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Hi Bill,
That is an excellent presentation of your results. You certainly had to do some detective work to find out where the lines came from, but I find that is part of the fun.
I’m not sure if you have any opinion on my post about the possibility of creating a BAA database of spectroscopic observations? Would you be interested in submitting meteor spectra to such a database? I should also run it by John Mason, and other section directors.
Best wishes,
Andy
Hi James,
Along the lines of what Grant says, good flat fields would be very important for this to work. Otherwise the shifting position of the stars would introduce variability due to vignetting, dust motes, and any other variation in sensitivity across the image.
Assuming you’ve got good flats then I think you would get good results. You can check how well it is working by including a non-variable check star in your processing, to check that it stays roughly constant rather than varying.
Andy
Robin, that is exactly what I was thinking. The data in the FITS header would be read by the database, so potentially any of it could be used for searches to compile lists of spectra that could be viewed or downloaded.
The users would only have to enter data the once, in the fits header, and things like lat/long just once in their processing software. The data would probably be extracted and stored as fields within the database, an automated process. Ideally this would not be needed but to make the website responsive and quick this would almost certainly need to happen, though this would be invisible to users.
I’ve taken a quick look at FITS file formats and I need to spend some more time on it. The header is very straight forward, while the actual spectrum data more complex. There are options to build software to read the data from scratch or to use programs that already exist to do this instead. It would be very useful to make contact with the VdS spectroscopy group, so an introduction to any contacts would be most welcome. Knowing what has already been done and how could make the whole process of setting up a database and associated website much easier.
Thanks, Andy
Robin, thanks for the useful reply.
I agree using the FITS file header to store as much relevant information as possible is a good idea. My current thinking is the database would be a MySQL database that holds the FITS files in one of its fields. That way the data storage can benefit from the robustness of a relational database, while also enabling fast searches on data to make creating lists of spectra meeting user entered criteria nice and easy.
There would of course also need to be the ability for users to download spectra and to display them on screen.
Andy
Hi Steve,
It would probably have its own subsite on the BAA web server, separate to the VSS database website. That is not to say they can definitely not be accessed from the same website, but it could complicate matters. Especially if non variable star spectra are loaded into the database.
I would expect it to work in a similar way to the VSS database website. Users would login to upload their spectra. There would be pages to allow anyone to view spectra and also search for spectra.
Ideally the web front end would have the ability to change what is required depending on the type of object or campaign. For example it might be desirable to follow identical requirements to BeSS for some objects or campaigns, including for example response correction. However for other objects this might not be a requirement. On the other hand we might always allow observers to upload spectra without response correction, but flag up which spectra are corrected and which are not. It might be that meteor spectra would be loaded with a completely different non-fits file format, and so users would be required to manually populate basic information when they upload a meteor spectrum. This all adds to the complexity, but I think it would be doable.
Cheers,
Andy
Hi Steve,
Thanks for your reply. You have some very interesting ideas.
For the time being I am trying to keep my focus on the database aspect of spectroscopy in the BAA. In the event this is required then it would be a good use of my skills as I can make that happen. I think there are other things that can be done within the BAA to encourage and help observers new to spectroscopy. I’m certainly willing to help out more widely.
Best wishes,
Andy
Thanks Steve, it was nice to actually have clear skies so I could do some astronomy on the 23rd December. A rare occurrence recently! There is also gamma Cas nearby which is another bright star with interesting changes in H-Alpha.
Best wishes,
Andy
Hi Mike,
I’ve just finished watching the program. Dr Bangay sounds like a man of real character, getting someone to teach him to read and write, and then raising the money for his own education to become an medical Dr! He must have been a man with real drive. It was a shame that he wasn’t able to travel to see the solar eclipse when he was 96, though I can understand his family’s concerns.
Best wishes,
Andy
Wow, spectacular star trails James. I get the impression of looking down a tunnel of stars!
Best wishes,
Andy
Hi Bill,
Great spectra! Quite a catch to get everything to line up so well for the fireball. Interesting to see the differences in the flare, though I too do not know the reason for the difference.
Best wishes,
Andy
Fabulous image Nick! I could not face an all nighter, but I did get up for about 20 minutes from 3:10am. Your image has very faithfully captured the colours.
Cheers,
Andy
Fabulous image Nick! I could not face an all nighter, but I did get up for about 20 minutes from 3:10am. Your image has very faithfully captured the colours.
Cheers,
Andy
Hi Steve,
I’ve done some very rough back of the envelope calculations. Assuming the separation is 0.062 AU and the period is 2.867 days. Then I get an orbital speed of 235 km/s, which in direct line of sight would equate to about 5 Angstroms around H-Alpha. However the shift would be twice this since at one stage it would be moving towards us, then half an orbit later away from us. So an overall 10 Angstrom shift, requiring a minimum resolution of about 600.
It is possible I’ve made a slip somewhere in my calculation, but if not then it could be an interesting challenge.
Cheers,
Andy
Hi Steve,
Those are both nice spectra with clear atmospheric O2 absorption and stellar hydrogen absorption lines.
That is an interesting project to look for a change in the doppler shift. I do not know the velocity of the various components so can’t comment further on feasibility, but a great idea.
Cheers,
Andy
That is another interesting spectrum Steve. It will be interesting to see if you spot any changes over time.
Cheers,
Andy
Hi John and Steve,
Do I have your permission to post some of your spectra to the VSS Facebook page? John I think your above spectrum of CH Cyg would make a very interesting post. Steve, I was thinking of posting one of you Chi Cyg spectra, if that is OK?
Thanks,
Andy
Hi John,
Those are some very interesting changes that you have picked up in the spectrum of CH Cygni. If you are correcting the spectrum for instrumental and atmospheric response then there is no need to normalise it. In fact those corrections are better than normalising the spectrum. The bumpy spectrum is that of the red giant in the system. Rather than a smooth continuum it has absorption bands, almost certainly due to titanium oxide in the star’s atmosphere.
For comparison here is a spectrum I took on 6th August.
Best wishes,
Andy
