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IR wide field imaging MPIA IR projects and studies

Stability of IR-arrays for robotized observations at dome C Rainer Lenzen Max-Planck-Institut für Astronomie, Heidelberg. OMEGA2000: NIR WFI Calar Alto NACO: NIR AO-supported Imager and Spectr. (VLT) LUCIFER: NIR AO-supported Imager and Spectr. (LBT)

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IR wide field imaging MPIA IR projects and studies

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  1. Stability of IR-arrays for robotized observations at dome CRainer LenzenMax-Planck-Institut für Astronomie, Heidelberg 27.3.2007, Tenerife

  2. OMEGA2000: NIR WFI Calar Alto NACO: NIR AO-supported Imager and Spectr. (VLT) LUCIFER: NIR AO-supported Imager and Spectr. (LBT) T-OWL study: TIR and MIR at a 100m telescope Science case Atmospheric constrains Technical realization Problems MIDIR study: TIR and MIR at a 30m/42m/60m telescope Dito, especially for new E-ELT design PRIME/Dune (ESA Corner Stone) All sky 0.5µm – 1.8µm survey 4x0.5 square deg 0.15/0.3 arcsec/pixel ARENA: TIR and MIR wide field 0.18arcsec/pixel at J,H,K, 8 arrays Hawaii II 0.18 arcsec/pixel at L,M 8 arrays InSb 0.36 arcsec/pixel at N,M 8 arrays Si:As IR wide field imagingMPIA IR projects and studies 27.3.2007, Tenerife

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  5. Table 20: List of available TIR and MIR detector arrays Infrared Arrays 27.3.2007, Tenerife 1 Lucas et al., 1994

  6. Wise: cryogenic 40cm-telescope 3.5, 4.7, 12, 23 µm bands simultaneously 4x 1kx1k: 2 HgCdTe, 2 Si:As pixel size:2.7arcsec confirmation Oct 2006 50% budget reduction 1m->40cm Spitzer JWST MIR survey competitors Mission 27.3.2007, Tenerife

  7. NIR Quantum efficiency of Hawaii-2 array #1005 in H-band Dark current of Hawaii-2 array #1005 27.3.2007, Tenerife

  8. NIR/TIR Mosaic of 2x2 2Kx2K λc =5 µm HgCdTe arrays 27.3.2007, Tenerife

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  12. Readout noise as function of number of Fowler sample pairs. 27.3.2007, Tenerife

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  14. Gemini (NIRI science array) 27.3.2007, Tenerife *IMPORTANT NOTE regarding GCAL flats and flatfield accuracy:

  15. MIR Relative quantum efficiency of MIRI detectors. 27.3.2007, Tenerife

  16. basic specifications of the Aquarius 1Kx1K Si:As array. 27.3.2007, Tenerife

  17. Readout topology of Aquarius array. 27.3.2007, Tenerife

  18. 320x240 CRC 774 Si:As array used for ground based instruments such as Michelle, Timmi2, TRECS, VLTI-MIDI, COMICS ... 27.3.2007, Tenerife

  19. NIR: best choice: twilight flats sophisticated dome flats or instrumental flats calibrated by sky-flats, use variable DITs How to produce Flat-fields at Dome C • TIR/MIR: best choice: reconstruction from dithered science obs. Dark current frames required! 27.3.2007, Tenerife

  20. Detector temperature should be stable within +/- 0.005 K. Relatively easy to meet by temperature controller (NACO, CRIRES, ISAAC...) Stabilization of voltages typically within mV. Technically no problem if independent on external temperature variations (Temperature stabilization of electronics racks). d(ln Gain)/dT= (2-3)x10-4 /K NIR flat field should be taken every 24h. MIR flat field is deduced from dithered images. Flat field Stability 27.3.2007, Tenerife

  21. Continuous use over years Cold ambient No maintenance in situ, no human intervention Icing problem Solutions: CCC instead of LN2 and LHe, respectively Entrance window ventilation Pulse tube cooler at higher frequencies to avoid orientation dependence instead of Stirling type or Gifford-McMahon TB specified for low ambient temperatures Special constrains at Dome-C 27.3.2007, Tenerife

  22. Aging of IR arrays: storage aging (near ambient temperature at non-operation state) thermo-cycling aging (“significant only after hundreds of cycles”) operational aging (not considering radiation damage for space application) Based on experience at Omega2000, CRIRES, NACO etc. (Gert Finger, H.-U. Käufl), operational aging of arrays is not observed over > 5years, neither QE nor hot/dead pixels. Detector aging mainly due to thermal cycling (not a problem here) Main problems arise from long time contamination of the detector due to bad vacuum conditions, power interruption, dust within the cryostat (black painting abrasion, Zeolith, etc.). In consequence, special care should be taken in the design of the cryostat to avoid such long time problems. Long time Stability 27.3.2007, Tenerife

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