Effects of Atmospheric Turbulence on High Cadence Observations of Stellar Occultations
Por:
Guerrero, C. A., Hernandez-Aguila, J. B., Castro-Chacon, J. H., Hernandez-Valencia, B., Sanchez, E., Reyes-Ruiz, M., Silva, J. S., Alvarez-Santana, F. I.
Publicada:
1 jun 2020
Resumen:
In this paper we study the effects of systematic noise and atmospheric
turbulence on image quality and signal-to-noise ratio for high cadence
(similar to 20 fps) observations, in the context of fortuitous stellar
occultation surveys. We performed an analysis of the spatial
distribution of the weighted centroid of a reference star, in the X and
Y direction (in the detector), and we also analyze the FWHM behavior to
study the effect on the stellar profile. This information allowed us to
find both the shift and the deformation of each image, which are the
most significant effects of atmospheric turbulence on such images. Our
observations were carried out at the 84 cm telescope of the San Pedro
Martir Observatory, located in Ensenada, Baja California, Mexico. In
order to isolate the atmospheric turbulence contribution on image
quality and motion, the systematic noise due to telescope motion and
other low frequency components were filtered-out from the distribution
curve for the centroids. We used the APPHi pipeline as our analysis tool
to study the effect of the size of the Region of Interest (ROIs) on
energy loss in the photometry of the stars. We find for example that
using ROI of 7 x 7 pixels in our study, the shifting and deformation of
the images will produce an energy loss of similar to 10%, for more than
9% of the observations, even after removing the systematic noise. Such
energy loss can be comparable to the flux drop expected for some TNO
occultations, thus leading to spurious detections. We also find that the
algorithm developed to calculate an optimal ROI in the APPHi pipeline,
makes a good compromise between avoiding the flux loss and keeping a
reasonably small ROI, to reduce the data storage requirements and
maximize the number of stars that can be simultaneously observed while
limiting the overlap of ROIs for stars which are very close to each
other.
Filiaciones:
Guerrero, C. A.:
Univ Nacl Autonoma Mexico, Inst Astron, Ensenada, Baja California, Mexico
Hernandez-Aguila, J. B.:
Univ Nacl Autonoma Mexico, Inst Astron, Ensenada, Baja California, Mexico
Castro-Chacon, J. H.:
Univ Nacl Autonoma Mexico, Inst Astron, CONACYT, Ensenada, Baja California, Mexico
Hernandez-Valencia, B.:
Univ Nacl Autonoma Mexico, Inst Astron, Ensenada, Baja California, Mexico
Sanchez, E.:
Univ Nacl Autonoma Mexico, Inst Astron, Ensenada, Baja California, Mexico
Reyes-Ruiz, M.:
Univ Nacl Autonoma Mexico, Inst Astron, Ensenada, Baja California, Mexico
Silva, J. S.:
Univ Nacl Autonoma Mexico, Inst Astron, CONACYT, Ensenada, Baja California, Mexico
Alvarez-Santana, F. I.:
Univ Nacl Autonoma Mexico, Inst Astron, Ensenada, Baja California, Mexico
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