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ATel #259; S.V. Molkov, A.A. Lutovinov (IKI, Moscow), A.M. Cherepashchuk (SAI, Moscow), R.A. Sunyaev (IKI, Moscow; MPA Garching)
on 26 Mar 2004; 21:10 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Sergei Molkov (molkov@hea.iki.rssi.ru)

Subjects: X-ray, Gamma Ray, Request for Observations, Binaries, Neutron Stars, Transients
Referred to by ATel #: 279, 280, 286

We report a detection of Aql X-1 in the unusual hard spectral state. The source was significantly detected up to 150 keV with INTEGRAL on 24-25 March, 2004 during the Sagitarius Arm Tangent observations. Its spectrum can be described by a simple powerlaw with the photon index of ~2.1 and flux of ~35 mCrab in both 18-60 and 60-120 keV energy bands. We encourage the follow-up observations in different wavelengths.