In this repository I am going to upload daily the work on my thesis.
I decided to manage data with Python. Since the frames are calibrated and pre-reduced, it is not necessary to use softwares like IRAF. In the repository are also present the notes that I am writing while doing the work and can be used as a detailed report of the work and an explanation of what you can find in the script source code.
I am going to update my work daily during the week.
In this work I analyze the spectral evolution of the night sky at the Asiago Observatory between 2006 and 2021. I developed an automatic pipeline to extract and analyze the background data from spectroscopic observation of astronomical objects. Sky spectra from Asiago are dominated by different artificial sources, which were studied in detail in this work. I conclude that between 2006 and 2021 mercury vapor lamps got reduced by 88%, sodium ones by 67%. Between 2016 and 2021 emission from LED lamps increased by 207%. LED lamps continuum pollutes the blue band of the visible spectrum – previously untouched by artificial emission – and replaces HPS emission in the green-red bands, thus polluting the whole visible spectrum.
Fast links to the main results:
- The full thesis here.
- The presentation here (work in progress).
- Recap of the results here (in italian).
- Status of the work here (in italian).
- Thesis and presentation. Definitive thesis available. Started the presentation, completed the introduction and working on the methods part.
- Bkg analysis. Define the underlying continuum by performing a double median filter (analogous to the one for the bkg extraction), lines are fitted with Lorentzian profiles and EW is computed using the best fit profile in replacement of the actual signal. This allows me to fit also partially blended lines. The 1D continuum spectrum and the table of the EWs are saved in partitions of a new file.
- I tried to find correlation in the bkg spectra. In particular I checked whether the total integrated flux correlates with the position on the celestial sphere and the positions of the Moon and the Sun. There are no evident correlation with Sun and Moon positions (probably also due to a bat choice of params) while brightest frames seems to be those takes towars S/W direction.
- Bkg extraction. I wrote a script that automatically reads and processes all the files in a directory. For each file a preliminary cosmic ray and noise cleaning is performed. After that all the astronomical sources are detected by looking at the luminosity profile along the slit (wavelength integration). The systematic bkg trend is detected and removed to highlight actual source peaks. These areas are removed and the remaining ones are saved in a new file, accompanied with new information about the procedure in the header.
- Extend the dataset.
- Analyze the spatial distribution of the sources.