Comets – PekDar – Astrophotography Engineering https://astrophotography.pekdar.net Autorskie rozwiązania Hardware, Projekty 3D i Zaawansowane Poradniki Mon, 09 Feb 2026 07:56:30 +0000 en-US hourly 1 https://wordpress.org/?v=6.7.8 https://astrophotography.pekdar.net/wp-content/uploads/2021/07/favicon.png Comets – PekDar – Astrophotography Engineering https://astrophotography.pekdar.net 32 32 SynScan: Manually Adding Comets and Custom Objects (User Object) https://astrophotography.pekdar.net/en/synscan-goto-manual-comet-input-user-object/ Tue, 28 Apr 2020 11:00:08 +0000 https://astrophotography.pekdar.net/?p=3952

SynScan User Object – The Database is Not Enough

The object database in SynScan hand controllers (used in Sky-Watcher NEQ6, HEQ5, EQ6-R mounts) contains thousands of entries from the Messier, NGC, and IC catalogs. However, it is helpless against dynamic objects: new comets, fast-moving asteroids, or supernovae. To point the telescope at such an object without using a computer (EQMOD), we must use the User Object function and manually input equatorial coordinates.

Step 1: Obtaining Ephemerides (J2000)

Before touching the controller, you must know the object’s current position. Comets move relative to the background stars. Yesterday’s coordinates might be useless today.

  • Source: Use TheSkyLive or Minor Planet Center.

  • Format: You need Right Ascension (RA) and Declination (Dec).

  • Important: Ensure the coordinates are for the J2000.0 epoch (standard for SynScan), not “JNow” (Topocentric), although for wide fields the difference might be negligible, in astrophotography it matters.

Step 2: Shortened SynScan Procedure

  • Power up the mount and perform the standard alignment (1, 2, or 3-Star Alignment).

  • In the main menu, select: Object List -> User Object.

  • Select New Object (or edit an existing one).

  • Enter the coordinates:

    • RA (Right Ascension): In HH:MM:SS format.

    • Dec (Declination): In DD:MM:SS format. Remember to toggle the + / - sign depending on the celestial hemisphere.

  • Confirm and select View Object -> Slew. The mount will point to the defined position.

Technical Limitation: Tracking

By entering an object this way, the mount treats it like a fixed star. It will track it at the sidereal rate. However, comets have their own proper motion. During long exposures (over 60-120 seconds) or with comets very close to Earth, the comet’s nucleus might appear trailed on the image, even if the stars are pinpoint sharp.

  • Solution: This is a “point-in-time” method. If the comet is fast, you must update the coordinates in the controller every 30-60 minutes using fresh ephemeris data.

read more]]> Stellarium: Adding New Comets and Asteroids https://astrophotography.pekdar.net/en/stellarium-adding-comets-asteroids/ Mon, 20 Apr 2020 11:51:51 +0000 http://www.astrofoto.pekdar.net/?p=1263

Stellarium – Beyond the Standard Catalog

The Solar System database in Stellarium is updated regularly, but new comets appear faster than official data packages. To plan a photography session for an object that has “just arrived,” you must use the Solar System Editor plugin.

The Mechanism: Orbital Elements (MPC)

Stellarium does not store images of comets but rather their orbital elements (including perihelion, eccentricity, inclination). Based on these, the software engine calculates the object’s current position in the sky for your specific location. The most reliable source for this data is the Minor Planet Center (MPC).

Shortened Step-by-Step Instructions

  • Activate the Plugin: Go to “Configuration Window” [F2] -> “Plugins” -> “Solar System Editor”. Ensure “Load at startup” is checked and restart the program.

  • Import Data: In the plugin settings, select the “Solar System” tab and click “Import orbital elements in MPC format”.

  • Select Object Type: Choose “Comets” or “Asteroids.”

  • Online Source: Select an MPC server from the list (e.g., MPC’s list of observable comets). The program will connect to the web and download the list.

  • Search: Type the comet’s name (e.g., “C/2023 A3”). Once it appears, check it and click “Add objects”.

Why is this better than manual entry?

Manual entry of orbital elements is prone to formatting errors, leading to incorrect position calculations. Automatic import from the MPC ensures that parameters are up-to-date, which is crucial as comet orbits undergo subtle changes due to planetary gravity.

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