10654(  1) - 04/05/05 12:20  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      10654
                                                       Version: 1
                                                       Check-in Date: 05-Apr-2005
                                                                      16:19:53

1.Proposal Title:
Absolute Spectrophotometric Calibration to 1% from the FUV through the near-IR
------------------------------------------------------------------------------------
2. Proposal For  3. Cycle  4. Parallel Pointing Tolerance
AR               14        <none>
------------------------------------------------------------------------------------
5. Investigators
                                                                                     Contact?
    PI: Dr. David S. Finley               Eureka Scientific Inc.
   CoI: Dr. Ralph Bohlin                  Space Telescope Science Institute             N
   CoI: Dr. Ivan Hubeny                   University of Arizona                         N
   CoI: Dr. Claus Leitherer               Space Telescope Science Institute             N

------------------------------------------------------------------------------------
6. Abstract

We propose a significant improvement to the existing HST calibration. The current
calibration is based on three primary DA white dwarf standards, GD 71, GD 153, and G
191-B2B. The standard fluxes are calculated using NLTE models, with effective
temperatures and gravities that were derived from Balmer line fits using LTE models.
We propose to improve the accuracy and internal consistency of the calibration by
deriving corrected effective temperatures and gravities based on fitting the
observed line profiles with updated NLTE models, and including the fit results from
multiple STIS spectra, rather than the (usually) 1 or 2 ground-based spectra used
previously. We will also determine the fluxes for 5 new, fainter primary or
secondary standards, extending the standard V magnitude lower limit from 13.4 to
16.5, and extending the wavelength coverage from 0.1 to 2.5 micron. The goal is to
achieve an overall flux accuracy of 1%, which will be needed, for example, for the
upcoming supernova survey missions to measure the equation of state of the dark
energy that is accelerating the expansion of the universe.
------------------------------------------------------------------------------------
                                                10654(  1) - 04/05/05 12:20  - [  2]

            Summary Form for Proposal  10654

  Item                         Used in this proposal
------------------------------------------------------------------------------------------------------------------------------------
  Proposal Category            AR
------------------------------------------------------------------------------------------------------------------------------------