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High-Energy Transient Experiment


Designation 26561 / 00061A
Launch date 9 Oct 2000
Country of origin United States
Mission Scientific: gamma-ray astronomy
Perigee/Apogee 592/634 km
Launch vehicle Pegasus XL #30
Launch site Kwajalein Missile Range (KMR) in the South Pacific (Marshall Islands)

This satellite was funded to replace HETE which was lost right after launch. The launch site was chosen because it is optimum for equatorial orbits. The mission control center was in Cape Canaveral and communication channels were setup for remote control.

It will carry out the first multiwavelength study of gamma-ray bursts with UV, X-ray, and gamma-ray instruments mounted on a single, compact spacecraft. A unique feature of the HETE mission is its capability to localize GRBs with ~10 arc second accuracy, in near real time aboard the spacecraft, and to transmit these positions directly to a network of receivers at existing ground-based observatories, enabling rapid, sensitive follow-up studies in the radio, IR, and optical bands.

External resources


sat-index articles

Technical data


Prime contractor MIT
Mass at launch 123 kg
Mass in orbit  
Solar array  
DC power  
Design lifetime  

Omnidirectional Gamma-Ray Spectrometer (Fregate)

Build by CESR (France)
Instrument type NaI(Tl); cleaved
Energy range 6 keV to > 1 MeV
Timing resolution 4 ms
Spectral resolution ~40% @ 6 keV; ~7% @ 662 keV
Effective area 120 cm^2
Sensitivity (10 sigma) 3 x 10^-8 erg/cm**2/s for 8-1000 keV
FOV ~ 2 pi sr
Angular resolution ~ 1 sr

Wide Field X-ray Monitor

Build by RIKEN (Japan) and Los Alamos
Instrument type Coded Mask with Position Sensitive Proportional Counter
Energy range 2 to 25 keV
Timing resolution 1 ms
Spectral resolution ~15% @ 6 keV
Effective area 200 cm^2 (each of 2 units)
Sensitivity (10 sigma) 8 x 10^-9 erg/cm^2/s for 2-10 keV
FOV ~ 2 sr (combined)
Angular resolution (1 sigma) +-6 arcmin

Soft X-ray Camera

Build by MIT CSR
Instrument type 4 CCD20 Detectors, 2 optical CCD22
Energy range 500 eV to 14 keV
Timing resolution 1 s
Spectral resolution 46 eV @ 525 eV, 129 eV @ 5.9 keV
Effective area 6.1x6.1 cm^2 (each of 2 units)
FOV ~0.91 sr
Dimension 10 cm x 10 cm x 17.5 cm

The spacecraft hardware and software is being developed by Aeroastro (USA).

Downlink frequencies: 137.963, 2255.5 & 2272 MHz

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