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SBDB Search Engine - Help

Introduction

The JPL Small-Body Database Search Engine provides a tool to perform a variety of custom database queries. Typical use includes generation of custom tables of orbital and/or physical parameters for all asteroids and comets, or a specified sub-set (for example NEOs). Output can be provided in an HTML table (i.e. in your browser), a CSV (comma-separated variables) format download file (for use in a spreadsheet program or Matlab or other tool), or simply a count of the number of bodies matching your specified constraints.

Using the search engine comprises three steps:

  1. specify Search Constraints (if any)
  2. specify Output Fields (if any)
  3. specify Format Options
Each step is clearly delimited on the search engine main page and each is described in detail in the following sections. Examples for a number of different uses are described below as well.

Search Constraints

Search constraints are divided into three main categories: object type/group, orbit class, and object characteristics. The last is sub-divided into "physical" and "orbital" parameters.

Limit by object type/group:

This category allows you to limit your search to the specified object type, object kind, and/or numbered state. The object group can be NEOs (near-Earth objects) or PHAs (so called, potentially hazardous asteroids). The object kind can be asteroids or comets. And finally, the numbered state can be "numbered" (meaning the object has been officially numbered by the IAU) or "unnumbered". So, for example, if you want only NEAs (near-Earth asteroids), you could select both "NEOs" and "asteroids".

Limit to selected orbit class(es):

This category allows you to limit your search to one or more orbit classes. Orbit classes are split into two groups: one for asteroids and the other for comets. If no classes are selected, then the search is unrestricted. If more than one class is selected, then the search is constrained to objects matching either class. For example, to constrain your search to main-belt asteroids, you could select "Inner Main-belt Asteroid", "Main-belt Asteroid", and "Outer Main-belt Asteroid". Each class is defined by the object's orbital elements and are non-overlapping (i.e. only one class can be set for any given object). There are two special classes (one for asteroids and the other for comets) which are set when no other class matches the object's orbit.

Limit by object characteristics:

This category is split into two sub-groups: "physical parameters" and "orbital parameters". The former includes not only physical parameters such as diameter, but also object designation parameters such as the comet prefix. The latter includes orbital elements such as eccentricity (e) and orbit determination parameters such as the number of observations used in the fit and the number of days spanned in the fit.

These constraints are defined by first selecting the parameter of interest (for example eccentricity), then selecting an "operator" (such as "<" or "range"), then entering the constraint value (such as "0.8" or "0.5-0.7" for a range), and finally clicking the "Add=>" button. You should then see your specified constraint in a list to the right. Once you specify such a constraint, you can not edit the constraint value. To change the value, you must first delete the constraint, then add the new desired constraint.

Since each "operator" requires different "values", the following describes the current list of "operators" in more detail.

 <   less than the specified single "value" 
 <=   less than or equal to the specified single "value" 
 >   greater than the specified single "value" 
 >=   greater than or equal to the specified single "value" 
 range   within the range specified (e.g. "4 9.2", "0.8-1.3", "-40:-2") 
 !=   not equal to the specified "value" 
 REGEXP   matching the specified "regular expression
 defined   the parameter is defined (has a non-NULL value) 
 not defined   the parameter is not defined (NULL value) 

REGEXP operator

The REGEXP (regular expression) operator provides a sub-set of so-called "regular expressions". The most likely forms to be useful here are the "match from the beginning" (for example, "^C" will match any string staring with the letter "C"), "match from the set of characters" (for example "[CD]" will match any string containing either "C" or "D"), and perhaps "match from the end" (for example, "Levy$" will match any string ending with "Levy"). Currently, the database uses MySQL. More details on the MySQL REGEXP operator are available from the MySQL on-line documentation.

Output Fields

If you are only interested in how many objects match your specified constraints, you do not need to select any output fields.

Output fields can be selected using various methods. The easiest method is to select from the Pre-defined field sets: list something like "asteroid - basic", assuming that set gives you what you want. Otherwise, you can select individual fields from the Object Fields: list and/or the Orbital and Model Parameter Fields: list. Multiple fields can be selected using appropriate key-shift (or control or...) mouse-click combinations (dependent on your browser and OS). After selected the desired output field(s), press either the "Append Selected" or "Prepend Selected" button to add those fields to your list. Repeat this process as needed. Your selected fields will appear in the Selected Fields list below where you can adjust the output order and/or removed selected fields.

Having selected your desired output field(s), you can optionally sort by any field (or even a combination of fields). Sorting can be set to either ascending or descending for each field. If you do not specify any field for sorting, the default sort is used which is by object kind (numbered asteroids, unnumbered asteroids, numbered comets, unnumbered comets) and designation.

Format Options

The final step is the selection of output format. You can either select "HTML" which will produce output in your browser (this is what most will prefer and is the default), or "CSV" which will prompt you for downloading a so-called comma-separated variables text file. The CSV formatted file should be compatible with most spreadsheet programs and similar programs (such as Matlab). If you select HTML format, you can restrict the maximum number of rows to display per page (the smaller the number the faster the rendering in your browser), and/or specify "compact" or "full" output precision. Then, press the "Generate Table" button to display/download your results.



