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 pixels_per_hour ra dec vmag hmag sun_distance obs_distance phase_angle
time
2458437.5 5 1 4 1541.303105 1102.826838 0.069068 57.12707 7.65227 20.803 1.49 84.948291 83.983859 0.1482
2458438.5 5 1 4 1543.100766 1102.946276 0.074363 57.11724 7.64961 20.803 1.49 84.947515 83.981039 0.1450
2458439.5 5 1 4 1544.975690 1102.998615 0.075353 57.10692 7.64724 20.802 1.49 84.946739 83.978850 0.1423
2458440.5 5 1 4 1546.862705 1103.025319 0.075362 57.09651 7.64500 20.801 1.49 84.945964 83.977315 0.1403
2458441.5 5 1 4 1548.747559 1103.038136 0.075132 57.08610 7.64284 20.801 1.49 84.945188 83.976314 0.1394
... ... ... ... ... ... ... ... ... ... ... ... ... ...
2460254.5 71 2 4 1984.592691 1003.520110 0.072528 60.21660 8.36089 20.750 1.49 83.592715 82.661747 0.2395
2460255.5 71 2 4 1984.822681 1001.701217 0.072889 60.20673 8.35803 20.749 1.49 83.591992 82.656583 0.2304
2460256.5 71 2 4 1985.051503 999.875207 0.073002 60.19682 8.35517 20.747 1.49 83.591270 82.651896 0.2214
2460257.5 71 2 4 1985.272750 998.048780 0.072664 60.18690 8.35235 20.745 1.49 83.590547 82.647726 0.2127
2460258.5 71 2 4 1985.475079 996.244021 0.071257 60.17708 8.34965 20.744 1.49 83.589824 82.644125 0.2044
[78 rows x 13 columns]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 pixels_per_hour ra dec vmag hmag sun_distance obs_distance phase_angle
time
2018-11-21 17:35:00.000 5 1 4 1553.855013 1103.032894 0.074053 57.05786 7.63721 20.802 1.49 84.943069 83.975873 0.1419
>>> from astropy.time import Time
>>> ephem("Sedna", time=Time([2458441.5,2460258.5], format='jd'))
sector camera ccd column row pixels_per_hour ra dec vmag hmag sun_distance obs_distance phase_angle
time
2458441.5 5 1 4 1548.747559 1103.038136 0.075132 57.08610 7.64284 20.801 1.49 84.945188 83.976314 0.1394
2460258.5 71 2 4 1985.475079 996.244021 0.071257 60.17708 8.34965 20.744 1.49 83.589824 82.644125 0.2044Orbital 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': 76.13300496827914, 'eccentricity': 0.8413468330602263, 'orbital_inclination': 11.929585189509927}You can alternatively obtain the ephemeris during a specific sector by passing
the sector parameter:
>>> ephem("Sedna", sector=70)
sector camera ccd column row pixels_per_hour ra dec vmag hmag sun_distance obs_distance phase_angle
time
2460208.5 70 4 2 1965.969985 1827.030603 0.025550 60.53693 8.49483 20.815 1.49 83.625984 83.171959 0.6161
2460209.5 70 4 2 1966.279804 1826.423362 0.029493 60.53386 8.49248 20.814 1.49 83.625260 83.156129 0.6112
2460210.5 70 4 2 1966.614906 1825.724165 0.032766 60.53030 8.48989 20.813 1.49 83.624537 83.140186 0.6058
2460211.5 70 4 2 1966.971035 1824.956892 0.035144 60.52638 8.48711 20.812 1.49 83.623813 83.124437 0.6001
2460212.5 70 4 2 1967.339271 1824.141075 0.037045 60.52220 8.48421 20.811 1.49 83.623090 83.108950 0.5940
2460213.5 70 4 2 1967.718547 1823.280470 0.038666 60.51778 8.48120 20.810 1.49 83.622366 83.093746 0.5878
2460214.5 70 4 2 1968.103146 1822.383332 0.040092 60.51316 8.47812 20.809 1.49 83.621642 83.078838 0.5813
2460215.5 70 4 2 1968.491641 1821.451723 0.041354 60.50835 8.47498 20.808 1.49 83.620919 83.064240 0.5747
