Skychart

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====== Add elements manually ======
From the menu: **Settings-> Solar Sytem... -> Comet -> Add** \\
or\\
From the menu: **Settings-> Solar Sytem... -> Asteroid -> Add** \\

It can be helpful to add manually elements to your existing list of comets or asteroids. You also can display one asteroid amidst the stars by deleting the position data of the other asteroids and entering the element data for your single asteroid. 
=== Warning === 
Elements are used to define conical section orbits like ellipses of asteroids and ellipses and parabolas of comets. The resulting calculated positions are only useful for objects that are not close to planets. In the case of Near Aarth Objects (NEOs) that are close to the Earth, the calculated postions based on the elements are totally useless. If you want to display the postion or path of a NEO with Cartes du Ciel, you can do this based on a list of calculated postions and adding this list to your catalogs. **[[en:documentation:display_of_neos|Here]]** you find instructions on how to do that.
===== Requesting elements =====
You can request elements from **NASA JPL Horizons**. Open this link in a new window: [[http://ssd.jpl.nasa.gov/horizons.cgi]] \\
Copy the settings below, of course with your adjustments. Select for //Ephemeris Type// ''Orbital Elements''. Choose for //Target Body// your demanded object. You need to set //Center// as **''@sun''**. Set at //Time Span// the time range for which you want to retrieve the elements.\\

|Ephemeris Type | [change] |:  ELEMENTS|
|  Target Body |[change] |:  Asteroid 5610 Balster (2041 T-3)|
|  Center |[change] |:  Sun (body center) [500@10]|
|  Time Span |[change] |:  Start=2014-08-09, Stop=2014-08-10, Step=1 d|
|  Table Settings |[change] |:  defaults|
|  Display/Output |[change] |:  default (formatted HTML)|

===== Entering the data =====
====== Data from the Object Data page ======
Enter a clear designition of the object. In this example I choose "Asteroid 5610 Balster (2041 T-3)". \\
In the part //Physical Parameters// you find the value **H= ..**. Copy this as **//H absolute magnitude//**.\\ Copy the value **G= ..** as **//G Slope parameter//**.

====== The Results data======
Further, in the **Results** part we find more data to enter. The results list shows data in mathematical notation. Cartes du Ciel can process this data both in this form as in decimal notation.\\
''
$$SOE\\
2456878.500000000 = A.D. 2014-Aug-09 00:00:00.0000 (CT)\\
 **EC**= 4.410631654154605E-02 QR= 2.680223611595490E+00 **IN**= 3.348991791769490E+00\\
 **OM**= 2.437396671671045E+02 **W** = 3.329253281089416E+02 Tp=  2456381.044945736416\\
 N = 2.099239155691789E-01 **MA**= 1.044277128106851E+02 TA= 1.092504742118517E+02\\
 **A** = 2.803893003977550E+00 AD= 2.927562396359610E+00 PR= 1.714907036789549E+03\\
2456879.500000000 = A.D. 2014-Aug-10 00:00:00.0000 (CT)\\
 EC= 4.410698013669621E-02 QR= 2.680219915877766E+00 IN= 3.348991402148423E+00\\
 OM= 2.437396179792080E+02 W = 3.329246715210186E+02 Tp=  2456381.042354188394\\
 N = 2.099241311623329E-01 MA= 1.046382882182052E+02 TA= 1.094556083560238E+02\\
 A = 2.803891084235605E+00 AD= 2.927562252593444E+00 PR= 1.714905275571270E+03\\
$$EOE\\
''

Take note of the abbreviations and copy the corresponding data:

  - 2456338.500000000 as value for **Epoche (JD)** (on top, directly under $$EOE)
  - **MA**: 1.044277128106851E+02 as value for **Mean anomaly**
  - **W**:  3.329253281089416E+02 as value for **Argument of perihelion**
  - **OM**: 2.437396671671045E+02 as value for **Longitude of ascending node**
  - **IN**: 3.348991791769490E+00 as value for **Inclination**
  - **EC**: 4.410631654154605E-02 as value for **Excentricity**
  - **A**:  2.803893003977550E+00 as value for **Semimajor axis**
At **//Reference//** enter the reference to the source of which you retrieved your data. In this example **"Horizons"**. \\
At **//name//** you enter the name that will show up in the label. 
To discriminate between previously calculated positon data it may be useful to enter your object name extended with some sort of extra information. 

Click at the button **Add**. If you entered all data in a format that CdC can process, you will recieve an **"OK!"**. \\

Now, do a new **//prepare monthly data//**, compute the postitions according **[[solar_system#asteroid|these]]** instructions.