JWST Moving Target Visibility Tool Help
The JWST Moving Target Visibility Tool (MTVT) is a command-line Python tool that provides quick-look assessments of moving target visibilities and position angles for all JWST instruments.
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See also: JWST General Target Visibility Tool Help, JWST Position Angles, Ranges, and Offsets, Solar System Special Requirements, JWST Target Observability and Observatory Coordinate System
The JWST Moving Target Visibility Tool (MTVT) is a Python command-line tool for calculating moving (solar system) target visibility windows as a function of time. It has similar functionality to that of the JWST General Target Visibility Tool (GTVT), with a few additional features specific to moving targets. The MTVT is packaged with the GTVT, and is automatically installed when users install the GTVT (no standalone installation process is provided for the MTVT). Both the GTVT and MTVT currently use the post-launch JWST ephemeris.
Unlike the GTVT, users input a solar system target designation, rather than a fixed (RA, Dec) sky position. The designation can be an official name (e.g., Saturn, Gaspra, Encke), number (e.g., 599, 20000), or provisional designation (e.g., 2002 MS4). MTVT uses the JPL Horizons system to resolve the designation, and retrieves the target ephemeris (RA, Dec) at one day intervals. At that point, the functionality of the MTVT is identical to that of the GTVT.
For a given RA and Dec, the MTVT provides aperture position angle (APA) information for all 4 science instruments and the FGS within the allowed visibility windows. It also outputs the V3-axis position angle (V3PA). Results are in the form of an ASCII file as well as one or more summary plots. A number of options are available from the command line for tailoring the output to your needs. Once the interactive plot is displayed, icons can be selected to pan and zoom in on the plot to see detailed information.
The allowable position angles output by the MTVT can, for example, be used to help users plan observations of giant planet satellites to ensure that the giant planet avoids falling on a nearby science or FGS aperture, or to determine the visibility windows and durations for Mars or fast moving near-Earth asteroids (NEAs). In order to visualize an observation in APT using Aladin, users should add a PA range special requirement that reflects the range of allowed position angles from MTVT, and create a fixed target proxy with coordinates consistent with those position angles. Once that is done, visualization can proceed as described in Tutorial on Visualizing Solar System Observations in APT.
The schedulability of a given target observation is more complex that just its visibility. It also involves the availability of guide stars as a function of time and other constraints that may be set with special requirements and/or Solar System special requirements in APT. The MTVT is a "quick look" tool for pre-planning purposes, but the Astronomers Proposal Tool is the true arbiter of schedulability for a given proposed observation.
Installation and dependencies
The MTVT is currently incompatible with Windows operating systems.
The MTVT comes packaged with the GTVT. The user is referred to the "Installation and usage" section on the JWST General Target Visibility Tool Help article for instructions on how to install the GTVT/MTVT (or update it if an older version of GTVT/MTVT was installed).
Similarly, the user should refer to the "Dependencies" section on the JWST General Target Visibility Tool Help page for information on the packages and libraries required to run GTVT/MTVT.
Once successfully installed, MTVT is run from the command line, as described below.
Usage tips
To see the MTVT help information, type jwst_mtvt -h or jwst_mtvt --help
$ jwst_gtvt -h Usage: jwst_gtvt --ra=<ra> --dec=<dec> [--start_date=<obs_start>] [--end_date=<obs_end>] [--instrument=<inst>] [--target_name=<name>] [--write_ephemeris=<write_path>] [--write_plot=<plot_path>] [--silent] Arguments: --ra=<ra> Right ascension of target in degrees --dec=<dec> Declination of target in degrees Options: [--start_date] Start date for plot (YYYY-MM-DD) [--end_date] End date for plot (YYYY-MM-DD) [--instrument] Instrument (fgs, miri, nircam, niriss, nirspec, default=all) [--target_name] User provided name for target (name for output, double-quoted if there are spaces) [--write_ephemeris] File name to write ephemeris to [--write_plot] File name to write plot out to [--silent] Boolean to print results to screen [default: False] --help Show this screen. --version Show version.
