[en] The objective of this conference was to bring together scientists and engineers involved in atmospheric science, space physics, aeronomy, remote sensing, and optical instrumentation to exchange ideas and discuss recent developments in spectroscopic techniques and instrumentation in atmospheric and space research. There is growing concern about the human environment: the atmosphere, ocean, and space. To address those concerns and understand their changing environment, increasingly complex computer models have been developed with the advent of more powerful computers. Therefore, the validation of those models against direct measurements with advanced techniques and instruments is becoming increasingly more difficult and important. Optical spectroscopic techniques and instrumentation have contributed greatly to the validation of those models and their understanding of the earth's atmosphere and space environment. Improving techniques and instrumentation is becoming ever more important with more demanding requirements on the accuracy and resolution of atmospheric and space observations. This conference had sessions addressing current techniques and instrumentation from the ultraviolet to the infrared and microwave, and from ground-based facilities to satellite-borne missions. Separate abstracts were prepared for most of the papers in this volume

[en] The WIND Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS) is a CCD imager which views a selection of airglow emissions at the limb through a field-widened Michelson interferometer. Winds are calculated from the Doppler shifts of the spectral lines, detected as changes in the phase of the fringes. WINDII has been operating in space for almost three years and its performance has been monitored over that time. It continues to function well, though subtle changes have been seen. This paper is a discussion of the endurance of the instrument and of the changes that have occurred during the mission

[en] In a companion paper (Swift and Torr), the authors demonstrate a capability to observe thermospheric dayglow emissions from the ground using a novel photometric approach. In this paper they incorporate the principles of the technique into the design of a spectrometric facility capable of measuring the dayglow spectrum over the wavelength range 300 to 880 nm at < 0.5 nm resolution with photometric like sensitivity, namely 50 counts/R at 300 nm and ∼ 200 counts/R at 600 nm. The design is an all refractive f/1.4 distortion correctable grating spectrograph capable of operating over a full diurnal cycle with high sensitivity. The field of view is 14 degree. The instrument has a dynamic range of 10⁸, no moving parts except shutters, and a noise equivalent detection threshold of ∼ 15R in the daytime and 0.01 to 0.1 R at night. The design comprises four spectrometric modules which provide simultaneous measurements of emissions in the 300--900 nm range. A 1024 x 1024 CCD is used for the detector. The facility should provide simultaneous measurements from the ground of the rich spectral content of the daytime mesosphere, thermosphere and ionosphere

[en] The Solar EUV Experiment (SEE) investigation contributes primarily to the NASA Thermosphere, Ionosphere, and Mesosphere Energetics and Dynamics (TIMED) mission goal to characterize the sources of energy responsible for the thermal structure of the mesosphere, the lower thermosphere, and the ionosphere (MLTI). These energy sources include solar radiation, solar energetic particles, Joule heating, conduction, dynamical forcing, and chemical energy release. Of these energy inputs, the solar vacuum ultraviolet (VUV) radiation below 200 nm is the dominant global energy source for heating of the thermosphere, creating the ionosphere, and driving the diurnal cycles of wind and chemistry. The Solar EUV Experiment selected for the NASA TIMED mission will measure the solar vacuum ultraviolet (VUV) spectral irradiance from 0.1 to 200 nm. To cover this wide spectral range two different types of instruments are used: a grating spectrograph for spectra above 25 nm and an avalanche photodiode for spectra below 25 nm. As part of the in-flight calibration plan, silicon XUV photodiodes with thin film filters are used as stable broadband photometers between 0.1 and 40 nm. In addition, redundant spectrograph and avalanche photodiode capabilities provide calibration checks on the time scale of a month, and annual rocket underflight measurements provide absolute calibration checks traceable to NIST photometric standards. All three types of instruments have been developed and flight proven as part of a NASA solar EUV irradiance rocket experiment

[en] An advanced Fabry-Perot interferometer with an innovative focal plane detection technique called the Circle-to-Line Interferometer Optical (CLIO) system and high quantum efficiency CCD has been developed and field tested. During the field test at Ann Arbor, Michigan, 9 interference orders were collected simultaneously for the OH(7,3) P₁(3). A signal-to-noise ratio (SNR) of 10-100 was achieved with 1-minute integration. Compared with conventional FPI, the CLIO-FPI is more sensitive and capable of collecting airglow data at much higher temporal resolution. The first operational CLIO-FPI will be deployed at the Polar Cap Observatory (PCO) at Resolute, Northwest Territories, Canada (74 degree 54'N, 94 degree 54'W), in 1994. This new instrument is expected to enhance the ability to study the Earth's mesosphere and lower thermosphere

[en] The High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite has been providing measurements of the wind field in the stratosphere, mesosphere and lower thermosphere since November 1991. Examination of various calibration data indicates the instrument has remained remarkably stable since launch. The instrument has a thermal drift of about 30 m/s/degree C (slightly dependent on wavelength) and a long-term temporal drift that has amounted to about 80 m/s since launch. These effects are removed in the data processing leaving an uncertainty in the instrument stability of -2 nVs. The temperature control of the instrument has improved significantly since launch as a new method was implemented. The initial temperature control held the instrument temperature at about ±1 degree C. The improved method, which holds constant the temperature of the optical bench instead of the radiator, keeps the instrument temperature at about 0.2 degree C. The calibrations indicate very little change in the sensitivity of the instrument. The detector response has shown no degradation and the optics have not changed their transmittance

