The Simons Observatory: Commissioning of the Mid-Frequency Small Aperture Telescopes
Abstract
The Simons Observatory (SO) is a cosmic microwave background (CMB) survey experiment observing from an altitude of 5,200 m in the Atacama Desert in Chile. The SO Small Aperture Telescopes (SATs) will cover six spectral bands between 30 and 280 GHz primarily to search for evidence of primordial gravitational waves in the large angular scale B-modes of the CMB polarization. The first two Mid-Frequency (MF) SATs, operating in the 90 and 150 GHz frequency bands, began commissioning observations in late 2023, and we present the results of those observations here. Each MF SAT operates with approximately 9,400 biased transition-edge sensors (TES) at 1 mm of precipitable water vapor (PWV), representing a typical 80% yield. Planet observations confirm the telescope optics performance, calibrate the instrument response, and measure the end-to-end optical efficiency of the SATs. The realized instrument efficiencies are within the range expected based on instrument model predictions. In nominal observing conditions, the noise equivalent temperatures from both telescopes combined are 2.4 μKCMB√s at 90 GHz and 3.2 μKCMB√s at 150 GHz, substantially outperforming the baseline instantaneous sensitivity targets for the observatory.
Related
- The Simons Observatory: Design and Initial Performance of the Detector Readout System for the Large-Aperture Telescope
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- Exploring the trade-space of distributed aperture telescopes for faint-object spectroscopy
- First Light with the Dark100 Array of PANOSETI Telescopes at Palomar Observatory
BibTeX
@misc{harrington2026simons,
title = {{The Simons Observatory: Commissioning of the Mid-Frequency Small Aperture Telescopes}},
author = {Kathleen Harrington and Remington Gerras and Nicholas Galitzki and Samuel Day-Weiss and Yoshinori Sueno and Thomas Alford and Michael J Randall and Kyohei Yamada and Maximiliano Silva-Feaver and Kevin Crowley and Shunsuke Adachi and Alexandre E Adler and Prakamya Agrawal and Simone Aiola and David Alonso and Kam Arnold and Susanna Azzoni and Andrew Bazarko and Sanah Bhimani and Simon Biquard and Bryce Bixler and Josh Borrow and Michael L Brown and Erminia Calabrese and Yuji Chinone and Steve K Choi and Nadia Dachlythra and Mark Devlin and Simon Dicker and Peter N Dow and Shannon M Duff and Jo Dunkley and Rolando Dunner and Daniel Dutcher and Hamza El Bouhargani and Josquin Errard and Allen Foster and Ken Ganga and John Groh and Yilun Guan and Jon E Gudmundsson and Saianeesh Haridas and Masaya Hasegawa and Matthew Hasselfield and Shawn W Henderson and Carlos Hervías-Caimapo and Adam D Hincks and Renée Hložek and Johannes Hubmayr and Bradley R Johnson and Yutaro Kasai and Brian Keating and Ben Keller and Theodore Kisner and Brian J Koopman and Akito Kusaka and Adrian Lee and Jb Lloyd and Anto Lonappan and Marius Lungu},
howpublished = {HAL},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.26938},
eprint = {2609.26938},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05780406v1},
}
RIS
TY - UNPB
TI - The Simons Observatory: Commissioning of the Mid-Frequency Small Aperture Telescopes
AU - Kathleen Harrington
AU - Remington Gerras
AU - Nicholas Galitzki
AU - Samuel Day-Weiss
AU - Yoshinori Sueno
AU - Thomas Alford
AU - Michael J Randall
AU - Kyohei Yamada
AU - Maximiliano Silva-Feaver
AU - Kevin Crowley
AU - Shunsuke Adachi
AU - Alexandre E Adler
AU - Prakamya Agrawal
AU - Simone Aiola
AU - David Alonso
AU - Kam Arnold
AU - Susanna Azzoni
AU - Andrew Bazarko
AU - Sanah Bhimani
AU - Simon Biquard
AU - Bryce Bixler
AU - Josh Borrow
AU - Michael L Brown
AU - Erminia Calabrese
AU - Yuji Chinone
AU - Steve K Choi
AU - Nadia Dachlythra
AU - Mark Devlin
AU - Simon Dicker
AU - Peter N Dow
AU - Shannon M Duff
AU - Jo Dunkley
AU - Rolando Dunner
AU - Daniel Dutcher
AU - Hamza El Bouhargani
AU - Josquin Errard
AU - Allen Foster
AU - Ken Ganga
AU - John Groh
AU - Yilun Guan
AU - Jon E Gudmundsson
AU - Saianeesh Haridas
AU - Masaya Hasegawa
AU - Matthew Hasselfield
AU - Shawn W Henderson
AU - Carlos Hervías-Caimapo
AU - Adam D Hincks
AU - Renée Hložek
AU - Johannes Hubmayr
AU - Bradley R Johnson
AU - Yutaro Kasai
AU - Brian Keating
AU - Ben Keller
AU - Theodore Kisner
AU - Brian J Koopman
AU - Akito Kusaka
AU - Adrian Lee
AU - Jb Lloyd
AU - Anto Lonappan
AU - Marius Lungu
PY - 2026
DA - 2026/09/22
PB - HAL
DO - 10.48550/arxiv.2609.26938
UR - https://hal.science/hal-05780406v1
AB - The Simons Observatory (SO) is a cosmic microwave background (CMB) survey experiment observing from an altitude of 5,200 m in the Atacama Desert in Chile. The SO Small Aperture Telescopes (SATs) will cover six spectral bands between 30 and 280 GHz primarily to search for evidence of primordial gravitational waves in the large angular scale B-modes of the CMB polarization. The first two Mid-Frequency (MF) SATs, operating in the 90 and 150 GHz frequency bands, began commissioning observations in late 2023, and we present the results of those observations here. Each MF SAT operates with approximately 9,400 biased transition-edge sensors (TES) at 1 mm of precipitable water vapor (PWV), representing a typical 80% yield. Planet observations confirm the telescope optics performance, calibrate the instrument response, and measure the end-to-end optical efficiency of the SATs. The realized instrument efficiencies are within the range expected based on instrument model predictions. In nominal observing conditions, the noise equivalent temperatures from both telescopes combined are 2.4 μK_CMB√s at 90 GHz and 3.2 μK_CMB√s at 150 GHz, substantially outperforming the baseline instantaneous sensitivity targets for the observatory.
ER -