Pan-STARRS observational requirements specification

Outline Benchmark design specs –Telescopes –Detectors –Pipeline –Data products –Precision goals Specification of observational requirements –Format for input to science DWG

Pan-STARRS in a Nutshell Who? –IfA - detectors, pipelines, science, site; MHPCC - data processing; SAIC - massive databases; Lincoln Lab - detectors What? –Dedicated wide field optical survey A  =54 m 2 deg 2 –“pilot project” for LSST How? –Funded by AFRL –1st year (design development) funded - 2nd year funding in place - total system cost ~$40M When? –To be operational in 2006

Telescope specs 4 x 1.8-2m RC + WF corrector 7 sq deg FOV F/4 or ~  m/arcsec A  = 4 x m 2 deg 2 –MEGACAM, SUPRIMECAM ~ 8 m 2 deg 2 Filters: BVRIZ, R+V (U?) Dedicated follow up telescope?

Detectors Array of arrays –4 x (8 x 8) x (8 x 8) x (512 x 512) = 4 x 1Bn pixels OTCCD 0”.3 pixels -> 12  m pitch ~2s read out ~3e read noise –  2 read = 0.1  2 t ~ 15 s (V+R)

The Orthogonal Transfer Array (OTA) A new paradigm in large imagers OTCCD pixel structure Basic OTCCD cell OTA: 8x8 array of OTCCDs

OTCCD Array

Electronics – Signal Chain SDSU dual channel video board –2 channels –150 kpixel/sec –CDS, 16 bit ADC –15 W power Analog Devices 9826 –3 channels (RGB) –15 Mpixel/sec –CDS, 16 bit ADC –250 mW power

Operation mode options Simultaneous –4 telescopes observe the same field –7 sq deg => ~6000 sq deg / 30s integration Independent –28 sq deg –Poorer rejection of cosmic ray and other backgrounds

The pipeline Image acquisition Flat fielding/sky subtraction/photo calibration Registration Warping to sky coordinates –0”.15-0”.2 sampling Stacking/cosmic ray rejection Convolution with PSF (rotated) Differencing Accumulation

Data products Cumulative sky images (BVRIZ…) –0”.15-0”.2 sampling –Catalogs Difference images –High resolution real-time stream –Lossy compressed -> archive –Transient catalogs Point source ML fits etc

Precision goals Photometry –~1% absolute –Better relative Astrometry –Statistical:  ~ 0”.07 (FWHM/0”.6)(5/SN) Floor at ~0”.003 –Systematics: < 0”.10 Coherent over ~10 arcmin

Performance summary Sensitivity (assuming 0.6” seeing) –T(R=24) = 58s –T(V=24.4) = 67s –T(R+V) = 31s 30s exposure -> 6000 sq deg / night Sky noise –7e/s/pixel from sky (R+V) –Read noise ~2-3e is negligible for t >~ 20s Astrometry –Sigma=0”.07 (FWHM/0”.6) / (SN/5) –Systematics limited by atmosphere

Observational Requirements Specification Fundamental parameters –Sky coverage  –Depth/integration time t int –Repeat visit cadence requirements (if any) –Filter requirements Other requirements –Need for follow up? –Need for archival image data? –Time criticality? –Simultaneous multi-passband imaging?

Inputs to science design working group: Science case: –Science objectives –Why will this be interesting in ? Requirements for optimal performance –I.e. what if Pan-STARRS were used exclusively for this task Minimum requirements –Filters, integration times, follow up needs etc. External requirements (if any)