Microwave kinetic inductance detectors (MKIDs) are increasingly used in ground-based (sub)millimeter-wave astronomy experiments. Two existing challenges to operating detector arrays remain in selecting excitation tones for each MKID where there are hundreds of resonators on the same feedline or network and that will yield the best combination of linearity and sensitivity. This is further complicated when operating arrays at ground-based telescopes, where variations in background loading from the atmosphere can induce significant shifts in MKID resonant frequencies and affect quality factors. We describe a quantitative method for optimal tuning of MKID arrays under dynamic loading conditions. We apply this new readout tuning technique to the 1.1 mm MKID array of the TolTEC camera at the Large Millimeter Telescope, where we incrementally change the readout power applied to investigate its effect. We perform in lab optical characterization of a CCAT Observatory MKID array to investigate optimal tuning under different loading conditions.
The TolTEC Camera, mounted on the Large Millimeter Telescope (LMT), is a 3-band continuum camera and polarimeter operating at millimeter wavelengths. This paper reviews our progress on the camera commissioning and its inaugural scientific programs, spanning the 2022/2023 commissioning phases and reviewing the winter 2024 science program. We report on mapping speed estimations, optical performance, and the first scientific imaging and polarimetry findings. Additionally, advancements in out-of-focus holography and the integration of two novel maximum likelihood mapmakers are discussed. We conclude with scientific forecasts for the first four TolTEC Legacy Surveys and an overview of the initiatives aimed at facilitating public access to the camera and the broader LMT infrastructure.
KEYWORDS: Data archive systems, Data modeling, Equipment, Data acquisition, Telescopes, Data storage, Astronomy, Computing systems, Unattended ground sensors, Inspection
The Large Millimeter Telescope (LMT) is a 50m-diameter single dish millimeter-wave radio telescope located in Mexico, built by the country of Mexico and the University of Massachusetts Amherst. The National Science Foundation Mid-Scale Innovations Program (MSIP) is now supporting access to the LMT for any astronomer located at a US institution with a share of total 15% of the scientific observation time. The LMT cyber-infrastructure is being innovated to accommodate the new science operation workflow. We developed and deployed the LMT data archive, fully integrating the data pipeline, data model, and data management workflow of most LMT instruments. For the LMT data archive, we use our own installation of the Dataverse software as the backend, with a custom-built frontend to provide a user-friendly search interface for discovering data products. The data model and data management workflow are developed along with the commissioning (hardware and/or software) of the instrument specific pipelines. The software package dvpipe is developed to package the data products from the instrument specific pipelines as science-ready data products and put them into the LMT data archive.
An ambient-temperature Continuously Rotating Half-Wave Plate (CRHWP) modulates the input polarization signal thereby enabling removal of low-frequency (1/f) noise from polarized flux measurements. This 1/f noise arises from atmospheric turbulence as well as from effects intrinsic to certain detectors. Here, we describe the design and performance of the half wave plate rotator and achromatic half-wave plate for the the new imaging polarimeter, TolTEC. These components are mounted in front of the cryostat window and operate at ambient temperature. The Half-Wave Plate Rotator (HWPR) spins the half-wave plate at 2 revolutions per second. The rotation mechanism consists of nine air bearings to provide low-friction motion and a frameless torque motor to directly drive rotation. The orientation of the rotor and half-wave plate are recorded using a high-precision optical encoder. We review the experimental requirements and technical design of the rotator as well as the associated electronics, pneumatics, and software.
The TolTEC camera is an imaging polarimeter installed at the Large Millimeter Telescope (LMT) in Mexico during December 2021. This new camera uses polarization-sensitive Kinetic Inductance Detectors (KIDs) coupled to the 50 m LMT to produce high resolution images simultaneously at 1.1, 1.4, and 2.0 mm wavelengths. We present a description of the cryogenic camera optics, the warm coupling optics, and the techniques used for on-site alignment of TolTEC with the telescope and characterization of the optics.
