Compared to the FPSQ-model oscillator 
parameters given in Zeidler et al., 
A&A 553, A81 (2013), the present data 
have been slightly modified in order 
to avoid unphysically low values in 
the imaginary part of the refractive 
index. 

Concerning the fit of the measured 
reflectance spectra and the modeling 
of infrared bands in the paper, the 
changes made here are neglectable. 

Despite the update of the data, low 
values of the imaginary part of the 
refrective index, both between the 
bands and outside the band region, 
are still poorly constrained and 
should not be taken for granted. 

These are the updated oscillator 
parameters given as 
omega(TO), gamma(TO), omega(LO), gamma(LO) 
all in cm^-1:

for quartz - ordinary ray (compare Table 4 
in Zeidler et al.): 

RT:
264.128470 6.777467 265.358610 7.000396 
393.548970 4.246974 402.875640 4.327499 
449.781370 3.431813 507.885890 3.371197 
694.295490 11.971138 697.310070 12.118222 
795.359490 7.753094 808.715770 8.109266 
1064.566100 6.978050 1226.339000 10.907516 
1160.027800 8.383480 1157.022200 7.976290 
eps(inf)=2.34

551 K:
257.691720 9.109717 258.356420 9.053042 
395.032200 5.556179 401.962870 4.783354 
445.610790 4.904350 504.579980 7.882753 
695.372850 13.543554 697.126350 12.521049 
790.198210 13.440694 804.584230 13.016176 
1063.299500 9.307140 1221.605500 18.655700 
1157.620100 10.574591 1155.846300 9.978609 
eps(inf)=2.36

738 K:
255.057890 9.585182 255.768400 9.865548 
396.501840 10.443184 402.986500 11.046771 
438.272460 9.276743 499.844350 9.292233 
688.587380 15.172412 688.988710 14.505189 
786.144190 16.965453 799.523440 16.615296 
1058.356900 15.168398 1217.957100 20.434682 
1155.900900 36.826260 1153.288100 34.454716 
eps(inf)=2.38

833 K:
256.465820 11.071491 256.611890 10.826625 
400.808980 8.228347 403.823260 8.165394 
433.720320 13.863793 496.064320 14.363471 
680.409210 37.967362 680.746480 37.666377 
783.502580 19.793854 796.368770 20.332697 
1059.348100 20.456874 1220.930800 26.140169 
1155.262200 44.005514 1154.839900 43.521140 
eps(inf)=2.39

928 K:
423.039010 11.849474 491.445950 12.180189 
780.279970 22.850661 793.679080 23.319267 
1060.365700 19.533924 1226.384300 43.428394 
eps(inf)=2.36


for quartz - extra-ordinary ray (compare 
Table 5 in Zeidler et al.): 

RT:
363.033460 5.176336 386.415300 3.755036 
494.989090 9.995890 552.823700 7.301877 
775.583620 8.476563 789.165630 7.514539 
1073.365800 15.206128 1238.422200 16.413027 
eps(inf)=2.39

551 K:
369.719760 7.894312 388.871690 11.918637 
486.100180 17.854908 547.220040 13.281300 
775.089330 13.780212 785.373130 15.289427 
1070.083900 20.030133 1237.020400 30.036855 
eps(inf)=2.38

738 K:
376.108430 15.021024 392.476800 18.900802 
473.932920 23.829551 540.149810 17.115792 
775.274380 19.984497 782.466030 20.583227 
1066.911900 22.755829 1234.710500 39.725672 
eps(inf)=2.38

833 K:
386.594790 20.096429 396.638900 20.049912 
465.199200 24.903295 533.837240 22.525275 
777.020220 31.448255 782.291500 30.851420 
1065.910100 26.522797 1239.848900 50.928553 
eps(inf)=2.38

928 K:
442.199600 30.037866 527.433320 24.192736 
1064.139100 32.904925 1240.890700 45.583313 
eps(inf)=2.44