Binders World
three.js - Astronomy
Astronomical apps using WebGL and three.js. CC BY 4.0
Interactive stellarium showing up to 377,880 (default 46,954) of the brightest stars down to apparent magnitude 10.0 (default 8.0), or up to 527453 of the nearest galaxies.
Contents
On this page.
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Introduction
General properties of the app and preset examples.
- Displays proper star sizes and colors on black sky.
- Star name is shown when pointer is on a star.
- Camera can be orbited by left-dragging.
- Stellar motions can be animated for various time frames.
- Star attenuations, camera and animation parameters can be set.
- Constellation can be selected by searching.
- Star can be selected by clicking or searching.
- Camera can be orbited to track or animated to move to selected star.
- User interface can be toggled on and off.
- Preset example: Stellar sky auto-rotating and sweeping declinations (proj.),
1 minute rotation period, 6 minutes sweep period.
- Preset example: Stellar sky auto-rotating focus on near stars (proj.),
1 minute rotation period, 6 minutes sweep period, camera orbit at 10 pc, all stars absolute magnitude 0.0, spotlight to distance 10 pc.
- Preset example: Stellar motions around the constellation Orion (proj.),
proper motion from -1,000,000 CE to 1,000,000 CE in 2 minutes.
- Preset example: Tracked stellar motion of the star Sirius in Canis Major (proj.),
proper motion from -1,000,000 CE to 1,000,000 CE, from Lynx to Indus, in 2 minutes.
- Preset example: Travel to the star Alnilam in Orion (proj.),
606 pc (1976 ly) from the Sun in 1 minute.
- Preset example: Exaggerated parallaxes around the constellation Orion (proj.),
1 year parallax of 1 AU transformed to 5 s (1/6,311,520 year) parallax of 1 pc (3.26 ly, 206,265 AU).
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Constellation and star search
Constellations can be searched by IAU abbreviation (3 letters) or (part of) Latin name.
Stars can be searched by catalog index (e.g. "[1]..." for Sirius) or (part of) name, where only one name is given in catalog in approximate priority order:
- IAU name (e.g. "Sirius")
- short Bayer designation (e.g. "β Mus"/"bet Mus"/"beta Mus", "γ02 Vel"/"gam02 Vel"/"gamma02 Vel" or "q Car")
- short Flamsteed designation (e.g. "3 Cen")
- short variable designation (e.g. "T CrB" or "V415 Car")
- Henry Draper catalog number (e.g. "HD 102350")
- SAO catalog number (e.g. "SAO 228708")
- other catalog number (e.g. "HIP 59050")
- GAIA DR2 catalog number (e.g. "GDR2 2892312723242963072")
See JSON catalog file for full list of searchable names.
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Scenes
Scenes tailored by call arguments (described below):
Nearby galaxies
(year 2000 CE, 863 galaxies from Karachentsev 2013 with R < 11 Mpc or RV < 600 km/s)
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User interface parameters
- ∨ / >
Click button to toggle user interface on (∨) and off (>).
- Object count max
Change value to set max object count (stars: 0 - 377880, default 46954, galaxies: 0 - 527453, default 326)).
- Object diameter max
Change value to set max object diameter in pixels (1 - 10000, default 5000).
- Object attenuation
Change value to scale object diameters (0.01 - 10, default 0.1).
- Camera FOV
Change value in degrees to set vertical angle the camera view covers (1 - 150, default 50).
- All abs.mag.
Change value and check box to set all object absolute magnitude (-30 - 10, default 0).
- Color depth
Change value to set color depth in parsecs from origo, 0 disables (0 - 100000, defaukt 0).
- Spotlight
Change value to set spotlight radius in parsecs around origo, 0 disables (0 - 100000, defaukt 0).
- Dark
Change value to set dark outside spotlight, (0 - 1, default 0.2).
- Move time
Change value to set move duration in seconds (1 - 3600, default 5).
