Supernova Search - University of Maryland...
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Supernova Search Theo Leasca ([email protected]) Science, Discovery and the Universe Mechanical Engineering Methodology Discovering Supernovae requires careful photography of different galaxies throughout the universe. Our telescope uses a 14 inch mirror to focus light onto a CCD chip which is essentially a bank of tiny capacitors, one for each pixel. Every photon that hits the chip will charge the capacitor slightly, and the cumulative charge can be measured after each exposure to create a black and white image. We usually used clear filters, allowing all wavelengths through, and 20-60 second exposures to photograph galaxies since they are so faint and far away. To take accurate scientific data, images must be calibrated by subtracting away a “dark frame” and dividing by a “flat frame”, usually an exposure of the sky during twilight before stars are visible. A new supernova would look like a bright spot in the disk of the galaxy that wasn’t there before. Therefore, to discover a new supernova, we would subtract a previous image from a new one, and see if any bright spots remain. Control Sequence Supernovae in each galaxy are pretty rare, occurring only a few times in every century. Therefore, in order to have a good chance at finding one over the course of only one semester, we needed to make a lot of observations. To optimize our chance of success, we wanted to develop a control sequence which would automate the transition between different galaxies, instead of having to manually choose the target after every photo. We tried writing code to do this ourselves as well as installing CCD Commander, a preexisting program which allows you create action lists for both the camera and the telescope mount in advance and run through the sequence automatically. All that was required to start observing with this method was to pick constellations which are prominent in the sky at this time of day/year, look up galaxies in those constellations, and then input the coordinates of those target galaxies into a text file which the computer could read. We successfully generated the sequence we wanted the telescope to complete, but ran into numerous permission errors getting the computer to run the program. We eventually abandoned this approach after many nights of unsuccessfully trying to resolve these issues. Introduction A supernova is the explosion of a large star at the end of its life cycle. Supernovae are important to the practice of astronomy because certain types are one of only a few kinds of “standard candles”- objects in space whose luminosity, or energy output, we know. We can deduce that object’s distance from earth by comparing the total expected energy output to the amount of energy (in the form of light) we receive on Earth. In the case of Type Ia supernovae, the luminosity is determined by correlation to the duration of time over which the supernova fades (on the order of months), making it critical that new supernova events are spotted early on. In fact, many of the most productive supernova searches are conducted by amateur “citizen scientists” because the crucial limiting factor is only how often each different galaxy can be observed. Conclusions While we didn’t actually find a supernova, we still learned a lot throughout this process- from the frustrations of resolving software errors to learning image processing. We’d like to thank Mrs. Warner for teaching us invaluable lessons about establishing a routine process and system for organizing data in order to minimize hang-ups later as a result of forgetting a calibration step or improperly labeling. Finally, we’ve also gained an appreciation for the significant number of projects that amateur “citizen” scientists can contribute meaningfully to. Procedure • Cool camera • Find a target star which is easily identifiable • Focus and center the star on the camera chip • Make Data Logs • Take Calibration images • Begin sequence of photographic predetermined target galaxies NGC 3556 (above) and NGC 4258 (below), captured with the 14” telescope Equipment • Celestron 14” Schmidt- Cassegrain reflecting telescope • Astro-Physics 7" refracting telescope • Astro-Physics GTOCP1 German Equatorial Mount • SBIG ST-8 CCD camera • Software: MaxIm DL control AstroImageJ CCD Commander RGB image of NGC 7331 taken with the 7” telescope
Transcript of Supernova Search - University of Maryland...
Supernova SearchTheo Leasca ([email protected])
Science, Discovery and the UniverseMechanical Engineering
MethodologyDiscovering Supernovae requires careful photography of different galaxies throughout the universe. Our telescope uses a 14 inch mirror to focus light onto a CCD chip which is essentially a bank of tiny capacitors, one for each pixel. Every photon that hits the chip will charge the capacitor slightly, and the cumulative charge can be measured after each exposure to create a black and white image. We usually used clear filters, allowing all wavelengths through, and 20-60 second exposures to photograph galaxies since they are so faint and far away. To take accurate scientific data, images must be calibrated by subtracting away a “dark frame” and dividing by a “flat frame”, usually an exposure of the sky during twilight before stars are visible. A new supernova would look like a bright spot in the disk of the galaxy that wasn’t there before. Therefore, to discover a new supernova, we would subtract a previous image from a new one, and see if any bright spots remain.
Control SequenceSupernovae in each galaxy are pretty rare, occurring only a few times in every century. Therefore, in order to have a good chance at finding one over the course of only one semester, we needed to make a lot of observations. To optimize our chance of success, we wanted to develop a control sequence which would automate the transition between different galaxies, instead of having to manually choose the target after every photo. We tried writing code to do this ourselves as well as installing CCD Commander, a preexisting program which allows you create action lists for both the camera and the telescope mount in advance and run through the sequence automatically. All that was required to start observing with this method was to pick constellations which are prominent in the sky at this time of day/year, look up galaxies in those constellations, and then input the coordinates of those target galaxies into a text file which the computer could read. We successfully generated the sequence we wanted the telescope to complete, but ran into numerous permission errors getting the computer to run the program. We eventually abandoned this approach after many nights of unsuccessfully trying to resolve these issues.
IntroductionA supernova is the explosion of a large star at the end of its life cycle. Supernovae are important to the practice of astronomy because certain types are one of only a few kinds of “standard candles”- objects in space whose luminosity, or energy output, we know. We can deduce that object’s distance from earth by comparing the total expected energy output to the amount of energy (in the form of light) we receive on Earth. In the case of Type Ia supernovae, the luminosity is determined by correlation to the duration of time over which the supernova fades (on the order of months), making it critical that new supernova events are spotted early on. In fact, many of the most productive supernova searches are conducted by amateur “citizen scientists” because the crucial limiting factor is only how often each different galaxy can be observed.
ConclusionsWhile we didn’t actually find a supernova, we still learned a lot throughout this process- from the frustrations of resolving software errors to learning image processing. We’d like to thank Mrs. Warner for teaching us invaluable lessons about establishing a routine process and system for organizing data in order to minimize hang-ups later as a result of forgetting a calibration step or improperly labeling. Finally, we’ve also gained an appreciation for the significant number of projects that amateur “citizen” scientists can contribute meaningfully to.
Procedure• Cool camera• Find a target star which is easily
identifiable
• Focus and center the star on the camera chip
• Make Data Logs
• Take Calibration images• Begin sequence of photographic
predetermined target galaxies
NGC 3556 (above) and NGC 4258 (below), captured with the 14” telescope
Equipment• Celestron 14” Schmidt-
Cassegrain reflecting telescope• Astro-Physics 7" refracting
telescope• Astro-Physics GTOCP1 German
Equatorial Mount• SBIG ST-8 CCD camera• Software: MaxIm DL control
AstroImageJCCD Commander
RGB image of NGC 7331 taken with the 7” telescope
