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SkyMapper Protected Science Project

The Interstellar Extinction Curve for 2.2 < RV < 2.9

David Nataf (RSAA), Luca Casagrande (RSAA), Martin Asplund (RSAA)

The interstellar extinction toward the inner Galaxy is known to be steeper-than-standard (Udalski 2003; Zasowski et al. 2009), to be very high (Gonzalez et al. 2013) and to be spatially variable on very small scales in both its normalisation and in its wavelength-dependence (Nataf et al. 2013). As the extinction curve in the case of steep extinction is poorly-constrained empirically, systematic errors remain outstanding in either interpreting data toward the inner Galaxy, let alone applying steeper-than-standard extinction to extragalactic observations. We will exploit SkyMapper photometry in its unique filter combination - the filters are somewhat distinct from Sloan and DECam filters of the same name - to precisely calibrate the shape of the extinction curve in this low RV regime.