Examples


Example 1:   Create a table of orbital elements for all near-Earth asteroids.

To generate a table of Keplerian orbital elements for all near-Earth asteroids, follow these steps.

  1. Under the "Search Constraints" section, select "NEO" from the "object group" buttons and select "Asteroids" from the "object kind" buttons.
  2. Under the "Output Fields" section, select the "object full name/designation" from the "Object Fields" list, select the "Keplerian elements" from the "Pre-defined field sets" list, then press the the "Append Selected" button. (You should see the selected fields appear in the "Selected Fields" list below. Note that the pre-defined set "Keplerian Elements" is expanded into individual fields.)
  3. Under the "Format Options" section, press the "Generate Table" button.

This should result in a table of Keplerian orbital elements for all near-Earth asteroids.


Example 2:   Create a table of known asteroid diameters including albedo and SMASSII taxonomic classification.
  1. Under the "Search Constraints" section:
    1. Select "Asteroids" from the "object kind" buttons.
    2. Under the "Limit by object characteristics" sub-section, select "diameter" from the "(select physical parameter)" popup menu, select "defined" from the "(operator)" popup menu, then press the "Add =>" button. (The constraint should appear to the right of the "Add =>" button.)
  2. Under the "Output Fields" section:
    1. Select the "object full name/designation" from the "Object Fields" list, then press the the "Append Selected" button.
    2. Select the "object diameter" from the "Object Fields" list, then press the the "Append Selected" button.
    3. Select the "geometric albedo" from the "Object Fields" list, then press the the "Append Selected" button.
    4. Select the "spectral taxonomic type (SMASSII)" from the "Object Fields" list, then press the the "Append Selected" button.
  3. Under the "Format Options" section, press the "Generate Table" button.

An alternate and perhaps easier way to select multiple output fields (as described under step 2. above), is to select all desired fields from the "Object Fields" list first, then press the "Append Selected" button. On most web browsers, this is done by clicking on the first item in the list, then CNTL-clicking on each additional item. Your browser may use a different method.


Example 3:   Create a table of orbital elements including comet non-gravitational parameters for all comets with orbital periods less than 20 years.
  1. Under the "Search Constraints" section:
    1. Select "Comets" from the "object kind" buttons.
    2. Under the "Limit by object characteristics" sub-section, select "period (years)" from the "(select orbital parameter)" popup menu, select "<" from the "(operator)" popup menu, enter "20" into the value field, then press the "Add =>" button. (The constraint should appear to the right of the "Add =>" button.)
  2. Under the "Output Fields" section, select "comet - basic" from the "Pre-defined field sets" list, then press the the "Append Selected" button.
  3. Under the "Format Options" section, press the "Generate Table" button.

Example 4:   Create a table of main-belt asteroids with orbits where inclination is less than 11 degrees, Tholen taxonomic classification is "C*", and absolute magnitude (H) is 14.0 or brighter.
  1. Under the "Search Constraints" section:
    1. from the "Limit orbit classes" sub-section, select "Inner Main-belt Asteroid", "Main-belt Asteroid", and "Outer Main-belt Asteroid".
    2. Under the "Limit by object characteristics" sub-section, select "i (deg)" from the "(select orbital parameter)" popup menu, select "<" from the "(operator)" popup menu, enter "11" into the value field, then press the "Add =>" button. (The constraint should appear to the right of the "Add =>" button.)
    3. Under the "Limit by object characteristics" sub-section, select "spec. type (Tholen)" from the "(select physical parameter)" popup menu, select "REGEXP" from the "(operator)" popup menu, enter "^C" into the value field, then press the "Add =>" button. (The constraint should appear to the right of the "Add =>" button. Note the the REGEXP "^C" says, match any Tholen class starting with capital 'C'.)
    4. Under the "Limit by object characteristics" sub-section, select "H (mag)" from the "(select physical parameter)" popup menu, select "<=" from the "(operator)" popup menu, enter "14" into the value field, then press the "Add =>" button. (The constraint should appear to the right of the "Add =>" button.)
  2. Under the "Output Fields" section:
    1. Select "asteroid - basic" from the "Pre-defined field sets" list, then press the the "Append Selected" button.
    2. Select the "spectral taxonomic type (Tholen)" from the "Object Fields" list, then press the the "Append Selected" button.
  3. Under the "Format Options" section, press the "Generate Table" button.

Example 5:   Determine the number of comets for which a diameter is "known".
  1. Under the "Search Constraints" section:
    1. Select "Comets" from the "object kind" buttons.
    2. Under the "Limit by object characteristics" sub-section, select "diameter" from the "(select physical parameter)" popup menu, select "defined" from the "(operator)" popup menu, then press the "Add =>" button. (The constraint should appear to the right of the "Add =>" button.)
  2. Under the "Format Options" section, press the "Generate Table" button.

You should see the number of matching comets under the "Results:" header.

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