tess-astrometry

Tools to measure the astrometry of TESS solar-system objects.

This package contains two modules:

• MovingTargetPixelFile -- Generates a moving TargetPixelFile (mtpf) object for use with the FITs file output of tess_cloud.asteroid_pipeline.
• astrometry -- Tools to measure the centroids of the moving target pixel files and compare them to the expected astrometry given by JPL Horizons.

Usage

To read in a mtpf FITS file:

>>>from astropy.io import fits
>>>from tess_astrometry.MovingTargetPixelFile import MovingTargetPixelFile
>>>f = fits.open(file_path)
>>>mtpf = ast.MovingTargetPixelFile(f, quality_bitmask="hardest")

the mtfp inherents lightkurve.TargetPixelFile and adds functionality specific to moving objects.

Measuring centroids is via use of the MovingCentroids class. There are two methods to compute the centroids:

1. compute_centroids_simple_aperture -- Uses a static aperture for all cadences based on the median image
2. compute_centroids_dynamic_aperture -- Uses a dynamic aperture where a unique aperture is computed for each cadence

You can then generate an animation of the computed centroids:

>>>f = fits.open('.../EDR3/pdart-edr3/pdart-edr3-asteroid49016-s10-mtpf.fits')
>>>mtpf = MovingTargetPixelFile(f, quality_bitmask="hardest")
>>>centroids = MovingCentroids(mtpf)
>>>centroidsMatrix = centroids.compute_centroids_dynamic_aperture(aper_mask_threshold=3)
>>>centroids.mtpf.animate(aperture_mask=centroids.aper, centroidsMatrix=centroidsMatrix, fps=2, step=1)

You can also compare the measured astrometry to that given by JPL Horizons:

>>>centroids.detrend_centroids_expected_trend(plot=True, extra_title='Target {}'.format(centroids.targetid));