User Object – 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=6.7.5 https://astrophotography.pekdar.net/wp-content/uploads/2021/07/favicon.png User Object – 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.

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