Wed, 04/29/2015 - 18:37
Hello,
I'm an IB (International Baccalaureate) student and I'm required to do an Extended Essay about a topic I would like to explore and reach some conclusions. I have chosen Physics and I think photometry would be an interesting topic related to astrophysics. The problem is that I don't know in which topic should I focus, for example "Can we detect exoplanets by using conventional methods like a DSLR camera?".
I would like to know more topic in which I can reach to some fascinating conclusions.
Thank you!
Please check-out this informative .pdf Bruce Gary put out a few years ago on the subject:
http://brucegary.net/book_EOA/EOA.pdf
There are probably shorter guides on the Net about exoplanet imaging, but Gary is pretty thorough in this text; keep in mind he was a professional scientist at Cal tech/JPL for many years!
I think its VERY difficult if not impossible to get the cadence and photometric accuracy with an SLR. Even with thermoelectrically cooled amateur CCDs, getting good photometric data for exoplanets its at the limits of what amateur CCD cameras/telescopes can do. I know SLR are cheaper and can do nice non-astronomical imaging, but SLRs are not thermoelectrically cooled (invariant signal with strong noise), have a bayer mask which wipes out more than 1/2 of your pixel resolution, and have more image processing steps to go through, your better off researching the use of CCDs for the exoplanet observations open to the amateur.
James Foster
Los Angeles, CA
James, you are correct in general. Catching exoplanets with DSLRs is probably not for beginners. At the same time, please take a look at:
http://www.astrosurf.com/buil/exoplanet/phot.htm
That page is in French, but Google Translate does fine job when translating it:
https://translate.google.com/translate?sl=fr&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.astrosurf.com%2Fbuil%2Fexoplanet%2Fphot.htm&edit-text=
There is an even more detailed page, containing also spectroscopic radial velocity measurements of host stars of exoplanets - all done by amateur astronomers:
https://translate.googleusercontent.com/translate_c?depth=1&hl=en&ie=UTF8&prev=_t&rurl=translate.google.com&sl=fr&tl=en&u=http://www.astrosurf.com/buil/extrasolar/obs.htm&usg=ALkJrhg9e8ZJIogaCeI4w_TBG6fesk847w#Observation%20of%20HD189733%20b
One should definitely keep in mind, that using a DSLR does not mean that one has to limit him-/herself with photographic lenses! Compared to classical CCD-s, DSLR-s have just a slightly different type of multielement sensor. With differents flaws and benefits.
Otherwise, processing DSLR data is exactly the same compared to CCD data processing. High-quality darks (many tens to hundreds of frames averaged) and flats (free of scattered light as much as possible) are key to success in both case.
And of course - fundamental requirement is to have your data in TRUE raw format. E.g. Nikon cameras - very good for typical imaging - are not always the best ones for astrophotography and/or measurements, because their raw files will be filtered before even getting saved on memory card. I have heard rumours, that some (all?) newer Nikon cameras do not have that issue. The best choice for DSLR astrophotography (and photometry) till now have been Canon cameras. Few others brands being good as well.
Best wishes,
Tõnis
Thank you for your answer! So, would you know other topics which I could explore?