Bibcode
in't Zand, J. J. M.; Cornelisse, R.; Kuulkers, E.; Heise, J.; Kuiper, L.; Bazzano, A.; Cocchi, M.; Muller, J. M.; Natalucci, L.; Smith, M. J. S.; Ubertini, P.
Bibliographical reference
Astronomy and Astrophysics, v.372, p.916-921 (2001)
Advertised on:
6
2001
Journal
Citations
82
Refereed citations
71
Description
Data of the 1996 outburst of the single-known accreting millisecond
pulsar SAX J1808.4-3658, taken with the Wide Field Cameras (WFCs) on
BeppoSAX, are revisited with more complete data coverage and more
comprehensive analysis techniques than in a previous report. An
additional type-I X-ray burst was identified which occurred at a time
when the persistent emission is below the detection limit, roughly 30
days after outburst maximum. This burst is three times longer than the
first two bursts, and 50% brighter. It is the brightest burst within the
~ 1700 type-I bursts detected so far with the WFCs. A spectral analysis
of the data reveals a distance to SAX J1808.4-3658 of ~ 2.5 kpc. This is
an update from a previously reported value of 4 kpc. We present the
evidence that we have for the presence of oscillations at the pulsar
frequency during part of the newly found burst. Such an oscillation
would lend support to the idea that the frequency of millisecond burst
oscillations in other objects is very close to the neutron star rotation
frequency.