TolTEC is an imaging polarimeter installed on the Large Millimeter Telescope that simultaneously images the sky at 1.1, 1.4, and 2.0 mm. We have developed the open-source, fully parallelized C++ data reduction pipeline, citlali, to process TolTEC’s raw time-ordered data for science and calibration observations into on-sky maps, while also performing map coaddition and post-map-making analyses. Here, we describe citlali’s structure, including its reduction stages, algorithms, and parallelization scheme. We also present the results of the application of citlali to both TolTEC commissioning data and synthetic observations, characterizing the resulting map properties, as well as the software performance and memory usage.
The TolTEC camera is a next generation three-band imaging polarimeter for the Large Millimeter Telescope. With 7514 lumped element kinetic inductance detectors across three simultaneously observing passbands at 1.1 mm, 1.4 mm, and 2.0 mm, TolTEC has diffraction-limited beams with FWHM of 5, 7, and 11 arcsec, respectively. Herein, we cover a brief overview of the instrument along with the first quantitative measures of TolTEC’s performance at the LMT. We also provide initial reductions of commissioning targets - demonstrating TolTEC's ability to detect both faint and extended structures over a wide dynamic range of flux and angular scales.
TolTEC is an imaging polarimeter that will be mounted on the 50m diameter Large Millimeter Telescope (LMT) in Mexico. This camera simultaneously images the focal plane at three wavebands centered at 1.1, 1.4, and 2.0mm. TolTEC combines polarization-sensitive Kinetic Inductance Detectors (KIDs) with the LMT to produce 5-10 arcmin resolution maps of the sky in both total intensity and polarization. The light from the telescope is coupled to the TolTEC instrument using three room temperature mirrors. Before entering the cryostat, the light passes through a rapid-spinning achromatic half-wave plate, and once inside it passes through a 1 K Lyot stop that controls the telescope illumination. Inside the cryostat, a series of aluminum mirrors, silicon lenses, and dichroic filters split the light into three wavelength bands and direct each band to a different detector array. We will describe the design, and performance of the optics before installation at the telescope.
TolTEC is a 3-band millimeter-wave imaging polarimeter scheduled for deployment to the Large Millimeter Telescope (LMT) in January 2020. TolTEC consists of three, kilopixel-scale, monolithic arrays of microwave kinetic inductance detectors (MKIDs), together comprising over 7,000 polarization sensitive detectors. Here we describe many of the unique aspects of the TolTEC all-silicon focal plane design. We then present both laboratory and fully integrated in-receiver measurements in the lab with which we characterize the optical, resonator, and noise properties of the arrays.
TolTEC is a new camera that will shortly be mounted on the Large Millimeter Telescope (LMT). It provides simultaneous, polarization-sensitive imaging at wavelengths of 1.1, 1.4 and 2.0 mm through its 7718 Lumped element Kinetic Inductance Detectors (KIDs). The TolTEC data analysis software stack, TolTECA, has been developed to facilitate the data analysis tasks, producing science-ready data products for both the TolTEC legacy surveys and for future principal investigator projects. The software stack consists of a high performance fully parallelized C++ data reduction pipeline engine citlali, and an infrastructural Python package tolteca, which works at the highest level, with many notable features including data product management, a web-based data visualization framework, timely analysis and quick-look tools for on-site observing, and a TolTEC observation simulator.
TolTEC is a three-band imaging polarimeter for the Large Millimeter Telescope. Simultaneously observing with passbands at 1.1mm, 1.4mm and 2.0mm, TolTEC has diffraction-limited beams with FWHM of 5, 7, and 11 arcsec, respectively. Over the coming decade, TolTEC will perform a combination of PI-led and Open-access Legacy Survey projects. Herein we provide an overview of the instrument and give the first quantitative measures of its performance in the lab prior to shipping to the telescope in 2021.
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