Welcome to the first update about Sector 1751, TESS’s special observation of interstellar comet 3I/ATLAS!
Sector start and end times: Sector 1751 began 2026 January 15 around 6:00 UTC and ends 2026 January 22 around 12:00 UTC. This is an ecliptic pointing, with the comet’s trajectory during this time entirely contained on Camera 2 CCD 3. The comet’s trajectory avoids detector straps and expected areas of significant scattered light. We expect one ~5-hour data downlink during Sector 1751 on January 19. TESS will resume Sector 99 and then transition to Sector 100 following pre-established schedules for Cycle 8.
Data collection and downlink: TESS will collect FFIs and a series of 20-s and 120-s target pixel files (TPFs) surrounding the path of 3I/ATLAS. The TPFs will be 50x50 pixel boxes centered on various TIC sources along the comet’s path. 20-s and 120-s TPFs of bright calibration stars will also be collected. The data are expected to be downlinked from the spacecraft on January 19 and January 26.
Data availability: All data will be made publicly available on MAST with no proprietary period following standard data processing. The FFIs (SPOC and TICA) are expected to be available to the public within a few days of each downlink. FFI cubes will be available a few days later. TPFs will be available on MAST in February. Standard mission light curves derived from the TPFs along the comet’s path are not expected to be useful and so will not be archived. Light curves of the calibration targets will be archived, but planet search products will not be. Visit MAST’s TESS Holdings webpage for updates about data availability.
High-level science products: 3I/ATLAS is expected to be roughly 16th magnitude and moving ~0.5 pixels per 200-s cadence. To assist the TESS community in making use of this unique dataset, the mission team will be archiving data cubes centered on the comet derived from the 20-s TPFs and 200-s FFIs. These products are expected to be available a couple weeks after the relevant mission products are archived.
Want more information?
- Visit the TESS Science Support Center website to view all updates about the TESS observation of Comet 3I/ATLAS.
- Email tesshelp@bigbang.gsfc.nasa.gov with any questions you have about the observation, data, and analysis techniques.
- Join a Slack workspace to connect with experts from the mission team and other researchers interested in TESS and comets. By joining, users agree to abide by the standards of ethical behavior outlined in the AAS code of ethics.
- We are planning a virtual community meeting in early February. This will be an opportunity to learn more about TESS, its special 3I/ATLAS observations, and ask questions about how to work with TESS data of 3I/ATLAS.Finalized scheduling details will be distributed to this list, the TESS Science Support Center website, and the Slack workspace.
For more information, join the TESS 3I/ATLAS mailing list by signing up here.