The software PIXY System 2 is produced by Seiichi Yoshida, a well-known amateur astronomer in Japan. For more information about this software please pay a visit here, including his detailed tutorials. I'm now just going to show you the main procedure by a sample in doing astrometry of objects in STEREO/SECCHI images.
First, please download PIXY System 2 and necessary supported catalog(s). A guide full of details on the catalogs could be read here: http://www.aerith.net/misao/pixy/catalog.html.
Second, launch the software and press Image Examination button. Then please go to "Operations - Open Image" to open your image(s). Note that reasonable interception of the original file is strongly recommended.
Third, please select "Operations - Detect Stars" and wait for a few seconds then. Soon you'll get windows like this:
The bright object in a white circle is comet 2P/Encke.
Fourth, Input the accurate R.A., Decl. and magnitude for each comparison star you click on the "Detected Stars" window. The more data of comparison stars you input, the better result you may get. You'll get such windows like this:
The green dots represent the comparison stars you've input.
When complete, you have to check the residuals on the "Astrometry Table" and "Photometry Table". Now reject the one(s) that is/are enormously erroneous.
Astrometry Table:
Photometry Table:
After finishing all of the work, press "Apply" in the upper right corner. You can now look at your "Image Information" window.
Now you could do astrometry of objects you're in favor of by clicking them on the "Detected Stars" window. Immediately, a message box jumps out and shows the coordinates and magnitude of the object you're clicking.
I'm binding the results of doing astrometry of comet 2P/Encke below.
| Time | R.A. (J2000) | Decl. | Magnitude (m1) |
| 2007/04/17 03:30:00 UTC | 03h12m50.77s | +18o34'55.4" | 7.54 |
Closer coordinates measured from Comet for Windows:
R.A. (J2000)= 03h12m46.81s, Decl. = +18o34'47.6"
High residuals is due to low resolution of images of STEREO/SECCHI. Magnutide is in R band.
Copyright @ Wentao Xu 2007/05/19
Feel free to e-mail me with any doubts or questions.