XTE (X-ray Timing Explorer) is an American astronomy spacecraft that was launched by a Delta-2 rocket from Cape Canaveral AFS on 30 December 1995 at 13:48 UT. The 3,000 kg spacecraft carries three major instruments with large collecting areas, wide bandwidths, and high resolution. Initial orbital parameters were period 96.1 min, apogee 583 km, perigee 565 km, and inclination 22.9 deg.
The X-Ray Timing Explorer (XTE) mission has the primary objective to study the temporal and broad-band spectral phenomena associated with stellar and galactic systems containing compact objects in the energy range 2--200 KeV, and in time scales from microseconds to years. The scientific instruments consists of two pointed instruments, the Proportional Counter Array (PCA) and the High-Energy X-ray Timing Experiment (HEXTE), and the All Sky Monitor (ASM), which scans over 70% of the sky each orbit.
The PCA (Proportional Counter Array, of NASA/Goddard) consists of five xenon counters of area 7,000 sq-cm, field-of-view 1.0 deg, bandwidth 2-60 keV, resolution 1.0 microsecond, and sensitivity 0.1 milliCrab.
The HEXTE (High Energy X-ray Timing Experiment of UC-San Diego) contains eight sodium/cesium iodide crystals of area 1,600 sq-cm, field-of-view 1.0 deg, bandwidth 20-200 keV, resolution 10 microsecond, and sensitivity 1.0 milliCrab.
The ASM (All Sky Monitor of MIT) is an array of three xenon proportional counters of area 90 sq-cm, field-of-view 6 deg x 90 deg, bandwidth 2-10 keV, resolution 1.5 hr, and sensitivity 20 milliCrab. One Crab is the intensity of X-ray emission from the Crab nebula. Unlike the telescopes PCA and HEXTE, the ASM scans most of the sky every 1.5 hr in order to monitor about 75 bright sources; the positional resolution of ASM is about 0.05 deg x 0.25 deg.
XTE uses a new spacecraft design that allows flexible operations through rapid pointing, high data rates, and nearly continuous receipt of data at the Science Operations Center at Goddard Space Flight Center via a Multiple Access link to the Tracking and Data Relay Satellite System (TDRSS).
XTE is highly maneuverable with a slew rate of greater than 6 degrees per minute. The PCA/HEXTE can be pointed anywhere in the sky to an accuracy of less than 0.1 degree, with an aspect knowledge of around 1 arc-minute. Rotatable solar panels enable anti-sunward pointing to coordinate with ground-based night-time observations. Two pointable high gain antennas maintain nearly continuous communication with the TDRSS. This, together with 1 GB (approximately four orbits) of on-board solid-state data storage, give added flexibility in scheduling observations.
Alternate Names
Explorer 69
Rossi X-Ray Timing Explorer
Facts in Brief
Launch Date: 1995-12-30
Launch Vehicle: Delta II 7920
Launch Site: Cape Canaveral, United States
Mass: 3200.0 kg
Nominal Power: 800.0 W