- Rotation time
Change value to set rotation duration in seconds (1 - 3600, default 2).
- Anim time (only stars)
Change value to set animation duration in seconds (1 - 3600, default 60)
- Anim start (only stars)
Change value to set present and start year CE for stellar motion animation (-1000000000 - 1000000000, default 0)
- Anim end (only stars)
Change value to set end year for stellar motion animation (-1000000000 - 1000000000, default 1000000).
- Start animation (only stars)
Click button to start object motion animation.
- f
Check to set fixed asterisms.
- a
Check to show asterism lines.
- g
Check to show equatorial grid lines.
- h
Check to show header with status
- -
Check for clean animation, click in display to "unclean"
- Reset
Click button to reset all parameters to original values.
- Camera dolly
Change value to set distance (dolly) in parsecs (3.26 light years) at which the camera orbits the scene origo (e.g. Sol) (0.001 - 1000000, default 0.001).
- Par. pole r.a. (hidden)
Change value to set parallax pole right ascension in degrees (0 - 360, default 270).
- Par. pole dec. (hidden)
Change value to set parallax pole declination in degrees (-90 - 90, default 66.6).
- Parallax (pc) (only stars)
Change value to set parallax distance in parsecs (3.26 light years) at which the camera orbits the scene origo (e.g. Sol) (0 - 100, default 0).
- Parallax (s) (only stars)
Change value to set parallax time in seconds at which the camera orbits the scene origo (e.g. Sol) (0 - 3600, default 0).
- Highlight
Select one or more groups to highlight its members in red.
- Select object
Enter part of object name and click button to search for object.
- Origo object
Click button to move scene to center on select object.
- Watch object
Click button to track select object, left-drag in scene to release.
- Point object
Displays name of object under pointer, distance from origo in parsecs (3.26 light years).
- Year CE
Displays year CE for stellar positions in J2000.0 grid.
- α & δ
Displays equatorial coordinates for center of scene.
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Call arguments
The default start view shows the stars around α 06h δ 00°, mainly the constellation Orion, but various parameters can be set by adding arguments to the URL, so the basic call
http://binders.world/threejs/astro/stars1.html
corresponds to the defaults
http://binders.world/threejs/astro/stars1.html?json=simbad_magv10_05&j=2000&sd=0&n=46954&dpx=5000&att=0.1&fov=50&u=0&m=0&cold=0&spot=0&dark=0.2&moves=5&rots=2&anims=120&animbeg=0&animend=1000000&f=0&a=0&g=0&h=0&c=0&d=0.001&grpmark=&con=&r_a=6&dec=0&s=-1&o=0&w=-1&near=0
This permits tailoring scenes directly in the URL, e.g. to share with others. The *show parameters can be used to tailor the user interface by hiding (=0) or showing (=1) parameters. The arguments are (type /unit/ [default] min - max / step):
- json: object data file name (string [simbad_magv10_05]).
Name of a JSON file without path and extension.
- j: epoch of object positions (float year 2000.0).
Base year for astronomical object positions and motions.
- sd: settings/display toggle (integer [0] 0 - 1).
1 enables toggle between settings and display for small screen.
- a1c: color of asterism major lines (hexcode [000099] 000000 - ffffff).
Intensity of asterism major lines: red (char.1-2), green (char.3-4) and blue (char.5-6) in hexadecimal notation 00=0 - ff=255.
- a1w: width of asterism major lines (float [1.0] 0.1 - 10.0 / 0.1).
Width in pixels of asterism major lines, usually doesn't affect default 1.0.
- a2c: color of asterism minor lines (hexcode [000066] 000000 - ffffff).
Intensity of asterism minor lines: red (char.1-2), green (char.3-4) and blue (char.5-6) in hexadecimal notation 00=0 - ff=255.
- a2w: width of asterism minor lines (float [1.0] 0.1 - 10.0 / 0.1).
