SHIPsphotLinks

Purpose of this page:

• Provide all the references we need to perform photometry and related topics

Photometry Reference

• Aperture Photometry Overview (from Luisa Rebull).
• Summary of Aperture photometry steps (taken from above Overview).
  • Once you have calibrated data (ground- or space-based), the basic series of steps for doing aperture photometry are as follows, with many different options and parameters for each step:

1. Detect objects in image, if doing this automatically (human eyes are good at this).
2. Determine center of object.
3. Determine background -- e.g. determine what the signal would be in the aperture if the star was not there. (Usually means defining an annulus around the object at some distance from it.)
4. Summing up the light in the object (define the size of the aperture to use, subtracting off the background).
5. Apply aperture corrections, if necessary.
6. Check your numbers!

Photometry Tools

NITARP's own vintage.

APT: Aperture Photometry Tool

www.aperturephotometry.org

Using APT

Youtube Tutorial (by Luisa Rebul)

Feedback for Russ on APT Tool

• Overall layout: Here are my recommendations
  • Left panel should be split in three clearly defined segments: (Top) All photometry definition and parameter values. (Middle) Photometry Reporting, including the clever 'snap' button. (Bottom) Image Display controls.
  • Top Panel should be organized in rows. Top row = left as is. 2nd Row: Define photometry parameters. Split as define apertures and background, and photometry setting. 3rd row, 'Recompute Photometry', 'Pick/Zap', 'Save Results' 'List Results, 'Plot Results' buttons. 4th Row: 'Aperture Slice', 'source Scatter', 'Curve of Growth', 'Radial Profile'
• Please allow users to drag the image via the mouse a la Spot, its successors and google. That makes it a lot easier. I realize that you need the left mouse for defining aperture, but this can be a radio button to switch the role of the mosue. While you are at it, you might want to add a third role for the mouse and that is to change the stretch a la ds9.
• Please allow users to zoom the main image as well. Or, I have not figured out how to do it.
• The output photometry file (by default APT.tbl) should have a header listing the photometry parameters used to make the computations. This is a dump of the selections made in 'More Settings' and Aperture definition dialog boxes. Yes, a lot of the info is repeated but still its a good reference.