Abstract for Proposal 092301
Observation of the Be/X-ray transient 1A 0538-66 in outburst
1A0538-66 is a Be/X-ray transient containing a 69 ms X-ray pulsars, one
of the fastest known in high-mass X-ray binaries. The X-ray luminosity
reaches 1E39 erg/s. We propose a 15 ks TOO observation to perform the
first detailed study of 1A0538-66 in the super-Eddington regime. This
observation will allow us to measure the current spin frequency
to independently confirm the neutron star origin of 1A0538-66. The
transient behaviour of 1A0538-66 has been so far explained as a result
of the interaction of the accretion flow with the magnetosphere of the
neutron star. This scenario implies a surface magnetic field of B~1E11
G, a prediction which will be tested by the detection of a cyclotron
resonance scattering feature in the X-ray spectrum.
Details on Observing Strategy and Trigger Criteria
Trigger criteria: observation triggered by any ATel or GCN which reports
a source detection, from any observatory, which implies a flux level >=
2E-10 erg/cm^2/s in the energy range 0.2-12 keV, or a visual magnitude
V<13. Reaction times: 2 working days. Observing strategy: one continuous
15ks observation.