Download - De-Fringing Michelle Spectra Through Fourier Filtering GEMINI NORTH TELESCOPE HILO, HAWAII
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De-Fringing Michelle Spectra Through Fourier
Filtering GEMINI NORTH TELESCOPE
HILO, HAWAII
INTERN: MEGAN ANSDELLADVISOR: SCOTT FISHER
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MICHELLE
• Facility imager and high-resolution spectrometer• Mid-Infrared (7-26 microns)
• Dust, comets, planet forming disks, black holes
• Cold Objects (300-500K)
• IR spectrum used to study mineralogy and composition
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INTERFERENCE WITHIN DETECTOR
BACKGROUND FRINGES ON SPECTRA
FOURIER FILTERING
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FOURIER FILTERING
• DOESN’T DISTORT SIGNAL
• MATHEMATICAL PROCESS THAT REMOVES FRINGES
• FREQUENCY DOMAIN
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SPATIAL DOMAIN
SHORT λ LONG λ
} SIZE OF OBJECT
A RAW SPECTRUM FROM MICHELLE
(what we see at the telescope)
OBJECT SIZE
.
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FREQUENCY DOMAIN
POWER SPECTRUM (same data, Fourier transformed)
Scott Fisher, Spatial Domain
Scott Fisher, Frequency Domain
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FOURIER TRANSFORM
MICHELLE SPECTRUM (Spatial Domain)
POWER SPECTRUM (Frequency Domain)
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CREATING THE MASK
POWER SPECTRUM(frequency domain)
THE MASK(symmetrical)
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REVERSE-FOURIER TRANSFORM
MASKED POWER SPECTRUM
DE-FRINGED SPECTRUM(Spatial Domain)
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SEEING THE DIFFERENCE
BEFORE AFTER
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THE PROJECT
• Available on Gemini North website
• Make Fourier Filtering of high-resolution MICHELLE spectra as easy as the click of a few buttons
• Use IDL (Interactive Data Language) to write program and GUI (Graphical User Interface)
• Distribute to researchers who acquire MICHELLE spectra
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Interactive Data Language
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EXPERIMENTAL PROGRAM
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FINAL PROGRAM
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• Distributed to anyone who acquires MICHELLE spectra from Gemini
• Available to download from Gemini North website
• Can be modified for use on any spectral data
THE FUTURE
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ACKNOWLEDGEMENTS
I would like to recognize Scott Fisher at Gemini North Observatory in Hilo for
donating his time and expertise to guide me through this project. Thanks
to Sarah Anderson, Malika Bell and everyone at CfAO in Santa Cruz for
making this internship possible. This work has been funded in part by the
National Science Foundation.