Last updated 16 Oct 2021

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Custom Software used at Great Shefford

Ephemeris Interpolator

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Ephemeris Interpolator User Guide

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Ephemeris Interpolator provides the following functionality:
  • Download ephemerides from the MPC's MPES and NEOCP services (details)
  • Manually copy/paste ephemerides in from other sources (details)
  • Interpolate RA, Dec, Speed and PA° using a second order method (details)
  • Includes a small detachable 'Pad' to appear above other windows, for convenience when using Astrometrica (details)
  • Send Speed and PA° details to Astrometrica during Track & Stack operations (details)
  • Send RA and Dec position information to Astrometrica "Coordinates" window if field centre is not available (details)
  • Calculate when an object reaches a specified RA or Dec value (details)
  • Retrieve astrometry from the MPC's MPES and NEOCP services (details)
  • Display calculated position in GoogleSky (details) (requires GoogleEarth is installed)
  • Configured to interpret common ephemeris formats from the MPC, FindOrb, JPL Horizons, NEODyS, Scout and GNSS satellites ephems (B. Gray)
  • Includes an editor to add other (fixed column format) ephemeris formats (details)

Ephemeris Interpolator has been tested to integrate successfully with Astrometrica versions 4.11.1.442 and 4.12.0.448 (ADES beta version)

Quick start guide

To retrieve an ephemeris and interpolate position and motion for a date and time:

More detailed information, including integration with Astrometrica follows:

Example screen:

Hover mouse over red boxes for brief descriptions. Click to go to more detailed information:

Ephemeris Interpolator main form

Object and Object qualifier

Object: Enter the MPC assigned name of the object, e.g. a designated object available via the MPES service (numbered and unnumbered minor planets and comets), or a NEOCP object name. If left blank and the +N button pressed (see next section), ephemerides for all NEOCP objects that match the selection criteria will be downloaded.

Qualifier: Normally left blank but if a numeric value is entered and the +M or +N buttons are pressed, the ephemeris for the associated variant orbit will be downloaded if it exists.
Can also be used to work with different ephemerides for the same Object, e.g. if several different solutions are used in FindOrb to generate ephemerides, these can be entered with qualifiers such as FO1, FO2, e=1 etc. and added as separate ephemerides in their own tab.

Copying the object name to the clipboard by right-clicking:

  • Right click in the object name to copy the name to the clipboard. If the name is a packed designation the unpacked version is copied to the clipboard.
  • Hold Shift while right clicking to copy the name and qualifier to the clipboard.
  • Hold Ctrl while right clicking to copy the packed name to the clipboard.

The resulting contents of the clipboard after the right-click operation is displayed in the status message area, e.g. 'Designation K21F00U copied to clipboard'.

MPES and NEOCP buttons (+M, +N and -N)

+M: Download ephemeris for Object from MPC's MPES service. If a numeric qualifier is also entered it will be used to retrieve an MPES variant ephemeris for Object.

+N: Download ephemeris for Object from MPC's NEOCP service (includes NEOCP and PCCP objects).  If a numeric qualifier is entered it will be used to retrieve a NEOCP variant ephemeris for Object. If Object is left blank ephemerides for all NEOCP/PCCP objects matching selection criteria will be downloaded. See the NEOCP Section.

-N: Delete all NEOCP/PCCP objects from the list of stored objects (see tabs). If Ctrl is held while clicking -N then all stored NEOCP/PCCP variant objects will also be deleted.

Note: the ephemerides will be requested from the MPC with a starting time as specified by the Date and time. To get good ephemeris coverage for the time required (i.e. ephemeris lines covering before and after the time required) the time used to download the ephemeris may need to be adjusted by one unit (e.g. hour) to force the retrieval to cover a more appropriate range of times.

Add manual ephemerides ('Paste and add' and 'Add')

Paste and add: Manually copy an ephemeris to the Windows clipboard, enter an object name (and optional qualifier) into the Object area then press the 'Paste and add' button to paste the clipboard contents into the ephemeris lines area and add the object into the list of tabs.

