ASIAIR based workflow

Target and Mosaic Planing using Telescopius.com and ASIAIR

updated: 2022-10-04

Purpose

Preparing image capturing for mosaic images

Previous Step

Equipment SetUp

Next Step

Processing Mosaic Images

See also

Target  and Mosaic Planning on Telescopius.com

Setting the correct Camera Orientation

Preparation and Picture Acquisition

My first experience using 4 panes of mosaic images or NGC7000, each consisting of 10 frames at 300s exposure time and a gain of 120. Planning was done with Telescopius.com:


click on copy CSV, go to the Plan Mode of ASIAIR and click on the import symbol. This will add 4 plans each with it's own R.A. and DEC coordinates. 


After rotating the camera to 247° as targeted by Telescopius,com the plate solved picture returned by ASIAIR  SkyAtlas looked quite different compared to the the planned orientation in Telescopius.com. Although both tools now indicate a 247° orientation, the pictures don't match and the camera rotation is not correct. The reason why the orientation differs from the deseired field of view will be explained later.

Plate-solving one captured image returned -52.335 deg (flipped) as result which is 360° - 52.305° = 307° but this value doesn't match the original planned 247,9° at all.


HINT: See also Setting the correct camera orientation in the previous chapter.


The correct camera orientation can be obtained by a simple calculation and depends on the position angle returned by Telescopius,com and the initial camera orientation:

  • Position angle between 0° and 180°
    • if camera orientation is upside up: ASIAIR Rotation = Position Angle
    • or if the initial camera orientation is upside down: ASIAIR Rotation = 360° - Position Angle
  • Position angle between 180° and 360°
    • if camera orientation is upside up: ASIAIR Rotation = 360° - Position Angle
    • or if the initial camera orientation is upside down:ASIAIR Rotation = 360°+ 180° - Position Angle or: 540° - Position Angle
      as in the above case. Planned rotation position =  540° - 247° = 293°


HINT: this means to be careful regarding planning of the correct camera orientation already in Telescopius,com and to avoid camera angles above 180° to make it easier for the next steps!


After manually rotating the camera to a similar visual orientation as in Telescopius,com, the final orientation on the ASIAIR looked like this and read 307.6°:


Instead of manually rotating the camera to this 307° position, it should have been turned to 293° (calculation:540° - 247° = 293°), that would have solved the wrong orientation during the capture phase, so the pictures were 14° off the correct orientation!


The capturing process was then started using this wrong camera orientation. 


This is an improved mosaic plan using a camera orientation of just 73°for the same target:


Please  have a look at the post-processing steps in the chapter Processing Mosaic Images


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