Where are Solar System objects located in TESS FFI data?
tess-ephem is a user-friendly package which enables users to compute the positions of Solar System objects -- asteroids, comets, and planets --
in the data archive of NASA's TESS Space Telescope.
python -m pip install tess-ephemtess-ephem allows you to search the entire archive of TESS FFI's for the presence of a known minor planet, and obtain the result as a Pandas DataFrame. The output pixel coordinates (column and row) follow the TESS convention, with (1,1) being the middle of the pixel in the lower left corner of the FFI. For example:
>>> from tess_ephem import ephem
>>> ephem("Sedna")
sector camera ccd column row tdb-ut ... dec vmag hmag sun_distance obs_distance sto_angle
time ...
2458438.5 5 1 4 1543.104021 1102.948351 69.182738 ... 7.64961 20.803 1.49 84.947536 83.981060 0.1466
2458439.5 5 1 4 1544.978969 1103.000701 69.182758 ... 7.64724 20.802 1.49 84.946760 83.978870 0.1435
2458440.5 5 1 4 1546.866007 1103.027415 69.182777 ... 7.64500 20.801 1.49 84.945985 83.977335 0.1412
2458441.5 5 1 4 1548.750885 1103.040242 69.182797 ... 7.64284 20.801 1.49 84.945209 83.976334 0.1397
2458442.5 5 1 4 1550.627199 1103.044020 69.182818 ... 7.64074 20.801 1.49 84.944433 83.975802 0.1393
... ... ... ... ... ... ... ... ... ... ... ... ... ...
2460254.5 71 2 4 1984.578578 1003.555888 69.182570 ... 8.36089 20.750 1.49 83.592740 82.661771 0.2440
2460255.5 71 2 4 1984.808484 1001.737047 69.182584 ... 8.35803 20.749 1.49 83.592017 82.656607 0.2347
2460256.5 71 2 4 1985.037223 999.911091 69.182599 ... 8.35517 20.747 1.49 83.591294 82.651920 0.2257
2460257.5 71 2 4 1985.258387 998.084718 69.182615 ... 8.35235 20.745 1.49 83.590572 82.647750 0.2168
2460258.5 71 2 4 1985.462457 996.279638 69.182631 ... 8.34964 20.744 1.49 83.589849 82.644149 0.2083
[75 rows x 14 columns]The time is in the UT scale. To convert this to the TDB timescale, the column tdb-ut (offset in seconds) should be used.
You can also obtain the ephemeris for one or more specific times
by passing the time parameter:
>>> ephem("Sedna", time="2018-11-21 17:35:00")
sector camera ccd column row tdb-ut ... dec vmag hmag sun_distance obs_distance sto_angle
time ...
2018-11-21 17:35:00.000 5 1 4 1553.858404 1103.035027 69.182854 ... 7.63721 20.802 1.49 84.94309 83.975894 0.1409
>>> from astropy.time import Time
>>> ephem("Sedna", time=Time([2458441.5,2460258.5], format='jd'))
sector camera ccd column row tdb-ut ... dec vmag hmag sun_distance obs_distance sto_angle
time ...
2458441.5 5 1 4 1548.750885 1103.040242 69.182797 ... 7.64284 20.801 1.49 84.945209 83.976334 0.1397
2460258.5 71 2 4 1985.462457 996.279638 69.182631 ... 8.34964 20.744 1.49 83.589849 82.644149 0.2083Orbital elements can be obtained by passing the orbital_elements=True parameter. The function returns the average orbital elements of the target during the queried time. Perihelion distance is in AU and orbital inclination is in degrees.
>>> df_ephem, orbital_elements = ephem("Sedna", time="2018-11-21 17:35:00", orbital_elements=True)
>>> orbital_elements
{'perihelion_distance': 76.13306961191206, 'eccentricity': 0.8413469227223953, 'orbital_inclination': 11.929585162007143}You can alternatively obtain the ephemeris during a specific sector by passing
the sector parameter:
>>> ephem("Sedna", sector=70)
sector camera ccd column row tdb-ut ... dec vmag hmag sun_distance obs_distance sto_angle
time ...
