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SpaceEngineer
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

12 Oct 2018 05:02

Thanks for update guys! I integrated the whole catalog, removing "Remove" objects manually from other catalog files. It will be in the next Steam update. Since now, please also add new objects to a separate sc file as "update for 0.990 patch 14", so I could track them and add manually.

Some errors (probably?)

Fixed Lempo discovery date, added alternate designations to all its components
Fixed discovery date of 2007 OR10 and its satellite, I also moved them to SolarSys.sc
Fixed many missing-slash names like this: "S2007 (1453) 1" -> "S|2007 (1453) 1"
Fixed a lot of syntax errors and missing parameters (for example, (5112) Kusaji have missing Mass value, a lot of asteroids have empty DiscMethod)
Asteroid "Siding Spring /(2343) Siding Spring" (with space before /) is renamed to "Siding Spring$AS/(2343) Siding Spring" ($AS are non-printable characters). Comet "Siding Spring/C|2013 A1 (Siding Spring)" is also renamed to Comet "Siding Spring$CO/C|2013 A1 (Siding Spring)".

I also added a code which reduces model radius of small asteroids, which are too "bumpy" and thus looks too large (significantly larger than selection pointer "radius"). Now small asteroids are more or less fit into provided mean radius. They became more round though...
 
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SpaceEngineer
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

12 Oct 2018 05:04

JackDole wrote:
Source of the post I use SE 0.980_e.
But I meant for the asteroid '3122 Florence (1981 ET3)'. That's probably not in the ephemeris database at all.
And if it should be in, I do not know its parameters. (AnalyticModel, RotationModel)

Of course no, I didn't implemented ephemerides for asteroids.
 
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Mosfet
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

12 Oct 2018 09:22

SpaceEngineer wrote:
Source of the post a separate sc file as "update for 0.990 patch 14"

Sure will do.
As you probably suspected, since the catalog is intended to be compatible also with 0980, that's the reason for missing slashes. Same reason for that space for (2343) Siding Spring, it's a "trick" in order to separate comet and asteroid in Object Finder in a pleasing way, without changing official definitions. For patch 14+ updates we'll use correct syntax (thanks, notepad++ macros! ;)) as well as the special character $ if needed.

The rest slipped through my checkings. v_v

SpaceEngineer wrote:
Source of the post I also added a code which reduces model radius of small asteroids

That was indeed a visual discrepancy, great! We'll see how it goes.
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

16 Oct 2018 01:08

Updated asteroid (809) Lundia: mass ratio and shape parameters from this article. This will work only in 0.990, because it supports tri-axial ellipsoid shape.

For 0.990, if you find dimensions data for asteroids, you can use them in catalog script. Note that dimensions are usually twice larger than radius: they are "diameters". In the Dimensions (X, Y, Z) parameter, X component is along orbital path, Y is rotation axis, Z is in direction of second companion. Usually Y is smallest, Z is largest.

To make asteroid shape more "round", reduce venusMagn: it is amplitude of the global "random shape" of the asteroid (and venusFreq is its frequency). This will work in the next patch (build 15).

Asteroid "Lundia/(809) Lundia"
{
   ParentBody   "Lundia system"
   Class      "Asteroid"

   DiscMethod      "Imaging"
   DiscDate      "1915.08.11"

   Dimensions   (6.6, 6.4, 7.8)   // km
   Mass      7.0588e-11      // Mearth, mass ratio 0.7
   TidalLocked true

   Surface
   {
      venusMagn 0.0   // make shape more round
   }

   Orbit
   {
      SemiMajorAxisKm 6.5059   // separation 15.8 km, mass ratio 0.7
      Period          0.001759
      Eccentricity    0
      Inclination     0
      AscendingNode   0
      ArgOfPericenter 180
      MeanAnomaly     0
      RefPlane        "Equator"
   }
}

Asteroid "S|2005 (809) 1"
{
   ParentBody   "Lundia system"
   Class      "Asteroid"

   DiscDate   "2005.09.18"
   DiscMethod "OrbitLight"

   Dimensions   (5.8, 5.6, 7.0)   // km
   Mass      4.9412e-11       // Mearth, mass ratio 0.7
   TidalLocked true
   
