Common Problem - Simple Solutions

DON'T PANIC

These are common problems with simple solutions.

LOST FIBERS

You get an error while configuring where an annoying little grey box pops up and says: "Error:configure: OrderMoves Error: phys move. MoveButt couldn't pick up button xxx" where xxx is some fiber name.

What has happened is that the gripper has gone to the position of xxx and could not pick up the button. Much of the time this is because the button is slightly off from where it should be, possibly because it was placed down on a small piece of dust. Sometimes too much stress builds up in the hypodermic needle which houses the fiber and the fiber simply slides out of the gripper.

However a fiber might get lost, to recover use the gripper TV to place the gripper on top of the fiber. Then, in the command window, type "thisis". This tells the software that the gripper is on top of whichever fiber is currently lost. Note the use of small letters in this command. (The related command "ThisIs xxx" tells the software explicitly that fiber xxx is under the gripper.)

If the fiber is not visible in the gripper TV, you can use the GUI to cruise near where it should be and see if you can find it. If you find it, tell the gripper where it is using the "thisis" command. Don't go very far cruising or you may find another button and get Hydra really mixed up by identifying it incorrectly.

If you can't find the lost fiber near the nominal position, return the gripper to the "parked" position of the lost fiber. There is a good chance that the fiber will be there and was never picked up in the first place.

If the fiber is not in the parked position, you will see the hypodermic tubing enclosing the fiber crossing the field going to wherever the button actually is. Use the gripper motion controls to follow the tube out into the field until you find the button, put the gripper on top of it and then use the "ThisIs" command to tell Hydra where it is.

If the button appears tilted there is sometimes a tiny piece of ferrous material stuck to the bottom. There may be damage to the button. In either case if this happens, call Observer Support and have them inspect and retire the fiber manually.

Once the fiber is returned to the park position, you can use it again. If it keeps on getting lost, you should lock it and not use it for the rest of the run.

If the fiber is really totally lost, or this procedure doesn't work, you will have to have Observer Support come and retire the fiber manually.

CAN'T CONFIGURE THE FIBERS WITH THE HYDRA PROGRAM

You were able to configure the program with hydrasim, but you get an error about a transformation problem when doing the real configuration. This error happens just after you start the configuration.

What is happening here is that the hydra program is doing one extra step beyond the hydrasim program. It is taking the coords and assignments, and appplying a transformation to the appropriate zenith distance for the observations. For some reason, the transformation is producing a collision.

Possible causes:

1. you have some objects with the same names or the same postions in your file. Fix the file.
    
2. two fibers are really very close so that the atmospheric dispersion correction is causing them to collide. This happens most often if you have successfully configured a field, observed for a few hours, and you reconfigure. The new atmospheric dispersion correction is different enough that the fibers collide. Look for fibers which are very close and retire one.
    
3. one fiber is really quite bent, and the dispersion correction is trying to bend it beyond its software limits. Look for a really bent fiber on the GUI.