2460208.5 70 4 2 1965.994639 1827.049672 69.182409 ... 8.49483 20.815 1.49 83.626009 83.171983 0.6184
2460209.5 70 4 2 1966.304467 1826.442414 69.182402 ... 8.49248 20.814 1.49 83.625285 83.156153 0.6137
2460210.5 70 4 2 1966.639579 1825.743198 69.182395 ... 8.48989 20.813 1.49 83.624561 83.140210 0.6085
2460211.5 70 4 2 1966.995717 1824.975902 69.182389 ... 8.48711 20.812 1.49 83.623838 83.124461 0.6029
2460212.5 70 4 2 1967.363962 1824.160062 69.182383 ... 8.48421 20.811 1.49 83.623114 83.108974 0.5970
2460213.5 70 4 2 1967.743247 1823.299432 69.182377 ... 8.48120 20.810 1.49 83.622391 83.093770 0.5908
2460214.5 70 4 2 1968.127856 1822.402268 69.182372 ... 8.47812 20.809 1.49 83.621667 83.078862 0.5845
2460215.5 70 4 2 1968.516359 1821.470633 69.182367 ... 8.47498 20.808 1.49 83.620944 83.064264 0.5779
2460216.5 70 4 2 1968.909479 1820.507912 69.182363 ... 8.47178 20.806 1.49 83.620220 83.049995 0.5712
2460217.5 70 4 2 1969.301139 1819.520671 69.182359 ... 8.46856 20.805 1.49 83.619497 83.036082 0.5644
2460218.5 70 4 2 1969.690629 1818.514364 69.182355 ... 8.46533 20.804 1.49 83.618773 83.022562 0.5575
2460219.5 70 4 2 1970.070096 1817.504775 69.182353 ... 8.46215 20.803 1.49 83.618050 83.009481 0.5504
2460220.5 70 4 2 1970.413447 1816.527398 69.182350 ... 8.45920 20.802 1.49 83.617326 82.996774 0.5435
2460221.5 70 4 2 1970.685594 1815.593040 69.182349 ... 8.45668 20.800 1.49 83.616603 82.983681 0.5369
2460222.5 70 4 2 1970.945096 1814.590453 69.182347 ... 8.45415 20.799 1.49 83.615879 82.969891 0.5301
2460223.5 70 4 2 1971.228110 1813.505068 69.182347 ... 8.45140 20.798 1.49 83.615156 82.956113 0.5228
2460224.5 70 4 2 1971.528584 1812.361144 69.182347 ... 8.44849 20.796 1.49 83.614433 82.942589 0.5152
2460225.5 70 4 2 1971.840095 1811.172397 69.182347 ... 8.44547 20.795 1.49 83.613709 82.929377 0.5074
2460226.5 70 4 2 1972.160145 1809.944650 69.182348 ... 8.44236 20.794 1.49 83.612986 82.916495 0.4993
2460227.5 70 4 2 1972.484084 1808.682404 69.182350 ... 8.43919 20.792 1.49 83.612263 82.903956 0.4911
2460228.5 70 4 2 1972.811565 1807.392809 69.182352 ... 8.43597 20.791 1.49 83.611539 82.891774 0.4827
2460229.5 70 4 2 1973.139007 1806.076605 69.182354 ... 8.43272 20.790 1.49 83.610816 82.879968 0.4742
2460230.5 70 4 2 1973.467494 1804.738876 69.182358 ... 8.42944 20.788 1.49 83.610093 82.868566 0.4657
2460231.5 70 4 2 1973.791305 1803.387890 69.182361 ... 8.42617 20.787 1.49 83.609370 82.857609 0.4570
2460232.5 70 4 2 1974.102222 1802.037747 69.182365 ... 8.42297 20.785 1.49 83.608646 82.847150 0.4483When passing the sector parameter, the time_step is by default 1 day.
This can be changed as follows:
>>> ephem("Sedna", sector=70, time_step=0.1)
sector camera ccd column row tdb-ut ... dec vmag hmag sun_distance obs_distance sto_angle
time ...
2460207.6 70 4 2 1965.698467 1827.543203 69.182416 ... 8.496977 20.815973 1.49 83.626660 83.185519 0.622423
2460207.7 70 4 2 1965.734658 1827.487317 69.182415 ... 8.496720 20.816002 1.49 83.626588 83.184049 0.621956
2460207.8 70 4 2 1965.769986 1827.432018 69.182415 ... 8.496468 20.816045 1.49 83.626515 83.182573 0.621497
2460207.9 70 4 2 1965.804411 1827.377187 69.182414 ... 8.496221 20.816058 1.49 83.626443 83.181091 0.621046
2460208.0 70 4 2 1965.837889 1827.322705 69.182413 ... 8.495980 20.816000 1.49 83.626370 83.179599 0.620600
... ... ... ... ... ... ... ... ... ... ... ... ... ...
2460233.0 70 4 2 1974.248380 1801.371667 69.182368 ... 8.421430 20.785000 1.49 83.608285 82.842110 0.444000
2460233.1 70 4 2 1974.275695 1801.240320 69.182368 ... 8.421134 20.784886 1.49 83.608212 82.841115 0.443137
2460233.2 70 4 2 1974.302128 1801.109815 69.182369 ... 8.420844 20.784707 1.49 83.608140 82.840122 0.442275
2460233.3 70 4 2 1974.327659 1800.980176 69.182369 ... 8.420560 20.784486 1.49 83.608068 82.839129 0.441414
2460233.4 70 4 2 1974.352268 1800.851430 69.182370 ... 8.420282 20.784243 1.49 83.607995 82.838136 0.440555
[259 rows x 14 columns]