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.
We describe the operational capabilities of the Las Cumbres Observatory Global Telescope Network. We summarize our hardware and software for maintaining and monitoring network health. We focus on methodologies to utilize the automated system to monitor availability of sites, instruments and telescopes, to monitor performance, permit automatic recovery, and provide automatic error reporting. The same jTCS control system is used on telescopes of apertures 0.4m, 0.8m, 1m and 2m, and for multiple instruments on each. We describe our network operational model, including workloads, and illustrate our current tools, and operational performance indicators, including telemetry and metrics reporting from on-site reductions. The system was conceived and designed to establish effective, reliable autonomous operations, with automatic monitoring and recovery - minimizing human intervention while maintaining quality. We illustrate how far we have been able to achieve that.
The Las Cumbres Observatory Global Telescope Network comprises nine 1-meter and two 2-meter telescopes, all robotic and dynamically scheduled, at five sites spanning the globe. Instrumentation includes optical imagers and low-dispersion spectrographs. A suite of high-dispersion, high-stability spectrographs is being developed for deployment starting late this year. The network has been designed and built to allow regular monitoring of time-variable or moving objects with any cadence, as well as rapid response to external alerts. Our intent is to operate it in a totally integrated way, both in terms of scheduling and in terms of data quality. The unique attributes of the LCOGT network make it different enough from any existing facility that alternative approaches to optimize science productivity can be considered. The LCOGT network V1.0 began full science operations this year. It is being used in novel ways to undertake investigations related to supernovae, microlensing events, solar system objects, and exoplanets. The network’s user base includes a number of partners, who are providing resources to the collaboration. A key project program brings together many of these partners to carry out large projects. In the long term, our vision is to operate the network as a part of a time-domain system, in which pre-planned monitoring observations are interspersed with autonomously detected and classified events from wide-area surveys.
Our global network of telescopes is designed to provide maximally available optical
monitoring of time variable sources, from solar system to extra-galactic objects, and ranging
in brightness from about 7-20m. We are providing a distributed network with varied apertures
but homogeneous instrumentation: optical imaging, with spectroscopic capabilities. A key
component is a single centralized process that accepts (in real time) and schedules TAC
approved observing requests across the network; then continuously updates schedules based
on status, weather and other availability criteria. Requests range from occasional to continuous
monitoring, at slow to high-speed cadences (imaging and fast photometry), and includes rapid
response to targets of opportunity. Each node of the network must be fully autonomous, with
software agents to control and monitor all functions, to provide auto-recovery as necessary,
and to announce their status and capabilities up the control structure. Real-time monitoring or
interaction by humans should be infrequent. Equipment is designed to be reliable over long
periods to minimize hands-on maintenance, by local or LCOGT staff. Our first 1m deployment
was to McDonald Obs. in April 2012. Eight more 1m telescopes are close to deployment to
complete the Southern ring, scheduled by end-2012.
LCOGT are currently building and deploying a worldwide network of at least fifteen 1-meter
and twenty-four 0.4-meter telescopes to three sites in each hemisphere, enabling
extended, redundant and optimally continuous coverage of time variable or transient
sources. Each site will support two or more 1m telescopes and four or more 0.4m
All telescope classes provide a full range of optical narrow-band and broad-band UBVRI
and ugriZY imaging filters. All telescopes are being equipped with a moving light-bar flatfielding
system called Lambert.
The 1m network is intended primarily for science observing while the 0.4m network
additionally provides educational opportunities to participating schools and institutes. The
global network is designed to accommodate multiple science, educational and rapid
For LCOGT, the network IS the telescope.
