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Title: Hubble space telescope calspec flux standards: Sirius (and Vega)

The Space Telescope Imaging Spectrograph (STIS) has measured the flux for Sirius from 0.17 to 1.01 μm on the Hubble Space Telescope (HST) White Dwarf scale. Because of the cool debris disk around Vega, Sirius is commonly recommended as the primary IR flux standard. The measured STIS flux agrees well with predictions of a special Kurucz model atmosphere, adding confidence to the modeled IR flux predictions. The IR flux agrees to 2%-3% with respect to the standard template of Cohen and to 2% with the Midcourse Space Experiment absolute flux measurements in the mid-IR. A weighted average of the independent visible and mid-IR absolute flux measures implies that the monochromatic flux at 5557.5 Å (5556 Å in air) for Sirius and Vega, respectively, is 1.35 × 10{sup –8} and 3.44 × 10{sup –9} erg cm{sup –2} s{sup –1} Å{sup –1} with formal uncertainties of 0.5%. Contrary to previously published conclusions, the Hipparcos photometry offers no support for the variability of Vega. Pulse pileup severely affects the Hp photometry for the brightest stars.
Authors:
 [1]
  1. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
Publication Date:
OSTI Identifier:
22340247
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 147; Journal Issue: 6; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AIR; ATMOSPHERES; FORECASTING; INFRARED RADIATION; MONOCHROMATIC RADIATION; PHOTOMETRY; PULSE PILEUP; RADIO TELESCOPES; SPACE; STARS; WEIGHT; WHITE DWARF STARS