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What is Pan-STARRS?

Telescopes 4 x 1.8m 7 square degree FOV possible sites on Mauna Kea and Haleakala Operation mode: simultaneous imaging of the same field for transient/moving object detection broad band optical imaging multiple survey modes. Detectors 1Bn pixels per camera array of arrays 0”.3 pixels

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What is Pan-STARRS?

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  1. Telescopes 4 x 1.8m 7 square degree FOV possible sites on Mauna Kea and Haleakala Operation mode: simultaneous imaging of the same field for transient/moving object detection broad band optical imaging multiple survey modes Detectors 1Bn pixels per camera array of arrays 0”.3 pixels few second readout <5e- read-noise Data-Processing System Core pipeline will generate: snapshot images difference/summed images basic catalogs NEO system What is Pan-STARRS?

  2. Performance Summary • Sensitivity (assuming 0.6” seeing) • T(R=24) = 58s • T(V=24.4) = 67s • T(R+V=24) = 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

  3. Small vs Large Apertures • Why size matters: • small telescopes are cheaper for given collecting area • CCD costs scale with detector area (not Npixels) • Optimal design matches seeing to CCD resolution • rapid construction and low risk • Fast guiding for enhanced image quality • Low environmental impact

  4. Trends • Moore’s Law growth in CCD capabilities • Gigapixel arrays on the horizon • Improvements in computing and storage will track growth in data volume • Investment in software is critical, and growing • Future dominated by detector improvements Total area of 3m+ telescopes in the world in m2, total number of CCD pixels in Megapix, as a function of time. Growth over 25 years is a factor of 30 in glass, 3000 in pixels.

  5. For (D ~ 4 r0) ~35% of light is in a single bright speckle • guiding at ~10Hz gives PSF with diffraction limited core • “tip-tilt” on large apertures is relatively ineffective D = 1.5m D = 8m D=4m

  6. Detector Details – Orthogonal Transfer • Orthogonal Transfer • remove image motion • high speed (few usec) Normal guiding (0.73”) OT tracking (0.50”)

  7. File : C:\ZEMAX\panstars\PS-prelim-9.ZMX Title: Pan-STARRS preliminary design review Date : TUE DEC 9 2003 SURFACE DATA SUMMARY: Surf Comment Radius Thickness Glass Diameter Conic r**2 r**4 r**6 6 Primary -7850 -2257.85 MIRROR 1800 -1.52934 2.24e-21 7 Secondary -6658 2057.85 MIRROR 900 -18.6695 4.68e-19 9 LENS-1A 994.5 60 F_SILICA 640 0 10 LENS-1B 1732.7 10 640 0 11 LENS-2A 801.7 45 F_SILICA 620 0 12 LENS-2B 540.0 815 620 0 13 FILTER-A Infin 20 F_SILICA 530 0 14 FILTER-B Infin 100 530 0 15 LENS-3A -1928.5 50 F_SILICA 520 0 4.02e-10 1.51e-15 16 LENS-3B -1790.1 198.07 520 0 IMA CCD-ARRAY Infin 500 0

  8. Performance in U and Y • Optical Performance deteriorates at extreme ends of the optical region • Using a curved filter helps by giving extra refractive power

  9. Distortion

  10. Ghost Image Analysis • Pupil ghosts • Image ghosts

  11. Fabrication of the aspheric Optics • The asphericity of the mirrors is within established fabrication capability. • Dewar window is an order of magnitude less aspheric than the Sloan window ( 1 mm vs. 8mm)

