arXiv subjects

John J. Piotrowski

Publications and source records attributed to John J. Piotrowski.

3 recordsLinked to original sources

arXiv2026

The Lightspeed project: high-speed, ultra-low read noise imaging and polarimetry for the Magellan telescopes

Lightspeed will be an ultra-fast (> kHz), ultra-low read noise, multicolor (ugriz + IR) imager for the 6.5 meter Magellan Clay telescope. In a single-channel configuration, Lightspeed will also enable single-shot linear polarimetry, narrowband imaging, or white-light imaging. Lightspeed is designed around groundbreaking single-photon-resolving detector technologies: deep sub-electron read noise CMOS image sensors from Fairchild Imaging and a HgCdTe avalanche photodiode array from Leonardo. Here we present Lightspeed's basic optical design concept, predict its on-sky performance, and highlight science cases that Lightspeed has the potential to revolutionize. Lightspeed builds upon the success of proto-Lightspeed, a single-channel prototype employing commercial-off-the-shelf re-imaging optics. proto-Lightspeed is now available as a PI instrument on the Clay telescope. We also discuss the current status of proto-Lightspeed and lessons learned from its commissioning, applicable to the development of Lightspeed and any other instrument seeking to integrate scientific CMOS image sensors.

astro-ph.IM↗

arXiv2026

Operational capabilities and on-sky performance of SAMOS at the completion of science commissioning

We present the operational capabilities and on-sky performance of the SOAR Adaptive Module Optical Spectrograph (SAMOS) at the completion of its science commissioning phase. SAMOS is a Digital Micromirror Device (DMD)-based multi-object spectrograph and imager installed behind the SOAR Adaptive Module (SAM) ground-layer adaptive optics system. The instrument relays the full 3 x 3 arcmin AO-corrected field onto a large-format DMD, where each micromirror can direct light to either a spectroscopic or a parallel imaging channel. This architecture enables programmable slit-mask patterns that can be generated and reconfigured within seconds. SAMOS provides low-resolution spectroscopy over the 4000-10000 A wavelength range at resolving power R ~ 2500 and high-resolution spectroscopy (R ~ 10,000) in the 4500-5150 A and 6 000-7000 A bands. We summarize the operational workflow established during commissioning, including target acquisition, astrometric registration, DMD slit-mask generation, simultaneous imaging and spectroscopy, and automated data reduction. Science-verification observations demonstrate accurate target acquisition, reliable programmable slit-mask operation, multiplexed spectroscopy of crowded stellar fields, wavelength-calibration accuracy of about 0.3 A, and end-to-end spectrophotometric calibration through the combination of imaging and spectroscopic data. These results establish SAMOS as a unique facility instrument that combines adaptive-optics-assisted imaging, programmable multi-object spectroscopy, and rapid slit-mask reconfiguration for efficient spectroscopic surveys, transient follow-up, and studies of crowded stellar populations.

astro-ph.IM↗

arXiv2026

proto-Lightspeed: a high-speed, ultra-low read noise imager on the Magellan Clay Telescope

proto-Lightspeed is a new instrument that has been commissioned on the Nasmyth East port of the Magellan Clay Telescope at Las Campanas Observatory to deliver high-speed optical imaging with deep sub-electron read noise. Making use of commercial re-imaging lenses and the ORCA-Quest 2 camera from Hamamatsu, proto-Lightspeed images a field $1'$ in diameter at up to $200$ Hz or windowed fields at higher rates, up to 6600 Hz for a $1.6''\times 1'$ field of view. proto-Lightspeed delivers seeing-limited image quality in the $g'$, $r'$, and $i'$ bands and adjustable magnification for pixel scales between $0.017''-0.050''$. proto-Lightspeed is well suited to studying compact binary systems, exoplanet transits, rapid flaring associated with accretion, periodic optical emission from pulsars, occultations of background stars by small trans-Neptunian Objects, and any other rapidly variable source. proto-Lightspeed will be a P.I. instrument beginning in 2026B, available for use by members of the Magellan Consortium. In this paper, we discuss the design and performance of the instrument, results from its two commissioning runs, and plans for a facility instrument, Lightspeed, to support simultaneous multicolor imaging across a $7'\times4'$ field.

astro-ph.IM↗