I would like to plot TESS measurements of Beta Dor, using data from TESScut. In the Gaia DR2 archive I look up RA and DEC values of Beta Dor, I get:
RA: 83.40630967798376 DEC: -62.48977125108528
I go to TESScut, put these two values in, select Sector 1, then Download FFI Cutout
. Unzip downloaded file, then in Python I do:
import matplotlib.pyplot as plt
from lightkurve import TessTargetPixelFile
import numpy as np
sector1ffi_cutout='tess-s0001-4-4_83.40630967798376_-62.48977125108528_64x64_astrocut.fits'
tpf_s1 = TessTargetPixelFile(sector1ffi_cutout)
fig = plt.figure(figsize=(5,5))
fig.add_subplot(111, projection=tpf_s1.wcs)
plt.pcolormesh(np.log(tpf_s1.flux[0]))
plt.show()
Giving me:
Which, looking at the coordinates (~ -53°, ~6h30min) is clearly wrong, the star is not in this position according to Gaia (and other sources).
What am I doing wrongly, and how can I plot this star to the place it should be?
For completeness, when I plot the star, I get these warnings:
/home/szabopal/.local/lib/python3.5/site-packages/ipykernel_launcher.py:10: RuntimeWarning: divide by zero encountered in log # Remove the CWD from sys.path while we load stuff. /home/szabopal/.local/lib/python3.5/site-packages/ipykernel_launcher.py:10: RuntimeWarning: invalid value encountered in log # Remove the CWD from sys.path while we load stuff. /home/szabopal/.local/lib/python3.5/site-packages/astropy/visualization/wcsaxes/grid_paths.py:73: RuntimeWarning: invalid value encountered in greater discontinuous = step[1:] > DISCONT_FACTOR * step[:-1] /home/szabopal/.local/lib/python3.5/site-packages/astropy/visualization/wcsaxes/grid_paths.py:73: RuntimeWarning: invalid value encountered in greater discontinuous = step[1:] > DISCONT_FACTOR * step[:-1] /home/szabopal/.local/lib/python3.5/site-packages/astropy/visualization/wcsaxes/grid_paths.py:73: RuntimeWarning: invalid value encountered in greater discontinuous = step[1:] > DISCONT_FACTOR * step[:-1] /home/szabopal/.local/lib/python3.5/site-packages/astropy/visualization/wcsaxes/grid_paths.py:73: RuntimeWarning: invalid value encountered in greater discontinuous = step[1:] > DISCONT_FACTOR * step[:-1]
Further developments
I believe the issue above is caused by the wcs refering to the whole FFI, not the cutout.
print(tpf_s1.wcs)
gives:
WCS Keywords
Number of WCS axes: 2
CTYPE : 'RA---TAN-SIP' 'DEC--TAN-SIP'
CRVAL : 90.634460449219 -57.666290283203
CRPIX : 250.0 -984.0
PC1_1 PC1_2 : 1.0 1.0
PC2_1 PC2_2 : 1.0 1.0
CDELT : 0.00571299832697903 0.005705604460241471
NAXIS : 81986 1282
from How to plot a star from TESScut to the right place on the sky using Python (and not with a ~10 degree error)?
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