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Table 1

Summary of the observations.

Blue arm Red arm
Year Nights Grating λcen (Å) Range (Å) Grating λcen (Å) Range (Å)

2010 3 580V 4500 ~2100 1700D 8600 ~500
2011 2 1500V 4400 ~800 1700D 8700 ~500
2012 1 1500V 5200 ~800 1700D 8700 ~500
2012 2 580V 4800 ~2100 1700D 8700 ~500
2013 1 580V 4800 ~2100 1700D 8700 ~500

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