Add: Enter an object name (and optional qualifier) into the Object area, manually paste an ephemeris into the ephemeris lines area then press the 'Add' button to add the object and ephemeris into the list of tabs.

If the object is already present in the stored list of objects then the old ephemeris will be replaced by the new information.

Copy object name to clipboard

Copies the object name to the clipboard.
Hold Shift to also include object qualifier.
Hold Ctrl to copy packed name to clipboard for an already designated object (not NEOCP/PCCP)

The 'Copy object name to clipboard' button appears in the main form and Pad.

Copy astrometry from MPC to the clipboard <Obs>

Retrieves the available astrometry for the object from the MPC's MPES or NEOCP services and copies the text to the Windows clipboard. The number of lines retrieved is displayed in the status area.

The 'Copy astrometry from MPC to the clipboard' button appears in the main form and Pad.

Obs Code

Enter the MPC Observatory code to be used for topocentric ephemerides (required). If you do not have an MPC code, choose a nearby code.

Note: The latitude of the observatory is also used to limit the information returned from the MPES and NEOCP services, i.e. if the declination of the object means it is not observable from the observatory then no ephemeris will be returned. To disable this behaviour, change 'LimitDecByObsCode' in Settings to False.

Ephemeris Format Editor

Opens the Ephemeris Format Editor. The Ephemeris Interpolator needs to understand the format of the ephemerides that it is given. A set of common ephemeris formats is built in (Minor Planet Center formats such as MPES and NEOCP, JPL Horizons formats for the Small Bodies and Default Table Settings presets etc.). If an ephemeris format that is not already built in is needed to be handled then the Ephemeris Format Editor can be used to set it up. The columns where Date and time, RA and Dec appear are needed (Speed and PA° are optional) as well as a representative 'model' ephemeris line that will be used to identify the format when an ephemeris is added to the Ephemeris Interpolator.

See the Ephemeris Format Editor overview for further details.

Edit GoogleSky KML template

See Display position in Google Sky. Opens the KML template file with a text editor (text editor must be configured within Settings). If a KML template file is not found a default one is created. Use the Settings form to specify 'GoogleSkyFieldSize', the size in arc minutes of the initial field of view displayed in Google Sky.

Substitution variables will be recognised within the KML template as follows:

  • {PlacemarkName} replaced by Object name (+ optional qualifier) and time in ObjectName@HH:mm:ss format
  • {ObjectName} replaced by Object name (+ optional qualifier)
  • {RA} replaced by Right Ascension in GoogleSky decimal longitude format
  • {Dec} replaced by Declination in GoogleSky decimal latitude format
  • {RAHMS} replaced by Right Ascension in HH MM SS.S format
  • {DecDMS} replaced by Declination in DD MM SS format
  • {Date} replaced by Date in yyyy-MM-dd format
  • {Time} replaced by Time in HH:mm format
  • {Range} replaced by Range for the GoogleSky LookAt Element
  • {Speed} replaced by Speed in arcsec / minute to 2 decimals
  • {PA} replaced by Position angle of direction of motion to 1 decimal

 See also (external) Google KML files documentation.

Configuration settings

Opens the Settings form where changes can be made to the program settings. Some settings are read-only and appear greyed out. See the Settings form for more details.

About

Shows a Help/About dialogue with links to online help (this page), program version details and Registration.

Exit

Ends program execution

Object tabs

A tab is displayed for each object (and optional qualifier) added. Click on a tab to select that object and use its ephemeris.

The currently selected tab is highlighted in yellow, e.g.:

To remove the selected tab, press the Del key. To remove all NEOCP objects press the -N key. Use left and right arrow keys to select adjacent tabs, the Home key selects the first tab and the End key selects the last tab.

