Brian Schmidt, Paul Francis, Mike Bessell, Stefan Keller

The SkyMapper Telescope A 1.3m telescope with an 8-sq degree FOV Located at Siding Spring Observatory First light in 2006 Fully Automated Replacement of the Great Melbourne Telescope

Why SkyMapper? There is no deep digital map of the southern sky and no instrument planned in the near future that can map the entire southern sky in multiple colours and at multiple epochs. Poor seeing of Australian sites a benefit – we can use larger pixels and cover sky more quickly. Science capabilities are broadly relevant to Australian Astronomy. Matched to capabilities of AA  on the Anglo-Australian Telescope. Natural Replacement for the destroyed 1.3m Great Melbourne Telescope.

Fundamental Goals of SkyMapper SkyMapper’s competitive advantage over other facilities is the ability to map sky to a depth required for its scientific goals as fast as possible, while retaining photometric and astrometric accuracy over a wide dynamic range of brightness and wavelength coverage. This implies: Maximising the imaged field of view of the telescope Obtaining best possible image quality with fully sampled pixels Broadband wavelength coverage from nm Minimal readout time Instrument which can be accurately characterised and calibrated.

The Skymapper Telescope Being built by Electro Optics Systems, (Queanbeyan & Tucson) 1.35m primary hyperbolic.71m secondary hyperbolic 0.54m fused silica asphere 2 x 0.45m fused silica spherics

The SkyMapper Imager 268 million pixel CCD mosaic constructed at Mount Stromlo Observatory 32 E2V CCD44-82 devices 2048x micron pixel CCDs Broadband coated 40 micron Deep depletion devices Leach III read out electronics, one channel per CCD Read-out time 20 seconds, readnoise 5e- 6 filters slots Cooled using closed cycle helium coolers Shack-Hartmann/autoguider.

SkyMapper Science 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 shape is it? Discovery of the metal poor stars in the halo Galactic Archaelogy – gravity and metallicity for 100,000,000 stars Accurate photometric calibration of Galaxy redshift surveys Identification of z>5 quasars Survey of quasars by variability Planetary transits Large number of intermediate z Supernovae Microlensing NEO

Virtual Observatory Optical Photometric and Astrometric Framework Complete sky coverage with photometry accurate globally to 0.03 mag and astrometry accurate, globally to 50mas. We will do the South – and matched to Pann-starrs in the north.

Expected Survey limits ugriz 90s- 1 epoch s - combined of 6 epochs Sloan Digital Sky Survey comparison

How Long is this going to take? SSO Astronomical hours per year: 3285 SSO useable hours per year: 1971 Seeing SSO obs time (hrs/yr)Any <2<1.5<1.2<0.9 Dark Grey Bright

Approximately 1000hrs per year where conditions are better than 2” in Dark and Grey 6 6 epochs * 4000 pointings of 120s each yields 4800 hours of telescope time, or roughly 4.8 years. (3 epoch survey will be completed within 2.4 years) A 5 second survey (for calibration) to be done in Bright time as will low galactic latitude r,i,z measurements.

Filter Choice Use SDSS standard ugriz –u to be a stellar- friendly (no flux above 3750A) –use vs filter ( A) to help with stellar work – potentially use Mg filter to get gravity of K giants

How do we do?

SkyMapper filters and Tycho bands(red)

SkyMapper Time Approx 75% of time for first 5years will go to survey, with the survey competing for the remaining time against other proposals which are not covered by the survey Survey can observe fields preferentially as needed by members of the community Data can be delivered flatfielded and with survey software to provide calibrated data for stars and galaxies within Hardware limits. Specialised software is the proposer’s responsibility

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 (maximum size will be limited) Images to be available through a web- served interface which provides images over a used defined area (maximum size will be limited)

How Much Data? 6 epochs x 6 colours x ,000,000 pixel images ~150 Terabytes 3 epochs x 6 colours 5 second survey image ~75 Terabytes + 25 Terabytes of calibration images 1 Billion Objects observed 36 times with Database is ~2 Terabytes (1 billion rows x 500 columns)

How Served Image data to be served as a tangent projected image over a specified RA, DEC range. These will be fully reduced and combined data and served as FITS All Individual frames (reduced) will be served as un-projected FITS files by RA DEC as full images Catalog will initially be served as RA and DEC regions only, with full relational operations on database to be done via some allocation process to keep within allowable resources.

Timeline Funding Decision, Jun 2004 Optical elements ordered Conceptual Design Review, Oct 2004 CCDs ordered, Feb 2004 Critical Design Review, July 2005 Site Works begin Dec 2005 First Light, Sep 2006 Regular Operations, 2007