The HEASARC is running nominally. If you are trying to download a lot of data, please consider using the AWS cloud copy of most HEASARC data. As an alternative to locally installing HEASoft, SciServer is an online platform which has the software installed and data available when you login.
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srcut: synchrotron spectrum, cutoff power law
srcut describes the synchrotron spectrum from an exponentially cut off power-law distribution of electrons in a homogeneous magnetic field. This spectrum is itself a power-law, rolling off more slowly than exponential in photon energies. Though more realistic than a power-law, it is highly oversimplified, but does give the maximally curved physically plausible spectrum and can be used to set limits on maximum accelerated-electron energies even in remnants whose X-rays are thermal. See Reynolds & Keohane (1999) and Reynolds (1998). Note that the radio spectral index and flux can be obtained from Green's Catalogue for galactic SNRs.
| par1 | alpha: radio spectral index |
| par2 | break Hz: approximately the frequency at which the flux has dropped by a factor of 10 from a straight power law. |
| norm | 1 GHz flux (Jy) |