Summary object information / drop-down list

Displays a summary of available information for the currently selected tab. Click on the drop-down arrow on the right hand side to show a scrollable list of summary information for all objects, any selection made will change the currently selected tab. Note that NEOCP/PCCP objects include the greatest detail, other sources only display RA, Dec and Speed.

MPES section

Customise MPES ephemeris parameters, including number of dates to return, ephemeris interval and unit. These are used when retrieving ephemerides using the M+ button.

NEOCP section

Customise NEOCP/PCCP ephemeris parameters, including selection of class 1, 2 and 3 objects, NEO rating, ephemeris units and Faint magnitude limit. These settings are used when retrieving ephemerides using the N+ button.

Class 1 includes objects with high NEO ratings, likely to be NEOs
Class 2 includes objects with lower NEO ratings, may not be NEOs
Class 3 includes objects with lower NEO ratings and also PCCP objects

NEOCP Class is listed here: https://minorplanetcenter.net/iau/NEO/ToConfirm.html

NEO rating is also known as NEO desirability score and NEO probability.

Faint limit is only used when Object is left blank and the N+ button pressed to retrieve ephemerides for all NEOCP/PCCP objects matching the selection criteria in the NEOCP Section. Objects fainter than the Faint limit will not be retrieved.

Note that entering a NEOCP ID directly into the Object field (or using the dropdown list to select an ID) allows an ephemeris to be retrieved for any currently available NEOCP object, regardless of Faint limit.

Ephemeris input area

Ephemerides automatically retrieved using the +M and +N (MPES and NEOCP) buttons are displayed here. Ephemerides from other sources can also be manually pasted in before being added using the Add manual ephemerides buttons.

Date / time

Enter the date and time in UTC, used to calculate an ephemeris position. The current date and time can be set using the 'Set time to Now' button. The time can also be incremented and decremented by hours, minutes or seconds using the time controls on the Pad. After setting the time, press the Calculate button to update the calculated RA, Dec, Speed and PA°.

To quickly set the day, hour, minute and second to the time of an astrometric measurement, copy the day and decimal days from an astrometry line to the clipboard and paste it into the day field, then press tab, or click elsewhere with the mouse. For instance, for astrometry line:

K21D01W KC2021 03 03.77203408 47 32.06 +26 25 05.8 03.772034 ...

Copy the day+decimals "03.772034" to the clipboard, then paste into the day field:

Pressing tab causes the decimal day to be split into hours, minutes and seconds:

Note, this only applies to the day field of the main form, not the Pad.

Right Ascension (RA) and Declination (Dec)

Press the Calculate button to update the calculated RA, Dec (Speed and PA°). The currently displayed RA and Dec can be copied to the clipboard with the 'Copy RA and Dec to the clipboard' button.

Calculate time when RA reaches ... context menu option
Calculate time when Dec reaches ...
context menu option

The RA field can be manually typed into and then right-clicked with the mouse to display the 'Calculate time when RA reaches ...' context menu option. If the option is taken the Date and time are updated to show when the manually entered RA value is reached. This can be useful to judge when a moving object may reach the proximity of a star, or edge of field etc. The Dec field can also be used in the same way. Note that the range of ephemeris RA and Dec values need to include the manually entered values for an accurate date and time to be calculated.

Copy RA and Dec to the clipboard

Copies the RA and Dec to the clipboard in the format displayed.

The 'Copy RA and Dec to the clipboard' button in the main form and Pad provide the same functionality.

Display position in Google Sky

Combines the entered date and time and the calculated RA and Dec with the current GoogleSky KML template and starts up GoogleEarth. GoogleEarth will then ask the user to switch to GoogleSky. Click the Switch to Sky button and then double click the new entry in 'Temporary Places'. The field will be displayed, centred on the calculated RA and Dec with the field size as specified in the 'GoogleSkyFieldSize' setting. Each generated KML file is stored in a folder shown in the read-only setting 'GoogleSkyKMLFolder'.

