Amateur astronomers have increasingly better access to affordable spectrographs they can use with their telescope to take spectra of objects in the night sky. This opens up a whole new domain for citizen science. #SAOIMAGE DS9 GET POSITION OF STAR SOFTWARE#īut to do real science, it helps to understand exactly how the data are gathered.įor most amateurs, their spectrograph might come with some canned software that is for all intents and purposes a black box that you put the CCD images from the spectrograph in one end and get one-dimensional spectra out the other with no hint of what happens in-between. One goal of this tutorial is to de-mystify that process and make amateurs as confortable with reducing spectra as they are with reducing CCD images or photometry. The other goal is to dymystify the reduction of spectra and unchain the enthusiastic amateur from their black-box to let them understand and take more control of how their data is reduced. does not support SIP, you should either download a copy of SAOImage DS9 or uncheck this option. Many of the basic principles of CCD image reduction also apply to the reduction of spectra. SAOImageDS9 is an astronomical imaging and data visualization application. Add image distortion polynomials to the WCS solution. Each pixel can be thought as a mini-detector of light with its own calibration properties. In order to calibrate the pixel we need to know how much noise it would have gathered without the light falling on it and how it responds relative to the other pixels around it. The Dark frame is used to tell how much noise there is in the pixel. The Flat frame is used to calibrate its relative response to other pixels.In spectroscopy the Dark is an important calibration. And we will apply the dark in very much the same way you would use a Dark frame for normal CCD imaging. The Dark will be subtracted from the spectrum to remove the background noise in each pixel. ![]() The Flat plays a different roll in spectroscopy. The Flat is not directly divided into the CCD frame containing the spectra. Instead it is extracted identically to the spectra and modeled with a low-order polynomial. That polynomial of the extraction from the Flat is divided into the data. These pixel values will be used by an IRAF task to shift each image to that of the. #SAOIMAGE DS9 GET POSITION OF STAR SOFTWARE# After reducing, calibrating, and performing photometry on data.
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