Argument reference

This page documents the accepted values for CLI arguments.

You can pass IDs (integers) or names (case-insensitive strings) for --columns, --mooncols, --moons, and --planet, and mix them in one list (e.g. --columns 1 2 ymdhms radec, --moons 1 io europa, --planet saturn).

Planet (--planet)

The --planet argument accepts either a number (4-9) or a case-insensitive name:

Planet number and name

Number	Name
4	mars
5	jupiter
6	saturn
7	uranus
8	neptune
9	pluto

Viewpoint and observatory (--viewpoint, --observatory)

--viewpoint selects the type of observer: observatory (default) or latlon. It does not take a spacecraft name. To observe from a spacecraft, use --viewpoint observatory and set --observatory to the spacecraft or observatory name (e.g. --observatory Cassini, not --viewpoint cas).

• observatory (default): Observe from a named observatory or spacecraft. The name is given by --observatory (default: "Earth's center").

• latlon: Observe from a geographic position on Earth, specified with --latitude, --longitude, --lon-dir (east/west), and --altitude.

When --viewpoint is observatory, --observatory accepts the following spacecraft names or abbreviations (case-insensitive):

Accepted observatory/spacecraft names

Full Name	Abbreviation	NAIF Code
Earth’s center	(default)
Voyager 1	VG1	-31
Voyager 2	VG2	-32
Galileo	GLL	-77
Cassini	CAS	-82
New Horizons	NH	-98
Juno	JNO	-61
Europa Clipper	EC	-159
JUICE	JCE	-28
JWST	JWST	-170
HST	HST	-48

For spacecraft observers, use --sc-trajectory to select the trajectory file variant (0 = default).

Ring options (--rings)

The --rings argument accepts integer option codes or case-insensitive ring names. The available options depend on the planet. Integers and names can be mixed (e.g. --rings main 62 for Saturn).

Jupiter (--planet jupiter)

Jupiter ring options

Code	Name	Description
51	main	Main ring (Halo + Main)
52	gossamer	Gossamer rings (Amalthea + Thebe)

Saturn (--planet saturn)

Saturn ring options

Code	Name	Description
61	main	Main rings (A, B, C, F)
62	ge	G and E rings
63	outer	Outer rings (beyond G)

Uranus (--planet uranus)

Uranus ring options

Code	Name(s)	Description
71	examples: alpha, beta, eta, gamma, delta, epsilon (any ring name maps to this code)	All Uranus rings (Six, Five, Four, Alpha, Beta, Eta, Gamma, Delta, Lambda, Epsilon, Nu, Mu). Any ring name maps to the same code.

Neptune (--planet neptune)

Neptune ring options

Code	Name	Description
81	rings	Neptune rings (Galle, Le Verrier, Adams)

Mars and Pluto have no ring options.

FOV unit (--fov-unit)

The --fov-unit argument accepts angle units, distance units, planet-relative units, and instrument FOV names:

FOV unit values

Value	Meaning
deg	Degrees (default)
arcmin	Arc minutes
arcsec	Arc seconds
mrad	Milliradians
urad	Microradians
km	Kilometres (converted using observer range)
<Planet> radii	Planet equatorial radii (e.g. Saturn radii, Neptune radii)
Cassini ISS narrow	Cassini ISS Narrow Angle Camera FOV
Cassini ISS wide	Cassini ISS Wide Angle Camera FOV
Voyager ISS narrow	Voyager ISS Narrow Angle Camera FOV
Voyager ISS wide	Voyager ISS Wide Angle Camera FOV
Galileo SSI	Galileo SSI FOV
Cassini VIMS	Cassini VIMS 64x64 FOV
Cassini UVIS	Cassini UVIS slit FOV
LORRI	New Horizons LORRI FOV

Use quotes for multi-word values so the shell does not split them (e.g. --fov-unit "Saturn radii" or --fov-unit "Cassini ISS narrow").

Ephemeris column index (--columns)

The ephemeris table can include the following columns. Use --columns with column IDs or names (e.g. --columns 1 2 3 15 8 or --columns ymdhms radec phase). Accepted names (case-insensitive): mjd, ymdhm, ymdhms, ydhm, ydhms, obsdist, sundist, phase, obsopen, sunopen, obslon, sunlon, subobs, subsol, radec, earthrd, sunrd, radius, raddeg, lphase, sunsep, lsep.

Planet/moon geometry columns

ID	Name	Description
1	mjd	Modified Julian Date
2	ymdhm	Date/time (year-month-day hour:min)
3	ymdhms	Date/time (year-month-day hour:min:sec)
4	ydhm	Year and day-of-year + hour:min
5	ydhms	Year and day-of-year + hour:min:sec
6	obsdist	Observer–planet distance (km)
7	sundist	Sun–planet distance (km)
8	phase	Phase angle (deg)
9	obsopen	Ring opening angle to observer (deg)
10	sunopen	Ring opening angle to Sun (deg)
11	obslon	Sub-observer longitude (deg)
12	sunlon	Sub-solar longitude (deg)
13	subobs	Sub-observer latitude (deg)
14	subsol	Sub-solar latitude (deg)
15	radec	RA and Dec (deg)
16	earthrd	Earth range and declination (deg)
17	sunrd	Sun range and declination (deg)
18	radius	Apparent radius (arcsec)
19	raddeg	Apparent radius (deg)
20	lphase	Lunar phase angle (deg)
21	sunsep	Sun separation (deg)
22	lsep	Lunar separation (deg)

Moon column index (--mooncols)

Moon blocks in the ephemeris table use these column IDs with --mooncols. You can use IDs or names (e.g. --mooncols 5 6 8 9 or --mooncols radec offset orblon). Accepted names (case-insensitive): obsdist, phase, subobs, subsol, radec, offset, offdeg, orblon, orbopen.