Note: The free GoogleEarth application must be installed for this option to be enabled. See Google Earth Pro on Desktop.

The 'Display position in Google Sky' button in the main form and Pad provide the same functionality.

Speed and PA

The calculated speed of motion and Position angle of direction of motion (PA°) for the entered date and time. Left click into either field to copy the value to the clipboard (the field background turns red momentarily to show the copy has been done).

Set time to Now

Update the date and time fields with the current time (in UTC). Seconds are set to zero.

Calculate

Uses the currently entered date and time to interpolate values in the ephemeris using a second order method, causing the RA, Dec, Speed and PA values to be updated.

If the entered date and time are outside the first or last ephemeris date then the accuracy of calculation will be considerably reduced and the calculated quantities will be shaded yellow as a warning. Consider downloading the ephemeris again with an adjusted start time (see note).

If there are not enough ephemeris lines available to interpolate then the calculation cannot proceed and the calculated quantities will be shaded red.

If the ephemeris values are accelerating or decelerating rapidly (e.g. during the close approach of a NEO) then consider reducing the ephemeris interval to get more accurate results. Note that there are separate controls to change MPES and NEOCP/PCCP ephemeris intervals and units.

The 'Calculate' button in main form and Pad provide the same functionality.

Previous calculated times for current object

Each time Calculate is pressed with a new date and time for an object, that date and time are added to this drop-down list. They can be selected later to re-establish the same date and time as used previously if e.g. re-stacking the same set of images again after having changed the date and time for a different stack. The most recently used date and time is at the top of the list.

The times can be cleared if required by right-clicking in the list and selecting the option to clear the previous calculator times for the currently selected object.

The 'Previous calculated times for current object' drop-down list in the main form and Pad provide the same functionality.

'Undock pad' and 'Undock pad and minimise'

'Undock pad' causes the Pad form to be displayed, leaving the main Ephemeris Interpolator form also visible.

'Undock pad and minimise' causes the pad to be displayed but minimises the main Ephemeris Interpolator form to free up screen space.

See also the complementary 'Dock' and 'Dock and minimise' controls on the Pad.

Note that the Pad attempts to keep itself 'on-top' of other windows when not minimised and therefore always visible but this is sometimes affected by the behaviour of other applications (including Astrometrica) and can result in it being occasionally covered by another application's window. If this occurs you may need to click on the Ephemeris Interpolator in the task bar to make it visible.

Status messages

Area where informational, warning and error messages are displayed

Packed designation

For the currently selected tab displays the MPC packed style ID for a designated object. For undesignated objects (e.g. NEOCP) shows the source of the ephemeris in square brackets, e.g. [NEOCP]

Ephemeris format

Displays the name of the format that best matches the current ephemeris lines. See the Ephemeris Format Editor for more information.

Use the Settings form to change the 'ShowEphFormatMatches' setting to True to see how each of the stored ephemeris formats scored during the matching process, scores are displayed in a pop-up box when an ephemeris is added or replaced. The setting can be reset to false either through the Settings form, or by pressing the Cancel button when the scores are displayed.

Ephemeris Interpolator Pad

The Pad is displayed using the 'Undock pad' and 'Undock pad and minimise' buttons on the main form. It is hidden again using the 'Dock' and 'Dock and minimise' buttons on the pad.

Date and time

Enter the day of the month and time in UTC, used to calculate an ephemeris position. This is a cut-down version of the same date and time shown on the main Ephemeris Interpolator form, where the year and month can also be entered. Changes made to date and time in the Pad are reflected in the main form and vice versa.

See also the Decrement, Set time to Now and Increment Pad buttons.

Right Ascension (RA) and Declination (Dec)

Press the Calculate button to update the calculated RA, Dec (Speed and PA°). Copy the currently displayed RA and Dec to the clipboard with the 'Copy RA and Dec to the clipboard' button.

Changes made to RA and Dec in the Pad are reflected in the main form and vice versa.