Scientific performance specifications, a necessity for ease of commissioning and minimal maintenance, and a desire for
automated sensing and remote collimation have led to novel designs and features in LCOGT's one-meter Optical Tube
Assembly (OTA). We discuss the design and performance of the quasi-RC optical system with 18 point whiffletree and
radial hub mount. Position probes and IR temperature sensors on the primary and secondary mirrors give feedback for
active collimation and thermal control. A carbon fiber/epoxy composite truss, with unique spherical node connections,
mounts to parallel and offset Invar vanes. A flexure based, closed loop, 3-DOF secondary mirror mechanism is used for
tip/tilt collimation. The optics and deflections of the OTA components were iteratively designed for passive collimation
with a changing gravity vector. We present the FEA predictions, measured deflections, and measured hysteresis for
many of the components. Vibration modes, amplitudes, and damping of the system are presented with an FFT frequency
analysis. Thermal CTE effects on loading and focal position are quantified. All of these system effects are then related to
the overall scientific performance of the 1.0 m telescope.
Capturing the very faint optical communications signals expected from the Mars Laser Communication Demonstration (MLCD) experiment to fly aboard the Mars Telecommunications Orbiter (MTO) in 2009 requires a sensitive receiver placed at the focus of a large collecting aperture. For the purpose of demonstrating the potential of deep-space optical communication, it makes sense to employ a large astronomical telescope as a temporary receiver. Because of its large collecting aperture, its reputation as a well-run instrument, and its relative convenience, the 200-inch Hale Telescope on Palomar Mountain is being considered as a demonstration optical 'antenna' for the experiment. However, use of the telescope in this manner presents unique challenges to be overcome, the greatest of which is pointing the telescope and maintaining the communication link to within a few degrees of the Sun. This paper presents our candidate approaches for adapting the Hale telescope to meet the demonstration requirements, modifications to the facilities and infrastructure, the derivation of requirements for baffles and filters to meet the near-Sun pointing objectives, and initial data on the potential of candidate modifications to meet the requirements.
We have developed the Wide Field Grism Spectrograph 2 (WFGS2) for the f/10 focus of the University of Hawaii 2.2 m telescope (UH88). This instrument provides slit-less, wide-field spectroscopy as well as imaging and long-slit spectroscopy. Two CCD cameras of UH88, Tektronix 2k x 2k and OPTIC 4k x 4k, can be used as a detector. The spectral coverage is 380 - 970 nm, and the field of view is 11'.5 x 11'.5 with a pixel scale of 0".34 (Tektronix) or 0".21 pixel-1 (OPTIC) in the imaging mode. WFGS2 has two replica grisms (R = 620 at 650 nm and R = 730 at 400 nm) and a Volume-Phase Holographic (VPH) grism (R = 2500 at 664 nm). The VPH grism enables intermediate-dispersion spectroscopy with this transmission system. Two long-slits with widths of 0".6 and 0".9 can be used. The Sloan Digital Sky Survey (g', r', i', z') and narrow-band (wide Hα, Hα, and [SII]+Li) filters are equipped. The first light observation was done in November 2003. We present the details of WFGS2, including the results of the first light observation.
The University of Hawaii Wide-Field Imager (UHWFI) is a focal compressor designed to project the full half-degree field of the UH 2.2m telescope onto the refurbished 8K×8K CCD camera. The optics use Ohara glasses and are mounted in an oil-filled cell to minimize light losses and ghost images from the large number of internal surfaces. The UHWFI is equipped with a six-position filter wheel and a rotating sector shutter, both driven by stepper motors. The instrument is currently in the design phase and will be commissioned early in 2003.
The IFA and collaborators are embarking on a project to develop a 4-telescope synoptic survey instrument. While somewhat smaller than the 6.5m class telescope envisaged by the decadal review in their proposal for a LSST, this facility will nonetheless be able to accomplish many of the LSST science goals. In this paper we will describe the motivation for a 'distributed aperture' approach for the LSST, the current concept for Pan-STARRS -- a pilot project for the LSST proper -- and its performance goals and science reach. We will also discuss how the facility may be expanded.
