ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O B-Model O O O O B-Model I-Model O B-CelestialObject O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O B-Model I-Model O O O O O O O O O O O O O O O O B-Model I-Model I-Model O O O O O O O O O O O B-Wavelength O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O B-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Model O O O O O O O O O O O O O O O O O O O B-Model O O O O O B-Model O O O O O O B-Model I-Model I-Model O O O O O O O B-ObservationalTechniques I-ObservationalTechniques O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O O B-Wavelength O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O B-CelestialObject O B-CelestialObject O B-CelestialObject O O B-CelestialObject O O O O O O O O O O O O O O O O O O B-Model O O B-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength O O B-CelestialObject I-CelestialObject B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject O O O O O O O O O O O O O O O O O B-CelestialObject O O O O O O O O O O O O O O O O O O B-Citation I-Citation O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation O O B-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O B-Wavelength O O
tokens: of mag, with mag. The power law removes any degeneracy in the slope of the dust extinction law, and thus excludes the possibility of significant grey dust. Another example is GRB 120815A , whose SED is fit by a power law and SMC-like extinction to give an value of 0.08 mag, which is significantly smaller than the of 0.44 mag. We find that GRB 121024A is also best fit with a power law. Indeed, Fig. 9 shows that only one object that has an overpredicted was fit with a broken power law. Although there is strong evidence for dust destruction caused by the GRB itself ( Morgan et al. 2014 ), this would not cause a discrepancy between and . Any dust that extinguishes the GRB would also be visible in depletion, so if that dust is destroyed it is no longer visible in depletion or extinction. Fig. 9 as measured directly from the SED against that calculated from the DTM. The green line indicates a 1:1 conversion between the two. Blue circles represent SEDs best fit with a simple power-law, whereas red triangles are used for broken power-law fits. Empty points refer to depletion measured from low-resolution spectra. Large error bars are due to significant errors in several measured parameters being combined in quadrature. Intervening systems such as absorbers are known to contain similar quantities of dust as galaxies (e.g. Ménard Fukugita 2012 ), although QSO-DLAs tend to show very little reddening ( Krogager et al. 2016 ; De Cia et al. 2016 ). For the group (2) objects, we notice that 050820A , 100219A , 111008A , and 130408A all have intervening absorbing systems. Should these objects have a high dust content, they could significantly affect the SED of the GRB afterglow, such that the reddening caused by dust in the host galaxy itself is indeed smaller, and thus pushes these objects towards the 1:1 line. However, for these intervening systems to be the reason for a much higher than from DTM, they would need to contribute around 80% of the extinction along the line of sight, whereas the systems in our sample are much weaker in metal line absorption than the host DLA (e.g. in GRB 100219A, Thöne et al. 2013 ). We therefore find it unlikely that a significant amount of the extra extinction is caused by intervening systems. 6.5. Equivalent dust column density Having established that depletion is a good tracer of the dust, and with being accurate and reliable, we look to the relation used to calculate , Eq. ( 10 ). This is based upon the relation between hydrogen and dust in the Galaxy, where a column of cm results in an of 0.45. We note that the value of the Galactic gas-to-dust ratio varies depending on the sample and technique used to measure it. We use the result of Watson (2011) . Measurements of this value have been consistent over the past few decades, and include those by Bohlin et al. (1978) , Predehl Schmitt (1995) , and Güver Özel (2009) . The value used does not alter the fact that a significant discrepancy is observed. In DLAs, the hydrogen