Astronomical Spectroscopy

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The overall goal of the Astronomical Spectroscopy Project is to be able to collect and reduce data gathered from astronomical objects. This will be done using a Celestron CPC 800 GPS (XLT) telescope and a fiber-fed Ocean Optics USB2000+ spectrometer. The current setup includes the telescope with a beam splitter attached to the back. The beam splitter attaches to an eye piece on top as well as a lens tube with a converging lens and the fiber attached at the end. There are three degrees of freedom for the fiber: 1 along the z axis where we can change the length of the lens tube on the outside, and 2 and 3 are the x and y axis where we can move the position of the fiber using thumb screws.

At the end of the 2012-2013 school year, the group was able to collect a spectra of vega, however, the integration time was 600 seconds in order to get data that resembled Vega. The group (Annika Gustafsson, Gerald Buxton, and Zach Small) concluded that the large integration time was necessary for multiple reasons: 1.) the fiber alignment was not perfect, so light was being lost, 2.) the use of a 50:50 beam splitter in the fiber adapter cost us too much light, and 3.) the Ocean Optics spectrometer might not be sensitive enough to gather spectra of astronomical objects.

This term, the current students on the project, which include Annika Gustafsson, Justin Stockwell, and Gerald Buxton, are going to work on the spectrometer-telescope setup to rule out some of these factors. First, the group will order a flip mirror. The flip mirror will replace the beam splitter in the fiber adapter. This will allow us to retain all of the light, instead of dividing it 50:50 between the fiber and the eyepiece. Second, the group will work on fine alignment of the fiber by first aligning the eyepiece to the finderscope, and then the fiber to the eyepiece. Finally, we want to characterize the Ocean Optics Spectrometer. The overall goal for this term is to be able to calculate a sensitivity measurement for the spectrometer to determine if it is feasible to use this spectrometer for astronomical purposes.