2460216.5 70 4 2 1968.884752 1820.489031 0.042441 60.50337 8.47178 20.806 1.49 83.620195 83.049971 0.5680
2460217.5 70 4 2 1969.276403 1819.501819 0.043287 60.49825 8.46856 20.805 1.49 83.619472 83.036058 0.5611
2460218.5 70 4 2 1969.665886 1818.495541 0.043699 60.49302 8.46533 20.804 1.49 83.618748 83.022538 0.5541
2460219.5 70 4 2 1970.045345 1817.485982 0.043112 60.48776 8.46215 20.803 1.49 83.618025 83.009457 0.5471
2460220.5 70 4 2 1970.388690 1816.508633 0.040265 60.48264 8.45920 20.802 1.49 83.617302 82.996750 0.5403
2460221.5 70 4 2 1970.660834 1815.574303 0.039919 60.47768 8.45668 20.800 1.49 83.616578 82.983656 0.5337
2460222.5 70 4 2 1970.920335 1814.571748 0.043872 60.47232 8.45415 20.799 1.49 83.615855 82.969867 0.5266
2460223.5 70 4 2 1971.201557 1813.486767 0.046801 60.46652 8.45141 20.798 1.49 83.615131 82.956089 0.5192
2460224.5 70 4 2 1971.503820 1812.342507 0.048934 60.46041 8.44849 20.796 1.49 83.614408 82.942565 0.5115
2460225.5 70 4 2 1971.815329 1811.153797 0.050643 60.45406 8.44547 20.795 1.49 83.613685 82.929353 0.5035
2460226.5 70 4 2 1972.135377 1809.926088 0.052095 60.44750 8.44236 20.794 1.49 83.612961 82.916471 0.4954
2460227.5 70 4 2 1972.459314 1808.663881 0.053363 60.44075 8.43919 20.792 1.49 83.612238 82.903932 0.4871
2460228.5 70 4 2 1972.786794 1807.374325 0.054473 60.43385 8.43597 20.791 1.49 83.611515 82.891750 0.4787
2460229.5 70 4 2 1973.114235 1806.058161 0.055414 60.42680 8.43272 20.790 1.49 83.610791 82.879944 0.4701
2460230.5 70 4 2 1973.442721 1804.720474 0.056123 60.41963 8.42944 20.788 1.49 83.610068 82.868542 0.4615
2460231.5 70 4 2 1973.766531 1803.369529 0.056414 60.41238 8.42617 20.787 1.49 83.609345 82.857585 0.4528
2460232.5 70 4 2 1974.077449 1802.019428 0.055711 60.40512 8.42297 20.785 1.49 83.608622 82.847125 0.4442When 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 pixels_per_hour ra dec vmag hmag sun_distance obs_distance phase_angle time 2460207.6 70 4 2 1965.673822 1827.524121 0.026894 60.539373 8.496977 20.815973 1.49 83.626635 83.185495 0.620233 2460207.7 70 4 2 1965.710011 1827.468236 0.026487 60.539100 8.496720 20.816002 1.49 83.626563 83.184025 0.619771 2460207.8 70 4 2 1965.745339 1827.412939 0.026102 60.538829 8.496468 20.816045 1.49 83.626491 83.182549 0.619312 2460207.9 70 4 2 1965.779762 1827.358109 0.025764 60.538559 8.496221 20.816058 1.49 83.626418 83.181067 0.618856 2460208.0 70 4 2 1965.813240 1827.303629 0.025498 60.538290 8.495980 20.816000 1.49 83.626346 83.179575 0.618400 ... ... ... ... ... ... ... ... ... ... ... ... ... ... 2460233.0 70 4 2 1974.223608 1801.353369 0.054524 60.401530 8.421430 20.785000 1.49 83.608260 82.842086 0.439900 2460233.1 70 4 2 1974.250923 1801.222026 0.054170 60.400820 8.421134 20.784886 1.49 83.608188 82.841090 0.439050 2460233.2 70 4 2 1974.277356 1801.091524 0.053786 60.400114 8.420844 20.784707 1.49 83.608115 82.840098 0.438204 2460233.3 70 4 2 1974.302887 1800.961890 0.053386 60.399412 8.420560 20.784486 1.49 83.608043 82.839105 0.437364 2460233.4 70 4 2 1974.327497 1800.833148 0.052985 60.398714 8.420282 20.784243 1.49 83.607971 82.838112 0.436529[259 rows x 13 columns]