HSP was selected for the NASA Astrophysics Science SmallSat Study (AS3) program
as a SmallSat mission concept that will be proposed for a 1 – 2 year science mission to demonstrate performance and cost goals to enable a future Explorer-class SmallSat Constellation mission for the first simultaneous full-sky imager with 2X finer resolution. HSP is a 36 x 36deg (FWHM) coded aperture telescope with 16 x 16 CdZnTe detectors, each 20 x 20 x 3mm with 32 x 32 0.6mm pixels and ~1.5keV energy resolution. The 1024 cm^2 HSP imaging detector array views the sky through the Tungsten coded aperture mask (0.7 mm pixels) at 68cm, providing 4’ imaging and <30” source positions over the 3 – 200 keV band. This is mounted on a Blue Canyon Technologies (BCT) SmallSat (S5) bus, with ~10arcsec pointing and star camera aspect, extends the capabilities of Swift/BAT and INTEGRAL/IBIS. HSP will promptly localize long and short GRBs and outbursts of X-ray transients: from nearby M dwarf flares, to BH-LMXB outbursts, Blazar flares and Jetted TDEs. HSP will daily-monitor the Galactic Bulge and adjacent Galactic plane and > 2 nearby OB association regions for 1 yr, providing high cadence light curves of black hole X-ray binaries (with low and high mass companions) in the Galaxy. HSP matches the on-axis sensitivity of Swift/BAT in the 15 – 200 keV band with 5X finer spatial resolution, and the simultaneous 3 – 15 keV imaging and spectra surpass MAXI with 15X finer spatial resolution, all within an ESPA class mission in LEO at ~500-600 km and <~30 deg inclination.