The Precision Solar Photometric Telescope (PSPT) is the centerpiece of the National Science Foundation (NSF) Radiative Inputs from Sun to Earth (RISE) program whose aim is to measure and understand variability in the solar radiative output. The PSPT produces seeing-limited full-disk digital (2048x2048) images in the blue continuum ( 409.4nm, FWHM 0.3nm ), red continuum ( 607.1nm, FWHM 0.5nm ), CaII K ( 393.4nm, FWHM 0.3nm ), CaII K Narrow Band Wing (NBW) (393.6nm, FWHM 0.1nm) , and CaII K Narrow Band Core (NBC) (393.4nm, FWHM 0.1nm) , with an unprecedented 0.1% pixel-to-pixel relative photometric precision. The upcoming addition of two narrow band CaIIK filters will also allow imaging of the CaIIK core to wing ratio with nearly the same precision.
The National Solar Observatory (NSO) designed and built three PSPT units, a prototype which is currently in operation at the Osservatorio Astronomico di Roma (OAR) , and two primaries for installation at NSO Sac Peak and Mauna Loa Solar Observatory (MLSO) . Currently, the units at MLSO and OAR are operated daily, with the NSO Sac Peak unit set aside for debugging and spare parts.
The High Altitude Observatory (HAO) of the National Center for Atmospheric Research (NCAR) operates the MLSO PSPT and has been processing and archiving the data since 1998. Requests for data from March 1998 through December 2004 can be made by email to HAO/NCAR. Data from January 2005 onward is available using the Downloads tab at the top of this page.
The PSPT at Mauna Loa Solar Observatory has been acquiring daily images of the Sun since April 1998. Data for the period April 1998 to 31 December 2004 is available by request from the HAO/NCAR . Data extending back to 1996 can be obtained from Osservatorio Astronomico di Roma . Images from 1 January 2005 to present are available from the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder through the Downloads tab at the top of this page.
The Solar Radiation Physical Modeling (SRPM) image mask is based on a semi-empirical center-to-limb corrected thresholding scheme (Fontenla et al. 1999, ApJ 518, 480). The scheme (briefly described in mask image header) employs the red continuum images to isolate sunspot umbral and penumbral pixels and the CaIIK images to separate the facular (bright plage), plage, active network, network, and quiet Sun components. Pixel values in the mask are assigned as follows: off disk (0), quiet-sun (2), network (3), active network (4), plage (5), faculae (6), sunspot umbra (7), and sunspot penumbra (8). All pixels with cosine of the heliocentric angle (mu) less than 0.15 are arbitrarily labeled quiet Sun.
Full disk magnetograms taken at Mauna Loa can be obtained from the Global Oscillation Network Group (GONG) .