34th Solar Physics Division Meeting, June 2003
Session 20 Instrumentation
Poster, Wednesday, June 18, 2003, 3:30-5:00pm, Mezzanine

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[20.02] The Solar Bolometric Imager: Characteristics and Performance.

P.N. Bernasconi (JHU/ Applied Physics Laboratory), P. Foukal (Heliospherics, Inc.), D.M. Rust (JHU/ Applied Physics Laboratory)

The Solar Bolometric Imager (SBI) is an innovative solar telescope capable of recording the first bolometric (integrated light) maps of the photosphere. It will enable evaluation of the photometric contribution of magnetic structures more accurately than has been achievable with spectrally selective imaging. The SBI has an angular resolution of ~5", sufficient to distinguish sunspots, faculae and enhanced network. These photospheric magnetic structures are known to be linked closely to irradiance variations. Accurate removal of irradiance variations linked to the magnetic features will enable us to determine if other solar irradiance variation mechanisms exist.

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 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 sun with a flat spectral response between 0.28 microns and 2.6 microns, over a field of view of 917" x 687", and a pixel size of 2.8". After completion of ground tests, the balloon-borne instrument will make a one-day stratospheric flight in September 2003.

Observing from an altitude of over 30 km, the SBI will image the sun over nearly the full spectral range accepted by non-imaging satellite-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 to verify the thermal performance of the SBIís optics in a vacuum environment.

Here we will describe the SBI in more detail and present the results of various instrument performance tests, including solar observations from the ground, in preparation for the balloon flight.

This work is 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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