schierd.conf

The schierd controls the mount as well as the focus motor. It can model pointing either from a simple two-star model represented as a ${3\times 3}$ matrix, or from a more involved model from the Tpoint package. The focus model comes from a simple linear model based on telescope temperature and elevation. For instructions for how to get a pointing model see Chapter 5. For a focus model, see Chapter 6.

The first part of schierd.conf is self explanatory:

# configuration file for schierd

#

# format is "key   value"

# comments start with `#' and go to end of line

# blank lines are okay

# lines cannot be continued

loglevel             1                                  # 0,1,2 = terse,verbose,debug

logfile              /rotse/run/log/schierd.log

poll_time            0.1                                # main loop time quantum

sample_time          3.0                                # sample time in seconds

err_tout             5.0

#

mntman               AlanSchier                         # mount manufacturer

mntmodel             Equatorial                         # mount model

mntsn                2                                  # mount serial number

errormail            observer@rotse3a.lanl.gov          # where to send error messages

The next section contains numbers that should be general across the Schier mounts:

enctol               300                                # tolerance for encoder stop

slewacc              16.4   20.6                        # acceleration for mount (deg/s2)

maxvel               35.0   35.0                        # slew velocity for mount (deg/s)

homevel              2.0     2.0                        # velocity to find home (deg/s)

stowpos              -85.0  35.0                        # Stow pos. in Axis coords (deg)

standbypos           -85.0 140.0                        # Standby pos. in Axis coords (deg)

deg2enc              24382   19395                      # encoder counts per deg

rarange              -185.0  0.0                        # range of the ra axis (deg)

decrange             0.0   220.0                        # range of the dec axis (deg)

foctol               0.001                              # focus tolerance

The acceleration and velocity parameters are stated in degrees for the RA axis (axis 0) first, and the Dec axis (axis 1) second. The deg2enc values were calculated from the radius of the encoder tape on each drive wheel. The RA range and Dec range were determined experimentally, and are just short of the hardware limit switches. Under normal operation, the mount controller should never be told to move the telescope to an illegal position, and we have multiple redundancies. The maximum velocities were determined by how fast we could move the telescope without any odd noises coming from the mount. (Very scientific, eh?) The home velocity is the default from Mr. Schier.

The stow position is (for the northern hemisphere) pointed north, slightly below the horizon. The standby position is very close to the zenith. These values can change depending on the polar alignment of the telescope.

# the following keyword defines a file that contains the 2-star rotation matrix

matfile              /rotse/run/etc/mat0529c.mat        # full path

# The following keyword defines a file that contains a tpoint model

modfile              /rotse/run/etc/mod_011211c.dat     # full path

focusmodfile         /rotse/run/etc/focusmod011214.dat  # full path

obsfile              /rotse/run/etc/observatory.conf    # site information

statdir              /rotse/data/pipeline/prod          # idlpacman stat dir.

statroot             rotse3a                            # root for statfile

The matfile matrix file specifies a two-star pointing model matrix file. The modfile is a Tpoint pointing model file. If a Tpoint model file is specified it will use this pointing model instead of the two-star matrix. The lines containing matfile and modfile can be commented out if no relevant pointing models exist. The modelling schierd decides to use is logged in /var/log/rotse.log. The obsfile is the observatory information file used for coordinate conversion.

The focusmodfile focus model file specifies the constants for the bilinear focus model fit. The format is described in Section 3.8.1.

Due to the homing inaccuracies of the Schier mount (the homing can drift by tens of arcminutes), the first calibrated image of the night is used to improve the home position. The automated calibration pipeline outputs a summary of each calibrated image in a file called statdirstatroot_stat.dat. After a home command, schierd checks every ten minutes for the most recent calibrated image that was taken after the most recent telescope homing, and updates the offset values. This improves pointing considerably.