I decided to undertake a project to attempt observing the full period of a binary star, with full coverage of that period, plot the result, make some calculations on the orbit and mass of the stars!
I had done nothing like this yet, so I devoted my efforts to "how all the data would be processed with only the usual tools I use".
In a sense this project is more to teach me ways of coping with the data, and not so much to actually do something 100% correctly... I did learn a few things about the quality of the observations, and I am considering redoing a lot of observations to get better guiding, and choose better spectra.
This project started 3 months ago, and I planned on observing multiple stars, but I ended up sticking with only one for now. I chose delta Capricorni. It is 2 degrees away from the ecliptic, and in 3 months the radial velocity of the Earth changes a lot and must be taken into account.
The spectra vary in exposure time, in telescope used, in CCD cooling temperature, central wavelength... This made me lazy and skip the pre-processing steps of darkframes, flat frames, response curve corrections... (I am waiting for my Lhires upgrade to arrive, to do this better next time)
Even so, I am proud of the result! It is "crappy", and preliminary, but I was able to create and follow a procedure that can combine 1D graphical spectra in a plot by phase! All this using only IRIS and a spreadsheet program (including making the spreadsheet generate the appropriate scripts that are run in IRIS). This procedure took me one week to get working, but allows me to process 3 months of data relatively quickly! So now I only need to get good data, and pre-process it decently
Dateikommentar: H-alpha radial velocity variation along orbital phase for delta Capricorni
delCap_phaseplot.jpg [ 39.89 KiB | 374 mal betrachtet ]
del Cap has a period of 1.0228 days, which is so close to 1 day, that I need to observe it for 4 weeks to register the complete period from the same location. Add your availability on weekends, bad weather, desire for other targets, and now you need a good spreadsheet to plan your observations!
This was step one.
Step two involved keeping up with the observations already made, and which parts of the orbital period were still missing observations.
Step three was to be able to sort the files according to phase, and to make the spreadsheet generate the script that automatically averages/bins redundant spectra of the same phase! (this involves generating a script to query for the heliocentric corrections needed, and perform such corrections on the acquired spectra)
When my Lhires is upgraded, I will redo this for another EA/EB-binary of the winter sky, but I need not limit myself to such targets. This is something I can use for long term observation projects: the real purpose behind it
The EA-Binary is only the application that motivates me to "develop" the rest