Bruce Pirger

PHARO: A Near‐Infrared Camera for the Palomar Adaptive Optics System

We describe Cornells near-infrared camera system PHARO (Palomar High Angular Resolution Observer) built for use with the JPL Palomar Adaptive Optics System on the 5 m Hale telescope. PHARO uses a HgCdTe HAWAII detector for observations between 1 and 2.5 mm wavelength. An all-reflecting 1024 # 1024

A Wide-Field Infrared Camera for the Palomar 200-inch Telescope

The availability of both large aperture telescopes and large format near-infrared (NIR) detectors are making wide-field NIR imaging a reality. We describe the Wide-field Infrared Camera (WIRC), a newly commissioned instrument that provides the Palomar 200-inch telescope with such an imaging capability. WIRC features a field-of-view (FOV) of 4.33 arcminutes on a side with its currently installed 1024-square Rockwell Hawaii-I NIR detector. A 2048-square Rockwell Hawaii-II NIR detector will be installed and commissioned later this year, in collaboration with Caltech, to give WIRC an 8.7 arcminute FOV on a side. WIRC mounts at the telescopes f/3.3 prime focus. The instruments seeing-limited optical design, optimized for the JHK atmospheric bands, includes a 4-element refractive collimator, two 7-position filter wheels that straddle a Lyot stop, and a 5-element refractive f/3 camera. Typical seeing-limited point spread functions are slightly oversampled with a 0.25 arcsec per pixel plate scale at the detector. The entire optical train is contained within a cryogenic dewar with a 2.5 day hold-time. Entrance hatches at the top of the dewar allow access to the detector without disruption of the optics and optical alignment. The optical, mechanical, cryogenic, and electronic design of the instrument are described, a commissioning science image and performance analyses are presented.

The infrared spectrograph on the Spitzer Space Telescope

The Infrared Spectrograph (IRS) is one of three science instruments on the Spitzer Space Telescope. The IRS comprises four separate spectrograph modules covering the wavelength range from 5.3 to 38 μm with spectral resolutions, R~90 and 650, and it was optimized to take full advantage of the very low background in the space environment. The IRS is performing at or better than the pre-launch predictions. An autonomous target acquisition capability enables the IRS to locate the mid-infrared centroid of a source, providing the information so that the spacecraft can accurately offset that centroid to a selected slit. This feature is particularly useful when taking spectra of sources with poorly known coordinates. An automated data reduction pipeline has been developed at the Spitzer Science Center.

The Infrared spectrograph on the Spitzer Space Telescope

The Infrared Spectrograph (IRS) is one of three science instruments on the Spitzer Space Telescope .T he IRS comprises four separate spectrograph modules covering the wavelength range from 5.3 to 38 � m with spectral resolutions, R ¼ k=� k � 90 and 600, and it was optimized to take full advantage of the very low background in the space environment. The IRS is performing at or better than the prelaunch predictions. An autonomous target acquisition capability enables the IRS to locate the mid-infrared centroid of a source, providing the information so that the spacecraft can accurately offset that centroid to a selected slit. This feature is particularly useful when taking spectra of sources with poorly known coordinates. An automated data-reduction pipeline has been developed at the Spitzer Science Center. Subject headingg infrared: general — instrumentation: spectrographs — space vehicles: instruments

PHARO (Palomar high-angular-resolution observer): a dedicated NIR camera for the Palomar adaptive optics system

We describe Corneirs NIR camera system for the Hale 200” telescope adaptive optics system at Palomar Observatory. The instrument is under construction at this time, and we expect first light at the telescope in December 1997. Here we summarize the camera’s design as well as its expected performance.

Evaluation of Si:As and Si:Sb blocked-impurity-band detectors for SIRTF and WIRE

Cryogenic telescopes in space offer dramatic reduction in thermal IR background flux. Outstanding performance in the areas of detector dark current, read noise, and radiation hardness are required to take full advantage of the sensitivity improvements possible with such facilities, especially in very low flux (2 to 100 photons/pixel/sec) applications such as the Infrared Spectrograph on SIRTF. We present our testing methods and our results on Si:As and Si:Sb block impurity band (BIB) detectors produced by Rockwell International for our SIRTF and WIRE applications. Remarkable recent results are the reduction of the multiple-sampling read noise to 30 electrons, reduction of dark current to 10 e-/s for Si:As and 40 e-/s for Si:Sb, the use of an antireflective coating to improve the detective quantum efficiency for Si:As, extension of the useful wavelength range of Si:Sb to 40 microns, and confirmation that lab data on a 50 s time scale can be extrapolated to integration times at least 10 times longer.

SCORE 1+: enhancing a unique mid-infrared spectrograph

SCORE is a cross-dispersed echelle spectrograph, built as a prototype for the Short-High module of SIRTFs IRS instrument. It operates over the 7.5-15 micrometers N-band atmospheric window, and has ben used on Palomars Hale telescope several times since November, 1996. Since the initial run, a number of improvements have ben undertaken or are in the process being undertaken which enhance SCOREs performance and simplify its operation. One such addition, now completed, is a second detector array which serves as a slit-viewer with 12 inch diameter field of view around the slit. This viewer allows easy acquisition and guidance for sources with dim or absent optical counterparts, and accurately registers the position of the slit on the source with the recorded spectrum. Software written in the IDL environment optimizes the extraction of spectra form SCOREs mid-IR crossed-echelle data. The echelle, while providing the advantage of increased pixel utilization, introduces several difficulties, including curved orders, order cross- talk, and differentially slanted lines. These and other instrumental artifacts must be removed to achieve the highest spectral signal-to-noise. The pixel efficiency will be further increased by the use of a grism predisperser. The grism will provide approximately even spacing between orders of the echelle, in contrast with the decreasing spacing towards shorter wavelength orders generated by the current grating. SCORE is already one of the most powerful short- slit spectrographs operating in this wavelength band, and, with the implementation of these improvements, will deliver even greater capability.

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 > 15 microns. FORCAST will have a plate scale of 0.75 arcsec per pixel, giving it a 3.2 arcmin x 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.

The Infrared Spectrograph* (IRS) on the Spitzer Space Telescope

The Infrared Spectrograph (IRS) is one of three science instruments on the Spitzer Space Telescope .T he IRS comprises four separate spectrograph modules covering the wavelength range from 5.3 to 38 � m with spectral resolutions, R ¼ k=� k � 90 and 600, and it was optimized to take full advantage of the very low background in the space environment. The IRS is performing at or better than the prelaunch predictions. An autonomous target acquisition capability enables the IRS to locate the mid-infrared centroid of a source, providing the information so that the spacecraft can accurately offset that centroid to a selected slit. This feature is particularly useful when taking spectra of sources with poorly known coordinates. An automated data-reduction pipeline has been developed at the Spitzer Science Center. Subject headingg infrared: general — instrumentation: spectrographs — space vehicles: instruments

A Next‐Generation High‐Speed Data Acquisition System for Multichannel Infrared and Optical Photometry

We report the design, operation, and performance of a next‐generation high‐speed data acquisition system for multichannel 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 μs precision in Universal Time, as well as real‐time data monitoring and analysis. The system also allows simultaneous recording of multichannel observations with very flexible, reconfigurable observational modes. We present successful 20 μs resolution simultaneous observations of the Crab Nebula pulsar in the infrared (H band) and optical (V band) wave bands obtained with this system and 100 μs resolution V‐band observations of the dwarf nova IY UMa with the 5 m Hale telescope at the Palomar Observatory.