Second generation star trackers work by taking wide-angle optical pictures of star fields, correlating the image against a star catalogue in ROM, centroiding many stars to derive an accurate position and orientation. This paper describes a miniature instrument, fast and lightweight, including database and search engine. It can be attached to any telescope to deliver an accurate absolute attitude reference via a serial line. It is independent of encoders or control system, and works whenever it can see the sky. Position update rates in the range of 1 to 5 Hz enable closed-loop operations. The paper describes the instrument operational principles, and its application as an attitude reference unit for a telescope. Actual data obtained at the University of Hawaii's 0.6-m telescope are presented, and their utility for correcting mechanical alignment discussed. The system has great potential as a positioner and guider for (i) remotely operated optical telescopes, (ii) IR telescopes operating in dark clouds, and (iii) radio telescopes. Other application recommendations and the performance estimates are given.
A specially designed faint object spectrograph in the near-IR region from 1 to 2 micrometers is proposed for the Japanese National Large Telescope: SUBARU. The proposed instrument called OHS for SUBARU is kind of a pre-optics system capable of eliminating most of intense OH airglow emission lines from the incident beam in the J- and H-passbands. The detectivity for objects in the faintest end is supposedly enhanced with this spectroscopic filter system by removing nearly 95% of the natural sky background: the non-thermal night airglow emission. The sensitivity gain in terms of limiting magnitude in these wavelength bands is expected to be 1 to 1.5 mag, depending on the modes of observations. The expected performance of the prototype OHS when attached to SUBARU will also be presented.
A fast tip-tilt secondary is being implemented on the University of Hawaii 2.2-m telescope, to provide image quality to match the site characteristics of Mauna Kea, and complement the existing wide-field RC secondary.
The design of an OH airglow suppressor spectrograph for use on the University of Hawaii 2.2 m telescope is presented. The unique feature of the pre-optics system for low resolution spectroscopy in the 1.1 to 1.8 micrometers range is the capability of removing most of the intense OH emission lines by a specially designed spectroscopic mask. With the OH suppressor spectrography, the background flux is reduced to about 1/30 the natural background on the average. The sensitivity gain in terms of limiting magnitude is expected to be approximately 1.5 mag, compared with the conventional method.
This paper describes a low cost adaptive optics (AO) instrument that is being built for the f/31 focus of the UH 2.2m telescope. While operating within the low cost constraint, we have tried to maximize the flexibility and usefulness of the instrument, and minimize the impact of the necessary performance compromises. We have used off-the-shelf optical and electronic components wherever possible, and have emphasized simplicity of design throughout the instrument. The UH prototype AO system, on which the 2.2m AO system is based, is described elsewhere, thus the principles of operation of the UH 2.2m instrument will not be described in detail here.
A telescope aperture of 2.2-m on Mauna Kea that routinely experiences d/r sub 0 = 4 in the near-IR can achieve a factor of 2 gain in angular resolution by tip-tilt correction of atmospheric-induced wavefront errors. To utilize the gains possible from tip-tilt correction, collimation errors and focus errors must also be removed. For its 2.2-m f/31 telescope, the University of Hawaii is in the process of implementing a five-axis fast guiding secondary consisting of a fast steering mirror platform and slow remote detilt, decenter, and despace collimation and focus drives. The near-term goal is to implement closed-loop tip-tilt image motion correction with open-loop collimation and focus control. The long-term goal is to add closed-loop collimation and focus control. This paper documents the progress to date on the fast steering mirror platform and its spider support structure.
Results recently obtained for the use of the curvature-sensing method as a substitute for slope sensing in optical wavefront reconstruction, using long-exposure CCD images of the beam cross-section on either side of the telescope focal plane. A program based on the solution to the Poisson equation is then applied in order to reconstruct the wavefront. Relative to the existing Hartmann sensing methods, curvature-sensing yields sensitivity comparable to that of the Shack-Hartmann test. Additional optics and reference plane-based calibration are obviated. Tests of the new method on an 88-inch Ritchey-Chretien telescope have yielded a map of residual wavefront errors as a solution of the Poisson equation.