Astrometry .solved how to#
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To use the service, point your browser to this location: Ĭlick the Upload tab at the top of the screen.

Astrometry .solved archive#

Signing up gives you access to an archive of your previously solved images and allows you to set processing defaults. You can sign-up for using your Google account. If you use the JS9 FITS viewer to view a plate solved image, it shows you the celestial coordinates under your mouse pointer.

You can use various FITS file viewers as well as the free JS9 and JS9-4L online FITS processor ( I discuss using JS9-4L here).

Astrometry .solved download#

In fact, the final file you download from is a FITS file (this is the plate solved file). also does an all sky plate solve, which means that it compares your image against all of the stars in the sky to find a solution, which is very impressive.Īlthough works with images (JPEG, PNG, GIF), it’s ideally suited for FITS files. It figures out the resolution, scale, and other important parameters, so you don’t have to do anything other than provide your image. What’s unique about is that it does something called a blind solve, which means that it figures out everything it needs to know about your image on its own. I discuss the service in my book and explain there how you can download your own copy of the service to your local system for fast plate solving without having to wait in a queue. Using To Plate SolveĪ is a free plate solving service. Learn more about the things you observe in the sky with my free book, Introduction To The Cosmos.

Astrometry .solved how to#

The next part of this tutorial explains how to plate solve your images. Your images with the astrometric solution about where they’re from is a best In astronomy, it all boils down to your images, so enriching Plate solving writes the coordinates of the center of your image to the FITS header so that you can use planetarium software, Aladin, or a variety of other applications to analyze your images and figure out what is interesting about your images. I also show you how to use the resulting image in AstroImageJ and refer you to another tutorial where I show you how to use Aladin to investigate your image. This tutorial walks you through using the free plate solver service,. I discussed AstroImageJ in my book and discussed plate solving there too. Other applications like MaxIM DL, Aladin, and many others can take advantage of the information in a plate solved image. This information can be useful for locating things in your images that might be very small or might be very faint.

Astrometry .solved software#

When you open an image that has been plate solved in software like AstroImageJ, JS9, or JS9-4L, it will display the celestial coordinates of your pointer. The information about the plate solve is written to the FITS header of the plate solved image and is available for use by other applications. Along with the position of the stars in your image, the plate solve also provides details about the location of the center of your image in the sky, the image scale, and orientation. (there is an 'odds-to-tune-up' option, to try to tweak up an ok-but-not-good-enough solution to see if that helps.)Īlso, note that if the odds threshold is very high, then the index needs to have a lot of stars in the image to be able to hit the threshold - the odds increase by a maximum amount per star, so a given odds threshold is also a threshold on the number of stars required, and since the density of stars is related to the size of the features in the index, that means that if you set the odds very high, it will only be able to get solutions from index files with small quads, and these will generally have more relative noise in the solution.Plate solving your images is a process where you find a match between the stars on your own image and an astronomical catalog. But it could be that by rotating an initial solution by 0.001 degrees, we get a much better solution, so setting the odds higher doesn't guarantee you get a better final answer. The default 1e9 threshold is high enough that we basically never accept a false positive (except for cases where the stars in the image aren't randomly distributed in 2D - eg, when there are sources in a straight line, or things like globular clusters). Note that there is no 'tweaking' at this point - the prediction is evaluated entirely based on the four-star match. The 'odds' threshold is how much better than random chance that prediction has to be. Since there can be false matches (four-star features can look the same within error), it then predicts where *else* it should expect to find stars. Each of those is a proposed match between your image and a part of the sky.

Astrometry .solved code#

The code works by finding quadrangles of stars in your image, computing their shapes, and finding matching shapes in the index files.