Note that the Ephemeris Interpolator main form RA and Dec fields have extra right-click functionality to calculate time when RA or Dec reaches a manually entered value that is not available in the Pad, see details here.

Speed and PA

Calculated speed of motion and Position angle of direction of motion (PA°) for the entered date and time. Left click into either field to copy the value to the clipboard (the field background turns red momentarily to show the copy has been done).

Changes made to Speed and PA in the Pad are reflected in the main form and vice versa.

Decrement, Set time to Now and Increment time buttons

Update the date and time fields with the current time (in UTC) using the 'Set time to Now' button. Seconds are set to zero.

Decrement or increment the time by 1 hour by pressing the '<' and '>' buttons. Hold Ctrl to change by 1 minute and hold Alt to change by 1 second. For any of the combinations, also hold the Shift key to multiply the change by x10 e.g. clicking decrement while holding Ctrl + Shift will change the time by -10 minutes.

Changes made to date and time in the Pad are reflected in the main form and vice versa.

Paste Speed and PA to Astrometrica

This is intended to be used during Astrometrica Track & Stack processing to save the user from manually entering speed and PA details for an undesignated object, e.g. a NEOCP object, where the object is not contained in the MPCORB file that Astrometrica uses internally to calculate Speed and PA.

Steps:

  1. In Astrometrica press Stack Images button (Ctrl + S), press Add and select files to be stacked. Press OK.
  2. Astrometrica displays the 'Coordinates, Tracking and Stacking' window with the date and time of the images to be stacked.
  3. In the Ephemeris Interpolator Pad enter the date and time presented by Astrometrica in the 'Coordinates, Tracking and Stacking' window.
  4. Press the 'Paste Speed and PA to Astrometrica' button. The program recalculates the speed and PA using the newly entered date and time, sends the speed and PA values to Astrometrica, presses the Astrometrica OK button and copies the object name to the clipboard.
  5. Astrometrica proceeds with the stacking operation.
  6. When the target is being measured, the name is already on the clipboard, so can be pasted directly into the Astrometrica Object Verification window.
Paste RA and Dec to Astrometrica

This is intended to be used when Astrometrica presents either the Coordinates window, or the 'Coordinates, Track and Stack' window but there is no field centre available in the FITS files being processed. If the target object is actually within the image then use this option to put the calculated RA and Dec into Astrometrica as a first approximation of the actual field centre.

Steps:

  1. In Astrometrica either select files and press Data reduction button (Ctrl + A) or press the Stack Images button (Ctrl + S), select files and press OK.
  2. If the Coordinates window (Ctrl+A) or the 'Coordinates, Track and Stack' window (Ctrl+S) displayed do not have RA and Dec coordinates or they are incorrect, then in the Ephemeris Interpolator enter the appropriate date and time for the images being processed and press the 'Paste RA and Dec to Astrometrica' button. The program recalculates the RA and Dec using the newly entered date and time and sends the RA and Dec values to Astrometrica.

No final OK button is pressed at the end of this sequence so no further processing is started, allowing the RA and Dec to be manually amended if need be. For a Track and Stack operation, the Paste Speed and PA to Astrometrica button can be pressed immediately afterwards to initiate stacking using the newly calculated Speed and PA.

Note: If images can be relied on to always have good RA and Dec coordinates then this button can be disabled in Settings to stop it being pressed by mistake, by changing 'AstrometricaEnableSendRADec' to False.

'Dock' and 'Dock and minimise'

Dock pad causes the Pad to disappear and the main Ephemeris Interpolator form made visible.

Dock and minimise causes the Pad and the main Ephemeris Interpolator form to be minimised so neither are visible.

See also complementary 'Undock pad' and 'Undock pad and minimise' on the main Ephemeris Interpolator form.

Note that the Pad attempts to keep itself 'on-top' of other windows when not minimised and therefore always visible but this is sometimes affected by the behaviour of other applications (including Astrometrica) and can result in it being covered by another application's window. Occasionally you may need to click on the Ephemeris Interpolator in the task bar to re-display.

