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P. N. Bernasconi (JHU/ Applied Physics Laboratory), P. Foukal (CRI, Inc.), D. M. Rust (JHU/ Applied Physics Laboratory)
The Solar Bolometric Imager (SBI) is an innovative solar telescope capable of recording images in essentially total photospheric light, with an angular resolution of 5", sufficient to distinguish sunspots, faculae and enhanced network. These are the photospheric magnetic structures so far linked most closely to irradiance variation.
The balloon-borne SBI will provide the first bolometric maps of the photosphere, to evaluate the photometric contribution of magnetic structures more accurately than has been achievable so far, using spectrally selective imaging over restricted wavebands. More accurate removal of the magnetic feature contribution will enable us to determine whether other solar irradiance mechanisms exist besides the effects of photospheric magnetism.
The SBI detector is an array of 320 X 240 ferro-electric thermal IR elements whose spectral absorptance has been extended and flattened by a deposited layer of gold-black. The telescope itself is a 30-cm Dall-Kirkham design with uncoated primary and secondary pyrex mirrors. The combination of telescope and bolometric array provides an image of the solar irradiance with a flat spectral response between 0.28 um and 2.6 um, over a field of view of 15.2' X 11.4', and a pixel size of 2.8". After a successful set of ground-based tests, the instrument is being readied for a one-day stratospheric balloon flight that will take place in September 2003. The observing platform will be the gondola previously used for the Flare Genesis Experiment project (FGE), retrofitted to house and control the SBI telescope and detector. The balloon flight will enable SBI to image over essentially the full spectral range accepted by non-imaging space borne radiometers such as ACRIM, making the data sets complementary. The SBI flight will also provide important engineering data to validate the space worthiness of the novel gold-blackened thermal array detectors, and verify the thermal performance of the SBI's uncoated optics in a vacuum environment.
This work was funded by NASA under grant NAG5-10998.
The author(s) of this abstract have provided an email address for comments about the abstract: pietro.bernasconi@jhuapl.edu
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.