   Surface
   {
      venusMagn 0.0   // make shape more round
   }

   Orbit
   {
      SemiMajorAxisKm 9.2941   // separation 15.8 km
      Period          0.001759
      Eccentricity    0
      Inclination     0
      AscendingNode   0
      ArgOfPericenter 0
      MeanAnomaly     0
      RefPlane       "Equator"
   }
}
 
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Mosfet
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

10 Dec 2018 10:32

New additions:
(20882) 2000 VH57
(6100) Kunitomoikkansai
(2178) Kazakhstania
(100015) 1989 SR7

File updates are available in OP.
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SpaceEngineer
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

10 Dec 2018 19:43

Thanks, integrated.
 
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Silicon
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

11 Dec 2018 09:57

Hey Mosfet. I have been looking at the asteroids I have submitted and noticed that for most of them I gave incorrect axial-tilt data. I just thought you should know. Do you want me to remove the axial tilt data in the ones I provided?
 
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

11 Dec 2018 10:18

Silicon wrote:
Source of the post Do you want me to remove the axial tilt data in the ones I provided?

Hey Silicon. Shouldn't be a big issue, you could just help me with the list of asteroids you provided, and I'll check them.
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

12 Dec 2018 14:30

Sure, I'll give you the list of asteroids with tilt data. Tilt data is the only thing I provided incorrectly, so I wont bother posting the ones that have no tilt data.
► Show Spoiler

The only thing incorrect about these objects is their axial-tilt data. Because back when I made them I didn't know how The Johnston Archive organized axial-tilt. I thought it was relative to the ecliptic but it's actually the direction of the North Pole.

Also for two objects, 2002 VT130 and 5674 Wolff, they are both objects with a barycenter and no axial-tilt data. Because SpaceEngine will not procedurally generate axial-tilts for binary objects, how should these objects be handled? Should they be given tilts of 0 (0 tilt binary objects look weird) or a random tilt?

And as an apology letter, here's an asteroid. (4435) Holt.
► Show Spoiler
Last edited by Silicon on 13 Dec 2018 16:44, edited 1 time in total.
 
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

12 Dec 2018 18:57

Modern catalog uses IAU axial tilt notation, which describes celestial coordinates of the north pole while looking from the body. SE supports this as a RotationModel tag:

   RotationModel   "IAU"
   {
      Epoch      2451545      // J2000
      PoleRA         269.9949   // degrees
      PoleRARate     0.0031      // degrees/century (precession)
      PoleDec        66.5392      // degrees
      PoleDecRate    0.0130      // degrees/century (precession)
      PrimeMeridian   38.3213      // degrees
      RotationRate   13.17635815   // degrees/day (inverse of rotation period)
      RotationAccel   -0.0018677   // degrees/century^2 (deceleration of rotation period)
}


If precession and deceleration of rotation period data is missing, simply skip those parameters. Position of PrimeMeridian has little sense for procedural model, but if catalog provides this data, better to grab (can be used in future with a real model).

For binary asteriods, you may simple add TidalLocked true (to the main asteroid's code, no inside the RotationModel tag) to make it tidally-locked to the parent.
 
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

14 Dec 2018 17:46

(16974) Iphthime, A binary Jupiter trojan.
► Show Spoiler
 
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Mosfet
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

17 Dec 2018 15:54

Thanks Silicon, are you sure about epoch? that julian date apparently puts those orbital elements in year 4161773 :)
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

18 Dec 2018 07:05

No actually. I don't know how to convert dates to epoch, I just put the date in wolfram alpha and had it convert for me.

The dates should be September 4, 2017 for Holt and March 23, 2018 for Iphthime.
 
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COMMUNITY ADDON - Double/Multiple Asteroids fixes for SE

18 Dec 2018 12:24

Oh, Ok then. Epoch is expressed in Julian Days (Julian Date), which is the number of days counting from noon of January 1, 4713 BC. There are several converters online. In Wolfram Alpha, if your input is "March 23, 2018", you should get

Input interpretation:
Friday, March 23, 2018

If you click on "More formats/calendars" to the right you'll find the corresponding Julian Day Number, in this case 2458201.

Counting the date from midnight, it should be 2458200.5, probably Wolfram Alpha is rounding the decimal.
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