Width in pixels of asterism minor lines, usually doesn't affect default 1.0.
- g1c: color of equatorial grid (hexcode [330033] 000000 - ffffff).
Intensity of equatorial grid lines red (char.1-2), green (char.3-4) and blue (char.5-6) in hexadecimal notation 00=0 - ff=255.
- g1w: width of equatorial grid lines (float [1.0] 0.1 - 10.0 / 0.1).
Width in pixels of equatorial grid lines, usually doesn't affect default 1.0.
- g2c: color of ecliptic grid (hexcode [003300] 000000 - ffffff).
Intensity of ecliptic grid lines red (char.1-2), green (char.3-4) and blue (char.5-6) in hexadecimal notation 00=0 - ff=255.
- g2w: width of ecliptic grid lines (float [1.0] 0.1 - 10.0 / 0.1).
Width in pixels of ecliptic grid lines, usually doesn't affect default 1.0.
- g3c: color of galactic grid (hexcode [333366] 000000 - ffffff).
Intensity of calactic grid lines red (char.1-2), green (char.3-4) and blue (char.5-6) in hexadecimal notation 00=0 - ff=255.
- g3w: width of galactic grid lines (float [1.0] 0.1 - 10.0 / 0.1).
Width in pixels of galactic grid lines, usually doesn't affect default 1.0.
- ui: show user interface (integer [1] 0 - 1).
Toggle user interface off when 0, can be changed in app.
- n (nmin, nmax, nstep, nshow): number of objects considered for rendering (integer [46954] 0 - 377880 / 10000).
High numbers can make the app slow or even crash, low numbers suit slow devices, can be changed in app but not recommended to increase from original.
- dpx (dpxmin, dpxmax, dpxstep, dpxshow): max diameter of objects (float [5000.0] 1.0 - 10000.0 / 100.0).
Max object diameter in pixels, regardless of attenuation, can be changed in app.
- att (attmin, attmax, attstep, attshow): attenuation of objects (float [0.1] 0.01 - 10.0 / 0.01).
Scales object diameters, can be changed in app.
- fov (fovmin, fovmax, fovstep, fovshow): camera field of view vertically (float ° [50.0] 1.0 - 150.0 / 10.0).
The vertical angle the camera view covers, can be changed in app.
- u: use same absolute magnitude for all objects (integer [0] 0 - 1).
1 enables use of the allabsmag magnitude, can be changed in app.
- m (mmin, mmax, mstep, mshow): same absolute magnitude for all objects (float [0.0] -30.0 - 10.0 / 1.0).
Avoids bright object smears and faint objects disappearances, can be changed in app.
- cold (coldmin, coldmax, coldstep, coldshow): color coding depth (float pc [0.0] 0.0 - 100000.0 / 1.0).
Distance from origo where stars shift color depending on distance, 0 => no color coding, can be changed in app.
- spot (spotmin, spotmax, spotstep, spotshow): spotlight radius (float pc [0.0] 0.0 - 100000.0 / 1.0).
Radius from origo inside which objects are fullbright, 0 => no spotlight, can be changed in app.
- dark (darkmin, darkmax, darkstep, darkshow): brightness outside spotlight (float [0.2] 0.0 - 1.0 / 0.1).
Fraction of fullbright outside spotlight radius.
- moves (movesmin, movesmax, movesstep, movesshow): time in seconds to move origo position (float s [5.0] 1.0 - 3600.0 / 30.0).
The number of seconds it takes the camera to fly from one star to another, can be changed in app.
- rots (rotsmin, rotsmax, rotsstep, rotsshow): time in seconds to rotate camera (float s [2.0] 1.0 - 3600.0 / 30.0).
The number of seconds it takes the camera to rotate to a new watch, can be changed in app.
- anims (animsmin, animsmax, animsstep, animsshow): animation duration in seconds (float s [120.0] 1.0 - 3600.0 / 30.0).
