 21CMA pods pointing to thenorth celestial pole | |
| Location(s) | Xinjiang, PRC |
|---|---|
| Coordinates | 42°55′27″N86°42′58″E / 42.9242°N 86.716°E /42.9242; 86.716 |
| Altitude | 2,500 m (8,200 ft) |
| Website | 21cma |
  Location of Primeval Structure Telescope | |
 Related media on Commons | |
ThePrimeval Structure Telescope (PaST), also called21 Centimetre Array (21CMA),[1] is a Chinese radio telescope array designed to detect the earliest luminous objects in the universe, including the first stars, supernova explosions, and black holes, in the range of 100 to 1 billion years ago.[2] All of these objects were strong sources ofultraviolet radiation, so they ionised the material surrounding them. The structure of thisreionisation reflects the overall density structure at the redshift of luminous-object formation.
The telescope is built on the high plateau ofUlasitai (Chinese:乌拉斯台) inXinjiang, close to the southern entrance of theTianshan Shengli tunnel. This is a remote area away from most television and radios signals that may interfere the weak21 cm background signals. It is also close to the existing UrumqiVLBI station (Nanshan Observatory) inGangou township.[2]
PaST consists of an array of some ten-thousand log-periodic antennas spread over several square kilometers. It will capture a detailed radio image of the sky in the range of 1420 MHz.
The first stars ionized the gas around them, which produced a specific pattern of ionization. PasT detects the brightness of the 21 cmhydrogen line at redshift from 6 to 25. This hydrogen cosmic background radiation disappears on ionization, allowing the study of large scale structure and of star formation at this very early epoch.[2]
PaST's detection antennas are located over an area measuring several km². The redshift of 6 to 25 corresponds to a frequency range of 200 MHz to 50 MHz. Despite the remote location, some man-made frequency lines are to be filtered out.[2]
At 100 MHz, the telescope covers an area of the sky of 3 arcminutes.[2]
For detection, PaST's antennas use 20 off-the-shelfinterferometers and a total of 10,000 antennae.[2]
Media related toPrimeval Structure Telescope at Wikimedia Commons
