Non-detection of the 4.1 keV Absorption Lines in the Burst Spectra of X1608-52 during a Long ASCA Observation Mahasena, P. ; Dotani, T. ; Mitsuda, K. ; Inoue, H. Abstract Publication: New Century of X-ray Astronomy Pub Date: 2001 Bibcode: 2001ASPC..251..382M