Minor Planets

• Astrometry using TheSky/CCDSoft
• Extended minor planets - defined
• How Accurate are the Minor Planet Positions?
• How can I plot ALL minor planets at ALL zoom levels?
• How many minor planets can I have in the local group?
• Interested in only one or two minor planets? <-------------NEW FEATURE!
• IAU Minor Planet Center
• Local Group defined
• Lowell Observatory
• NEO 2007 TU24 close approach Jan. 2008
• Occultation Page
• Special Case Minor Planets
• Where do I find good orbital elements?
• Where can I generate an Ephemeris?

Background

TheSky has a "Local Group" of minor planets and an "Extended" group of minor planets. Why?? Both are defined here!

The Local Group of minor planets defined

The "local group" of minor planets are always loaded with TheSky (i.e. the become part of TheSky and are internal) and they can be used with TheSky's Time Skip feature. This is not the case with Extended Minor Planet. The current limit is 1,000 minor planets in the "local group". See the following dialog showing how to access the "Local Group" of Minor planets.

Data | Comets and Minor Planets

Local Group shown

To search for a minor planet in the "local group" just use Edit | Find and the name or number. Example, Edit | Find Nemasua or Edit Find 51 or Edit | Find Bisque. Or you can use View | Display Explorer and expand the entire list showing them all individually.

Edit | Find

Expand Solar System | Minor Planets

How many minor planets can I have in the local group?

Currently TheSky is limited to a total of 1,000 minor planets in the "local group". That is a reasonable number to compute in real-time using the widely available PC's today. The faster the processor the faster the minor planets can be computed.

If you attempt to "Import" more than 1,000 you will see the following message.

Exceeded 1,000 on Importing to local group

No problem just use the "Extended Minor Planets" instead

Extended Minor Planets - defined

NOTE: To search for minor planets found in the Extended Minor Planets you must use Edit | Find MPL then the minor planet name or number.

The "Extended minor planets" as opposed to the "Local Group" are computed for the instant in time that you have set in TheSky's Data | Site and Data | Time settings. They can be used for a 24 hour period without having to re-compute the entire set of minor planets. When working with a minor planet over time it is best to COPY the local minor planet into the local group.

The "Extended Minor Planets" are not computed in "real time" like the Local Group so they cannot be used with the Time Skip feature. The reason for this is the program would be unbearably slow if it had to update hundreds of thousands of minor planets (approaching 1/2 a million now) when re-computing the display.

NOTE:  If you skip more than 24 hours of time the Extended Minor Planet will no longer plot!  At that point you must use the Compute button on the Extended Minor Planets dialog to re-compute them all!  Better again to copy the minor planet into the local group.

To "SEARCH" for an "Extended Minor Planet" as opposed to searching the "Local Group" use Edit | Find MPL "MINOR PLANET NAME". Precede the minor planet name with MPL to search the extended group. As in Edit | Find MPL 12934 and minor planet Bisque will be found in the Extended group. To search the local group just use Edit | Find and the minor planet name or number. Example Edit | Fine ATE 111. Assuming the minor planet in question is part of the local group.

NOTE:  Importing Minor Planets out of the Extended Group and into the "Local Group" can take considerable time!  BE PATIENT!  Computing 400,000+ minor planets is slow on any PC!

Extended Minor Planets

Choose text file with elements here

NOTE:  Total number of minor planets at this time is displayed at 353,389.

24 hour path plotted for Extended Minor Planets

If you wish to see where the minor planet is heading and how much it will move in a day use the Show 24-hour path option. Great for finding fast movers!

Show a 24-hour path

Sample 24 hour vector for 66391 1999 KW4

Normally when plotting a full set of extended minor planets you would not use the option "Compute on startup". If this is done EVERY time you launch TheSky it will load and optimize the Extended minor planets and that takes time. However, if you are working with a small select group of minor planets in a day by day fashion by all means load them each time TheSky is started!

Plotting all extended minor planets at all zoom levels

Also, if you choose the option to plot ALL extended minor planets at all zoom levels with a large dataset you may regret it. The following screen shot demonstrates plotting over 300,000 minor planets at all zoom levels.

A bit confusing to say the least!

And painfully sloooow!!

How Accurate are TheSky's Minor Planet Positions?

To show the accuracy of TheSky's computed position for a known minor planet I used our Image Link technology to supply the following example. The image is an ST-6 CCD image taken with a Celestron 8" scope at f/10 the year 1994 March 10 at 1:22 a.m. local time for Golden CO Time zone 7.

Image Link of CCD image

Turquoise symbol shows
position plotted by TheSky

The positions for the both the "Extended" and "Local Group" are good to the arc-second (possible even better) when you have up-to-date orbital elements or those that have been integrated for the proper date. If you want to use a minor planet in TheSky's Time-Skip feature for longer than 24 hours the minor planet must be copied into the Local Group. This is done using the Utility Tab then "Copy To Local" button. See below.

