We discussed implementing a new procedure about how to change occulter and Ben wrote a document on this [Ben: can you please add the link to the document here?]. The key points are summarized below:
- the occulter should be changed as scheduled (this is not always done at the scheduled time)
- the new occulter should be installed at the beginning of the observing day when the occulter is cold, not in the middle of the day, unless there is a specific reason to do so.
- care should be taken to install the occulter in the proper position and data should be evaluated to verify the occulter shape is round
- care should be taken to record the proper number of the occulter in the logs and header and a photo of the occulter installed should be taken before installing it to avoid any uncertainty on the occulter used.
Note: I added taking a picture of the occulter because we had instances when the occulter number was not recorded or was inconsistently recorded in the header and logs. Moreover, we found a case when occulter #31 was supposedly inserted in the Fall of 2022 and we see a jump in the plate scale that starts and ends with this occulter. The plate scale difference is much bigger than the difference that we can attribute to different size of occulter 31 and 31A, that is negligible. There is nothing else that we could identify to change the plate scale during the time this occulter was used. Most likely, the occulter installed was not #31 nor #31A, or the occulter was not properly set. Taking a picture of the occulter before installing it will unquestionably identify the occulter used and rule out any doubt that can later arise.
We discussed implementing a new procedure about how to change occulter and Ben wrote a document on this [Ben: can you please add the link to the document here?]. The key points are summarized below:
Note: I added taking a picture of the occulter because we had instances when the occulter number was not recorded or was inconsistently recorded in the header and logs. Moreover, we found a case when occulter #31 was supposedly inserted in the Fall of 2022 and we see a jump in the plate scale that starts and ends with this occulter. The plate scale difference is much bigger than the difference that we can attribute to different size of occulter 31 and 31A, that is negligible. There is nothing else that we could identify to change the plate scale during the time this occulter was used. Most likely, the occulter installed was not #31 nor #31A, or the occulter was not properly set. Taking a picture of the occulter before installing it will unquestionably identify the occulter used and rule out any doubt that can later arise.