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2006), then one should add in 0.063 to all of the Bayestar17 extinction coefficients. If one assumes that A H / A K = 1.74 ( Nishiyama et al. 2005), then an additional 0.141 should be added to all of the Bayestar17 extinction coefficients. If one instead assumes that A H / A K = 1.55 ( Indebetouw et al. This necessarily produces an underestimate of the gray component of the extinction vector. The Bayestar17 extinction coefficients were derived under the assumption of zero reddening in the WISE W 2 passband. Because the near-infrared extinction coefficients are smaller than those at optical wavelengths, near-infrared extinction estimates are more affected (percentually) by uncertainty in the gray component than optical extinctions.
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For example, the ratio of E( g-r ) to E( J-K ) is better constrained than A g, A r, A J or A Ks individually. This is due to the uncertainty in the gray component of the extinction vector (corresponding to an overall additive change to all extinction coefficients), which is not as well constrained as the ratios of reddenings in different filter combinations. Note that the Bayestar15 extinction coefficients differ more from those used by Bayestar17 in the near-infrared than in the optical. Table 3: Bayestar15 extinction coefficients ( R ) g The extinction coefficients assumed by Bayestar15 are as follows: For 2MASS passbands, Bayestar15 assumes a Cardelli et al. Therefore, in order to convert our values of E( B-V ) to extinction in various filter systems, consult Table 6 of Schlafly & Finkbeiner (2011) (use the values in the R V = 3.1 column), which are based on the Fitzpatrick (1999) reddening law. Although this was originally supposed to be the excess B-V in the Landolt filter system, Schlafly & Finkbeiner (2011) found that it differs somewhat from the true stellar B-V excess. In contrast, Bayestar15 reports uses the same units as Schlegel, Finkbeiner & Davis (1998) reddenings. (1) and (2) above also hold for Bayestar17, and reddening in non-PS1 passbands can be obtained by multiplying Bayestar17 by the coefficients in Table 6 of Schlafly & Finkbeiner (2011).
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Just as with Bayestar19, the normalization of Bayestar17 was chosen to predict the same E( g-r ) as one unit of the original SFD reddening map, so Eqs. In order to convert Bayestar17 to extinction in Pan-STARRS 1 or 2MASS passbands, multiply the value reported by the map by the following coefficients: Table 2: Bayestar17 extinction coefficients ( R ) g (1) to hold, then Bayestar19 is equivalent to SFD, and reddening in non-PS1 passbands can be obtained by multiplying Bayestar19 by the coefficients in Table 6 of Schlafly & Finkbeiner (2011). The overall normalization of Bayestar19 was chosen so that one unit of Bayestar19 reddening predicts the same E( g-r ) as one unit of the original SFD reddening map. For example, applying the R V = 3.1 Fitzpatrick (1999) reddening law to a 7000 K source spectrum, as done in Table 6 of Schlafly & Finkbeiner (2011), one obtains the relationsīecause the Fitzpatrick (1999) reddening law is different from the reddening law we assumed when producing Bayestar19, the two above relations give slightly different conversions between the values reported by Bayestar19 and E( B-V ). In order to convert to extinction or reddening in other passbands, one must assume some relation between extinction in Pan-STARRS 1 or 2MASS passbands and other passbands. In order to convert Bayestar19 to extinction in Pan-STARRS 1 or 2MASS passbands, multiply the value reported by the map by the following coefficients: Table 1: Bayestar19 extinction coefficients ( R ) g 1998), which is not quite equal to E( B-V ) (see the recalibration of SFD undertaken in Schlafly & Finkbeiner 2011). All three versions of the map are intended to provide reddening in a similar unit as SFD ( Schlegel et al. (2016), Bayestar15 relies on the extinction relations of Fitzpatrick (1999) and Cardelli et al. While Bayestar19 and Bayestar17 assume the slightly different versions of the reddening vector derived by Schlafly et al. This is primarily due to the different extinction laws assumed by the three versions of the dust map. The units of Bayestar19, Bayestar17 and Bayestar15 differ.