The default start date is the local date for the user and the default end date is 2 years after the start date. This range can be updated by specifying both --start_date and --end_date values. Note that both --start_date and --end_date must be supplied in order to modify the date range; specifying either a start or end date will result in the default window being used instead. The JWST ephemeris extends roughly 5 years into the future from the current date but results for later dates are likely to be less accurate due to future station-keeping maneuvers.
The --version flag is currently subject to a bug where the version output is that of the docopt package, rather than the version of the GTVT itself. If you type jwst_gtvt --version and you do not receive an error, you are using version 1.0 or greater, since the --version flag was not available previously. This issue will be fixed in a future update.
MTVT command line examples
The user is referred to the "GTVT command line examples" section of the JWST General Target Visibility Tool Help article for basic GTVT/MTVT commands.
Basic use of the MTVT is shown with the example command below:
jwst_mtvt Ceres
Note that the following command will produce the same results, i.e., the provided designation is not case-sensitive:
jwst_mtvt ceres
After running this command, a table will be output in the terminal and a plot will open in a new window that includes the allowable aperture position angles as a function of time for the 4 science instruments (NIRCam, MIRI, NIRSpec, NIRISS), the FGS, and the V3-axis. Examples of these outputs are shown in the "MTVT outputs" section below.
Official names such as "Ceres," "Jupiter," and "Chiron" are not case-sensitive. However, primary designations such as "2002 MS4" and "2003 AZ84" are case-sensitive. Specifically, provisional designations must use capital letters or else the MTVT will output an error.
Evaluating planet visibility
An example command for running the MTVT for a planet is shown below:
jwst_mtvt Jupiter
However, running the above command will result in the following message
ValueError: Ambiguous target name; provide unique id:
ID# Name Designation IAU/aliases/other
------- ---------------------------------- ----------- -------------------
5 Jupiter Barycenter
599 Jupiter
In order to obtain a result from the MTVT, the user must select Jupiter Barycenter as the target using ID# 5:
jwst_mtvt 5
Or Jupiter as the target using ID# 599:
jwst_mtvt 599
The ID# of the planet barycenters and the planets themselves used by JPL Horizons are presented in Table 1.
Table 1. JPL Horizons planet ID numbers
ID# | Name |
|---|---|
4 | Mars barycenter |
5 | Jupiter barycenter |
6 | Saturn barycenter |
7 | Uranus barycenter |
8 | Neptune barycenter |
9 | Pluto barycenter |
499 | Mars |
599 | Jupiter |
699 | Saturn |
799 | Uranus |
899 | Neptune |
999 | Pluto |
Evaluating minor body visibility
An example command for running the MTVT for a minor body using its name is shown below.
jwst_mtvt Makemake
An example command for running the MTVT for a minor body using its provisional designation is shown below (quotation marks are required).
jwst_mtvt '2002 MS4'
An example command for running the MTVT for a minor body using its number and the --smallbody optional argument is shown below. The purpose of this optional argument is to remove ambiguity between low-numbered minor bodies and major bodies. The example below will return information on the asteroid 4 Vesta. But, without the --smallbody optional argument, the MTVT would return information for the Mars barycenter.
jwst_mtvt 4 --smallbody
For higher-numbered minor bodies, the --smallbody optional argument is not necessary, as shown below for the dwarf planet Haumea.
jwst_mtvt 136108
The special case of comets
An example command for running the MTVT for a comet using its name is shown below:
jwst_mtvt Encke
An example command for running the MTVT for a comet using its designation is shown below. Use of the --smallbody optional argument is not necessary for comets when using the designation as the identifier.
