The Atacama Cosmology Telescope: Millimeter Observations of a Population of Asteroids or: ACTeroids

John Orlowski-Scherer, Ricco C. Venterea, Nicholas Battaglia, Sigurd Naess, Tanay Bhandarkar, Emily Biermann, Erminia Calabrese, Mark Devlin, Jo Dunkley, Carlos Hervías-Caimapo, Patricio A. Gallardo, Matt Hilton, Adam D. Hincks, Kenda Knowles, Yaqiong Li, Jeffrey J. McMahon, Michael D. Niemack, Lyman A. Page, Bruce Partridge, Maria SalatinoJonathan Sievers, Cristóbal Sifón, Suzanne Staggs, Alexander van Engelen, Cristian Vargas, Eve M. Vavagiakis, Edward J. Wollack

Research output: Contribution to journalArticlepeer-review


We present fluxes and light curves for a population of asteroids at millimeter wavelengths, detected by the Atacama Cosmology Telescope (ACT) over 18,000 deg2 of the sky using data from 2017 to 2021. We utilize high cadence maps, which can be used in searching for moving objects such as asteroids and trans-Neptunian Objects, as well as for studying transients. We detect 170 asteroids with a signal-to-noise of at least 5 in at least one of the ACT observing bands, which are centered near 90, 150, and 220 GHz. For each asteroid, we compare the ACT measured flux to predicted fluxes from the near-Earth asteroid thermal model fit to WISE data. We confirm previous results that detected a deficit of flux at millimeter wavelengths. Moreover, we report a spectral characteristic to this deficit, such that the flux is relatively lower at 150 and 220 GHz than at 90 GHz. Additionally, we find that the deficit in flux is greater for S-type asteroids than for C-type.

Original languageEnglish (US)
Article number138
JournalAstrophysical Journal
Issue number2
StatePublished - Apr 1 2024

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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