Moon columns

ID	Name	Description
1	obsdist	Observer–moon distance (km)
2	phase	Phase angle (deg)
3	subobs	Sub-observer lat and long (deg)
4	subsol	Sub-solar lat and long (deg)
5	radec	RA and Dec (deg)
6	offset	Offset from planet (arcsec)
7	offdeg	Offset (deg)
8	orblon	Orbital longitude (deg)
9	orbopen	Orbital opening angle (deg)

Moon index (--moons)

The --moons argument takes 1-based indices into the planet’s moon list (e.g. --moons 1 2 3 or --moons io europa ganymede); you can mix indices and names. Moon order is fixed per planet. Below: index to moon name for each planet. Names are case-insensitive (e.g. io, Io).

Jupiter (--planet 5 or --planet jupiter)

Jupiter moon index

Index	Moon name
1	Io
2	Europa
3	Ganymede
4	Callisto
5	Amalthea
6	Thebe
7	Adrastea
8	Metis
9	Himalia
10	Elara

Saturn (--planet 6 or --planet saturn)

Saturn moon index

Index	Moon name
1	Mimas
2	Enceladus
3	Tethys
4	Dione
5	Rhea
6	Titan
7	Hyperion
8	Iapetus
9	Phoebe
10	Janus
11	Epimetheus
12	Helene
13	Telesto
14	Calypso
15	Atlas
16	Prometheus
17	Pandora
18	Pan
19	Methone
20	Pallene
21	Polydeuces
22	Daphnis
23	Anthe
24	Aegaeon

Uranus (--planet 7 or --planet uranus)

Uranus moon index

Index	Moon name
1	Ariel
2	Umbriel
3	Titania
4	Oberon
5	Miranda
6	Cordelia
7	Ophelia
8	Bianca
9	Cressida
10	Desdemona
11	Juliet
12	Portia
13	Rosalind
14	Belinda
15	Puck
16	Perdita
17	Mab
18	Cupid

Neptune (--planet 8 or --planet neptune)

Neptune moon index

Index	Moon name
1	Triton
2	Nereid
3	Naiad
4	Thalassa
5	Despina
6	Galatea
7	Larissa
8	Proteus
9	Hippocamp

Mars (--planet 4 or --planet mars)

Mars moon index

Index	Moon name
1	Phobos
2	Deimos

Pluto (--planet 9 or --planet pluto)

Pluto moon index

Index	Moon name
1	Charon
2	Nix
3	Hydra
4	Kerberos
5	Styx

Additional moons (--moremoons)

--moremoons is used only by the viewer command. It is a flag: presence turns on the feature; it does not take a value.

• Omitted: Only the moons selected by --moons are displayed. Irregular moons are not added.

• Present (e.g. --moremoons): In addition to --moons, the viewer displays all irregular moons for that planet.

Which moons count as “irregular” is planet-specific (e.g. Jupiter: Himalia, Elara; Saturn: Phoebe and many others).

Viewer star catalogs and plot options

Standard star catalog (--standard-star-catalog)

Flag: when present, overlay the planet’s standard star list (e.g. starlist_sat.txt for Saturn). Omit for no overlay.

Additional star (--additional-star)

Flag: when present, overlay one user-defined star; provide --extra-ra and --extra-dec (and optionally --extra-name, --extra-ra-type). Omit for no additional star.

Moon labels (--labels)

Label size for moons and stars. Only the size word is required: small, medium, or large (case-insensitive). Full strings like Small (6 points) are also accepted. The number of points is implied by the size; you do not need to specify it. Quote values containing spaces or parentheses (e.g. --labels "Small (6 points)").

Blank disks (--blank-disks)

Flag: when present, white out planet and moon disks. Omit for normal disks.

Ring opacity (--ring-opacity, Saturn only)

Ring rendering style. Values: Transparent, Semi-transparent (2x file size), Opaque. Quote values containing spaces or parentheses (e.g. --ring-opacity "Semi-transparent (2x file size)").

Ring pericenter markers (--ring-pericenter-markers)

Saturn: None, F Ring. Uranus: None, Epsilon Ring only, All rings. --ring-pericenter-size sets the marker size in points (default 4). Quote multi-word or parenthesized values (e.g. --ring-pericenter-markers "Epsilon Ring only").

Neptune arc model (--neptune-arc-model, Neptune only)

Arc motion model. Values: #1 (820.1194 deg/day), #2 (820.1118 deg/day), #3 (820.1121 deg/day). --neptune-arc-thickness sets the arc line weight in points (default 4). Quote values containing spaces or parentheses (e.g. --neptune-arc-model "#1 (820.1194 deg/day)").

Io torus (--io-torus, --io-torus-inc, --io-torus-rad; Jupiter only)

--io-torus: flag; when present, show the Io plasma torus. Omit to hide. --io-torus-inc: inclination in degrees (default 6.8). --io-torus-rad: radius in km (default 422000.0).