C/2026 A1 (MAPS), formerly known by its temporary designation as 6AC4721, was a Kreutz sungrazer comet discovered on 13 January 2026 from the AMACS1 Observatory in the Atacama Desert. This comet was discovered through the , which was led by Alain Maury, , Daniel Parrott and Florian Signoret. On 4 April 2026, it passed about from the surface of the Sun. When near the Sun, the forward scattering of light would have made the comet significantly brighter, but hard to see against the glare of the Sun. At 4 April 08:15 UT, ~6 hours before perihelion, CCOR-1 showed the comet's head to be about apparent magnitude –0.6, shortly after which it disintegrated.

Observational history

C/2026 A1 (MAPS) was discovered from the AMACS1 Observatory at San Pedro de Atacama, using a f/2.2 Schmidt telescope with a CCD camera. It was discovered at a distance of from the Sun, making it the furthest Kreutz sungrazer ever discovered, surpassing the record previously held by Comet Ikeya–Seki, allowing a lead time of observations for approximately 81 days before perihelion.

The comet was 17.8 magnitude at the moment of discovery and was located in the constellation Columba.

Earliest precovery date is December 2025, when it was about magnitude 20. Its discovery was officially announced on 20 January 2026. It is expected to become visible in 8 to 10-inch telescopes by late March, a few days before perihelion. By mid March it had brightened to an apparent magnitude of about 10. It will cross the celestial equator on 30 March 2026. Due to its relatively low declination in the sky relative to the Sun, it will become more favorable to view from the Southern hemisphere than in the north.

Throughout March 2026, the comet was seen from the western horizon roughly until 30–45 minutes after sunset. The comet steadily brightened until 22 March.

The comet disintegrated a few hours before it came to solar conjunction on 4 April 2026. Larger debris would have passed behind the Sun at around 13:20 and then again at 15:36 UT (in front of the Sun). For both, it was 0.04 degrees from the center of the Sun (the Sun has a width of 0.5 degrees). It entered SOHO–LASCO's field-of-view on 2 April 2026 and CCOR-1 on 3 April.

Submicron-sized dust being pushed by solar radiation pressure re-emerged on the opposite side of the Sun post-perihelion.

Orbit

C/2026 A1 was a Kreutz group comet. It was initially thought to belong to the Pe subgroup, a subgroup of the Kreutz Sungrazers closely associated with subgroup I, which all fragmented from the Great Comet of 1106. This specific subgroup include some bright members like the Great Comet of 1843 and C/1963 R1 (Pereyra). However, its extraordinarily long orbital period suggested it's only a coincidence and it may possibly be a member of a yet-unknown distinct subgroup instead. Further research by Zdenek Sekanina and Malgorzata Krolikowska suggested that based on the detection of three other small Kreutz sungrazers that preceded C/2026 A1, the comet may have been part of a larger object related to the parent body of C/1843 D1 that separated around 363 AD and therefore a part of the Population I subgroup. It is hypothesized that increasingly complex outgassing contributed to its unusually long orbital period compared to other Kreutz sungrazers shortly after separating from its parent body.

The comet disintegrated shortly（ approximately 1 ～ 5 hours） before reaching perihelion. It was projected to reach perihelion around 14:22 UT on 4 April 2026 when it would have been from the center of the Sun or about km from the surface of the Sun. There was no chance of a solar impact as the 5-sigma uncertainty was only ±, giving a minimum possible approach of about . If it had not disintegrated, it would have then made its closest approach to Earth the next day around 5 April 2026 23:57 UT when it would have been from Earth.

With an observation arc of 74 days, the comet's inbound orbital period (calculated at epoch 1800, which is before entering the planetary region of the Solar System) suggests it previously reached perihelion around 1695 years ago, suggesting that it may be a second-generation fragment from the Great Comet of 371 BC itself, specifically one of the daylight comets of 363 AD that was witnessed by Ammianus Marcellinus.

Physical characteristics In January 2026, initial estimates of the upper limit for the size of its nucleus placed it at less than in diameter. A study published in March 2026 using the data from the James Webb Space Telescope (JWST) concluded that the comet is roughly in diameter, about the size of C/2011 W3 (Lovejoy), however its authors noted that the comparison has to be treated with caution as C/2026 A1 is the only Kreutz comet that we have direct measurements of its nucleus out of the more than 5,000 members of the family we had known so far.

Gallery

See also 115P/Maury, the first comet discovered by one of Comet MAPS' discoverers, Alain J. Maury List of Kreutz sungrazers C/2011 W3 (Lovejoy), the Great Comet of 2011 C/2012 E2 (SWAN) C/2024 S1 (ATLAS)

Notes

References

External links

at the Minor Planet Center database C/2026 A1 at the Comet OBServation database C/2026 A1 an NEOCP report from Project Pluto (13 January 2026). C/2026 A1 at Gideon van Buitenen's website. C/2026 A1 at Seiichi Yoshida's website. HDR Astrophotography: Comet tails simulations by Nicolas Lefaudeux