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Item The Interface Region Imaging Spectrograph (IRIS)(2014-02) De Pontieu, Bart; Title, Alan M.; Lemen, James; Kushner, G.D.; Akin, D.J.; Allard, A.; Berger, T.; Boerner, P.; Cheung, M.; Chou, C.; Drake, J.F.; Duncan, D.W.; Freeland, S.; Heyman, G.F.; Hoffman, C.; Hurlburt, Neal E.; Lindgren, R.W.; Mathur, D.; Rehse, R.; Sabolish, D.; Seguin, R.; Schrijver, C.J.; Tarbell, Ted D.; Wülser, J.P.; Wolfson, C.J.; Yanari, C.; Mudge, J.; Nguyen-Phuc, N.; Timmons, R.; van Bezooijen, R.; Weingrod, I.; Brookner, R.; Butcher, G.; Dougherty, B.; Eder, J.; Knagenhjelm, V.; Larsen, S.; Mansir, D.; Phan, L.; Boyle, P.; Cheimets, P.N.; DeLuca, E.E.; Golub, Leon; Gates, R.; Hertz, E.; McKillop, Sean; Park, Saehan; Perry, T.; Podgorski, W.A.; Reeves, Kathy K.; Saar, Steven; Testa, Paola; Tian, Hui; Weber, Mark A.; Dunn, C.; Eccles, S.; Jaeggli, Sarah; Kankelborg, Charles; Mashburn, K.; Pust, Nathan J.; Springer, LarryThe Interface Region Imaging Spectrograph (IRIS) small explorer spacecraft provides simultaneous spectra and images of the photosphere, chromosphere, transition region, and corona with 0.33 0.4 arcsec spatial resolution, twosecond temporal resolution, and 1 km s1 velocity resolution over a fieldofview of up to 175 arcsec × 175 arcsec. IRIS was launched into a Sunsynchronous orbit on 27 June 2013 using a PegasusXL rocket and consists of a 19cm UV telescope that feeds a slitbased dualbandpass imaging spectrograph. IRIS obtains spectra in passbands from 1332 1358 Å, 1389 1407 Å, and 2783 2834 Å, including bright spectral lines formed in the chromosphere (Mg ii h 2803 Å and Mg ii k 2796 Å) and transition region (C ii 1334/1335 Å and Si iv 1394/1403 Å). Slitjaw images in four different passbands (C ii 1330, Si iv 1400, Mg ii k 2796, and Mg ii wing 2830 Å) can be taken simultaneously with spectral rasters that sample regions up to 130 arcsec × 175 arcsec at a variety of spatial samplings (from 0.33 arcsec and up). IRIS is sensitive to emission from plasma at temperatures between 5000 K and 10 MK and will advance our understanding of the flow of mass and energy through an interface region, formed by the chromosphere and transition region, between the photosphere and corona. This highly structured and dynamic region not only acts as the conduit of all mass and energy feeding into the corona and solar wind, it also requires an order of magnitude more energy to heat than the corona and solar wind combined. The IRIS investigation includes a strong numerical modeling component based on advanced radiativeMHD codes to facilitate interpretation of observations of this complex region. Approximately eight Gbytes of data (after compression) are acquired by IRIS each day and made available for unrestricted use within a few days of the observation.Item Correcting for focal-plane-array temperature dependence in microbolometer infrared cameras lacking thermal stabilization(2013-01) Nugent, Paul W.; Shaw, Joseph A.; Pust, Nathan J.Advances in microbolometer detectors have led to the development of infrared cameras that operate without active temperature stabilization. The response of these cameras varies with the temperature of the camera’s focal plane array (FPA). This paper describes a method for stabilizing the camera’s response through software processing. This stabilization is based on the difference between the camera’s response at a measured temperature and at a reference temperature. This paper presents the mathematical basis for such a correction and demonstrates the resulting accuracy when applied to a commercially available long-wave infrared camera. The stabilized camera was then radiometrically calibrated so that the digital response from the camera could be related to the radiance or temperature of objects in the scene. For FPA temperature deviations within ±7.2°C changing by 0.5°C/min, this method produced a camera calibration with spatial-temporal rms variability of 0.21°C, yielding a total calibration uncertainty of 0.38°C limited primarily by the 0.32°C uncertainty in the blackbody source emissivity and temperature.Item Radiometric calibration of infrared imagers using an internal shutter as an equivalent external blackbody(2014-12) Nugent, Paul W.; Shaw, Joseph A.; Pust, Nathan J.Advances in microbolometer long-wave infrared (LWIR) detectors have led to the common use of infrared cameras that operate without active temperature stabilization, but the response of these cameras varies with their own temperature. Therefore, obtaining quantitative data requires a calibration that compensates for these errors. This paper describes a method for stabilizing the camera’s response through software processing of consecutive images of the scene and images of the camera’s internal shutter. An image of the shutter is processed so that it appears as if it were viewed through the lens. The differences between the scene and the image of the shutter treated as an external blackbody are then related to the radiance or temperature of the objects in the scene. This method has been applied to two commercial LWIR cameras over a focal plane array temperature range of ±7.2°C, changing at a rate of up to ±0.5°C/min. During these tests, the rms variability of the camera output was reduced from ±4.0°C to ±0.26°C.