The number of seconds stellar motion animation takes, can be changed in app.
- animbeg (animbegmin, animbegmax, animbegstep, animbegshow): animation start year (float year [0] -1000000000.0 - 1000000000.0 / 1000.0).
Start year CE for stellar motion animation, can be changed in app.
- animend (animendmin, animendmax, animendstep, animendshow): animation end year (float year [1000000] -1000000000.0 - 1000000000.0 / 1000.0, not 0.0).
End year CE for stellar motion animation, can be changed in app.
- anim (animshow): click "Start animation" button.
- f: use fixed asterisms (integer [0] 0 - 1).
1 uses fixed asterism lines projected onto background, can be changed in app.
- a: add asterism lines (integer [0] 0 - 1).
1 shows asterism lines, can be changed in app.
- g: add equatorial grid lines (integer [0] 0 - 1).
1 shows grid lines, can be changed in app.
- h: add status header (integer [0] 0 - 1).
1 shows watch star, year and position as header, can be changed in app.
- c: make animation display clean (integer [0] 0 - 1).
1 hides user interface, toggle button and mouse cursor during animation, can be changed in app.
- reset (resetshow): click "Reset" button.
Show also affects checkboxes f a g h c above.
- d (dmin, dmax, dstep, dshow): camera dolly (float pc [0.001] 0.001 - 1000000.0 / 1.0).
The distance in parsecs (3.26 light-years) at which the camera orbits the scene origo, can be changed in app.
- declo: view auto-orbit lowest declination (float ° [-60.0] -90.0 - 90.0 / 0.1).
The lowest view center declination in ° when the camera auto-orbits the scene origo.
- dechi: view auto-orbit highest declination (float ° [60.0] -90.0 - 90.0 / 0.1).
The highest view center declination in ° when the camera auto-orbits the scene origo.
- r_as: view auto-orbit right ascension period (float s [0.0] -3600.0 - 3600.0 / 0.1).
The period in s it takes the view to auto-orbit the scene origo, 0 disables.
- decs: view auto-orbit declination period (float s [0.0] -3600.0 - 3600.0 / 0.1).
The period in s it takes the view to make a full declination cycle during auto-orbit, 0 disables.
- ppa (ppashow): parallax pole right ascension (float ° [270.0] 0.0 - 360.0 / 0.1).
Parallax plane, usually ecliptic, pole position right ascension in °, hidden in app.
- ppd (ppdshow): parallax pole declination (float ° [66.561] -90.0 - 90.0 / 0.1).
Parallax plane, usually ecliptic, pole position declination in °, hidden in app.
- pd (pdmin, pdmax, pdstep, pdshow): parallax distance (float pc [0.0] 0.0 - 100.0 / 0.001).
The parallax distance in parsecs (3.26 light-years) at which the camera orbits the scene origo, can be changed in app.
- ps (psmin, psmax, psstep, psshow): parallax time (float s [0.0] 0.0 - 3600.0 / 1.0).
The parallax orbital period in s at which the camera orbits the scene origo, can be changed in app.
- grpmark (grpmarkshow): highlight object groups (string []).
comma-separated object group short IDs, can be changed in app.
- con: watch constellation (string []).
IAU abbreviation (e.g. CMa) or (part of) Latin name of the constellation the view is centered on, can be changed in app.
- r_a: view right ascencion (float h [6.0] 0.0 - 24.0, not 0).
The center right ascension of the view, can be changed in app.
- dec: view declination (float ° [0.0] -90.0 - 90.0).
The center declination of the view, can be changed in app.
- eqcshow: position (RA, Dec).
- s (sshow): select star (integer [-1] 0 - 377880).
Index of selected star (0=Sol/Sun, 1=Sirius, 2=Canopus, 3=Arcturus, ...), -1 => none, can be changed in app.
- origo: click origo "=>" button to animate (integer [0] 0 - 1).
Affected by oshow below.
