Setup of the Probes

There are 4 probes:

• Guide probe 1 (GC1)
• Guide probe 2 (GC2)
• Wave Front Sensor 1 (WFS1)
• Wave Front Sensor 2 (WFS2)

Home of the guider probes

The guider probes are on absolute encoders so the purpose of the home is simply to move the probes 90 degrees from each other. In the near future we will likely change the end position of the home to be mid range on axis.

Command: syscmd -v -P 'HomeProbes()'

Move of the guide probes in their X and Y coordinate system

The probes actually move along a annulus and have a swing arm moving from that position. This results in 180 degrees of motion (overlapping for each probe). While one could reference these angles of motion (in degrees) we usually fall back on a X and Y coordinate transform which are nearly aligned with the tracker X and Y coordinate system.

The process is actually two steps. Select the location to move the probes and then tell pfip to move the probes.

One can move the probes in this X and Y coordinate system:

Command: syscmd -v -T 'Guider1_set_position( x_ang=XVALUE, y_ang=YVALUE) ' where XVALUE and YVALUE are in degrees

syscmd -v -T 'pfip_move_probes()'

Examples: <br>

syscmd -T -v 'Guider1_set_position( x_ang=0.16, y_ang=0.00) '
syscmd -T -v 'Guider2_set_position( x_ang=-0.16, y_ang=0.00) '
syscmd -T -v 'WFS1_set_position( x_ang=0.00, y_ang=0.16) '
syscmd -T -v 'WFS2_set_position( x_ang=0.00, y_ang=-0.16) '
syscmd -v -T 'pfip_move_probes()'

If you want TCS to forget the probe positions (because you want to work with fewer probes)

syscmd -T -v 'pfip_clear_positions()'

The probes can be placed with RA and DEC commands as well.

Command: syscmd -v -P 'Guider1_set_position( ra=RAVALUE, dec=DECVALUE, equinox=yearVALUE )' where RAVALUE are in decimal hours, DECVALUE are in decimal degrees and yearVALUE is the year and the default equinox is 2000.0 and could be excluded. The positions are always referenced to what object the tracker was pointed at, ie. what came from htopx3. Thus in theory the target needs to be at the reference location, usually the IHMP position.

Examples: <br>

syscmd -T -v 'Guider1_set_position( ra=12.0403092, dec=-5.0593855, equinox=2000.0) '
syscmd -T -v 'Guider1_set_position( ra=12.0403092, dec=-5.0593855 ) '
syscmd -v -T 'pfip_move_probes()'

Moving small offsets

You can offset the probes by small amounts (UNITS ARE ARCSEC):

syscmd -T -v 'Guider1_offset_probe( dx_ang=10, dy_ang=10) '

Clearing Faults

If you command a probe to move and it has some trouble and you want to make it forget that it was ever commanded to move use the command:

Command: syscmd -T 'pfip_clear_positions()'

Note that homing probes rarely ever gets you out of trouble because the encoder is an absolute encoder and all it will do is move the probe into a corner.

Range of the Probe Motion

Below are some images that show the range of the guider positions. In these plots +X is to the right and +Y is up.