Pictures of azimuth pointer alignment
The azimuth pointer/scribe mark
There is a scribe mark on a plate on the fixed part of the platform
where the azimuth (gregorian side) equals 270 degrees.
- a retractable pointer is mounted on the encoder platform
- When the azimuth encoder reads 270 degrees, the pointer should
align with the scribe mark.
- this was developed to recover the azimuth position whenever an
encoder problem arose.
- If we have an encoder problem:
- move the pointer to the scribe mark and then reset the
encoder to 270 degrees.
- We can probably reset the position to about 1/64". at the 60
foot radius of the scribe mark this is about 1.2 milliDeg, or
- The system is calibrated using the pointing model.. the
- before a new pointing model is made
- move the azimuth to 270 degrees (using no pointing model
corrections.. just use the preset command on the vertex
- Make sure the pointer is aligned with the scribe mark
- If it is not aligned:
- move the pointer to the scribe mark
- reset the encoder to 270
- Take a picture of the pointer,scribe mark for later
- Make the new pointing model.
- If the pointer / scribeMark was not pointing at true 270
degrees, the pointing model will correct for it.
Pictures of aligning the az pointer with the scribe mark
back to agc
- 23jan12: encoder 1 becomes loose.
- 22jun15: encoder 1 fails.
replaced on 23jun16.
- the picture includes a metric ruler
- 01oct16: encoder 1
- pictures taken after new encoder aligned at az=270
corrected az encoder 1 jump by 1 tooth
- has before and after pictures
- It includes a ruler to show the offset distance.
- The jump occurred on 12aug19
The az encoder 1 jumped by 1 tooth.
- There is only an after alignment picture.