Reading about photometry (continued!)

I am going to read through this site to increase my photometry know-how(http://photutils.readthedocs.io/en/stable/) I will take some notes here:

Aperture Photometry!

aperture_photometry: The tool to perform aperture photometry with multiple apertures in photutils.

There are several sizes and types of apertures that can be used.

there are pixel and sky coordinate aperture classes.

Aperture Objects

to perform photometry, one must define the aperture objects that will define the aperture through which photometry will be done.

these objects are defined as lists of ordered pairs and then given a radius.

conversion between pixel and sky coordinates can be done using the SkyCoord command which extrapolates the coordinates of pixels in the image based on the central coordinate.

to deal with the intersection of the aperture with pixels, method= can be used with either exact(the default) (which calculates only the portion of the pixel within the aperture which is the longest and most accurate) subpixel (which divides each pixel into subpixels which are included or excluded depending on whether their center is in the aperture or not), and center (which accepts or rejects whole pixels based on whether their center is in or out of the aperture)

Multiple apertures at each position

one can use a list of apertures for the aperture_photometry function.

aperture_photometry assumes background subtracted data run it on: data - bkg (if bkg is a an array representing the background of the data)

you can mask bad pixels

you can display errors

you can do the apertures in sky coordinates

Trying it out

I have worked my way through most of the photutils documentation that I think will be immediately useful to us, so I am going to see what I can do putting into practice what I have learned thusfar.

When I run the photutils.test()it returns the error the module pytest has no attribute param. I dont think its a big deal. It is the only error, let’s run with it.