Alejandro Farah

First Light with RATIR: An Automated 6-band Optical/NIR Imaging Camera

The Reionization and Transients InfraRed camera (RATIR) is a simultaneous optical/NIR multi-band imaging camera which is 100% time-dedicated to the followup of Gamma-ray Bursts. The camera is mounted on the 1.5-meter Johnson telescope of the Mexican Observatorio Astronomico Nacional on Sierra San Pedro Martir in Baja California. With rapid slew capability and autonomous interrupt capabilities, the system will image GRBs in 6 bands (i, r, Z, Y, J, and H) within minutes of receiving a satellite position, detecting optically faint afterglows in the NIR and quickly alerting the community to potential GRBs at high redshift (z>6-10). We report here on this Springs first light observing campaign with RATIR. We summarize the instrumental characteristics, capabilities, and observing modes.

Performance and Calibration of H2RG Detectors and SIDECAR ASICs for the RATIR Camera

The Reionization And Transients Infra-Red camera has been built for rapid Gamma-Ray Burst followup and will provide simultaneous optical and infrared photometric capabilities. The infrared portion of this camera incorporates two Teledyne HgCdTe HAWAII-2RG detectors, controlled by Teledyne’s SIDECAR ASICs. While other ground-based systems have used the SIDECAR before, this system also utilizes Teledyne’s JADE2 interface card and IDE development environment. Together, this setup comprises Teledyne’s Development Kit, which is a bundled solution that can be efficiently integrated into future ground-based systems. In this presentation, we characterize the system’s read noise, dark current, and conversion gain.

Automation of the OAN/SPM 1.5-meter Johnson telescope for operations with RATIR

The Reionization And Transients Infra-Red (RATIR) camera is intended for robotic operation on the 1.5-meter Harold Johnson telescope of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. This paper describes the work we have carried out to successfully automate the telescope and prepare it for RATIR. One novelty is our use of real-time absolute astrometry from the finder telescopes to point and guide the main telescope.

Software solution for autonomous observations with H2RG detectors and SIDECAR ASICs for the RATIR camera

The Reionization And Transients InfraRed (RATIR) camera has been built for rapid Gamma-Ray Burst (GRB) followup and will provide quasi-simultaneous imaging in ugriZY JH. The optical component uses two 2048 × 2048 pixel Finger Lakes Imaging ProLine detectors, one optimized for the SDSS u, g, and r bands and one optimized for the SDSS i band. The infrared portion incorporates two 2048 × 2048 pixel Teledyne HgCdTe HAWAII-2RG detectors, one with a 1.7-micron cutoff and one with a 2.5-micron cutoff. The infrared detectors are controlled by Teledynes SIDECAR (System for Image Digitization Enhancement Control And Retrieval) ASICs (Application Specific Integrated Circuits). While other ground-based systems have used the SIDECAR before, this system also utilizes Teledynes JADE2 (JWST ASIC Drive Electronics) interface card and IDE (Integrated Development Environment). Here we present a summary of the software developed to interface the RATIR detectors with Remote Telescope System, 2nd Version (RTS2) software. RTS2 is an integrated open source package for remote observatory control under the Linux operating system and will autonomously coordinate observatory dome, telescope pointing, detector, filter wheel, focus stage, and dewar vacuum compressor operations. Where necessary we have developed custom interfaces between RTS2 and RATIR hardware, most notably for cryogenic focus stage motor drivers and temperature controllers. All detector and hardware interface software developed for RATIR is freely available and open source as part of the RTS2 distribution.

Mechanical design and integration of the support structure for the Reionization And Transients InfRared Instrument RATIR

In this article we present the mechanical design and the manufacturing of the support structure for the Reionization And Transients InfraRed (RATIR) camera. The instrument is mounted at the f/13 Cassegrain focus of the 1.5-meter Harold Johnson telescope of the Observatorio Astronómico Nacional at San Pedro Mártir (OAN/SPM) in Mexico. We describe the high-level requirements and explain their translation to the mechanical specifications and requirements. We describe the structural finite-element analysis and the boundary conditions, loads, and general assumptions included in the simulations. We summarize the expected displacements, rotations and stresses. We present the optomechanical components and the elements used to attach the instrument to the telescope. Finally, we show the instrument installed on the telescope.

