Pointing Origins

Pointing Origins (POs) are positions defined in the focal plane of the telescope (in units of mm in the X, Y plane). The telescope software (i.e. MAGIQ) will place the target coordinates at this point in the focal plane. In addition, for appropriate tracking modes (i.e. vertical angle mode), this defines the point around which stars in the field will appear to rotate.

The REF* pointing origin is defined on each guider. It is special in that it ties guider pixel coordinates to the XIM, YIM focal plane coordinates. When acquiring targets, the OAs will “adjust pointing” on the REF* PO. Adjust pointing updates the zero point of the telescope pointing model, called the CA/CE (collimations Az/El). The REF* PO is defined in a clear, easy to see position in the focal plane, so that the OAs can see the target (if it is bright enough of course) and perform any fine centering that is needed.

Once a target is centerred on REF, the OA would traditionally send it to a different pointing origin for science (e.g. SLIT). By simply selecting a new pointing origin, the target will move to the new position in the focal plane.

How-to update PO(s) when instrument is selected (i.e. dcs.CURRINST = <your instrument>)

As kNobstcs@kNobs, N=1/2:

1. tcsgui

2. TCS → Pointing Origins

   1. Per PO (each PO is one row of the PointingOrigins UI)

      1. Enter X/Y values for PO

      2. Click “Define” in row corresponding to PO

   2. When done, click “Save all POs to Config DB”

How-to update PO(s) when instrument is not selected

As kNobstcs@kNobs, N=1/2:

1. tcsgui

2. TCS -> configServiceUI

   1. click "+" next to sup<your instrument>, e.g. supNIRC2

   2. click on NIRC2po#, to find desired PO, "#" is a number 1-20

   3. click on poXpos value and enter value

   4. click on poYpos value and enter value

   5. click on "Submit Changes"

3. Repeat for additional POs