The heat of the daylight could have cooked the atmosphere evenly all the way down, Barman says, which reduces absorption of light by atmospheric molecules. (scientificamerican.com)
Based on the extreme, deduced photometric redshift of GRB 000131 indicating that the gamma rays had travelled an extreme long cosmological distance, astronomers predicted a «break» in the red region of the spectrum around 670 to 700 nm from the strong absorption of light from intervening intergalactic hydrogen clouds along the line of sight between GRB 000131 and the Solar System. (members.nova.org)
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. (en.wikipedia.org)