2 January 2016 at 10:56 am #573516
Over the past few months I’ve had some discussions about whether the BAA should create an online database for spectroscopic observations. I created the BAA VSS online observation database and I also carry out spectroscopy, hence my involvement. I am writing this post to make public a few of my thoughts and to give interested members the opportunity to provide feedback at this early stage.
There are already a couple of spectroscopic databases to which amateurs including BAA members submit, namely the ARAS and BeSS databases. Also the AAVSO are considering creating a database of spectroscopic observations. So there may not be a need for the BAA to create a database. However, a key activity of the BAA has always been to record member observations, and there is no guarantee that BAA members would submit to other organisations. Creating a database would also give the BAA control over how the database is operated to the benefit of our membership and it could stimulate interest in spectroscopy. The Instrument & Imaging Section Director Bob Marriott has already offered to store spectra. This in itself does not constitute a database or make them available for online review, as this would require a project to create an online database. It should also be noted up front that an online database would probably need spectra to be submitted in files of a particular format.
If a BAA database is created, then it would be a good idea to follow in the footsteps of the ARAS and BeSS databases. These were created with input from professional astronomers. A key outcome was an agreed submission format using 1D fits files with specific important fields populated with valid data. Files of this type can already be created by many of the spectroscopy software packages used by amateurs. It is possible that some of the detailed requirements of BeSS/ARAS would not apply to all types of object, but that would be for a more detailed discussion if the project goes ahead.
I’m of the opinion that if feasible then a BAA database should be capable of storing spectra of any type of astronomical object, rather than being dedicated to a particular type of object. It may turn out that there are practical reasons why this is not possible, but I think this should be the initial goal. For point sources like stars, fits files probably contain all the information that is required, e.g. object, observer and equipment details as well as the spectrum itself. For extended objects such as comets, nebulae and galaxies, I think it would be useful to store an additional image to indicate the location of the spectrograph slit. I know the BAA already has at least one member undertaking meteor spectroscopy. We would need to clarify whether meteor spectra could be supplied in the BeSS/ARAS format, and otherwise work out a way to include such observations.
I should emphasize that nothing is yet decided. If the BAA does create an online database then it would be a significant project that is likely to take a year or more to be realised.
I would be interested to hear the views of any members either in reply to this post, or by email to vssdbm <at> britastro.org.
Andrew Wilson, BAA VSS Database Secretary3 January 2016 at 2:20 pm #577201Steve CuthbertParticipant
Good to hear of continued interest in spectroscopy within the BAA. I haven`t submitted spectra yet to Bess so unfamiliar with their format requirements but I agree a set format would have to be laid down for any submitted observations.
I can forsee spectroscopic observations encompassing all sections of the BAA, Solar, Planetary,Deep sky, Comet, etc etc so it would make sense to have its own dedicated section/sub section rather than submit for example a solar spectrum to the solar section or maybe not?? expand interest in spectroscopy to visual observers??. One thought I had was maybe a `Star of the month` (I also thought star of the week but with the skies we get ;-() where contributors could submit their own observations of a common object and it would be interesting comparing results using different equipment.
What do others think?
BTW happy new year to all.
Steve3 January 2016 at 5:06 pm #577202
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.
Andy3 January 2016 at 5:20 pm #577203Steve CuthbertParticipant
In what sort of format do you envisage a spectro database or even access to it?. Would observers access/enter observations by going via say a button within the VSS section web site for instance?. Can two databases share resources like that?. It would appear that the interest in spectroscopy is maybe not enough to justify its own section yet.
Steve3 January 2016 at 5:48 pm #577204
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.
Andy4 January 2016 at 8:28 pm #577209Robin LeadbeaterParticipant
Since in principle it is possible to put any data into a fits file there is no fundamental reason why any spectrum profile could not use the fits format. The big advantage is that all the observation and reduction details can then be contained within the fits header provided apropriate keywords are included. The BeSS standard is a good starting point of course but perhaps the header could be generalised and extended to include further useful keywords/flags etc, for example to indicate things like the type of object, level of data reduction etc. Provided the keywords required by BeSS were still present, compatibility with BeSS (or potentially any other database which used a subset of the included keywords) could be maintained (Note also that the BesS database system actually rewrites parts of the the header, ignoring some keywords and filling in others based on the information in the submitted header ie the BeSS input standard header is slightly different from what is held in the database) The “BeSS standard header” generated by ISIS software for example has already been modified in this way with added keywords for the observatory coordinates for example to make it suitable for the simple but more general database (really just lists of spectra currently) already being developed by ARAS.
Robin4 January 2016 at 8:58 pm #577210
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.
Andy5 January 2016 at 12:33 am #577211Robin LeadbeaterParticipant
A bit detailed for a forum discussion but ideally could the database fields be read from the fits header? That way the need to enter all the info for each spectrum, with possible transcribing errors could be avoided and any search could then be done based on header information (eg with this you could potentially search for say “all spectra of a particular object covering H alpha at a resolution > 5000 and an SNR > 100” )
re the display of spectra, I wonder if any of the code used this VdS spectroscopy group database might be useful. I have contacts there if interested
(follow the link on the side to “database”)
Robin5 January 2016 at 7:22 am #577212
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.
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