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Photometric Evaluation and Calibration of the Earthshine Telescope

Badinez, Rodrigo (2011) PHYM01 20111
Department of Astronomy and Theoretical Physics
Department of Physics
Abstract
An earthshine telescope has been designed and is being fabricated at Lund Observatory in collaboration
with the Danish Meteorological Institute. The instrument will measure the albedo of the Earth by
observing the Moon in white light and in certain spectral bands.
The measurement is based on relative photometry of the dark and bright sides of the Moon, so the
optical design of the telescope has been carried out with special attention to photometric quality and
stray light performance. In addition, advanced operating modes have been developed. Hence, the
instrument is expected to be superior to existing earthshine telescopes.
The LO/DMI Earthshine Telescope was envisaged to provide produce albedo measurements with an
accuracy on the... (More)
An earthshine telescope has been designed and is being fabricated at Lund Observatory in collaboration
with the Danish Meteorological Institute. The instrument will measure the albedo of the Earth by
observing the Moon in white light and in certain spectral bands.
The measurement is based on relative photometry of the dark and bright sides of the Moon, so the
optical design of the telescope has been carried out with special attention to photometric quality and
stray light performance. In addition, advanced operating modes have been developed. Hence, the
instrument is expected to be superior to existing earthshine telescopes.
The LO/DMI Earthshine Telescope was envisaged to provide produce albedo measurements with an
accuracy on the order of 0.1%. The objective of this thesis was to evaluate the accuracy of some of the
main elements that contributes to the final photometric performance of the Earthshine Telescope. In
particular the performance of the shutter was analyzed, since it is very crucial to obtain accurate
photometry of the observation, especially due to the high range of the exposures from 10ms to few
minutes which is needed for the albedo calculation. Also the proper characterization of the spectral
filters transmission is very important for the precision of the spectro-photometric analysis of the Earth’s
albedo, and for this reason spectral measurements were done for all the filters of the Earthshine
Telescope.
It was found that for 10ms the accuracy of the shutter response is 0.4%, and this will affect the accuracy
of some of the operating modes of the Earthshine Telescope that require short exposures times.
Nevertheless it is possible to decrease the error in shutter response for these operating modes by
reducing the amount of light falling into the detector using a neutral density filter or reducing the
aperture.
Also spectral characterization of all the color filters and Knife Edge Optical Density filters of the
Earthshine Telescope was done, obtaining spectral curves that matched very well with the specified by
the manufacturers. (Less)
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author
Badinez, Rodrigo
supervisor
organization
course
PHYM01 20111
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
4400491
date added to LUP
2014-04-23 12:08:54
date last changed
2014-04-23 12:08:54
@misc{4400491,
  abstract     = {An earthshine telescope has been designed and is being fabricated at Lund Observatory in collaboration
with the Danish Meteorological Institute. The instrument will measure the albedo of the Earth by
observing the Moon in white light and in certain spectral bands.
The measurement is based on relative photometry of the dark and bright sides of the Moon, so the
optical design of the telescope has been carried out with special attention to photometric quality and
stray light performance. In addition, advanced operating modes have been developed. Hence, the
instrument is expected to be superior to existing earthshine telescopes.
The LO/DMI Earthshine Telescope was envisaged to provide produce albedo measurements with an
accuracy on the order of 0.1%. The objective of this thesis was to evaluate the accuracy of some of the
main elements that contributes to the final photometric performance of the Earthshine Telescope. In
particular the performance of the shutter was analyzed, since it is very crucial to obtain accurate
photometry of the observation, especially due to the high range of the exposures from 10ms to few
minutes which is needed for the albedo calculation. Also the proper characterization of the spectral
filters transmission is very important for the precision of the spectro-photometric analysis of the Earth’s
albedo, and for this reason spectral measurements were done for all the filters of the Earthshine
Telescope.
It was found that for 10ms the accuracy of the shutter response is 0.4%, and this will affect the accuracy
of some of the operating modes of the Earthshine Telescope that require short exposures times.
Nevertheless it is possible to decrease the error in shutter response for these operating modes by
reducing the amount of light falling into the detector using a neutral density filter or reducing the
aperture.
Also spectral characterization of all the color filters and Knife Edge Optical Density filters of the
Earthshine Telescope was done, obtaining spectral curves that matched very well with the specified by
the manufacturers.},
  author       = {Badinez, Rodrigo},
  language     = {eng},
  note         = {Student Paper},
  title        = {Photometric Evaluation and Calibration of the Earthshine Telescope},
  year         = {2011},
}