Mechanical configurations for the reionization and transients infrared camera (RATIR)

RATIR (The Reionization and Transients Infrared Camera/Telescope) is an optical infrared camera in the 1.5 m telescope in the Mexican National Astronomical Observatory, OAN, in San Pedro Martir, Baja California. The primary goal of RATIR is to remotely observe Gamma Ray Bursts as detected by the SWIFT satellite. This document describes the problem definition, the mechanical calculations, the conceptual design, the finite element analysis, the different configurations proposed and the mechanical performance of the main Support Structure and Dichroic Mounts for RATIR.

OSIRIS tunable imager and spectrograph for the GTC: from design to commissioning

OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy) was the optical Day One instrument for the 10.4m Spanish telescope GTC. It is installed at the Observatorio del Roque de Los Muchachos (La Palma, Spain). This instrument has been operational since March-2009 and covers from 360 to 1000 nm. OSIRIS observing modes include direct imaging with tunable and conventional filters, long slit and low resolution spectroscopy. OSIRIS wide field of view and high efficiency provide a powerful tool for the scientific exploitation of GTC. OSIRIS was developed by a Consortium formed by the Instituto de Astrofísica de Canarias (IAC) and the Instituto de Astronomía de la Universidad Nacional Autónoma de México (IA-UNAM). The latter was in charge of the optical design, the manufacture of the camera and collaboration in the assembly, integration and verification process. The IAC was responsible for the remaining design of the instrument and it was the project leader. The present paper considers the development of the instrument from its design to its present situation in which is in used by the scientific community.

Optomechanical design, manufacturing, assembly, and integration of contemporary camera barrels for astronomical instrumentation

Optical systems for scientific instrumentation frequently include lenses with critical mechanical requirements. Position and rotation issues of these components are inextricably bound to the efficiency of the instrument. This work describes the optomechanical design, manufacturing, assembly, and integration of the camera barrel located in the OSIRIS imager/spectrograph for the Gran Telescopio Canarias. The barrel was developed by the Instituto de Astronomia at the Universidad Nacional Autonoma de Mexico (IA-UNAM), in collaboration with the Instituto de Astrofisica de Canarias (IAC), Spain. The camera barrel (CB) includes a set of eight lenses with their respective supports and cells, as well as two compensators: the focusing unit and the passive displacement unit, which uses the third doublet as a thermal compensator to maintain the cameras focal length and image quality with changing ambient temperature. A brief description of OSIRIS, the design criteria, optomechanical requirements, and specifications for misalignment errors and stresses are included. The camera components, analytical calculations, FEA simulations, and error budgets are also described. The iterative process of the optomechanical stages for the development of the camera are also verified and summarized. Finally, notes about fabrication, metrology, assembly, and integration are proposed as guidelines for future developments in optomechanics.

Conceptual design and structural analysis for an 8.4-m telescope

This paper describes the conceptual design of the optics support structures of a telescope with a primary mirror of 8.4 m, the same size as a Large Binocular Telescope (LBT) primary mirror. The design goal is to achieve a structure for supporting the primary and secondary mirrors and keeping them joined as rigid as possible. With this purpose an optimization with several models was done. This iterative design process includes: specifications development, concepts generation and evaluation. Process included Finite Element Analysis (FEA) as well as other analytical calculations. Quality Function Deployment (QFD) matrix was used to obtain telescope tube and spider specifications. Eight spiders and eleven tubes geometric concepts were proposed. They were compared in decision matrixes using performance indicators and parameters. Tubes and spiders went under an iterative optimization process. The best tubes and spiders concepts were assembled together. All assemblies were compared and ranked according to their performance.

DDOTI: the deca-degree optical transient imager

DDOTI will be a wide-field robotic imager consisting of six 28-cm telescopes with prime focus CCDs mounted on a common equatorial mount. Each telescope will have a field of view of 12 deg2, will have 2 arcsec pixels, and will reach a 10σ limiting magnitude in 60 seconds of r ≈ 18:7 in dark time and r ≈ 18:0 in bright time. The set of six will provide an instantaneous field of view of about 72 deg2. DDOTI uses commercial components almost entirely. The first DDOTI will be installed at the Observatorio Astronómico Nacional in Sierra San Pedro Martír, Baja California, México in early 2017. The main science goals of DDOTI are the localization of the optical transients associated with GRBs detected by the GBM instrument on the Fermi satellite and with gravitational-wave transients. DDOTI will also be used for studies of AGN and YSO variability and to determine the occurrence of hot Jupiters. The principal advantage of DDOTI compared to other similar projects is cost: a single DDOTI installation costs only about US