six observatories were clustered around the launch site, with the closest situated from the launch pad. A second, nationwide observation complex was established to track the satellite after its separation from the rocket. Called the Command-Measurement Complex, it consisted of the coordination center in NII-4 and seven distant stations situated along the line of the satellite's ground track. These tracking stations were located at Tyuratam, Sary-Shagan, Yeniseysk, Klyuchi, Yelizovo, Makat in Guryev Oblast, and Ishkup in Krasnoyarsk Krai. Stations were equipped with radar, optical instruments, and communications systems. Data from stations were transmitted by telegraphs into NII-4 where ballistics specialists calculated orbital parameters. The observatories used a trajectory measurement system called "Tral", developed by OKB MEI (Moscow Energy Institute), by which they received and monitored data from transponders mounted on the R-7 rocket's core stage. The data was useful even after the satellite's separation from the second stage of the rocket; Sputnik's location was calculated from the data on the second stage's location which followed Sputnik at a known distance. Tracking of the booster during launch had to be accomplished through purely passive means such as visual coverage and radar detection. R-7 test launches demonstrated that the tracking cameras were only good up to an altitude of , but radar could track it for almost . Outside the Soviet Union, the satellite was tracked by amateur radio operators in many countries. The booster rocket was located and tracked by the British using the Lovell Telescope at the Jodrell Bank Observatory, the only telescope in the world able to do so by radar. Canada's Newbrook Observatory was the first facility in North America to photograph Sputnik 1. Design The chief constructor of Sputnik 1 at OKB-1 was Mikhail S. Khomyakov. The satellite was a diameter sphere, assembled from two hemispheres that were hermetically sealed with O-rings and connected by 36 bolts. It had a mass of . The hemispheres were 2 mm thick, and were covered with a highly polished 1 mm-thick heat shield made of an aluminium–magnesium–titanium alloy, AMG6T. The satellite carried two pairs of antennas designed by the Antenna Laboratory of OKB-1, led by Mikhail V. Krayushkin. Each antenna was made up of two whip-like parts, in length, and had an almost spherical radiation pattern. The power supply, with a mass of , was in the shape of an octagonal nut with the radio transmitter in its hole. It