jwst_mtvt 2P
The commands above are equivalent and will both result in the following message:
ValueError: Ambiguous target name; provide unique id:
Record # Epoch-yr >MATCH DESIG< Primary Desig Name
-------- -------- ------------- ------------- -------------------------
90000031 1786 2P 2P Encke
90000032 1796 2P 2P Encke
90000033 1805 2P 2P Encke
90000034 1819 2P 2P Encke
90000035 1822 2P 2P Encke
90000036 1825 2P 2P Encke
90000037 1828 2P 2P Encke
90000038 1832 2P 2P Encke
90000039 1835 2P 2P Encke
90000040 1838 2P 2P Encke
90000041 1842 2P 2P Encke
90000042 1845 2P 2P Encke
90000043 1848 2P 2P Encke
90000044 1852 2P 2P Encke
90000045 1855 2P 2P Encke
90000046 1858 2P 2P Encke
90000047 1862 2P 2P Encke
90000048 1865 2P 2P Encke
90000049 1868 2P 2P Encke
90000050 1872 2P 2P Encke
90000051 1875 2P 2P Encke
90000052 1878 2P 2P Encke
90000053 1881 2P 2P Encke
90000054 1885 2P 2P Encke
90000055 1888 2P 2P Encke
90000056 1891 2P 2P Encke
90000057 1895 2P 2P Encke
90000058 1898 2P 2P Encke
90000059 1901 2P 2P Encke
90000060 1904 2P 2P Encke
90000061 1908 2P 2P Encke
90000062 1911 2P 2P Encke
90000063 1914 2P 2P Encke
90000064 1918 2P 2P Encke
90000065 1921 2P 2P Encke
90000066 1924 2P 2P Encke
90000067 1928 2P 2P Encke
90000068 1931 2P 2P Encke
90000069 1934 2P 2P Encke
90000070 1937 2P 2P Encke
90000071 1941 2P 2P Encke
90000072 1947 2P 2P Encke
90000073 1951 2P 2P Encke
90000074 1954 2P 2P Encke
90000075 1957 2P 2P Encke
90000076 1961 2P 2P Encke
90000077 1964 2P 2P Encke
90000078 1967 2P 2P Encke
90000079 1971 2P 2P Encke
90000080 1974 2P 2P Encke
90000081 1977 2P 2P Encke
90000082 1980 2P 2P Encke
90000083 1984 2P 2P Encke
90000084 1987 2P 2P Encke
90000085 1990 2P 2P Encke
90000086 1994 2P 2P Encke
90000087 1995 2P 2P Encke
90000088 1998 2P 2P Encke
90000089 2004 2P 2P Encke
90000090 2016 2P 2P Encke
JPL Horizons contains multiple orbital solutions for periodic comets, so the user must select one option to proceed. The user is less likely to receive this message for long-period comets. If the user does not know the "Record #" for the orbital solution of interest ahead of time, this is an easy way to see a list of possible values. If the user knows the "Record #" ahead of time, they can skip the step of viewing the list. If the user wants the most recent orbital solution for 2P/Encke, they would type the following command:
jwst_mtvt 900090
Note that the most recent orbital solution is not selected as a default when running the MTVT.
MTVT outputs
The default outputs for the MTVT are identical to the GTVT: a 6-panel plot showing the allowable position angles for the V3 axis, the 4 science instruments, and the FGS; and an ASCII table containing the information in the plot in table form. See the "Example plots from GTVT" section of the JWST General Target Visibility Tool Help page for instructions on how to output a plot for only one instrument.
Figure 1. Default 6-panel MTVT output plot
Click on the figure for a larger view.
Allowable aperture position angles are shown on the y-axis in degrees plotted against date on the x-axis. The allowable position angles for each date can be found in the ASCII output table. In general, the visibility windows for Solar System objects along the ecliptic will be separated by position angles of ~180°; see the Moving Target Field of Regard article for a diagram of the JWST focal plane orientation for observations along the ecliptic. For a more distant, slower-moving target like the TNO 47171 Lempo, the range of allowable position angles will be very small. Objects closer to JWST will have a larger range of allowable position angles.
Figure 2. Zoom in on a MIRI visibility window
Click on the figure for a larger view.
The zoom tool (magnifying glass icon in the lower left corner of the plot window) can be used to zoom in on visibility windows of interest in individual plots. In the image above, the zoom tool was used to focus on one particular visibility window for MIRI, showing the allowable position angles in more detail.
The table below shows the dates and duration of each visibility window when the target is in JWST's field of regard, as well as the allowable position angles and the start and end RA and Dec values for these dates. The RA and Dec, along with the allowable position angles for the V3 axis, each of the 4 science instruments, and the FGS, are output for each date that the object is observable by JWST. The table written to the terminal is much longer than shown and has been truncated for the purpose of presentation in this article. The table can be scrolled horizontally to reveal the hidden columns.
