GWC Variables

1. Field and Slit GWC Status Variables

Hydra-CTIO software publishes through the GWC router the hydra.field and hydra.assign streams. The stream hydra.field define the following status variables:

hydra.field.fldname - Contains the name of the configuration file currently configured.

hydra.field.fldtime - Containd the time at the end of the configuration proccess.

hydra.field.fldlst - Contains the anticipated siderial time at the middle of the exposure.

hydra.field.fldcoord - This is an array of three string specifying the coordinates of the field center. The
first one is the right ascention, the second one is the declination and the third one is the current epoch.

hydra.field.cable - Contains the name of the cable in use (LARGE/SMALL).

hydra.field.cablesize - Contains the number of fibers for the current cable slit.

The stream hydra.assign contains several variables of type "hydra.assign.SLFIBX", where "X" is a number from 0 to the max number of fiber for the slit. This variables have a type of ENG_STRING
and are an array of five fields.

field[0] contains the slit position of the fiber.

field[1] contains the type code for this fiber:

-2 for fiducial fiber ("Gap").
-1 for not assigned fibers and broken fibers ("Broken Fiber" and "not assigned").
0 for skies
1 for objects ("Object Name (ID#))
3 for random positions ("Randon Position")

field[2] contains the right ascention

field[3] contains the declination

field[4] contains the name of the fiber:

"Broken Fiber"
"Gap"
"Random Position"
"not assigned"
"object name (ID#)"

2. FOPs GWC Variables

For the benefit of the Hydra Guider, (and anyone else who cares) the hydra program publishes, via GWC, a set of variables that contain useful information about the FOPs (Field Orientation Probes). The GWC names of these variables are

hydra.fops.fopX

where "X" is a character from "A" to "L" inclusive. There are,therefore, 12 fops and 12 variables. These variables have a type of ENG_FLOAT and are an array of seven fields. The contents of the flields are as follows.

field[0]

Contains the X axis coordinate of the FOP's button in the Hydra encoder coordiante system. Valid values range from 0.0 to +/- 90000.0 (appx)

field[1]

Contains the Y axis coordinate of the FOP's button in the Hydra encoder coordiante system. Valid values range from 0.0 to +/- 90000.0 (appx)

field[2]

Contains the distance from the origin to the mechanical center of the FOP in encoder units.

field[3]

Contains the angle (in radians) between this FOP's pivot point and the pivot point of fiber #0.

field[4]

Contains the angle (in radians) between a tangent to the tube at the button, and the radial line of the tube. (The radial line is the line drawn from the pivot point to the origin.)

field[5]

Contains the angle (in radians) between this FOP's button and the pivot point of fiber #0.

field[6]

A value indicating the current status of the FOP. Only the integer portion has any meaning. Valid values are:

0 FOP_INACTIVE This FOP is either parked or broken.

1 FOP_ASSIGNED_OBJ This FOP is assigned to a guide star and should be valid for guiding.

2 FOP_ASSIGNED_SKY This FOP is assigned to a known sky location.

3 FOP_RANDOM_SKY This FOP is extended but not guaranteed to be detecting only sky.

These variables will be updated under only two sets of circumstances.

1) The FOP is relocated.
2) The hydra operator marks the FOP to be ignored.