[en] A collaboration between Boston University and the Aerospace corporation has resulted in a germanium based detector used in conjunction with an infrared optimized Fabry-Perot spectrometer. Gold plated mirrors were installed and the appropriate transmissive optics are used in the Fabry-Perot to optimize the NIR transmission. The detector is a germanium PIN diode coated with a layer of silicon-nitride. Current produced by the detector is measured by using a Capacitive Trans-Impedance Amplifier (CITA). An A/D converter samples the amplified capacitor voltage and outputs a 12 bit word that is then passed on to the controlling computer system. The detector, amplifier, and associated electronics are mounted inside a standard IR dewar and operated at 77 K. The authors have operated this detector and spectrometer system at Millstone Hill for about 6 months. Acceptable noise characteristics, a NEP of 10^-17 watts, and a QE of 90% at 1.2 microm, have been achieved with an amplifier gain of 200. The system is currently configured for observations of thermospheric helium, and has made the first measurement of the He 10,830 angstrom nightglow emission isolated from OH contamination. In an effort to both increase the sensitivity of the Fabry-Perot in the visible and to adapt it for planetary astronomy the authors have entered into a collaboration with CIDTEC. A Charge Injection Detector or CID has some unique capabilities that distinguish it from a CCD and the authors are evaluating it as a detector for the Hadinger fringe pattern produced by a Fabry-Perot. The CID allows non-destructive readout and random access of individual pixels with in the entire frame, this allows for both ''electronic masking'' of bright objects and allows each fringe to be observed without having to readout a large number of dark pixels

[en] This paper describes Fabry-Perot/CCD annular summing applied to airglow observations. Criteria are developed for determining the optimal rectangular format CCD chip configuration which minimizes dark and read noise. The relative savings in integration time of the imaging Fabry-Perot/CCD system over the pressure-scanned Fabry-Perot/PMT system is estimated for the optimal configuration through calculations of the signal to noise ratios for three extreme (but typical) cases of source and background intensity. The largest savings in integration time in estimated for the daysky thermospheric [O¹D] (6,300 angstrom) case where the bright (∼ 5 x 10⁶R/angstrom) Rayleigh-scattered background dominates the read noise. The long integration times required to obtain useful signal to noise ratios for the faint (∼ 10R) nightsky exospheric hydrogen Balmer-α (6,563 angstrom) reduce the importance of the read noise term and yield large savings in integration time. The significance of the read noise term is greatly increased with the very short estimated integration times required for bright (∼ 200 R) nightsky lines such as thermospheric [O¹D]. Alternate CCD formats and applications methods that reduce read noise and provide improved performance in the latter case are compared against the CCD annular summing technique

[en] The authors describe a method for retrieving neutral thermospheric composition and solar EUV flux from optical measurements of the O+(²P) 732 nm and O(¹D) 630 nm airglow emissions. The parameters retrieved are the neutral temperature, the O, O₂, and N₂ density profiles, and a scaling factor for the solar EUV flux spectrum. The temperature, solar EUV flux scaling factor, and atomic oxygen density are first retrieved from the 732 nm emission, which are then used with the 630 nm emission to retrieve the O₂ and N₂ densities. Between the altitudes of 200 and 400 km the retrieval technique is able to statistically retrieve values to within 3.1% for thermospheric temperature, 3.3% for atomic oxygen, 2.3% for molecular oxygen, and 2.4% for molecular nitrogen. The solar EUV flux scaling factor has a retrieval error of 5.1%. They also present the results of retrievals using existing data taken from both groundbased and spacebased instruments. These include airglow data taken by the Visible Airglow Experiment on the Atmosphere Explorer spacecraft and the Imaging Spectrometric Observatory flown on the ATLAS 1 shuttle mission in 1992

[en] The Arizona Airglow Experiment (GLO) is a panchromatic Intensified CCD (ICCD) spectrograph, bore sighted with 12 monochromatic imagers. The spectrograph provides continuous spectral coverage from 1150 angstrom to 11,000 angstrom with a resolution of 5 angstrom to 20 angstrom. The spectrograph was designed to record simultaneously as much information as possible from a single column of gas. The resolution was selected to allow the determination of molecular emission vibrational and rotational structure. Molecular band emissions contain much more information than atomic lines, although interpretation of band emissions is more complicated. This complexity is due to the distribution of their energies over broad spectral ranges that overlap. The most productive method of interpreting molecular spectra is by modeling. The nature of the molecular transitions is well known, and synthetic spectra can be calculated to match the recorded spectrum accurately. Their knowledge of the transition probabilities allows accurate estimates of the intensity and shape of blended bands. It is the goal to synthesize all of the emissions recorded by the GLO as a tool to aid in detailed analysis of spectra. This work describes the approach used in calculating the synthetic spectra and references the source of parameters used for 14 band systems. This software utility will become a part of the GLO facility