AstroBKK

Rig Operating Procedure:

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This procedure describes the whole rig’s components operation. References are made to the StarSense user manual (English booklet © 2016, 28 pages) for specific hand controller instructions.

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1. Check equipment list and ensure cleanness of OSC captor, optical train, filter, and optical parts.

2. Place the mount’s tripod on the pre-marked ground positions, if unavailable; point the tripod to the north direction. Check for planarity with a spirit level. Assemble mount’s head.

3. Add required counterweights on the bar, install the scope on the mount, and adjust the DEC knob at the base of mount’s head to local latitude with a digital protractor. Previous PA may have significantly modified head’s position on tripod, a rough resetting of RA and DEC knobs positions at the base of the mount may be necessary. 

4. Attach imaging train, guidescope, finderscope, StarSense module (link), and equilibrate the scope.

5. If the rig was kept assembled from the last observation session and in the same position, start this procedure from here, omitting PA step (#13). If a scope different from the last observation session is installed, do not forget adjusting counterweights especially if changing to heavier OTA.

6. Ensure that mount’s white marks on the axis are in front each-others and that scope’s aperture side is located opposite to the marks.

7. Wire rig all components as per scheme above apart from the cable between ASIair and HC, which must not be connected before having finished the boot sequence when powering-up the mount (and usually not before having performed StarSense operations: go-to alignment, PA and calibration or synchronization).

8. Power-up all equipment, and connect HC to ASIair after boot sequence completed.

9. On iPad, change screen shut down time to never, and connect to ASIair wifi (pw: 12345678). 

10. In the ASIair app, ensure that mount selected is Celestron AVX/CGE/CGEM/CGX, and focal length values entered (and corrected with reducer factor if applicable).

11. Perform go-to alignment with StarSense. User manual alignment (SS manual p13) is the best option when the sky view is severely hindered. Ensure RA and DEC knobs on mount's head are well tightened and marks aligned, initiate manual alignment and slew the scope clockwise to unobstructed area. Auto-user alignment can also be used if the routine recorded takes into account sky obstruction, but bad seeing in a part of the visible sky it may prevent the procedure to complete successfully (goes into circles). Adding three or more alignment points besides the three points required to complete manual alignment helps to improve centering (SS manual p14).

12. Search a named star, and check if it is correctly centered though the OSC in ASIapp. If not, a calibration or a synchronization must be performed. Calibration: press align directly in named star, perform center calibration trough coarse and fine centering, and perform another user alignment (SS manual p12). Center calibration is necessary when the StarSense module is mounted for the first time or when moved from an OTA to another. At that stage, polar alignment may be performed (see #13). Synchronization: press Celestron and Align buttons simultaneously to center stars without performing a new auto-user alignment (SS manual p16). The use of finderscope in center calibration or synchronization may be useful (provided it is well aligned) for large decentering or small FOV such as when using C9.25” without reducer.

13. Check polar alignment error and if too high, polar align through (StarSense manual p16), checking error and its decrease if performed iteratively. From my experience, decent error values to get “good enough” guiding are in the range of 2' S, 2' E.

14. On the iPad, start SkySafari and connect scope. Check if the mount icon is active in ASIapp.

15. Focus with the Bahtinov mask, using a bright star (preferably visible but it also works with faint stars not visible by naked eyes). On the ASIair app, use focus at 0.05sec exposure, BIN2 if the target star is not visible at first. Shoot a frame in preview to validate symmetry of the diffraction pattern with longer exposure time, especially if a faint star was used.

16. Use SkySafari to select and slew to object. Emergency stop, in case of cables jam for example: press any direction key on HC.

17. Capture light and calibration frames using ASIair app. To save frames, use wireless transfer to the computer (WIFI network: ASIair, pw 1234567), and enter \\ASIAIR in file explorer to access to SD card and transfer frames. Always clear files from the ASIair app once saved, not from the computer.

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