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External Guider setup - bug - Printable Version

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External Guider setup - bug - Rodolgo - 2019-01-02

Hi
Not possible to enter the distance between the guider and the OTA in other units than arc min.
Help file specifies otherwise:

If you know the separation from other software, simply enter it in arc minutes and select arc min as the units. If starting from scratch it may be best to measure the distance between the center of the guider body and the center of the pick mirror in mm. When you enter this number, select mm as the units. This should get you pretty close. 

Screenshot


RE: External Guider setup - bug - theskyhound - 2019-01-02

Hello,

How this dialog works depends on the type of guider you are adding. For an external guide scope, as you have selected, it makes no sense to add the separation in mm, as this is seldom known and very difficult to measure.

Do you have some specific question regarding setting up your equipment?

Thanks,
Greg


RE: External Guider setup - bug - Rodolgo - 2019-01-02

OK - but the problem is that if I leave the first 4 fields blank, and populate the guide camera parameters, I get an error when clicking OK: "Focal length is out of scope" - entering the focal length causes another error message about distance between the OTA and the guider - entering 0 there is then OK, the dialog closes; but the setting is not retained when reopening the imaging systems parameters for that device combination.
I think this dialog is a bit confusing at the moment.
Hope my explanations are clear enough...
Regards,
Rodolphe


RE: External Guider setup - bug - theskyhound - 2019-01-02

Hi,

Assuming this is for an external scope: you must enter non-zero values for the separation and focal length. Both are required.

What are the actual numbers for the separation of the OTA and guide scope (even if only approximate) and the focal length of the guide scope?


RE: External Guider setup - bug - Rodolgo - 2019-01-02

Hi
I have approximately 150 mm separation and the focal length of the guide scope is 400mm.


RE: External Guider setup - bug - theskyhound - 2019-01-02

Unfortunately it isn't trivial to set up an external guide scope. There are many different ways to go about it, but what I would suggest is the following:

1. Enter an approximate separation in arc minutes. A good starting point is half your main camera FOV. But you tried to enter zero before. Is your external guider pointed at the same place as the main camera FOV? If this is the case, enter a small, but non-zero, value for the separation between the two.

2. At the telescope, at night, point the telescope at a fairly crowded star field, maybe an open cluster, maybe something like the Pleiades or the Beehive. Center the main FOV on a known star.

3. Open the SkyTools Interactive Atlas centered on the same star.

4. Determine the position angle of the main camera FOV, if you haven't already.

5. Now for the hard part. Try to identify the field displayed in the guider camera on the atlas. You may need to move things about and experiment.

6. Once you have identified the center of the guider FOV, and the center of the main camera is also known, right-click on the atlas at the center of the main camera FOV and select "Angular Measure." Drag the end of the line that appears on the screen to the center of the guider FOV. Write down the angular separation and position angle numbers in the bottom status area of the atlas.

7. Back at the Configure Guider dialog, enter the separation and position angle that you measured as the separation and position angle of the guider (top two fields) plus the focal length of the guide scope. Enter the guide camera CCD info too plue the allowed magnitude range for good guide stars.

8. Close the Imaging Systems dialog and on the atlas, press the Camera button. Select your imaging system. The main camera FOV and guide camera FOV will be displayed on the atlas. Check that they agree with what you are actually seeing in the cameras.


RE: External Guider setup - bug - theskyhound - 2019-01-02

I see that when you enter a focal length for an external guider and re-open the dialog, the focal length is being inadvertent cleared. I have verified that the focal length that you enter is saved correctly and is valid unless you open the dialog again. If you need to open it again, you will need to re-enter the number.

This will be fixed in the next update.


RE: External Guider setup - bug - Rodolgo - 2019-01-03

(2019-01-02, 08:07 PM)theskyhound Wrote: I see that when you enter a focal length for an external guider and re-open the dialog, the focal length is being inadvertent cleared. I have verified that the focal length that you enter is saved correctly and is valid unless you open the dialog again. If you need to open it again, you will need to re-enter the number.

This will be fixed in the next update.

Great, happy to test further if you wish so.
Good luck with the updates.
Kind regards 
Rodolphe