A Next Generation High-speed Data Acquisition System for Multi-channel Infrared and Optical Photometry

We report the design, operation, and performance of a next generation high-speed data acquisition system for multi-channel infrared and optical photometry based on the modern technologies of Field Programmable Gate Arrays, the Peripheral Component Interconnect bus, and the Global Positioning System. This system allows either direct recording of photon arrival times or binned photon counting with time resolution up to 1-$\mu$s precision in Universal Time, as well as real-time data monitoring and analysis. The system also allows simultaneous recording of multi-channel observations with very flexible, reconfigurable observational modes. We present successful 20-$\mu$s resolution simultaneous observations of the Crab Nebula Pulsar in the infrared (H-band) and optical (V-band) wavebands obtained with this system and 100-$\mu$s resolution V-band observations of the dwarf nova IY Uma with the 5-m Hale telescope at the Palomar Observatory.Comment: 11 pages, including 4 figures, to appear in PAS

Testing of mid-infrared detector arrays for FORCAST

This paper presents results on performance testing of mid-infrared detector arrays for the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST). FORCAST is a two-channel camera that utilizes a Si:As blocked impurity band (BIB) 256 × 256 detector array for imaging through discrete filters at 5 - 25 microns, and a Si:Sb BIB 256 × 256 detector array for imaging at 25 - 40 microns, over a 3.2\u27 × 3.2\u27 field of view, under high thermal background conditions. DRS Technologies has designed and fabricated several Si:As BIB and Si:Sb BIB engineering grade detector arrays which we test as candidate arrays for FORCAST. We present their initial laboratory test performance results

High speed, highly flexible reconfigurable data acquisition system for astronomy

We have developed a high speed, flexible, data acquisition system and targeted it to astronomical imaging. The system is based on Field Programmable Gate Arrays (FPGAs) and provides a gigabit/sec fiber optic link between the electronics located on the instrument and the host computer. The FPGAs are reconfigurable over the fiber optic link for maximum flexibility. The system has initially been targeted at DRS Technologies\u27 256×256 Si:As and Si:Sb detectors used in FORCAST1, a mid-IR camera/spectrograph built by Cornell University for SOFIA. The initial configuration provides sixteen parallel channels of six Msamples/second 14-bit analog to digital converters. The system can coadd 256×256 images at over 1000 frames per second in up to 64 different memory positions. Array clocking and sampling is generated from uploaded clocking patterns in two independent memories. This configuration allows the user to quickly create, on the fly, any form of array clocking and sampling (destructive, non-destructive, sample up the ramp, additional reset frames, Fowler, single frames, co-added frames, multi-position chop, throw away frames, etc.) The electronics were designed in a modular fashion so that any number of analog channels from arrays or mosaics of arrays can be accommodated by using the appropriate number of FPGA boards and preamps. The preamp/analog to digital converter boards can be replaced as needed to operate any focal plane array or other sensor. The system also provides analog drive capability for controlling an X-Y chopping secondary mirror, nominal two position chopping, and can also synchronize to an externally driven chop source. Multiple array controllers can be synchronized together, allowing multi-channel systems to share a single chopping secondary, yet clock the focal planes differently from each other. Due to the flexibility of the FPGAs, it is possible to develop highly customized operating modes to maximize system performance or to enable novel observations and applications

FORCAST: The facility mid-IR camera for SOFIA

We report on new development and testing of FORCAST, the Faint Object infraRed Camera for the SOFIA Telescope. FORCAST will offer dual channel imaging in discrete filters at 5 - 25 microns and 30 - 40 microns, with diffraction-limited imaging at wavelengths \u3e 15 microns. FORCAST will have a plate scale of 0.75 arcsec per pixel, giving it a 3.2 arcmin × 3.2 arcmin FOV on SOFIA. In addition, a set of grisms will enable FORCAST to perform long slit and cross-dispersed spectroscopic observations at low to moderate resolution (R ∼ 140 - 1200) in the bandpasses 4.9 - 8.1 microns, 8.0 - 13.3 microns, 17.1-28.1 microns, and 28.6 - 37.4 microns. FORCAST has seen first light at the Palomar 200-inch telescope. It will be available for astronomical observations and facility testing at SOFIA first flight