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| en:praktikum:sonnenrotation [2017/03/13 14:52] – [Analysis] rhainich | en:praktikum:sonnenrotation [2023/07/21 21:24] (current) – [Report] rhainich |
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| ====== S1 - Solar Rotation ====== | ====== S1 - Solar Rotation ====== |
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| ===== Analysis ===== | ===== Analysis ===== |
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| | {{section>deng:praktikum:a12:python#English&noheader}} |
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| The analysis can be done with a Python script (see ''~/scripts/s1s2/comparespecs.py'') that needs to be copied to your own directory, too. This script allows to cut those lines from the image matrix that shall be displayed as a spectrum. | The analysis can be done with a Python script (see ''~/scripts/s1s2/comparespecs.py'') that needs to be copied to your own directory, too. This script allows to cut those lines from the image matrix that shall be displayed as a spectrum. |
| Open the script with a text editor, e.g. | Open the script with a text editor, e.g. |
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| kate comparespecs.py | kate comparespecs.py |
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| In the upper part of the script, find "Script Parameters". Edit the names of the input files and the range of lines that shall be extracted. To find the latter, also open the image with //ds9// and select the coordinates of useful strips for the spectra. Choose those lines that are equally exposed and that contain as few (obvious) pixel errors as possible. Especially pay attention to the range where the spectral lines are situated. Once all required input parameters are set, save the script file and execute it by | In the upper part of the script, find "Script Parameters". Edit the names of the input files and the range of lines that shall be extracted. To find the latter, also open the image with //ds9// and select the coordinates of useful strips for the spectra. Choose those lines that are equally exposed and that contain as few (obvious) pixel errors as possible. Especially pay attention to the range where the spectral lines are situated. Once all required input parameters are set, save the script file and execute it by |
| ./comparespecs.py | |
| to obtain a PostScript file speccmp.ps, which can be opened with //GhostView// | python comparespecs.py |
| gv speccmp.ps & | |
| | to obtain a PDF file spectrum.pdf, which can be opened with //okular// |
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| | okular spectrum.pdf & |
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| This figure should now show the spectrum of the lines previously selected from the image. From this figure the Doppler shift of the spectral lines can be determined. To do this, the best strategy is to shift the spectra (with the help of the Python script) against each other, so that (1) the solar iron lines are superimposed and (2) the telluric oxygen lines are superimposed. The dispersion (''nm/pixel'') can be determined from the given wavelengths (see the following Table). | This figure should now show the spectrum of the lines previously selected from the image. From this figure the Doppler shift of the spectral lines can be determined. To do this, the best strategy is to shift the spectra (with the help of the Python script) against each other, so that (1) the solar iron lines are superimposed and (2) the telluric oxygen lines are superimposed. The dispersion (''nm/pixel'') can be determined from the given wavelengths (see the following Table). |
| Using the Doppler shift one can determine the rotational velocity of the sun and from that its rotational period. **Note, that the observation has not necessarily been performed at the sun's equator.** | Using the Doppler shift one can determine the rotational velocity of the sun and from that its rotational period. **Note, that the observation has not necessarily been performed at the sun's equator.** |
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| ===== Protocol ===== | ===== Report ===== |
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| //A usual protocol has to be prepared for both experiments, S1 and S2, together.// | //A usual report has to be prepared for both experiments, S1 and S2, together. A combined outline for the report's content is given in the description for [[https://polaris.astro.physik.uni-potsdam.de/wiki/doku.php?id=en:praktikum:sonnenspektroskopie#report|S2]].// |
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| The protocol should give a short introduction to the "Einsteinturm", before the rotational velocity and period is calculated. It is also required to discuss and to utilize the geometrical corrections for the rotational velocity and period. The necessary data can be obtained from the sun ephemerides. | /* |
| | **OLD BELOW** |
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| | The report should give a short introduction to the "Einsteinturm", before the rotational velocity and period is calculated. It is also required to discuss and to utilize the geometrical corrections for the rotational velocity and period. The necessary data can be obtained from the sun ephemerides. |
| | */ |
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| [[en:praktikum:index|Overview: Laboratory courses]] | [[en:praktikum:index|Overview: Laboratory courses]] |
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