OrbBrowser – a Minor Planet Orbit Browsing Utility

In my “day job”, I’m a scientific applications developer working in the life sciences domain. I have a science background but have always used computers in one form or another in research, from time sharing main frames, to Unix workstations and servers to Linux clusters.

So I wanted to write a utility to extract orbital elements of minor planets from the flat-file distributions provided by the IAU Minor Planet Center, to help identify candidates for observation. I started with a basic PERL utility to filter the full MPCOrb data file based on input criteria. That was useful but not very exciting! So I’ve started to write an HTML/Javascript based utility to browse and filter some of the existing subsets provided by the MPC in an interactive fashion. The current version can be found on a demo site I’ve setup for the utility which is named OrbBrowser.

The site is quite simple to use. First, you need a data file in the MPC Minor Planet Orbit format containing the subset of interest. The current set of Near Earth Asteroids is available on the MPC data page in the file NEA.txt. Or you can download the DAILY.DAT file for the daily orbit updates to see what’s new and newly updated.

From the OrbBrowser site, select Choose File and select the local file of interest. After a few moments, the file should be read in and displayed in a table showing all of the fields present in the data file including orbital elements, orbital uncertainty and observation stats, etc. You can even see the published MPC “bit flags” giving the orbit type classification, PHA, NEA and critical flags.

Selecting the header of any column will sort the data by that column. At the bottom of the column are input fields to enter a min and max value for numerical fields, or a pulldown for categorical fields for filtering. So, for example, you can select U >= 2 and U <= 5 to see all objects in the data file with that range of uncertainty values. Adding another filter such as Orbit Type = Aten will intersect with the first filter to give all Atens having U from 2 to 5. And so on!

Once you have a subset of interest, you can export the filtered set back out to a file in MPC format or a text-delimited format. The MPC subset can then be loaded into a planetarium package such as C2A so you can see which objects in the list are currently visible from your favorite observing site at a given apparent magnitude limit. A text delimited export can be loaded into Excel or other data management programs to add additional information or more refined filtering and sorting.

Because OrbBrowser runs totally in a browser, there is no need to install any additional software to use the utility. However, you are subject to the javascript performance of your browser! On 64-bit Windows 10, I’ve had better luck with Chrome and Firefox for viewing the full NEA file with 15,000 some entries.

Also, you can download the main page of the site and supporting javascript and CSS files to your local desktop and run it totally off line. All of the source is available to read and it is available under an open source license, so you are free to modify it in any way and make use of it in your own site if that is of interest! See the Download and More Info tab for a link to the current ZIP archive and instructions to run it locally.

I’ve found the utility quite useful to help identify some of the Aten-class objects I’ve observed and submitted. I’ve even found and observed a couple of Atira-class bodies as well, which are totally within the Earth’s orbit and fairly elusive.

I hope OrbBrowser is of use to others. Feel free to send questions, suggestions and tomatoes to the email address listed on the site!

Screen shot example showing the current NEA.dat loaded, and filtered for Atens with U=2 through 5 to suggest potential objects that may need updating. (Of course, not all of these will be observable).


Screen shot showing all NEA’s with U from 2 through 5 loaded into C2A with a magnitude filter. Objects can be selected that are well above the horizon – and out of the Milky Way.


Loading and working with the full MPCOrb database does not appear to be practical in javascript. So I’m working on another browser-based utility to filter and save subset of interest for interactive browsing. So stay tuned for a companion utility!

1 thought on “OrbBrowser – a Minor Planet Orbit Browsing Utility

  1. Pingback: Atiras | M57

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