Deep g'-band Imaging of Interstellar Comet 3I/ATLAS from the Two-meter Twin Telescope (TTT)
ATel #17264; Miguel R. Alarcon (IAC, ULL), Miquel Serra-Ricart (Light Bridges, IAC), Javier Licandro (IAC, ULL), Sergio Guerra Arencibia (IAC, ULL), Ignacio Ruiz Cejudo (IAC, ULL), Ignacio Trujillo (IAC, ULL)
on 3 Jul 2025; 18:33 UT
Credential Certification: Miquel Serra-Ricart (mserra@iac.es)
We report deep g'-band optical imaging of the interstellar comet 3I/ATLAS, also designated C/2025 N1 (ATLAS), obtained with the Two-meter Twin Telescope (TTT3) at Teide Observatory on the night of 2 July 2025. Between 21:28 and 02:47 UT, a total of 239 individual 50 s exposures in the g' band were acquired and co-added following the object's apparent motion, employing a noise-based non-parametric technique optimized for the detection of very low signal-to-noise features. The resulting composite image confirms clear cometary activity: the diffuse tail extends 9.8 arcsec along its principal axis at a position angle of 276 degrees, with a maximum width of 8.8 arcsec measured perpendicular to that direction. At a geocentric distance of 3.5 au, when the object was observed, these values correspond to a projected length along the tail of more than 25000 km.
An image displaying isophotal contours is attached to this telegram, and the corresponding FITS file is available to the community for further analysis. Continued monitoring of 3I/ATLAS with the Two-meter Twin Telescope will be performed to search for anisotropies and morphological evolution.
Stacked image: https://lightbridges.es/wp-content/uploads/2025/07/3I_stacked_20250702.png
Co-added image of 3I/ATLAS
