Gaia Observatory Snaps Photo of James Webb Space Telescope at L2
upstart writes:
Got it! Gaia Observatory Snaps Photo of James Webb Space Telescope at L2:
Both spacecraft are located in orbits around the Lagrange point 2 (L2), 1.5 million km from Earth in the direction away from the Sun. Gaia arrived there in 2014, and Webb in January 2022.
[...] A few weeks before Webb's arrival at L2, Gaia experts Uli Bastian of Heidelberg University (Germany) and Francois Mignard of Nice Observatory (France) realized that during Gaia's continuous scanning of the entire sky, its new neighbor at L2 should occasionally cross Gaia's fields of view.
Gaia is not designed to take real pictures of celestial objects. Instead, it collects very precise measurements of their positions, motions, distances, and colors. However, one part of the instruments on board takes a sort of sky images. It is the 'finder scope' of Gaia, also called the sky mapper.
[...] After Webb had reached its destination at L2, the Gaia scientists calculated when the first opportunity would arise for Gaia to spot Webb, which turned out to be 18 February 2022.
After Gaia's two telescopes had scanned the part of the sky where Webb would be visible, the raw data was downloaded to Earth. In the morning after, Francois sent an email to all people involved. The enthusiastic subject line of the email was "JWST: Got it!!"
The astronomers had to wait a few more days for Juanma Martin-Fleitas, ESA's Gaia calibration engineer, to identify Webb in the sky mapper images. "I've identified our target" was the message sent by him, with the images attached and the two tiny specks labelled as 'Webb candidates'.
After scrutinizing these carefully, Uli replied: "Your 'candidates' can be safely renamed 'Webb'."
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