Almería, 16 March 2026

While training with the Calar Alto 1.23 m telescope, a group of students from University College Dublin managed to observe the optical counterpart of a newly discovered transient event known as Gamma-Ray Burst, nearly three days after it violently exploded. This target of opportunity observation was key to coordinate observations with larger telescopes in Calar Alto and worldwide. This has allowed the students to significantly contribute to the process of building scientific evidence to reveal the true nature of this peculiar violent phenomenon.

Every year, the Calar Alto Observatory hosts, among others, an academy from University College Dublin (UCD), during which BSc (Hons) students in physics with Astronomy and Space Science have hands-on with a professional telescope. This is a great experience for every participating student, who prepares in advance a science program and observes it with the sensitive cameras of the Andalusian observatory.

From 9 to 14 March 2026, fourteen UCD students supervised by Assistant Professor Antonio Martin-Carrillo, used the CAHA 1.23-meter telescope to observe various planned programs, weather permitting. But also unexpected events called "Targets of Opportunity" (ToOs) if needed. Such a ToO was indeed triggered during the night of 12 to 13 March.

The young team, led by the experienced Spanish astronomer Antonio Martin-Carrillo, received an alert to observe a recently discovered optical source that had been tentatively associated with a new violent explosion (gamma-ray burst or GRB) discovered in gamma-rays nearly 3 days earlier in the Northern sky, in a position ideally accessible from Calar Alto. The goal was to help building evidence of its association with the GRB and coordinate observations with larger telescopes across the world.

The event, known as GRB 260310A, was indeed first reported on March 10th, 2026 by the Fermi satellite, a space telescope designed to detect sources in X-ray and gamma-rays, the most energetic kinds of light in the Universe, emitted by violent phenomena like super massive black holes, pulsars, or supernovas. This particular event is of interest due to the extraordinary behavior seen by the optical transient candidate associated with the GRB. In particular, because of its brightness after several days and its location on the outskirts of a relatively nearby galaxy.

After receiving the request from international collaborators, the UCD students halted their planned observations and repointed the 1.23 m telescope equipped with the DLR-MkIII camera towards the GRB 260310A optical candidate, with observations starting just before midnight (22:57 UT) on March 12th, about 2.75 days after the detection by Fermi.

Thanks to the good observing conditions, the likely optical counterpart (afterglow) of the GRB was visible. "Even with an exposure of only 30 seconds, we could perfectly see this peculiar GRB which remained very bright nearly three days after it exploded" says Martin-Carrillo, adding that "my students were ecstatic when the new image appeared on the screen and the source was clearly visible".

 

Field of the gamma-ray burst GRB 260310A and its optical counterpart, as seen in this 150-second exposure taken with the DLR-MkIII CCD camera on the CAHA 1.23-meter telescope. Credits: CAHA / DLR / UCD.

 

The results of these observations were quickly shared among different collaborations and to the whole scientific community via the NASA General Coordinates Network. In response to the 1.23m telescope observations, spectroscopic and polarimetric observations were carried out by different instruments confirming its association with the GRB and revealing the redshift of the explosion (z = 0.153). The local nature of this violent explosion and the external localization of the source with respect to its host galaxy, seems to suggest that this explosion could not have been originated by the death of a massive star, but the merger of two neutron stars.

Additional spectroscopic observations made with the 2.2 m telescope by J.F. Agüí Fernández & A. Fernández-Martín, the CAHA service observers on duty that night, provided further key information of the event from Calar Alto.

Jesús Aceituno, CAHA director, concludes, “One of the observatory’s commitments is to train the next generation of astronomers. In addition to giving each student the opportunity to operate state-of-the-art telescopes and instruments, the CAHA Academy program contributes to important scientific research, as we have seen this year with University College Dublin, which we hope to continue hosting for many years to come.“

 

The University College Dublin students and their professor observing comfortably from the Calar Alto library. Credits: UCD.

 

---

The Calar Alto Observatory is one of the infrastructures that belong to the national map of Unique Scientific and Technical Infrastructures (Spanish acronym: ICTS), approved on March 11th, 2022, by the Science, Technology and Innovation Policy Council (CPCTI).

 

CONTACTS:

Calar Alto observatory (CAHA)-  Gilles Bergond  This email address is being protected from spambots. You need JavaScript enabled to view it.

University College Dublin (UCD)-  Antonio Martin-Carrillo  This email address is being protected from spambots. You need JavaScript enabled to view it.

COMMUNICATION - CALAR ALTO OBSERVATORY

This email address is being protected from spambots. You need JavaScript enabled to view it. - Phone: (+34) 950 632 500

---