David's Astronomy Pages Notes - Session 610.3  (2018-05-10, Observatory Commissioning)

Notes (S610.2)

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Notes (S610.4)

	Session Aims & Highlights
	Operational Issues
	- Critical Issues (0),  Major Issues (2),  Minor Issues (5),  Small Defects (0),  Continuous Improvement (0)
	Periodic Error Assessment
	Polar Alignment
	No images from this session  >>

Session Aims & Highlights (2018-05-10)

Main aims of this session were to continue formal commissioning of the new Dome Observatory including :

1. Periodic Error. Check telescope's periodic error to confirm that installation of new RA Motor Unit (2018-04-27) has provided the necessary improvements to telescope's RA tracking .
2. Polar Alignment. Perform Polar Alignment of the LX200 Telescope mounted on its new pier base.
3. Telescope/Dome. Check stability of POTH.Hub working with LX200GPS scope and Pulsar dome controller

Equipment & Software

• 12" LX200 and ST-10XME
• CCDApp2, TheSky6, CCDSoft 5, POTH Hub

Highlights

• Periodic Error/ RA Drive.  Measurements showed 'normal' Periodic Error trace without the uncorrectable RA errors/jumps every 104s that have affected telescope performance over the past 18 months (results >>). Installation of the new RA motor unit (2018-04-27) therefore appears to have been a success.  PEC curves will be created and uploaded to the scope in a following commissioning session.
  Telescope / Dome.  Scope/Dome started up ok, and later closed down ok.   Dome's Sidereal Speed needs to set to 0.00x for slaving operations to work.
• Polar Alignment. Telescope/wedge were polar aligned to an acceptable initial tolerance with the aid of PemPro's Polar Align Wizard (results >>).  
  Polar alignment will be checked again at the next commissioning session using PemPro PAW, and at some point refined further after a TPoint run is completed.
• PemPro. PemPro's Polar Align Wizard (PAW) was used for the first time (this was due to issues using my own polar align software). The experience of using PAW was generally good, and will be better next time now that I understand it fully.
• Telescope/Dome.  There were some positive aspects / lesson learned from operating POTH.Hub,  but some critical conditions were encountered that remain a concern for future unattended operation.

Notes

Summary Plots & Logs

Night Sky Summary Plot - 2018-05-10 Top axis: Sky Brightness at Zenith (in ADU/s) Lefthand axis: Local Time (hh LT). Righthand axis: Sun Altitude (degs)

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Operational Issues (2018-05-10, S610.3)

• Critical Issues (0)
• Major Issues (2)
• Minor Issues (5)
• Small Defects (0)
• Continuous Improvement (0)

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Critical Issues

• None

Major Issues

• POTH.Hub destabilised when CCDApp2 Observatory Control Software crashes / or forcibly stopped and TheSky6 application and process stopped and restarted. Problem appears to be due to POTH.Hub being stopped with telescope and/or Dome still connected. Workaround is to Disconnect Dome and Scope in POTH.Hub before restarting TheSky6. Issue Largely Resolved by end 2018
  Resolved (CCDApp2/AstroMain, POTH.Hub)
  
• Slaved Dome begins to move to a different azimuth to direction that the telesscope is physical pointing.  This problem also arose on 1st commisioning session (2018-05-05). Investigating further shows that LST for telescope is incorrect in POTH.Hub (and incorrect in TheSky6), the scope is pointing to an incorrect position on the TheSky6 virtual sky. Attempting to 'Update Scope (including time)' from 'POTH Setup' produces a message that scope LST is some large number of seconds different from Computer Time.
  Investigating indicates that the immediate reason is that the LX200GPS scope as either somehow lost LST or POTH.Hub is otherwise holds an incorrect LST for the scope. The underlying cause for this glitch in LST in unknown but the movement of the slaved Dome is 'normal' given the information that POTH.Hub appears to have. 'Park Scope' caused the scope to move to the correct physical position for parking, however it remains to be seen if the Scope starts up from the the correctly reported RA/Dec position at the start of the next session). Largely resolved by end 2018.
    Largely Resolved (POTH.Hub, LX200)

Minor Issues

• CCDApp2 Observatory Control Software hanging when start Declination Tracking (polar align).  Problem may be due to the Threaded Operation trying to send messages to screen reporting box.   Issue fixed.
  Fixed (CCDApp2/AstroMain)
   
• CCDApp2 Observatory Control Software not finding a Plate Solution for Reference & Check images (polar align). Problem may be due to Plate Solution routine not attempted a 'FailSafe' Method or possibly due to too many hot pixels (Temperature regulation was accidently off?). Issue fixed.
  Fixed (CCDApp2/AstroMain)
   
• PemPro Polar Align Wizard sometime passing over obvious stars and returning (finding) boxes without stars. These are static and don't provide a drift measurement.   Process had to be aborted and the field jogged to an adjacent one containing a brighter star. Reason seems to be that temperature regulation was inadvertently turned off with the result that a particular hot pixel / pixel patch was getting returned instead of a relatively dim (though real) star image.
  Closed (PemPro, SBIG Camera)
   
• Polar Alignment process took considerably longer than it should.  Some fields in PemPro Polar Align Wizard not showing in the dialog window and the arrow indicating correction direction and distance was not visible. his was the first use of PemPro Polar Align Wizard and it wasn't realised that dialog window could be enlarged and the divider repositioned to see all data fields/buttons.  It was also not realised that one has to click on a star once reference image is taken (this is mentioned in program's guidance notes but not within the onscreen dialog instructions. Things should be quicker next time.
  Closed (PemPro)
   
• Interior Dome Roof covered with Dew. The dome roof interior (but not the dome walls, equipment or cabinets) became thoroughly covered in dew / condensation over the course of the 3 hour session.   There was no sign of any of this condensation when the observatory was visited at 5pm the following afternoon. Nor was there any sign of water drops on the floor or damage from water etc.
  Known issue (Observatory)

Small Defects

• None

Continuous Improvement

• None

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Periodic Error Assessment (2018-05-10)

Periodic Error Asssement / RA Tracking (2018-05-10) (22 minute assessment finished when star drifted out of view due to initially large Polar Alignment error but is nevertheless sufficient to show that scope shows a 'normal' periodic error trace without the 104s jumps in RA that have affected the scope for the last 18 months) Data suggests a peak-to-peak periodic error of 35 arc secs (without PEC) which is 'normal' for LX200GPS

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Polar Alignment  (2018-05-10)

Polar Alignment (2018-05-10) (Polar Alignment using PemPro Polar Align Wizard (PAW) - first time use of PAW) Note: An incorrect plate scale was used (2x2 one instead of 1x1) and the real errors are believed to be 50% of those shown in the graphs.

Azimuth Adjustment / South Sky Point (Clockwise(East) adjustment made by temporily easing the retaining knobs on the wedge that hold it to the Top Plate and rotating the right hand Azimuth control knob in a clockwise direction (clockwise when looking at knob from the west))

Altitude Adjustment / West Sky Point  (40 degs) Altitude axis raised by temporaily easing two side bolts with Allen Key and then rotating the Altitude Knob in an anticlockwise direction. (anticlockwise when looking at the wedge from the south)

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