San Pedro Mártir mid-infrared photometric system

 

L. Salas,¹ I. Cruz-González,² and M. Tapia¹

 

¹ Instituto de Astronomía, UNAM, Apdo. Postal 877, 22860 Ensenada, B. C., México (mt@astrosen.unam.mx, salas@astrosen.unam.mx).

² Instituto de Astronomía, UNAM, Apdo. Postal 70.264, 04510 México, D. F., México (irene@astroscu.unam.mx)

 

Received 2005 September 21
Accepted 2006 June 30

 

RESUMEN

Con el objetivo de definir el Sistema Fotométrico para el Mediano-Infrarrojo de San Pedro Mártir, se realizaron observaciones de estrellas de calibración bien estudiadas con la cámara del mediano-infrarrojo CID-BIB (2 - 28 µm) del Observatorio Astronómico Nacional, durante 9 temporadas de observación en 2000 a 2005. Se utilizó un conjunto de 9 filtros, los de la serie de "silicatos" SiN, SiO, SiP, SiQ, SiR, SiS, el filtro de banda ancha N (10.8 µm), y los filtros angostos QH2 (17.15 µm) y Q2 (18.7 µm), para determinar los coeficientes de extinción y los puntos cero en magnitud. Las correcciones por extinción atmosférica se llevaron a cabo mediante el uso de aproximantes de Padé, y los coeficientes involucrados se obtuvieron mediante una relación lineal con el coeficiente de extinción a baja masa de aire. Se presentan y comparan las curvas de transmisión atmosférica de SPM y los coeficientes de extinción con los del sitio astronómico Mauna Kea. Utilizando un conjunto de fuentes IRAS LSR observadas con el CID-BIB se encuentran términos de color.

 

ABSTRACT

With the goal of defining the San Pedro Martir Mid-infrared Photometric System (SPM-MIR), observations of well-defined calibration stars were carried out on 9 photometric runs from 2000 to 2005. The mid-infrared (2 - 28 µm) camera CID-BIB of the Observatorio Astronómico Nacional was used. A set of 9 filters, the "silicate" series SiN, SiO, SiP, SiQ, SiR, SiS, the broad-band N (10.8 µm) filter, and the narrow-band QH2 (17.15 µm) and Q2 (18.7 µm), was used to derive the extinction coefficients and zero magnitude points. Atmospheric extinction corrections were carried out making use of Padé approximants and we found a linear dependence on the parameters with the low air mass extinction coefficient. The atmospheric transmission curves and extinction coefficients of SPM were compared with those obtained for the Mauna Kea site. Color terms were derived using a set of IRAS LSR sources observed with the CID-BIB.

Key Words: INSTRUMENTATION: PHOTOMETERS - SITE TESTING - STARS: FUNDAMENTAL PARAMETERS - TECHNIQUES: PHOTOMETRIC.

 

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Acknowledgements

We are indebted to an anonymous referee for a series of comments and suggestions that lead to a significant improvement of the present paper. We would like to thank the staff of the Observatorio Astronómico Nacional at San Pedro Mártir, for their valuable assistance in the observations. The CID-BIB is part of the infrared facilities operating at the Observatorio Astronómico Nacional in San Pedro Mártir, and was financed primarly through grants PACIME-CONACYT F325-E9211, CONACYT 1021PE, 36574E supplemented by DGAPA-UNAM 1N501694, 1N108696, 1N105400, 1N102803, and 1N104693.

 

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