Esteban Luna

Destruction of the Environment of the BN-KL Nebula

Resumen en: We present the velocity structure of the 2.12 micron H2 emission in Orion, obtained with an IR Fabry-Perot interferometer with a spectral resolution of 2...

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.

Simulated urban climate response to historical land use modification in the Basin of Mexico

Numerical simulations of thermal field variation due to land use changes, such as the reduction of the lacustrine system and the growth of the urban area, in the Basin of Mexico are presented. It is shown that the historically recorded warming in the basin could be attributed, not only to the growth of the urban area, but more importantly to the drastic reduction in the lacustrine system that existed in the basin.

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.

Correlation Algorithm to recover the phase of a test surface using Phase-Shifting Interferometry

A correlation algorithm to recover the phase in phase-shifting interferometry is presented. We make numerical simulations to test the proposed algorithm and apply it to real interferograms with satisfactory results.

Deterministic convergence in iterative phase shifting

Previous implementations of the iterative phase shifting method, in which the phase of a test object is computed from measurements using a phase shifting interferometer with unknown positions of the reference, do not provide an accurate way of knowing when convergence has been attained. We present a new approach to this method that allows us to deterministically identify convergence. The method is tested with a home-built Fizeau interferometer that measures optical surfaces polished to lambda/100 using the Hydra tool. The intrinsic quality of the measurements is better than 0.5 nm. Other possible applications for this technique include fringe projection or any problem where phase shifting is involved.

Ronchi test with variable-frequency rulings

We present a new method for testing an optical surface. It uses the Ronchi test with variable-frequency rulings and a liquid-crystal display. The rulings can be formed by substructuring the spacing of a Ronchi ruling or combining several classical Ronchi rulings in a single variable-frequency ruling. This change allows us to observe smaller de- fects on the surface, because it enlarges the spatial-frequency domain of the ruling, and a larger dynamic range of detection of the Ronchi test can be obtained instead of increasing the resolution of the detection of the Ronchi test by iteratively changing classical Ronchi rulings with higher line density. As a result, we have found that it is possible to measure defects on a optical surface that are of size 57 nm /11.

Geometric method to measure astigmatism aberration at astronomical telescopes

A simple geometrical method to measure the aberration of astigmatism present in the wavefront that emerges from a telescope is presented. The method is based on the analysis of the external contour of the image of a slightly defocused star. An expression elliptical edge is obtained, which links the rms value of Z22 to the geometric parameters of the ellipse. This expression is tested as a function of introduced defocus and astigmatism aberration in telescopes of the San Pedro Martir Observatory. It is shown that the method gives comparable results to wavefront tests, being capable of measuring astigmatism values of approximately 60 nm and larger without the need for auxiliary optics.

Surface roughness results using a hydrodynamic polishing tool (HyDra)

HyDRa is a hydrodynamic radial polishing tool ideal for the corrective lapping and fine polishing of diverse materials by means of an accelerated abrasive flux. The roughness of an optical surface is analysed for a continuous manufacturing process, beginning with the basic generation steps up to a finished optical surface. These results were obtained using a Linnik interferometer.

Ronchi test can detect piston by means of the defocusing term

We present simulated results on piston detection applying the classical Ronchi test to a segmented surface. We have found that a piston error in a test segment, induces a change in the transversal aberration, that can be analyzed by mutually comparing the fringes frequency in each segment. We propose that the piston term of the segmented surface can be recovered by geometrically relating the change in transversal aberration with the piston term. To test this, we have simulated some ronchigrams for a known piston error, and we have been able to recover this term for a dynamic range comprised among 57nm and 550 microm. For piston errors > 550 microm a change in the transversal aberration can be appreciated and measured in the ronchigrams although these large pistons are now classical defocusings. Thus we have demonstrated that the Ronchi test can be an alternative method for the piston detection with a large dynamic range.