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The RSS-NIR Spectrograph Detector System Progress Gregory Mosby, Jr. RSS-NIR - PI Dr. Marsha Wolf University of Wisconsin - Madison NIR spectroscopy provides extensive scientific opportunities. Young/low mass stellar evolution. Obscured QSOs GLIMPSE Break age/Z degeneracy Urrutia et al 2008 (ACS Composite Images---I band for red, g band for blue and green) Richards et al 2009 RSS-NIR designed as a prime focus semi-warm instrument. The RSS-NIR detector system controlled with software from IUCCA. -40 oC Pre-Dewar Cryogenic Dewar H2RG + MUX 4 Primary Voltages SIDECAR ASIC IUCAA ISDEC preamps ADCs FPGA high speed USB interface clock reset flash memory voltage regulators 6 Currents 5 Voltages Many other options Data Acquisition Computer fiber optic link RSS-NIR is using a Hawaii-2RG HgCdTe detector. Hawaii H2RG (2048x2048) -HgCdTe -1.7 µm cutoff Teledyne SIDECAR ASIC -Optimized for 100 kHz -Re-optimized for 200 kHz IUCCA ISDEC controller w/ IUCCA Software NIR instrumentation has several unique challenges: NIR detector arrays have higher read noise than CCDs Loose et al 2007 NIR instrumentation has several unique challenges: Thermal background is a critical constraint. NIR instrumentation has several unique challenges: Persistence in NIR detector arrays must be minimized or calibrated. Smith et al. 2005 Initial tests were completed in a test dewar with engineering grade detector. Automated read noise testing was used to help optimize noise to <20 e-. Tests have begun with science detector in cooled instrument dewar. We have estimated the gain of the SG detector to be slightly higher than theoretically predicted. Tackling the read noise Fowler mode readout reduces noise by factor of 2. Up-the-ramp group should reduce noise and help with saturation and cosmic rays. Checking out the background. Thermal background measurements look promising. Opaque Cutoff Clear Empty Persisting. Initial persistence testing show a single trap emission time constant of ~103 s. Future work Implement up-the-ramp algorithm for read noise reduction. Measure persistence decay time constants—as a function of stimulus and relative intensity. Measure improvements of up-the-ramp group sampling and persistence calibration. RSS-NIR Detector Properties Characteristic RSS-NIR (200 kHz) CDS Read Noise (SIDECAR +IUCCA board ) 4.9 e- CDS Read Noise (Full System, 18dB) 17.7 e- Trap emission time constant 103 s Measured Gain (18 dB) 2.4 e-/DN Thermal background at -40 C (Cutoff filter) 0.021 e-/s Automated RSS longslit analysis (Ralf Kotulla ) results of quasar host galaxies Cosmic ray rejection algorithm selection in development. Flux calibration to follow as well. Code will be publicly available after testing. Summary Using diffusion k-means we make a reduced basis set for stellar population modeling. Y I1 We compared results of the DFK basis set with those of the TB basis set on 6 different SFHs and 2 SFHs including QSO light with synthetic data. I2 O 1) DFK recovers values within 25% of the input A_V, and mass fraction in the Y, I1, and O age bins (tie for I2) more often. 2) DFK has the fewest values outside of 100% (catastrophic failures) of the input value for A_V and the mass fractions in all age bins. Mosby et al 2015: http://arxiv.org/abs/1408.3335