A few days after it began calibrating the mirrors, the James Webb Telescope locked onto a guide star with its fine guidance sensor to keep the telescope pointed with high precision. After the telescope first detected starlight in a near-infrared (NIRCam) camera, engineers launched the Fine Guidance Sensor on Jan. 28 for activity and functional testing.
Developed in conjunction with Canada’s Near Infrared Imager and Slitless Spectrometer, the sensor measures the exact position of the guide star in its field of view 16 times per second and sends adjustments to the telescope’s fine-steering mirror about three times per second.
The sensor is so powerful that someone in New York City can see the blinking eye movement of someone 500 kilometers away on the Canadian border, said FGS and NIRISS principal investigators René Doyon and Nathalie Ouellette.
“Webb’s 18 primary segments are not yet aligned, so each star appears as 18 duplicate images. On February 13, FGS successfully acquired and tracked one of the constellations for the first time.
It should be noted that engineers now use FGS guidelines in most telescope mirror alignment procedures and provide diagnostic information for mirror alignment. The telescope is in a three-month commissioning phase as it receives the first batch of starlight photons that traveled through the observatory and were captured by the Near Infrared Camera (NIRCam) instrument.
Before the telescope was used in the vacuum of space, it made several sightings on the ground.
The James Webb Space Telescope, the successor to the legendary Hubble Space Telescope, was launched in December from the European Spaceport in French Guiana on a powerful Ariane 5 rocket to a destination nearly 15,00,000 kilometers from its parent star .
Developed by scientists and engineers from 14 countries around the world, the telescope required 40 million man-hours to complete before it was attached to the rocket. The telescope is so sensitive that it could theoretically detect bumblebee heat at the Moon’s distance from Earth.
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