X-ray variability of NLS1s and BLS1s

Evenly-sampled hard X-ray monitoring was obtained with RXTE for one NLS1 (A kn 564) and four BLS1s. The variability amplitude of the NLS1 was no larger than the mean of the BLS1s, and the NLS1 showed stronger variability in th e harder portion of the RXTE band, while the BLS1s were more strongly varia ble in the relatively soft part of the band. This contribution discusses po ssible explanations for these surprising results, including possible calibr ation errors or systematic differences between long and short time scale va riability in NLS1s and BLS1s. (C) 2000 Elsevier Science B.V. All rights res erved.