How to cut out Target Pixel Files from Kepler Superstamps or TESS FFIs?

You can use lightkurve to cut Target Pixel Files (TPFs) out of a series of standard astronomical images, such as K2 Superstamp Mosaics or TESS Full-Frame-Images (FFIs). This brief tutorial will demonstrate how!

Let’s assume you have downloaded a set simulated TESS FFI images to a local directory called data. lightkurve will assume that the files are given in time order. So we’ll sort the filenames first:

In [1]:
from glob import glob
import numpy as np
fnames = np.sort(glob('data/*.fits'))

Now we use the KeplerTargetPixelFile class and its function from_fits_images() to create the new TPF. This will cut out around the position keyword. You can pass a pixel position in units of the original image or RA and Dec coordinates.

In [5]:
from lightkurve import KeplerTargetPixelFile
from astropy.coordinates import SkyCoord
tpf = KeplerTargetPixelFile.from_fits_images(images=fnames,
                                             position=SkyCoord(257.13700, 24.48958, unit='deg'),
                                             size=(9,9),
                                             target_id='MyCutOut')
100%|██████████| 3/3 [00:00<00:00, 19.98it/s]

We then have a fully functioning KeplerTargetPixelFile object! You can read more about such objects in the tutorial on their use.

In [6]:
%matplotlib inline
tpf.plot();
../_images/tutorials_cutting-out-tpfs-from-tess-ffis_6_0.png