  12. Listing of surface sag File : C:\ZEMAX\panstars\PS-prelim-9.ZMX Title: Pan-STARRS rounded Date : MON NOV 24 2003 Units are Millimeters. Semi diameter of surface 6: 9.000000E+002. Best Fit Sphere curvature : -1.269040E-004. Best Fit Sphere radius : -7.879973E+003. Best Fit Sphere residual : 2.979204E-002. (rms) Y-coord Sag BFS Sag Deviation Remove 0.0E+000 0.00000E+000 0.00000E+000 0.00000E+000 6.31004E-002 5.0E+001 -1.59234E-001 -1.58631E-001 6.03222E-004 6.37036E-002 1.0E+002 -6.36929E-001 -6.34545E-001 2.38346E-003 6.54839E-002 1.5E+002 -1.43305E+000 -1.42779E+000 5.25245E-003 6.83528E-002 2.0E+002 -2.54755E+000 -2.53848E+000 9.06295E-003 7.21633E-002 2.5E+002 -3.98035E+000 -3.96674E+000 1.36087E-002 7.67091E-002 3.0E+002 -5.73137E+000 -5.71275E+000 1.86243E-002 8.17247E-002 3.5E+002 -7.80049E+000 -7.77670E+000 2.37849E-002 8.68854E-002 4.0E+002 -1.01875E+001 -1.01588E+001 2.87063E-002 9.18067E-002 4.5E+002 -1.28924E+001 -1.28595E+001 3.29439E-002 9.60444E-002 5.0E+002 -1.59149E+001 -1.58790E+001 3.59936E-002 9.90940E-002 5.5E+002 -1.92549E+001 -1.92176E+001 3.72901E-002 1.00390E-001 6.0E+002 -2.29121E+001 -2.28759E+001 3.62077E-002 9.93081E-002 6.5E+002 -2.68862E+001 -2.68542E+001 3.20589E-002 9.51593E-002 7.0E+002 -3.11771E+001 -3.11530E+001 2.40945E-002 8.71949E-002 7.5E+002 -3.57844E+001 -3.57729E+001 1.15029E-002 7.46033E-002 8.0E+002 -4.07078E+001 -4.07144E+001 -6.59053E-003 5.65098E-002 8.5E+002 -4.59470E+001 -4.59782E+001 -3.11241E-002 3.19762E-002 9.0E+002 -5.15017E+001 -5.15648E+001 -6.31004E-002 0.00000E+000

  13. Tolerance Analysis • Sensitivity analysis of alignment • Monte Carlo modeling

  14. Wavefront Sensing and Telescope Collimation • Tests with OPTIC using a calcite block to make extrafocal images • OPTIC design has 0.5” disk at 4” separation • PS design could be as much as an 8” disk at 10” separation, enough for 50-100 resolution elements over pupil.

  15. In/extra Focal Images for Pan-STARRS r = 1.6 deg, SS filter Extra Intra Extra – Intra Nominal intra- and extra focal images, 4.4” diameter pupil 100m secondary decenter 0.01 deg secondary tilt

  16. Atmospheric Dispersion • In the broad Solar System filter, atmospheric dispersion dominates other aberration for zenith distances over 10 deg.

  17. PSF Area vs. Air Mass dispersion seeing charge diffusion trailing loss pixel

  18. Design Pan-STARRS Post PDR 3, incorporating an ADC

  19. A traditional ADC contains many additional air-glass surfaces and does not achieve acceptable image quality over the wide Pan-STARRS field. Therefore we did not seriously consider ADCs before PDR.

  20. ADC The design chosen has a rotating prism between fixed lenses. This avoids the large rotary seal and presents less of an engineering challenge and schedule risk. • Refractive indices match at 656 nm • Zero deviation • No added glass/air interfaces • No large diameter rotating seals • Relaxed tolerances on the flat surfaces Maximum correction No correction Siloxane Fused silica

  21. ADC prototype during filling procedure

  22. Design Pan-STARRS Final 2: ADC on maximum dispersion Note: Box is 5"x5"

  23. At 75° zenith distance, the ADC fully corrects atmospheric dispersion

  24. Telescope Studies • Vertex RSI, Richardson TX • Common alt-az • Common equatorial • EOST, Tucson AZ • Common alt-az • Independent alt-az • Independent equatorial

  25. Haleakala

  26. Schematic of EOS Ice Dome as PS1 Dome PS1EOS Ice Dome MAGNUM

  27. Mauna Kea CFHT UKIRT

  28. Conceptual Configurations for Pan-STARRS-4 in the UH 2.2 m telescope building

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