The concept design for a laboratory based telescope emulator for the Giant Magellan Telescope (GMT) is described here. The Giant Magellan Telescope has a primary mirror comprised of 7 segments, and a ...secondary mirror with matching segmentation. The phasing of the GMT is a complex problem; a phasing testbed, Pocket-GMT, has been designed by a group within the Research School of Astronomy and Astrophysics at the Australian National University for the Giant Magellan Telescope Corporation. Pocket-GMT uses a novel technique to split the bending modes between a piston/tip-tilt surface and a deformable mirror. Pocket-GMT will demonstrate successful phasing of an optical miniature GMT by the planned prototype wavefront sensing systems. By reproducing the optical characteristics of the GMT on a small scale, Pocket-GMT will reduce the risk associated with the phasing system and provide a platform to test the telescope
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instrumentation prior to commissioning.
The view from the south is, more than ever, dominated by ominous signs of change. Antarctica and the Southern Ocean are intrinsic to the Earth system, and their evolution is intertwined with and ...influences the course of the Anthropocene. In turn, changes in the Antarctic affect and presage humanity's future. Growing understanding is countering popular beliefs that Antarctica is pristine, stable, isolated, and reliably frozen. An aspirational roadmap for Antarctic science has facilitated research since 2014. A renewed commitment to gathering further knowledge will quicken the pace of understanding of Earth systems and beyond. Progress is already evident, such as addressing uncertainties in the causes and pace of ice loss and global sea-level rise. However, much remains to be learned. As an iconic global “commons,” the rapidity of Antarctic change will provoke further political action. Antarctic research is more vital than ever to a sustainable future for this One Earth.
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Antarctica and the Southern Ocean are intrinsic to the Earth system, and their evolution is intertwined with, and influences, the course of the Anthropocene. In this review, Kennicutt et al. evaluate the progress made since the SCAR Horizon Scan charted the course for Antarctic science in 2014. They show that while much has been learned, open questions remain and that in the current climate of instability, Antarctic research is more vital than ever to a sustainable future for this one Earth.
In this article we present an analysis of the statistical and temporal properties of seeing and isoplanatic angle measurements obtained with combined Differential Image Motion Monitor (DIMM) and ...Multi-Aperture Scintillation Sensor (MASS) units at the Thirty Meter Telescope (TMT) candidate sites. For each of the five candidate sites we obtained multiyear, high-cadence, high-quality seeing measurements. These data allow for a broad and detailed analysis, giving us a good understanding of the characteristics of each of the sites. The overall seeing statistics for the five candidate sites are presented, broken into total seeing (measured by the DIMM), free-atmosphere seeing and isoplanatic angle (measured by the MASS), and ground-layer seeing (difference between the total and free-atmosphere seeing). We examine the statistical distributions of seeing measurements and investigate annual and nightly behavior. The properties of the seeing measurements are discussed in terms of the geography and meteorological conditions at each site. The temporal variability of the seeing measurements over timescales of minutes to hours is derived for each site. We find that each of the TMT candidate sites has its own strengths and weaknesses when compared against the other candidate sites. The results presented in this article form part of the full set of results that are used for the TMT site-selection process. This is the fifth article in a series discussing the TMT site-testing project.
We report the first measurement of the atmospheric optical turbulence profile using the transmitted beam from a satellite laser communication terminal. A ring image next generation scintillation ...sensor (RINGSS) instrument for turbulence profiling, as described in Tokovinin MNRAS 502 , 747 ( 2021 ) 10.1093/mnras/staa4049 , was deployed at the NASA/Jet Propulsion Laboratory’s Table Mountain Facility (TMF) in California. The optical turbulence profile was measured with the downlink optical beam from the Laser Communication Relay Demonstration (LCRD) geostationary satellite. LCRD conducts links with the Optical Communication Telescope Laboratory ground station and the RINGSS instrument was co-located at TMF to conduct measurements. Turbulence profiles were measured at day and night and atmospheric coherence lengths were compared with other turbulence monitors such as a solar scintillometer and Polaris motion monitor. RINGSS sensitivity to boundary layer turbulence, a feature not provided by many profilers, is also shown to agree with a boundary layer scintillometer at TMF ( R = 0.85). Diurnal evolution of optical turbulence and measured profiles are presented. The correlation of RINGSS with other turbulence monitors ( R = 0.75 − 0.86) demonstrates the concept of free-space optical communications turbulence profiling, which could be adopted as a way to support optical ground stations in a future Geostationary feeder link network. These results also provide further evidence that RINGSS, a relatively new instrument concept, correlates well with other instruments in daytime and nighttime turbulence.
Palomar Gattini-IR is a new wide-field, near-infrared (NIR) robotic time domain survey operating at Palomar Observatory. Using a 30 cm telescope mounted with a H2RG detector, Gattini-IR achieves a ...field of view (FOV) of 25 sq. deg. with a pixel scale of 8 7 in J-band. Here, we describe the system design, survey operations, data processing system and on-sky performance of Palomar Gattini-IR. As a part of the nominal survey, Gattini-IR scans 7500 square degrees of the sky every night to a median 5 depth of 15.7 AB mag outside the Galactic plane. The survey covers 15,000 square degrees of the sky visible from Palomar with a median cadence of 2 days. A real-time data processing system produces stacked science images from dithered raw images taken on sky, together with point-spread function (PSF)-fit source catalogs and transient candidates identified from subtractions within a median delay of 4 hr from the time of observation. The calibrated data products achieve an astrometric accuracy (rms) of 0 7 with respect to Gaia DR2 for sources with signal-to-noise ratio > 10, and better than 0 35 for sources brighter than 12 Vega mag. The photometric accuracy (rms) achieved in the PSF-fit source catalogs is better than 3% for sources brighter than 12 Vega mag and fainter than the saturation magnitude of 8.5 Vega mag, as calibrated against the Two Micron All Sky Survey catalog. The detection efficiency of transient candidates injected into the images is better than 90% for sources brighter than the 5 limiting magnitude. The photometric recovery precision of injected sources is 3% for sources brighter than 13 mag, and the astrometric recovery rms is 0 9. Reference images generated by stacking several field visits achieve depths of 16.5 AB mag over 60% of the sky, while it is limited by confusion in the Galactic plane. With a FOV 40× larger than any other existing NIR imaging instrument, Gattini-IR is probing the reddest and dustiest transients in the local universe such as dust obscured supernovae in nearby galaxies, novae behind large columns of extinction within the galaxy, reddened microlensing events in the Galactic plane and variability from cool and dust obscured stars. We present results from transients and variables identified since the start of the commissioning period.
We examine the experiences and ideas from operating observatories regarding the measurements of the characteristics of the atmosphere that must be gathered within the locality of the observatory in ...order to support safe, efficient and scientifically optimized observatory operations as well as commissioning, performance monitoring and support the scientific analysis of telescope observations. We describe the expected requirements for the measurement capabilities of the the TMT Site Conditions Monitoring System (SCMS) and discuss how these plans are being developed with input from staff at operating observatories and active observational astronomers.
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