$ jwst_mtvt Lempo +------------------------------------------+ | JWST General Target Visibility Tool | +------------------------------------------+ | Runtime/Date: 2023-07-05 20:35:21.299422 | +------------------------------------------+ | Version Number: 1.0.0 | +------------------------------------------+ Target Name: 47171 Lempo (1999 TC36) Ecliptic Latitude: 24.284867 ----------------------------------------------------------------- Checked Interval [2021-12-26 00:00:00.000, 2025-06-11 00:00:00.000] +--------------------------------+--------------------------------+-------------------+------------------+----------------+ | Window Start | Window End | Window Duration | V3 Angle Start | V3 Angle End | |--------------------------------+--------------------------------+-------------------+------------------+----------------| | A.D. 2021-Dec-27 00:00:00.0000 | A.D. 2022-Feb-12 00:00:00.0000 | 47 | 67.953 | 74.4873 | | A.D. 2022-Aug-11 00:00:00.0000 | A.D. 2022-Oct-01 00:00:00.0000 | 51 | 254.685 | 261.785 | | A.D. 2022-Dec-27 00:00:00.0000 | A.D. 2023-Feb-14 00:00:00.0000 | 49 | 68.5274 | 75.0445 | | A.D. 2023-Aug-13 00:00:00.0000 | A.D. 2023-Oct-03 00:00:00.0000 | 51 | 255.396 | 262.158 | | A.D. 2023-Dec-30 00:00:00.0000 | A.D. 2024-Feb-17 00:00:00.0000 | 49 | 69.5487 | 75.7348 | | A.D. 2024-Aug-15 00:00:00.0000 | A.D. 2024-Oct-05 00:00:00.0000 | 51 | 256.242 | 262.736 | | A.D. 2025-Jan-01 00:00:00.0000 | A.D. 2025-Feb-18 00:00:00.0000 | 48 | 70.5794 | 76.3487 | +--------------------------------+--------------------------------+-------------------+------------------+----------------+ +--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+-------------+-------------+ | NRC Max PA | NRC Min PA | NRS Max PA | NRS Min PA | NIS Max PA | NIS Min PA | MIR Max PA | MIR Min PA | FGS Max PA | FGS Min PA | V3 Max PA | V3 Min PA | |--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+-------------+-------------| | 74.7723 | 60.9911 | 213.418 | 199.637 | 75.4049 | 61.6237 | 79.6791 | 65.8979 | 73.6024 | 59.8212 | 74.8436 | 61.0624 | | 74.9025 | 61.3385 | 213.548 | 199.984 | 75.5351 | 61.9711 | 79.8093 | 66.2453 | 73.7326 | 60.1686 | 74.9738 | 61.4098 | | 75.0219 | 61.6646 | 213.668 | 200.311 | 75.6546 | 62.2973 | 79.9287 | 66.5714 | 73.8521 | 60.4948 | 75.0933 | 61.736 | | 75.1358 | 61.9749 | 213.782 | 200.621 | 75.7684 | 62.6075 | 80.0426 | 66.8817 | 73.9659 | 60.805 | 75.2071 | 62.0462 | | 75.2456 | 62.2713 | 213.892 | 200.917 | 75.8782 | 62.9039 | 80.1524 | 67.1781 | 74.0758 | 61.1014 | 75.317 | 62.3426 | | 75.3525 | 62.5554 | 213.998 | 201.201 | 75.9851 | 63.188 | 80.2593 | 67.4622 | 74.1826 | 61.3855 | 