In this post I will step through an example of using Kepler data with VStar‘s Kepler observation source plug-in.
After installing the plug-in as per the instructions on the plug-in library page, go to the Kepler data search page and type V0838 Cyg into the Target Name box:
Clicking Search takes you to this dataset result page:
Arbitrarily choose the last dataset entry to give this page:
Notice that the vertical axis is in units of flux instead of magnitude.
Near the top is text thats says: “Light curve file is online (“.fits”). If you click the “online” link you’ll get a page with the data in FITS format. What you really want to do is to save the link/file/page as a file locally, usually via a right-click context menu (in Windows; in Macintosh it’s ctrl-click).
The raw plot obtained from loading this file via VStar’s Kepler observation source plug-in looks like this, via:
and the phase plot (from a DCDFT standard scan; see VStar Analysis menu) at ~0.48 days is:
This looks like an RRAB given the amplitude, period, shape. I came to that conclusion before asking VSX. 🙂 A beautiful light curve. You have to zoom in quite a way to see any error bars, such is the nature of Kepler data.
By the way, you can get directly to the Kepler data page via the “External Links: Location” section of the V0838 Cyg VSX search result page!
One of the things I want to add to the Kepler and some other observation source plug-ins is the ability to specify the URL obtained from copying the link address (again from the context menu from the “online” link), in this case:
http://archive.stsci.edu/pub/kepler/lightcurves/0107/010789273/kplr010789273-2012277125453_llc.fits
The Kepler plug-in would then read the http stream directly rather than you having to download a file.
The Kepler plug-in converts flux values to a magnitude value. The amplitude should be what you’d expect but not necessarily the numerical value itself. For this star, VSX says “13.040 – 14.138”. In this case, adding 10 to each observation would bring it within the right range. It’s possible that the plug-in will be tweaked in future to produce a different magnitude range.
Other observation source plug-ins are available for VStar such as for:
- Catalina Sky Survey
- SuperWASP
- AAVSO upload format (as used by WebObs)
An ASAS plug-in is planned.
November 26, 2022 at 9:37 am |
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