Fernando Ángeles

San Pedro Mártir: astronomical site evaluation

The Observatorio Astronomico Nacional at San Pedro Martir is situated on the summit of the San Pedro Martir Sierra in the Baja California peninsula of Mexico, at 2800m above sea level. For as long as three decades, a number of groups and individuals have gathered extremely valuable data leading to the site characterization for astronomical observations. Here we present a summary of the most important results obtained so far. The aspects covered are: weather, cloud coverage, local meteorology, atmospheric optical extinction, millimetric opacity, geotechnical studies, seeing, optical turbulence profiles, wind profiles and 3D simulations of atmospheric turbulence. The results place San Pedro Martir among the most favorable sites in the world for astronomical observations. It seems to be particularly well-suited for extremely large telescopes because of the excellent turbulence and local wind conditions, to mention but two characteristics. Long-term monitoring of some parameters still have to be undertaken. The National University of Mexico (UNAM) and other international institutions are putting a considerable effort in that sense.

UNAM scanning Fabry-Perot interferometer (PUMA) for the study of interstellar medium

The system called PUMA is an instrument consisting of a focal reducer coupled to a scanning Fabry-Perot interferometer (SFPI), which is being developed for the Observatorio Astronomicao Nacional at San Pedro Martir, B.C. It will be installed at the 2.0 m Ritchey-Chretien telescope with a focal ratio of F/7.9. It has interference filters, a calibration system, and field diaphragms. The SFPI can be moved out of the optical path in order to acquire direct images. The images produced by this instrument will be focused on an optoelectronic detector, a CCD, or a Mepsicron, depending on the spectral range used.

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

COATLI: an all-sky robotic optical imager with 0.3 arcsec image quality

500,000. This makes it possible to contemplate a global network of DDOTI installations. Such geographic diversity would give earlier access and a higher localization rate. We are actively exploring this option.

Optical design of COATLI: an all-sky robotic optical imager with 0.3 arcsec image quality

COATLI will provide 0.3 arcsec FWHM images from 550 to 900 nm over a large fraction of the sky. It consists of a robotic 50-cm telescope with a diffraction-limited fast-guiding imager. Since the telescope is small, fast guiding will provide diffraction-limited image quality over a field of at least 1 arcmin and with coverage of a large fraction of the sky, even in relatively poor seeing. The COATLI telescope will be installed at the at the Observatorio Astronómico Nacional in Sierra San Pedro Mártir, México, during 2016 and the diffraction-limited imager will follow in 2017.

3D mapping of the optical turbulence around the San Pedro Martir site using the numerical model Meso-Nh. Perspectives for a flexible-scheduling application

COATLI is a new instrument and telescope that will provide 0.3 arcsec FWHM images from 550 to 920 nm over a large fraction of the sky. It consists of a robotic 50-cm telescope with a diffraction-limited imager. The imager has a steering mirror for fast guiding, a blue channel using a EMCCD from 400 to 550 nm to measure image motion, a red channel using a standard CCD from 550 to 920 nm, and an active optics system based on a deformable mirror to compensate static aberrations in the red channel. Since the telescope is small, fast guiding will provide diffraction-limited image quality in the red channel over a large fraction of the sky, even in relatively poor seeing. COATLI will be installed at the Observatorio Astronomico Nacional in Baja California, Mexico, in September 2016 and will operate initially with a simple interim imager. The definitive COATLI instrument will be installed in 2017. In this paper, we present some of the details of the optical design of the instrument.

Fast photometry of stars

Recently, a dedicated study for the seeing forecasting at the San Pedro Martir Observatory started in order to support the project of the TIM (Telescopio Infrarojo Mexicano) that will be installed on this mountainous region of Baja California. Here we present some preliminary results, we analyze the importance of using a vegetation model for simulations over a site surrounding by high trees and we study the influence of the analyzed surface on the simulations outputs. We present the results obtained integrating the optical turbulence respect lines of sight different from zenith. Finally, we report a brief description of some model modifications that are being introduced in order to apply this technique to the forecasting of optical turbulence for observations in the millimetric regime.

End-to-end simulations for COLIBRI, ground follow-up telescope for the SVOM mission.

A fast photometry methodology is described. We use a cooled Ixon Ultra emCCD in photon counter mode to acquire data. A dissipation system is added to stabilize the temperature down to -96 C. The sensibility of this system makes it ideal even for small telescopes.

Structural design techniques applied in astronomical instruments

We present an overview of the development of the end-to-end simulations programs developed for COLIBRI (Catching OpticaL and Infrared BRIght), a 1.3m robotic follow-up telescope of the forthcoming SVOM (Space Variable Object Monitor) mission dedicated to the detection and study of gamma-ray bursts (GRBs). The overview contains a description of the Exposure Time Calculator, Image Simulator and photometric redshift code developed in order to assess the performance of COLIBRI. They are open source Python packages and were developed to be easily adaptable to any optical/ Near-Infrared imaging telescopes. We present the scientific performances of COLIBRI, which allows detecting about 95% of the current GRB dataset. Based on a sample of 500 simulated GRBs, a new Bayesian photometric redshift code predicts a relative photometric redshift accuracy of about 5% from redshift 3 to 7.

Virtual reality and project management for astronomy

We present in this article some of the techniques applied at the Instituto de Astronomía of the Universidad Nacional Autónoma de México (IA-UNAM) to the mechanical structural design for astronomical instruments. With this purpose we use two recent projects developed by the Instrumentation Department. The goal of this work is to give guidelines about support structures design for achieving a faster and accurate astronomical instruments design. The main guidelines that lead all the design stages for instrument subsystems are the high-level requirements and the overall specifications. From these, each subsystem needs to get its own requirements, specifications, modes of operation, relative position, tip/tilt angles, and general tolerances. Normally these values are stated in the error budget of the instrument. Nevertheless, the error budget is dynamic, it is changing constantly. Depending on the manufacturing accuracy achieved, the error budget is again distributed. That is why having guidelines for structural design helps to know some of the limits of tolerances in manufacture and assembly. The error budget becomes then a quantified way for the interaction between groups; it is the key for teamwork.