LSST and Keck characterization of outer Main Belt comet P/2026 N2

Abstract: We characterize comet P/2026 N2, whose outer Main Belt orbit has $a=3.07$ au, $e=0.21$, and $i=2.25<sup>\circ$, using optical observations, archival imaging, and dynamical integrations. Observations from the Legacy Survey of Space and Time (LSST) at NSF-DOE Vera C. Rubin Observatory in 2026 June-July and Keck/LRIS imaging on October 7 show active morphology across perihelion over 102 days. Within a projected aperture radius of approximately 1,000 km, Keck colors of $g-r=0.50\pm0.05$ and $r-i=0.06\pm0.06$ mag are consistent with nearly neutral B/C-complex reflectance. Phase-corrected $a(0<sup>\circ)fρ=3.66\pm0.12$ cm in derived $r$ and $3.46\pm0.17$ cm in $i$ are comparable to LSST measurements. The geometry-corrected $i$-band aperture brightness changes by $0.07\pm0.07$ mag between July 9 and October 7; the 2,000 km $r$-band aperture measurements are also consistent between epochs. These results support sustained observable activity, consistent with prolonged or recurrent dust production. Archival DECam images recover N2 on 2021 July 4, but its activity state is inconclusive. A 5,000-particle forward integration retains a concentrated outer Main Belt core throughout 50 Myr. We hypothesize that volatile sublimation, possibly of water ice, sustains activity near perihelion.