Sky mapper
A couple of weeks prior to Webbs arrival at L2, Gaia specialists Uli Bastian of Heidelberg University (Germany) and Francois Mignard of Nice Observatory (France) understood that throughout Gaias continuous scanning of the whole sky, its brand-new neighbor at L2 need to sometimes cross Gaias field of visions.
Gaia orbits the 2nd Lagrange Point (L2) in a Lissajous orbit. The James Webb Space Telescope orbits L2 in a halo orbit. The telescopes are in between 400,000 and 1,100,000 km apart, depending on where they are in their particular orbits. This image reveals the relative sizes and areas of the Gaia orbit (yellow) and the Webb orbit (white). In this view, Earth lies to the left, not far beyond the frame. Gaias Lissajous loops have L2 right in their center, while Webbs halo orbit loops are better to Earth by about 100,000 km on average. Credit: ESA/Gaia/DPAC; CC BY-SA 3.0 IGO
Gaia is not developed to take real photos of celestial items. It is the finder scope of Gaia, likewise called the sky mapper.
Every six hours, Gaias sky mapper scans a narrow 360-degree strip around the whole celestial sphere. Within seconds, these slices are automatically inspected for star images, the positions of which are then used to forecast when and where those stars could be taped in Gaias primary clinical instruments.
The computer can be by hand asked for to extremely keep a stretch of the image information. The sky mapper was initially prepared for technical servicing functions, however during the objective it has also found some clinical uses. Why not use it for a picture of Webb?
Got it!
After Webb had reached its location at L2, the Gaia scientists calculated when the first chance would emerge for Gaia to spot Webb, which ended up being 18 February 2022.
After Gaias two telescopes had actually scanned the part of the sky where Webb would be visible, the raw information was downloaded to Earth. In the morning after, Francois sent out an email to all individuals included. The enthusiastic subject line of the e-mail was “JWST: Got it!!”.
Gaia snaps photo of Webb (zoom). Pictures of the James Webb Space Telescope taken by ESAs Gaia observatory on February 18, 2022. Background frame: Cutout of the specially recorded image from Gaias sky mapper instrument at the first of the two observations from Gaias 2 telescopes. The reddish color is synthetic, selected just for illustrative factors. The frame shows a few reasonably bright stars, a number of faint stars, a few disturbances– and a spacecraft. It is marked by the green circle.Left grey inset: Zoom into the frame revealing the Webb image at full resolution. It is the slightly extended speck of light in the center. The other three bright dots are traces of energetic cosmic-ray particles which hit the CCD chip throughout the 2.5 seconds of exposure. The on-board software can autonomously and reliably identifying these from star images.Right grey inset: The 2nd “photo” of Webb, taken in the 2nd field of view of Gaias telescopes about 106.5 minutes after the very first one. Each of the two images was produced by just under 1000 sunshine photons arriving from the Webb spacecraft.Credit: ESA/Gaia/DPAC; CC BY-SA 3.0 IGO.
The astronomers had to wait a few more days for Juanma Martin-Fleitas, ESAs Gaia calibration engineer, to recognize Webb in the sky mapper images. “Ive identified our target” was the message sent by him, with the images connected and the two small specks identified as Webb candidates.
After scrutinizing these carefully, Uli replied: “Your prospects can be securely renamed Webb.”.
Gaia now has a spacecraft friend at L2, and together they will uncover our home galaxy, and deep space beyond.
Gaias sky mapper image showing the James Webb Space Telescope. After Gaias two telescopes had actually scanned the part of the sky where Webb would be noticeable, the raw information was downloaded to Earth. Images of the James Webb Space Telescope taken by ESAs Gaia observatory on February 18, 2022. Background frame: Cutout of the specifically recorded image from Gaias sky mapper instrument at the first of the 2 observations from Gaias 2 telescopes. The on-board software is capable of autonomously and dependably differentiating these from star images.Right grey inset: The second “photo” of Webb, taken in the second field of view of Gaias telescopes about 106.5 minutes after the very first one.
Gaias sky mapper image showing the James Webb Space Telescope. The reddish color is artificial, picked simply for illustrative reasons. The frame shows a couple of fairly bright stars, a number of faint stars, a few disturbances– and a spacecraft. It is marked by the green arrow. Credit: ESA/Gaia/DPAC; CC BY-SA 3.0 IGO
On February 18, 2022, the NASA/ESA/CSA James Webb Space Telescope was photographed by ESAs Gaia observatory.
Both spacecraft lie 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.
On February 18, 2022, the 2 spacecraft were 1 million km apart, with an edge-on view of Gaia towards Webbs huge sunshield. Really little showed sunshine came Gaias method, and Webb therefore looks like a tiny, faint specification of light in Gaias two telescopes without any information visible.