75.4238 | 62.6267 | | 75.4568 | 62.8282 | 214.103 | 201.474 | 76.0895 | 63.4608 | 80.3637 | 67.735 | 74.287 | 61.6583 | 75.5282 | 62.8995 | | 75.5592 | 63.0906 | 214.205 | 201.737 | 76.1919 | 63.7232 | 80.466 | 67.9974 | 74.3894 | 61.9207 | 75.6306 | 63.1619 | | 75.6599 | 63.3434 | 214.306 | 201.989 | 76.2925 | 63.976 | 80.5667 | 68.2502 | 74.4901 | 62.1735 | 75.7313 | 63.4147 | | 75.7592 | 63.5871 | 214.405 | 202.233 | 76.3918 | 64.2198 | 80.666 | 68.4939 | 74.5893 | 62.4173 | 75.8305 | 63.6585 | | 75.8572 | 63.8225 | 214.503 | 202.468 | 76.4898 | 64.4551 | 80.764 | 68.7293 | 74.6873 | 62.6526 | 75.9285 | 63.8938 | | 75.9542 | 64.0499 | 214.6 | 202.696 | 76.5868 | 64.6826 | 80.861 | 68.9567 | 74.7843 | 62.8801 | 76.0255 | 64.1213 | | 76.0503 | 64.27 | 214.696 | 202.916 | 76.6829 | 64.9026 | 80.9571 | 69.1768 | 74.8804 | 63.1001 | 76.1216 | 64.3413 | | 76.1457 | 64.483 | 214.792 | 203.129 | 76.7783 | 65.1156 | 81.0525 | 69.3898 | 74.9758 | 63.3132 | 76.217 | 64.5544 | | 76.2404 | 64.6894 | 214.886 | 203.335 | 76.8731 | 65.3221 | 81.1472 | 69.5962 | 75.0706 | 63.5196 | 76.3118 | 64.7608 | | 76.3347 | 64.8896 | 214.981 | 203.536 | 76.9673 | 65.5222 | 81.2415 | 69.7964 | 75.1648 | 63.7198 | 76.4061 | 64.961 | | 76.4286 | 65.0839 | 215.074 | 203.73 | 77.0612 | 65.7165 | 81.3354 | 69.9907 | 75.2587 | 63.9141 | 76.4999 | 65.1553 | | 76.5221 | 65.2726 | 215.168 | 203.919 | 77.1548 | 65.9052 | 81.429 | 70.1794 | 75.3523 | 64.1027 | 76.5935 | 65.3439 | | 76.6155 | 65.456 | 215.261 | 204.102 | 77.2481 | 66.0886 | 81.5223 | 70.3628 | 75.4457 | 64.2861 | 76.6869 | 65.5273 | | 76.7088 | 65.6343 | 215.355 | 204.28 | 77.3414 | 66.2669 | 81.6156 | 70.5411 | 75.5389 | 64.4645 | 76.7801 | 65.7057 | | 76.8019 | 65.8079 | 215.448 | 204.454 | 77.4346 | 66.4405 | 81.7087 | 70.7147 | 75.6321 | 64.638 | 76.8733 | 65.8792 | | 76.8952 | 65.9769 | 215.541 | 204.623 | 77.5278 | 66.6095 | 81.802 | 70.8837 | 75.7253 | 64.807 | 76.9665 | 66.0482 | | 76.9885 | 66.1415 | 215.634 | 204.787 | 77.6211 | 66.7741 | 81.8953 | 71.0483 | 75.8186 | 64.9717 | 77.0598 | 66.2129 | | 77.082 | 66.3021 | 215.728 | 204.948 | 77.7146 | 66.9347 | 81.9888 | 71.2089 | 75.9121 | 65.1322 | 77.1533 | 66.3734 | | 77.1757 | 66.4587 | 215.822 | 205.105 | 77.8083 | 67.0913 | 82.0825 | 71.3655 | 76.0059 | 65.2888 | 77.2471 | 66.53 | | 77.2697 | 66.6115 | 215.916 | 205.257 | 77.9024 | 67.2441 | 82.1765 | 71.5183 | 76.0999 | 65.4417 | 77.3411 | 66.6829 | | 77.3641 | 66.7608 | 216.01 | 205.407 | 77.9967 | 67.3934 | 82.2709 | 71.6676 | 76.1943 | 65.5909 | 77.4355 | 66.8321 | | 77.459 | 66.9067 | 216.105 | 205.553 | 78.0916 | 67.5393 | 82.3658 | 71.8135 | 76.2891 | 65.7368 | 77.5303 | 66.978 | | 77.5543 | 67.0493 | 216.2 | 205.695 | 78.1869 | 67.6819 | 82.4611 | 71.9561 | 76.3844 | 65.8794 | 77.6256 | 67.1206 | | 77.6501 | 67.1888 | 216.296 | 205.835 | 78.2827 | 67.8214 | 82.5569 | 72.0956 | 76.4803 | 66.0189 | 77.7215 | 67.2601 | | 77.7466 | 67.3253 | 216.393 | 205.971 | 78.3792 | 67.9579 | 82.6534 | 72.2321 | 76.5767 | 66.1554 | 77.8179 | 67.3966 | | 77.8437 | 67.459 | 216.49 | 206.105 | 78.4763 | 68.0916 | 82.7505 | 72.3658 | 76.6739 | 66.2891 | 77.9151 | 67.5303 | | 77.9416 | 67.5899 | 216.588 | 206.236 | 78.5742 | 68.2225 | 82.8484 | 72.4967 | 76.7717 | 66.4201 | 78.0129 | 67.6613 | | 78.0402 | 67.7182 | 216.686 | 206.364 | 78.6728 | 68.3509 | 82.947 | 72.625 | 76.8704 | 66.5484 | 78.1116 | 67.7896 | | 78.1397 | 67.8441 | 216.786 | 206.49 | 78.7723 | 68.4767 | 83.0465 | 72.7509 | 76.9698 | 66.6742 | 78.211 | 67.9154 | | 78.2401 | 67.9675 | 216.886 | 206.613 | 78.8727 | 68.6002 | 83.1469 | 72.8744 | 77.0702 | 66.7977 | 78.3114 | 68.0389 | | 78.3414 | 68.0887 | 216.987 | 206.735 | 78.974 | 68.7213 | 83.2482 | 72.9955 | 77.1715 | 66.9189 | 78.4127 | 68.1601 | | 78.4437 | 68.2077 | 217.09 | 206.854 | 79.0763 | 68.8403 | 83.3505 | 73.1145 | 77.2739 | 67.0378 | 78.5151 | 68.279 | | 78.5471 | 68.3246 | 217.193 | 206.97 | 79.1798 | 68.9572 | 83.4539 | 73.2314 | 77.3773 | 67.1547 | 78.6185 | 68.3959 | | 78.6517 | 68.4394 | 217.298 | 207.085 | 79.2843 | 69.072 | 83.5585 | 73.3462 | 77.4818 | 67.2696 | 78.723 | 68.5108 | | 78.7574 | 68.5523 | 217.403 | 207.198 | 79.3901 | 69.185 | 83.6642 | 73.4592 | 77.5876 | 67.3825 | 78.8288 | 68.6237 | | 78.8645 | 68.6634 | 217.51 | 207.309 | 79.4971 | 69.296 | 83.7713 | 73.5702 | 77.6946 | 67.4936 | 78.9358 | 68.7348 | | 78.9728 | 68.7727 | 217.619 | 207.419 | 79.6054 | 69.4054 | 83.8796 | 73.6795 | 77.8029 | 67.6029 | 79.0441 | 68.8441 | | 79.0825 | 68.8803 | 217.728 | 207.526 | 79.7151 | 69.513 | 83.9893 | 73.7871 | 77.9127 | 67.7105 | 79.1539 | 68.9517 | | 79.1937 | 68.9863 | 217.84 | 207.632 | 79.8263 | 69.6189 | 84.1005 | 73.8931 | 78.0239 | 67.8165 | 79.2651 | 69.0577 | | 78.8763 | 69.5208 | 217.522 | 208.167 | 79.509 | 70.1534 | 83.7831 | 74.4276 | 77.7065 | 68.351 | 78.9477 | 69.5922 | | 78.3628 | 70.2516 | 217.009 | 208.898 | 78.9954 | 70.8842 | 83.2696 | 75.1584 | 77.193 | 69.0817 | 78.4342 | 70.3229 | | 77.8501 | 70.9818 | 216.496 | 209.628 | 78.4827 | 71.6144 | 82.7569 | 75.8886 | 76.6802 | 69.8119 | 77.9214 | 71.0531 | [ ... Additional output not shown ... ]
Credits
The MTVT was originally developed by Michael S. P. Kelley (University of Maryland) and is maintained by Mees Fix (Space Telescope Science Institute).