- o (oshow): origo star (integer [0] 0 - 377880).
Index of star the scene rotates around (0=Sol/Sun, 1=Sirius, 2=Canopus, 3=Arcturus, ...), -2 => same as s, can be changed in app.
- watch: click watch "=>" button to animate (integer [0] 0 - 1).
Affected by wshow below.
- w (wshow): watch star (integer [-1] 0 - 377880).
Index of star the view is centered on, -1 = > none, -2 => same as s, can be changed in app.
- pointshow: point star.
Star under pointer.
- near: nearest stars logged (integer [0] 0 - 100).
The number of nearest stars logged to console during animation.
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JSON data
The structure of the JSON file with object data is similar to below:
{
"el_la":[
{"el":"α","la1":"a","la3":"alp","la9":"alpha"},
...
{"el":"Ω","la1":"W","la3":"Ome","la9":"Omega"}
],
"figs":[
{"id":"And","name":"Andromeda","desc":"the chained princess","r_a":1.0,"dec":37,"fov":40,"line1is":[55,219,219,54,54,61],"line2is":[219,604,604,485,485,617,219,597,597,569,569,315,569,519,519,389,597,54,54,414,414,667,667,554,554,295]},
...
{"id":"Vul","name":"Vulpecula","desc":"the fox","r_a":20.2,"dec":24,"fov":40,"line1is":[],"line2is":[630,357]}
],
"figObjs":[
{"i":0,"name":"Sol ()","amag":4.850,"ci":0.656,"x":0.000005,"y":0.000000,"z":0.000000,"vx":0.000000000,"vy":0.000000000,"vz":0.000000000},
...
{"i":755,"name":"η Men","amag":-1.043,"ci":1.516,"x":14.417430,"y":49.614354,"z":-191.976142,"vx":-0.000008274,"vy":0.000053965,"vz":-0.000010069}
],
"grps":[
{"key":"LSC","name":"Laniakea SC","n":0},
...
{"key":"ACOS1165","name":"ACO S 1165","n":4}
],
"objs":[
{"i":0,"pgc":5064336,"name":"Milky Way","grps":",LSC,VirSC,LG,LG-MW,","amag":-21.50,"ci":0.70,"x":-437,"y":-6983,"z":-3879,"vx":0,"vy":0,"vz":0},
...
{"i":527452,"pgc":6773797,"name":"PGC 6773797","grps":"","amag":-20.80,"ci":0.70,"x":-173231748,"y":-290430094,"z":172971340,"vx":0,"vy":0,"vz":0}
]
}
The objects are:
- el_la: Greek-Latin dictionary.
- figs: Constellations/Asterisms.
- figObjs: Asterism stars.
- grps: Object groups.
- objs: Objects.
The parameters are:
- el: Greek letter (string).
- la1: Latin 1 letter key (string).
- la3: Latin 3 letter key (string).
- la9: Latin full key (string).
- id: constellation 3 letter abbreviation (string).
- name: object name (string).
- desc: constellation description (string).
- r_a: right ascension (h float).
- dec: declination (° float).
- fov: camera field of view (° float).
- line1is: primary asterism line star indices (integers list).
- line2is: secondary asterism line star indices (integers list).
- i: object index (string).
- name: object identifier (string).
- amag: object absolute magnitude (float).
- ci: object color index B-V (float).
- x: object position in parsecs along α=0h,δ=0° (float).
- y: object position in parsecs along α=6h,δ=0° (float).
- z: object position in parsecs along δ=90° (float).
- vx: object velocity in parsecs/year along α=0h,δ=0° (float).
- vy: object velocity in parsecs/year along α=6h,δ=0° (float).
- vz: object velocity in parsecs/year along δ=90° (float).
- key: group short identifier (string).
- n: number of identified objects in group (integer).
- pgc: Principal Galaxy Catalog number (integer).
- grps: CSV ","-padded list of membership groups short identifier (string).
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