Notes about EQMOD Mosaic
Notes about EQMOD Mosaic
  1. As of v106, the grid navigation pad has been removed - All grid navigation is now via mouse clicks. This feature is merely hidden from view at the moment and can come back if there are sufficient requests.
  2. The settings for EQMOD Mosaic are stored in a file EQMOSAIC.ini in folder:
    c:\Documents and Settings\YourLoginName\Application Data\EQMOD
  3. The [Get Position] button synchronises the grid to your scope. The object does not have to be in view when you [Get Position] - when you slew the grid moves with you where ever you go. Key to mosaic operation is to realize the difference between 'external' slews (planetarium, tour, joystick) and Mosaic slews. External slews will move the entire grid around, Mosaic slew move within the grid.
  4. Tracking: EQMOD Mosaic can only control the scope to accurately cover an area of sky if the mount is tracking. The tracking status is checked whenever the [Get Position] button is pressed and/or at completion of a slew. If the mount is found not to be tracking then a warning message is displayed in the message center and an attempt is then made to start tracking. If this fails a “Scope will not track” message is displayed.
  5. Non-sidereal tracking: Imaging the Sun and particularly the Moon needs special consideration Mosaic places a grid on the celestial sphere but objects such as the Sun and Moon move across that grid with time i.e. move at a non­sidereal rate. Mosaic incorporates an algorithm that will automatically compensate for this provided the mount is able to track the objects accurately . Currently EQMOD only does solar and lunar tracking in RA - the Moon & Sun both move in declination as well so over time will slip over mosaic grid. Clearly these are bright objects and imaging times will not be extended so the effect should be negligible unless there are long pauses between image captures.
  6. Prior to initiating a slew Mosaic, checks the scopes current position (both RA and DEC) and subtracts the position it thinks the scope should be at (i.e. the position used for the last slew). This gives a drift compensation in RA and DEC that is then applied to the grid centre coordinates, from which all other grid cell coords are calculated.
  7. If you use Mosaic session save/restore and your imaging target is the Moon, the initial session restore slew is unlikely to get you to the right place as the Moon will have moved on across the sky. The session save/load feature is really only practical for Deep Space Mosaics.
  8. Before starting your Mosaic sequence of images, you can adjust the alignment of the grid over your object by using the scopes slew controls.

For example: Whilst imaging the moon, try centering the moon and click the [Get Position] button to lock the grid in place. Then double click around the grid to find the frames the will constitute the boundaries of the mosaic. If any frames on the edge have an unacceptably small amount of moon in them, simply use the telescope slew controls to get more of the moon in the cell and the drift compensation code will automatically move the grid centre to compensate. Then check that the other extremity is satisfactory. This way, you can ensure that you capture the object with the minimum number of images.

/home/welshdra/public_html/eqmod/data/pages/notes_about_eqmod_mosaic.txt · Last modified: 2008/11/06 15:03 (external edit)
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