J/ApJ/933/L44ivo://CDS.VizieR/J/ApJ/933/L44doi:10.26093/cds/vizier/ba-x5/weeCDSKelley M.S.P.Kokotanekova R.Holt C.E.Protopapa S.Bodewits D.,Knight M.M.Lister T.Usher H.Chatelain J.Gomez E.Greenstreet S.,Angel T.Wooding B.2026-07-02T11:58:43Z2025-04-07T12:31:30ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frcometsphotometryvisible-astronomyabsolute-magnitudeCometary activity may be driven by ices with very low sublimation temperatures, such as carbon monoxide ice, which can sublimate at distances well beyond 20au. This point is emphasized by the discovery of the Oort cloud comet C/2014 UN_271_ (Bernardinelli-Bernstein) and its observed activity out to ~26au. Through observations of this comet's optical brightness and behavior, we can potentially discern the drivers of activity in the outer solar system. We present a study of the activity of comet Bernardinelli-Bernstein with broad-band optical photometry taken at 19-20au from the Sun (2021 June to 2022 February) as part of the LCO Outbursting Objects Key (LOOK) Project. Our analysis shows that the comet's optical brightness during this period was initially dominated by cometary outbursts, stochastic events that ejected ~10^7^ to ~10^8^kg of material on short (<1day) timescales. We present evidence for three such outbursts occurring in 2021 June and September. The nominal nuclear volumes excavated by these events are similar to the 10-100m pit-shaped voids on the surfaces of short-period comet nuclei, as imaged by spacecraft. Two out of three Oort cloud comets observed at large pre-perihelion distances exhibit outburst behavior near 20au, suggesting such events may be common in this population. In addition, quiescent CO-driven activity may account for the brightness of the comet in 2022 January to February, but that variations in the cometary active area (i.e., the amount of sublimating ice) with heliocentric distance are also possible.2022ApJ...933L..44Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/933/L44CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/comets : Database of the orbital elements of comets (Rocher, 2007)II/371 : The Dark Energy Survey (DES): Data Release 2 (Abbott+, 2021)J/A+A/374/712 : Photometric observations of comets (Szabo+, 2001)J/AJ/134/973 : SDSS Stripe 82 star catalogs (Ivezic+, 2007)J/A+A/527/A113 : 67P/Churyumov-Gerasimenko R-band light curve (Tubiana+, 2011)J/A+A/548/A12 : 67P/Churyumov-Gerasimenko R-band light curve (Lowry+, 2012)J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)J/ApJ/776/L20 : C/2012 S1 (comet ISON) R photometry (Meech+, 2013)J/ApJ/793/50 : Observed light curve of (3200) Phaethon (Ansdell+, 2014)J/AJ/154/196 : Properties of comet 49P/Arend-Rigaux, 1984-2012 (Eisner+, 2017)J/ApJ/867/105 : ATLAS all-sky stellar ref. cat. ATLAS-REFCAT2 (Tonry+, 2018)J/AJ/157/186 : r'-band photometry of comet 96P/Machholz 1 (Eisner+, 2019)J/ApJS/258/41 : TNOs from the full six years of DES (Bernardinelli+, 2022)J/MNRAS/521/1518 : Comet 162P/Siding Spring photometry (Donaldson+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/933/L44https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/933/L44http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/933/L44https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/933/L44https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/933/L44http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/933/L44GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/933/L44/table1Observational circumstances and photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateMid-observation time; UTCstime.epochnullableYear[2021.472/2022.145] Date as decimal year; UTCyrtime.epochdoubleFiltObservation filter (gp, rp, R, V or w) (1)meta.code;instr.filtercharCalPhotometric calibration filter, PS1 systemmeta.code;instr.filtercharrh[19.27/20.2] Target heliocentric distanceAUpos.distance;pos.heliocentricfloatDelta[19.34/20.2] Target-observer distanceAUpos.distance;pos.geocentricfloattheta[2.6/2.9] Sun-comet-observer (phase) angledegpos.posAngfloatAirmass[1.08/1.65] Mean airmass of the imagesobs.airMassfloatSeeing