C/2026 A1 (MAPS)

C/2026 A1 (MAPS) was discovered from the AMACS1 Observatory at San Pedro de Atacama, using a 0.28 m (11 in) f/2.2 Schmidt telescope with a CCD camera.^[1] It was discovered at a distance of 2.056 AU (307.6 million km; 191.1 million mi) from the Sun, making it the furthest Kreutz sungrazer ever discovered,^[13] surpassing the record previously held by Comet Ikeya–Seki,^[d] allowing a lead time of observations for approximately 81 days before perihelion.^[15]

The comet was 17.8 magnitude at the moment of discovery and was located in the constellation Columba.^[1]

Earliest precovery date is December 2025, when it was about magnitude 20.^[4] Its discovery was officially announced on 20 January 2026.^[1][2] It is expected to become visible in 8 to 10-inch telescopes by late March, a few days before perihelion.^[16][17] By mid March it had brightened to an apparent magnitude of about 10.^[9] It will cross the celestial equator on 30 March 2026.^[18] 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.^[16]

As seen from Earth, the comet will come to solar conjunction on 4 April 2026 around 13:20 (behind the Sun) and 15:36 UT (in front of the Sun).^[19] For both, it will be 0.04 degrees from the center of the Sun (the Sun has a width of 0.5 degrees).^[19] It is expected to enter SOHO–LASCO's field-of-view by 2 April 2026.^[20]

C/2026 A1 is 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.^[21] This specific subgroup include some bright members like the Great Comet of 1843 and C/1963 R1 (Pereyra).^[22][e] 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.^[23]

It will pass through the solar corona and reach perihelion on 4 April 2026 around 14:23 UT when it will be 0.005732 AU (1.233 R_☉) from the center of the Sun^[7] or about 162,000 km from the surface of the Sun.^[a] There is no chance of a solar impact as the 5-sigma uncertainty is only ±2000 km,^[3][f] giving a minimum possible approach of about 160000 km. It will then make closest approach to Earth the next day around 5 April 2026 23:59 UT when it will be 0.961 AU (143.8 million km) from Earth.^[24]

With an observation arc of 66 days, the comet's inbound orbital period (calculated at epoch 1800, which is before entering the planetary region of the Solar System) suggests it last reached perihelion around 1700 years ago,^[6] suggesting that it may be a second-generation fragment from the Great Comet of 371 BC itself,^[23] specifically the comet of 363 AD that was witnessed by Ammianus Marcellinus.^[25]

In January 2026, initial estimates of the upper limit for the size of its nucleus placed it at less than 2.4 km (1.5 mi) in diameter.^[16][26] A study published in March 2026 using the data from the James Webb Space Telescope (JWST) concluded that the comet is roughly 400 m (1,300 ft) in diameter,^[8] about the size of C/2011 W3 (Lovejoy),^[27] 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.^[8]

• 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/2024 S1 (ATLAS)
• C/2025 R3 (PanSTARRS), another naked eye comet for April 2026