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National Science Foundation Award #0440787

Bolometric Solar Imaging

Investigator(s):

David Rust (PI) ; Pietro Bernasconi (Co-PI) ; Barry LaBonte (Co-PI) ; Peter Foukal (Co-PI)

Sponsor:

Johns Hopkins University, MD 21218 4105168668

Start Date/Expiration Date

2005-03-01 to 2006-02-28 (amended 2005-02-25)

Awarded Amount to Date:

$150,797

Abstract: This proposal is to design, build, and launch the Solar Bolometric Imager (SBI) and a Multi-Spectral Imager (MSI) on the Long Duration Balloon (LDB) from McMurdo during the austral summer of 2006-2007. The instruments will provide bolometric (i.e., wavelength-integrated light) and color temperature images of the Sun, which will be aimed to understand better sources of the solar irradiance variation and the corresponding effects on global terrestrial climate change. The current view is that during the 11-year sunspot cycle the total solar irradiance varies in proportion to the changes of Sun's local magnetic fields. At the upcoming sunspot minimum (2007), SBI observations will be able to detect if there are other sources of solar irradiance variation with the least confusion by signals from the magnetic fields. The SBI is a new instrument, a new approach to studying one of the fundamental problems in solar physics. The imager uses a 30-cm diameter F/12 Dall-Kirkham telescope with uncoated mirrors, and neutral density filters to provide broadband (bolometric) sensitivity that varies only by +/-7 percent over the wavelengths from 0.28 to 2.6 microns The SBI sensor has the unique capability to record images of the solar photosphere with a flat photometric response. The sensor is an array of 320 x 240 infrared-sensitive barium strontium titanate (BST) ferroelectric elements, with a film of gold black on the surface. The film will uniformly convert all absorbed solar radiation into thermal emission detectable by the underlying BST array. MSI will provide diagnostics of solar magnetic and thermal structures while SBI assesses their radiance. Each frame from the SBI and MSI will be precisely calibrated. Bursts of 60 to 120 frames of the same scene will be co-registered and summed to increase the signal-to-noise ratio. The scenes will be mosaicked to form images with 5-arcsec resolutions over the entire Sun. Sunspots, faculae, and magnetic filed network will be identified from the MSI images. Sonic filtering of the MSI images will isolate the oscillatory signal. That signal will be used to remove oscillations from SBI averages to reduce the solar noise. The calibrated, mosaicked SBI images will be used to derive data products such as 3D plots of intensity contrast versus distance from Sun center and magnetic flux. The images and data products will be openly available via the Web. The SBI/MSI telescopes will be carried into the stratosphere by a balloon-borne gondola used in previous Antarctic programs. Scientific ballooning is an ideal educational tool because it is relatively inexpensive and quick to produce results. The science team will include experienced experimentalists and a post-doctoral associate, at least one graduate student, and several student interns. The campaign will involve many ground-based observatories and satellite-borne radiometers from several countries.

NSF Org:

ANT - Antarctic Sciences Section

Award Number:

0440787

Award Instrument:

Continuing grant

Program Manager:

Vladimir Papitashvili
ANT Antarctic Sciences Section
OPP Office of Polar Programs

NSF Program(s):

ANTARCTIC AERONOMY & ASTROPHYS

Field Application(s):

Program Reference Code(s):

UNASSIGNED, 0000

Program Element Code(s):

5115