Time domain astronomy has both increased the data volume and the urgency of data reduction in recent years. Spectra provide key insights into astrophysical phenomena but require complex reductions. Las Cumbres Observatory has six spectrographs - two low-dispersion FLOYDS instruments and four NRES high-resolution echelle spectrographs. We present an extension of the data reduction framework, BANZAI, to process spectra automatically, with no human interaction. We also present interactive tools we have developed for human vetting and improvement of the spectroscopic reduction. Tools like those presented here are essential to maximize the scientific yield from current and future time domain astronomy.
Las Cumbres Observatory global telescope (LCOGT) is a unique worldwide network of dynamically scheduled, fully robotic optical telescopes, purpose built for time domain astronomy. The LCOGT network enters its second decade of operations in 2024. A flood of transient alerts are expected from the Vera C. Rubin Legacy Survey of Space and Time (LSST) and multimessenger observatories. In 2023 LCOGT will complete the northern hemisphere 1-m telescope ring, currently four telescopes at McDonald and Teide Observatories, with the addition of two 1-m telescopes at Ali Observatory in Tibet. The southern ring is complete at the Siding Spring, Cerro Tololo and the South African Astronomical Observatories. LCOGT is an active partner in the Astrophysical Event Observatory Network (AEON) with NOIRLab facilities (Gemini Observatory, SOAR Observatory, and the Community Science and Data Center), to develop the infrastructure to efficiently carry out astronomical observations in the Vera C. Rubin Observatory LSST era. While the global pandemic has provided multiple operational challenges, hardware and software projects currently underway will make LCOGT an even more powerful transient follow-up facility in its second decade of operations.
We report the development of MuSCAT3, a four channel simultaneous imager installed on the 2m Faulkes Telescope North at Haleakala Observatory on Maui, Hawai’i. MuSCAT3 has a capability of 4-color simultaneous imaging in g (400–550 nm), r (550–700 nm), i (700–820 nm), and zs (820–920 nm) bands with four independent 2048×2048 pixel CCDs, each having a field of view of 9.1×9.1 arcmin2 with a pixel scale of 0.27 arcsec per pixel. The development of MuSCAT3 started from September 2019, and MuSCAT3 achieved its first light on September 28th, 2020. The Las Cumbres Observatory started science operations of MuSCAT3 since November 4th, 2020, although a part of its capabilities are still limited.
The Las Cumbres Observatory operates a fleet of robotically controlled telescopes currently two 2m, nine 1m, and ten 0.4m telescopes, distributed amongst six sites covering both hemispheres. Telescopes of an aperture class are equipped with an identical set of optical imagers, and those data are subsequently processed by a common pipeline (BANZAI). The telescopes operate without direct human supervision, and assessing the daily and long-term scientific productivity of the fleet of telescopes and instruments poses an operational challenge. One key operational metric of a telescope/instrument system is throughput. We present a method of long-term performance monitoring based on nightly science observations: For every image taken in matching filters and within the footprint of the PANSTARRS DR1 catalog we derive a photometric zeropoint, which is a good proxy for system throughput. This dataset of over 250000 data points enables us to answer questions about general throughput degradation trends, and how individual telescopes perform at the various sites. This particular metric is useful to plan the effort level for on-site support and to prioritize the cleaning and re-aluminizing schedule of telescope optics and mirrors respectively.
Work in time-domain astronomy necessitates robust, automated data processing pipelines that operate in real time. We present the BANZAI pipeline which processes the thousands of science images produced across the Las Cumbres Observatory Global Telescope (LCOGT) network of robotic telescopes each night. BANZAI is designed to perform near real-time preview and end-of-night final processing for four types of optical CCD imagers on the three LCOGT telescope classes. It performs instrumental signature removal (bad pixel masking, bias and dark removal, flat-field correction), astrometric fitting and source catalog extraction. We discuss the design considerations for BANZAI, including testing, performance, and extensibility. BANZAI is integrated into the observatory infrastructure and fulfills two critical functions: (1) real-time data processing that delivers data to users quickly and (2) derive metrics from those data products to monitor the health of the telescope network. In the era of time-domain astronomy, to get from these observations to scientific results, we must be able to automatically reduce data with minimal human interaction, but still have insight into the data stream for quality control.
Las Cumbres Observatory Global Telescope Network (LCOGT) has built the Network of Robotic Echelle Spectrographs (NRES), consisting of four identical, high-resolution optical spectrographs, each fiber-fed simultaneously by up to two 1-meter telescopes and a calibration source. Two units have been installed and are currently executing scientific observations. A third unit has been installed and is presently in commissioning. A fourth unit has been shipped to site and will be installed in mid 2018. Operating on four separate continents in both the Northern and Southern hemispheres, these instruments comprise a globally-distributed, autonomous spectrograph facility for stellar classification and high-precision radial velocity of bright stars. Simulations suggest we will achieve long-term radial velocity precision of 3 m/s in less than an hour for stars with V < 12. Radial velocity precision of 75 m/s has already been demonstrated with our automatic data-processing pipeline across multiple sites. Work is ongoing to improve several NRES system components including telescope control (robotic source acquisition in particular) and the data-processing pipeline. In this document we briefly overview the NRES design, its purpose and goals, results achieved to date in the field, and the ongoing development effort to improve instrument performance.
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