Ephemeris Format Editor

Allows the position and length of key information in an ephemeris to be stored together with a representative line of ephemeris which is used by the main Ephemeris Interpolator to recognise the type of ephemeris being used.

Ephemeris format information is stored in a text file called 'EphFormats.txt' in a folder specified in setting 'EphFormatsPath'. The editor manipulates this file and at the end of an editing session allows the user to save or discard any changes made. Each time the file is saved a copy of the previous version is archived in a sub-folder called 'Archive'.

The editor appears empty when first entered, ready for a new ephemeris format to be added:

A representative ephemeris line is needed to start the addition of a new ephemeris format, here a block of 6 ephemeris lines have been manually copy and pasted into the edit area, but only one line is required. The editor has automatically inserted a break between the first and subsequent lines as a reminder to only use the first line during editing:

A list of data elements that can be configured is listed down the side of the edit area (Year, Month, Day etc.) and the starting position and length of these elements within the ephemeris line is configured by selecting text in the first line with the mouse, then clicking on the matching element in the list of elements. Below, the year is selected in the ephemeris line and then (y)Year is clicked on the left, resulting in the new configuration being displayed in the right, Year starting in column 1, 4 characters long, picking up the value 2021 from the ephemeris line and placing 'yyyy' as a column heading:
As a minimum, the date, RA and Dec fields need to be configured (to the precision of the ephemeris lines, e.g. some may not supply the time to minutes and seconds). If Speed and PA are not present in the ephemeris the Ephemeris Interpolator will calculate interpolated values from the rate of change of RA and Dec in the ephemeris.

A unique Format name must be given to the new details before they can be saved (this format name is shown at bottom right of the main Ephemeris Interpolator during normal use). A description to indicate information such as the source of the ephemeris can also be entered. When complete, use the "Add new ephemeris format" button in the tool strip to save:

An existing format can be edited by selecting a format from the drop-down list:

Here a format has been selected and important parts of the display highlighted. The 'List of matches' is NOT the drop-down list used to select a format to edit, it indicates how unique the representative ephemeris line is compared to other ephemeris formats already stored. If two different formats score the same then they may not be interpreted at run-time correctly but in practice close matches generally only occur with ephemerides from the same source with very slight differences, e.g. a JPL Horizons ephemeris with just one column swapped for a different one.

The function of the tool strip buttons are shown here:

Note that the 'Edit file with external editor' button requires the 'TextEditor' setting to be configured within Configuration Settings.

Configuration Settings

Configuration Setting names are listed on the left hand side, with their values on the right. Most settings can be changed, but some values shaded light grey are read-only and cannot be changed. Values in bold text have been changed from their original, default values.

Clicking into the value of a setting allows text to be edited. Some settings have drop-down lists or colour selectors, these only appear when the setting is selected.

Each setting is grouped into a category (e.g. Astrometrica, Ephemeris etc.) and tool strip buttons at the top allow the settings to be sorted alphabetically or grouped back into categories.

When a setting is selected, further information is displayed in a resizable area below the settings list. In the screen above, the setting for AstrometricaSendKeysStack1 has been clicked on and the information at bottom shows the first few lines of an extensive description of how that setting can be configured, dragging the horizontal bar upwards will expose more of the text.

Press the OK button to save changes and exit.

Open settings export folder

Settings can be exported and imported into the program via text files (see Export and Import settings below). The settings export folder where the files are stored can be opened using Windows Explorer with this button.

Export Settings

Creates a tab delimited text file with a .cfg file extension in the Settings Export Folder, containing the current settings.

Import Settings

Any file that has been exported with the Export Settings button can be used to import settings back into the program. Either drag a valid .cfg file from Windows Explorer onto the Import Settings button, or press the button to start a dialogue to enter a valid .cfg file name, or to paste in valid tab delimited text for one or more settings.


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