3I/ATLAS: A new interstellar visitor

3I/ATLAS was discovered on July 1, 2025. It was first detected by the ATLAS telescope in Río Hurtado, Chile, when it was approximately 4.5 AU from the Sun, moving at about 61 km/s.

Its orbit is clearly hyperbolic, with an eccentricity of around 6.3, revealing an origin outside the Solar System.

Although it is currently classified as comet C/2025 N1 (ATLAS), its first observations were ambiguous: some astronomers did not detect a coma, but on the night of July 2 to 3, a faint coma and a tail about 3" in arc were observed.

On the night of July 14-15, 2025, I took a series of images to record this visitor, the third known interstellar object after 1I/Oumuamua (2017) and 2I/Borisov (2019).

Below is an image of the field of stars through which it was passing from our perspective on Earth:

With a Planewave 12.5“ telescope and a QHY268 camera, I took about 40 exposures of 90”. The result of stacking the images centered on 3I/Atlas is as follows: (small dot in the center of the image marked with red marks)

Zooming in a little makes the comet easier to see:

And in false color, the result is:

The images shown are the result of stacking the 40 images. The following image is a GIF in which the object remains in the center and we see how it moves among thousands of stars in the field: (look at the fixed point in the center of the image):