years to complete
    – Data supplied to the community without
      proprietary period as part of Virtual Observatory
      work
 • Complementary to SDSS but w. improvements!


     Research School of Astronomy & Astrophysics            Slide 4
SkyMapper
                             Survey Science

     The survey science goals are broad but some of the areas where I
     think SkyMapper stands to have largest impact are:

 •   What is the distribution of large Solar-System objects beyond Neptune?
 •   What is the history of the youngest stars in the Solar neighbourhood?
 •   How far does the dark matter halo of our galaxy extend and what is its
     shape?
 •   Gravity and metallicity for on order of 100 million stars  the assembly
     and chemical enrichment history of the bulge, thin/thick disk and halo?
 •   Extremely metal poor stars.
 •   Undiscovered members of the local group
 •   accurate photometric calibration of galaxy redshift surveys: 2dF/6dF.
 •   bright z>6 QSOs  probes of the ionization history of the Universe.




        Research School of Astronomy & Astrophysics                         Slide 5
SkyMapper
                SkyMapper Filter Set
                                                   Ex-atmosphere




     Research School of Astronomy & Astrophysics                   Slide 6
SkyMapper
                      Expected S4 limits

                         u             vs            g      r      i      z
   1 epoch             21.9          21.9           21.8   21.8   20.9   20.2
   expt. time            55            35           25     25     15     15

   6 epochs            22.9          22.9           22.8   22.8   21.9   21.2

    Sloan
  Digital Sky
                       22.0           n/a           22.2   22.2   21.3   20.5
    Survey
  comparison




      Research School of Astronomy & Astrophysics                               Slide 7
SkyMapper
                              z – coverage
                                                   Spectroscopic redshifts
               SDSS (EDR)                          r’<18 for SDSS
                                                   BJ<19.5 ( r’<18.5) for
                2dFGRS                                2dFGRS




                                                   Photometric redshifts
                                                   SDSS to r’=20.5
                                                   From SDSS EDR Csabai 2003


                                                   S4 to provide:
                                                   Spirals to z~0.3-0.4
                                                   E0 to z~0.7
     Research School of Astronomy & Astrophysics                           Slide 8
SkyMapper
   SkyMapper and SUMSS/SKAMP
  By cross-comparison of radio and optical
     sources we can ask:
  Which members of known classes of optical
     objects are detected as radio sources?
  …and with redshifts we can ask:
  • How does the radio luminosity function
     evolve with redshift?
  • Quantify 3D clustering of radio sources
                                                           SUMSS+DSS
                                                       From Sadler & Hunstead 1999

 • around 1.5% SUMSS detections are galaxies in the 2dFGRS (B<19.5)
 • 30% are bright enough to appear in the DSS (B<22) [Sadler + Hunstead 2001]
 The Stromlo Southern Sky Survey will go around a magnitude fainter than
 the DSS
          photometric z ±0.06 for 30% of SUMSS

         Research School of Astronomy & Astrophysics                                 Slide 9
SkyMapper

                   S4 Data Products
 • 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 (maximum size will be limited)




     Research School of Astronomy & Astrophysics       Slide 10
SkyMapper
                          S4 Data Products
 How Much Data???

 6 epochs x 6 colours x 4000 268,000,000 pixel images
    150 Terabytes
 + 25 Terabytes of calibration images

 1 Billion Objects observed 36 times with
 Database is ~2 Terabytes (1 billion rows x 500 columns)




      Research School of Astronomy & Astrophysics          Slide 11
SkyMapper
              A Concluding Timeline
 • Funding Decision, Jun 2004
 • Optical elements ordered
 • Conceptual Design Review, Oct 2004
 • CCDs ordered, Feb 2004
 • Critical Design Review, August 2005
 • Pipeline development,
   mirror Blank Failures, Sep-Oct 2005
 • Site Works begin Dec 2005
 • First Light, Dec 2006
 • Regular Operations, Apr 2007


     Research School of Astronomy & Astrophysics   Slide 12
SkyMapper
              A Concluding Timeline
 • Funding Decision, Jun 2004
 • Optical elements ordered
 • Conceptual Design Review, Oct 2004
 • CCDs ordered, Feb 2004
 • Critical Design Review, August 2005
 • Data reduction pipeline development,
   mirror Blank Failures, Sep-Oct 2005
 • Site Works begin Dec 2005
 • First Light, Dec 2006
 • Regular Operations, Apr 2007


     Research School of Astronomy & Astrophysics   Slide 13