Object Information

"Copy to Local" will move
an Extended minor planet into the local group

In testing occultation simulations predicted by IOTA using TheSky with LOCAL GROUP minor planets using the correct location on Earth, TheSky has achieved very accurate results when good orbital elements are supplied. When simulating an occultation of star that is not contained in the Hipparcos/Tycho UCAC-2 or USNO-B1 subset stellar catalogs you will need to Add a new auxiliary object like a reference point or a new star using the Data Add-User Defined data in order to accommodate a stars most accurate position including the effects of proper motion. Otherwise the occultation may not occur in TheSky because the stars position is slightly off.

The IOTA provides the precise positions for the stars (very up-to-date and refined up to the occultation) that will be occulted by taking into consideration the effects of proper motion. For occultation's you would need the most current up-to-date orbital elements for the minor planet too in order to expect extremely accurate results. Often times they will be refining the minor planets orbital elements right up to the day of the occultation!  See the Astrometry page for details on how to perform accurate astrometry for submission to the Minor Planet Center.

Special Case Minor Planets - Distant, Critical, and Unusual

A very handy feature of TheSky is the ability to download current comet and minor planet elements directly from the world wide web. In order to use the Import from the Web facility in TheSky you will need to have an Internet connection established. Use your Dial-Up Networking or direct Internet connection like ISDN, DSL, cable modem, or T1. When you are on-line you use the menu item Data | Comets and Minor Planets. You will see the following Dialog Box under the Minor Planets Tab.

Get Special Case Minor Planet Elements

From the Web

• Critical Minor Planets
• Distant Minor Planets
• Unusual Minor Planets Including (NEO's) Near Earth Orbits <- click for details

You can use the option in TheSky Data | Comets and Minor Planets | Minor Planets then the buttons found under From the web as shown below. Pick the group of interest here.

Distant, Critical and Unusual

Or By Name

After choosing one the groups you are presented with a list of minor planets to directly input into the Local Group.

By combining all three groups the Critical, Distant, and Unusual together you will have one large text file that can be used with the Extended Minor Planets option. This will plot something on the order of 1,000 "special case" minor planets but that is very manageable. If you find you need more then the 1,000 loaded at once you will need to use the Extended Minor Planet feature.

Interested in only one or two to twenty minor planets?

If you don't want to deal with any of the larger minor planet datasets, potentially hundreds of thousands of minor planets) you can create the orbital elements for one single minor planet or say a dozen of your choice if you like. Just use the Minor Planet Center's service.

A new feature found in the latest version of TheSky6 <--- Get latest version first is the ability to enter a minor planet(s) by name and have the Minor Planet Center's web site find the minor planet by name or number for you and that allows you to import it/them directly into the Local Group.

Minor Planet Tab

Click the By Name button

Enter the minor planet(s) here

Must be exact name/number
 sub string searches don't work

The above list will return the following matches,

Click on individually

or mouse drag them all
importing them into the local group

Approximately 10 names can be entered at a time!

HINT: If 10 is not enough just go back and add more! The above returns,

You can now import them all or individually into the local group. Double clicking a minor planet name will be import only that minor planet into the local group. Dragging the mouse by holding down the left button down the list allows you to highlight them all at once and import them into the local group. Then just press OK and they become part of the "Local Group". Easy enough! If you want to add only one instead of all of them at once you can.

WARNING!

The web site used is not forgiving by any means. The name and/or number of the minor planets entered in the list must be EXACT for all entries! Entering one name or number incorrectly will cause a complete failure. Sub strings do not work either, i.e. Apoph will not find Apophis. If any one of the entries is not perfect you will see the following error.

Ratty Data

One or more not found!

The "By Name" feature also works with comets using the Comets tab. And the same warning applies! All names or numbers must be exact! Example searching for comet fragment orbital elements for comet 73-PSchwassmann-Wachmann,

Enter the fragment designations

Must be exact!

The above list returns,

Click individually

or mouse drag all of them!

See the warning above about search criteria!

Using the Minor Planet Center to select a few minor planets by name

NOTE: The above described built in By Name feature in TheSky works the same and is easier to use!

Now you can enter one or more individual minor planets and have the orbital elements formatted for TheSky by the Minor Planet Center. This is very handy!  From the above page look at the following example for Ate 111 and 51 Nemausa and 12934 Bisque.

Get only those you want!

Enter names or minor planet number

Enter the minor planet designations you want the orbital elements for. At the bottom of the page choose the Format for Elements Output and check mark TheSky (Software Bisque).

Format for elements output

 Create the elements for TheSky!