1999A&AS..138..433Y

The ASCA satellite made a quick followup observation of GRB 970828 and detected its fading X-ray afterglow at the position localized by the All-Sky Monitor on the Rossi XTE satellite. Because of the quickness, the afterglow was still rather bright (∼4x10^–13ergs/cm²/s: 2-10keV), and ASCA obtained the data of good quality. We found the spectral features of the absorption which implies a column density of 4.1x10²¹cm^–2 at z=0, together with an emission line at ∼5keV. The line could be red shifted Fe K_α line. Hence, it suggests a relatively small red shift z≃0.33 for this GRB.