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S. Kent (FNAL), S. Allam (NMSU/FNAL), R. Bohlin (STScI), S. E. Deustua (AAS), M. Lampton (Berkeley), B. Laubscher (LANL), N. Mostek, S. Mufson (Indiana), M. W. Richmond (RIT), J. A. Smith (LANL/Wyoming), D. L. Tucker (FNAL)
The Supernova/Acceleration Probe (SNAP; http://snap.lbl.gov), a space mission planned for launch in 2009, will observe over 2000 Type Ia supernovae out to a redshift of z=1.7 in order to measure the equation of state of the Universe and its time derivative. In order to accomplish this goal, the supernova light curves must be accurately measured at a variety of wavelengths spanning the optical and near infrared. Furthermore, the fluxes measured in the optical and in the near infrared must be well calibrated relative to each other.
The flux calibration of the SNAP instruments will be based upon a combination of spectrophotometric standards, including hot white dwarfs and solar analogs. Most current HST spectrophotometric standards have apparent magnitudes brighter than about V = 13. SNAP, however, will routinely measure objects fainter than V = 25 and, under normal operations, the SNAP imaging detectors will saturate for such bright standards. Clearly fainter standards are needed.
To this end, we in the SNAP Calibration Group are currently pursuing a project to calibrate a set spectrophotometric standards in the SNAP North field down to V=19 using data from the Sloan Digital Sky Survey, the ARC 3.5m telescope, and the HST STIS and NICMOS instruments. Here, we describe this project and our initial results.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.