Abstract
In light of the increased application of absolutely calibrated data obtained in the infrared (IR) from space to a variety of very demanding scientific and applied fields, with global climate monitoring and modeling just two very obvious examples of such fields, it is increasingly important that the relative spectral response (RSR) of each sensor be measured in an end-to-end fashion. The RSR is a critical part of understanding where the photons came from in a scene, and in the interpretation of the data. Notwithstanding the criticality of such a measurement, sometimes programmatics (schedule drivers and cost constraints) drive a program to launch a sensor with only a model based on theory, or component characterization, or a combination, in place. Even sensors which have been measured end-to-end prior to launch may undergo changes during subsequent storage or handling on the ground, during the vibration of launch, or in the on-orbit environment. On-orbit changes may be induced by contamination events, high energy particle effects (including South Atlantic Anomaly effects) in coatings or detector arrays or even electronics, or interactions with the environment (such as chemical interactions with atomic oxygen, for example). While a scannable monochromatic source is not available on-orbit, one can at least check the validity of the RSR by observing a collection of well-calibrated stars with a range of temperatures. This paper will enumerate the range of sources that can be used for such an assessment that are currently being studied as part of The Aerospace Corporation's absolute calibration of stellar spectral energy distributions (SEDs) work, and how these SEDs can be used for the assessment of RSR models. While one may not be able to "fix" an RSR, there are potential work-arounds for some types of problems, and that effort will be discussed.
This work is supported at The Aerospace Corporation by the Independent Research and Development program. Partially based on data from the Maui Space Surveillance System, which is operated by Detachment 15 of the U.S. Air Force Research Laboratory's Directed Energy Directorate.
Russell, Kim, Skinner & Sitko: Visiting astronomers at the Infrared Telescope Facility, which is operated by the University of Hawaii under Cooperative Agreement no. NNX-08AE38A with the National Aeronautics and Space Administration, Science Mission Directorate, Planetary Astronomy Program.
The Use of Bright, Cool Variable Stars along with Hot Stars to Assess RSR Model Accuracy
In light of the increased application of absolutely calibrated data obtained in the infrared (IR) from space to a variety of very demanding scientific and applied fields, with global climate monitoring and modeling just two very obvious examples of such fields, it is increasingly important that the relative spectral response (RSR) of each sensor be measured in an end-to-end fashion. The RSR is a critical part of understanding where the photons came from in a scene, and in the interpretation of the data. Notwithstanding the criticality of such a measurement, sometimes programmatics (schedule drivers and cost constraints) drive a program to launch a sensor with only a model based on theory, or component characterization, or a combination, in place. Even sensors which have been measured end-to-end prior to launch may undergo changes during subsequent storage or handling on the ground, during the vibration of launch, or in the on-orbit environment. On-orbit changes may be induced by contamination events, high energy particle effects (including South Atlantic Anomaly effects) in coatings or detector arrays or even electronics, or interactions with the environment (such as chemical interactions with atomic oxygen, for example). While a scannable monochromatic source is not available on-orbit, one can at least check the validity of the RSR by observing a collection of well-calibrated stars with a range of temperatures. This paper will enumerate the range of sources that can be used for such an assessment that are currently being studied as part of The Aerospace Corporation's absolute calibration of stellar spectral energy distributions (SEDs) work, and how these SEDs can be used for the assessment of RSR models. While one may not be able to "fix" an RSR, there are potential work-arounds for some types of problems, and that effort will be discussed.
This work is supported at The Aerospace Corporation by the Independent Research and Development program. Partially based on data from the Maui Space Surveillance System, which is operated by Detachment 15 of the U.S. Air Force Research Laboratory's Directed Energy Directorate.
Russell, Kim, Skinner & Sitko: Visiting astronomers at the Infrared Telescope Facility, which is operated by the University of Hawaii under Cooperative Agreement no. NNX-08AE38A with the National Aeronautics and Space Administration, Science Mission Directorate, Planetary Astronomy Program.