AAS 204th Meeting, June 2004
Session 61 Structures in the Interstellar Medium
Poster, Wednesday, June 2, 2004, 10:00am-7:00pm, Ballroom

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[61.07] The Blue Tip of the Stellar Locus: Measuring Extinction with the SDSS

D. P. Finkbeiner, D. J. Schlegel, J. E. Gunn (Princeton), D. W. Hogg (NYU), Z. Ivezic, G. R. Knapp, R. H. Lupton (Princeton)

We present a robust procedure for measuring Galactic dust extinction with stars: the ``blue tip'' method. F turn-off stars (gabs ~4) reside on the blue tip of the stellar locus in ugriz color space and for g \ga 19m trace the total Galactic extinction along high-latitude lines of sight. We find this method to be robust, low noise, and relatively unbiased compared to common tracers such as the mean counts and colors of stars. Reddenings naively determined from mean stellar colors are found to be systematically biased by a factor of up to ~2 in (g-r) and (r-i) colors. The ``blue tip'' results are in excellent agreement with the SFD98 dust map for E(B-V) < 0.5m, with indications of deviations at higher reddening. The ugriz reddening vector is determined and found to agree with RV = 3.1 in most places.

The author(s) of this abstract have provided an email address for comments about the abstract: dfink@astro.princeton.edu

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