TAO - Slew time measurement script

' TELESCOPE SLEWING PARAMETERS
SlewTol = 100.                        ' Tolerance (deg) in checking for end of slew
SlewWait = 2200                       ' Time step (msec) for waiting while checking for
                                      ' end of slew
checkForSlewStart = False             ' True to check if the telescope reports that an issued slew 
                                      ' command has actually started; this should be set to False 
                                      ' for the Paramount, due to a 4-5 sec waiting time after a 
                                      ' slew command is issued, during which control is not 
                                      ' returned to this script; short slews are usually over after 
                                      ' this 4-5 sec period elapses
timeoutSlewStart = 5.                 ' Timeout (sec) when waiting for the telescope to report that
                                      ' an ordered slew has actually started
timeoutSlewEnd = 230.                 ' Timeout (sec) when waiting for the telescope to report that
                                      ' a slew in progress has actually ended
corrTgtCoords = False                 ' True to convert J2000 target coordinates to
                                      ' local topocentric coordinates before slewing
                                      ' (This option is most useful for Meade telescopes)

SlewTol. This parameter sets a tolerance (in degrees) to be used when checking if a telescope slew is finished. The SlewTime script will only believe that a slew is finished when the telescope reports that it is no longer slewing and the reported telescope position is within SlewTol degrees of the target position. The checking of telescope positions was introduced because some automated telescope mounts would sometimes produce false reports that a slew was over, resulting in opening the shutter when the telescope was still moving toward the target. A typical value for SlewTol would be 0.05 deg. If your telescope is not prone to this problem, you may effectively disable the checking of telescope positions by setting SlewTol to a very large value such as 100 deg.

SlewWait. This is the interval (in milliseconds) between successive checkings of the telescope state (slewing/not slewing) and position when a slew is in progress. This parameter should be neither too small (to avoid overwhelming the CPU and/or telescope with queries) nor too large (to avoid making the script too sluggish in reacting to the end of a slew). Typical values for SlewWait would be between 1000 and 3000 msec.

checkForSlewStart. If this parameter is set to True, the script will check if the telescope reports that it is slewing after each issued slew command. Althout this check should not be necessary, it has proved to be important with some telescopes, due to bugs in their lower-level telescope control software.

Note: If you use the Paramount, this parameter should be set to False.

timeoutSlewStart. If checkForSlewStart is set to True, this parameter specifies the maximum time (in seconds) the script will wait for the telescope to report that it is slewing after each issued slew command. A warning message results if this waiting period elapses without the telescope reporting that it is slewing. If checkForSlewStart is set to False, this parameter has no effect.

timeoutSlewEnd. This parameter specifies the maximum time (in seconds) the script will wait for the telescope to report that a slew in progress is finished, after it has started. It should be set to the duration of the longest slews which the telescope ever does, or a slightly larger value. If the slew appears to be still unfinished after this waiting period elapses, the script produces a warning message, reissues the slew command, and again waits up to timeoutSlewEnd seconds for the slew to end. If the slew is still unfinished after this second waiting period elapses, the script produces another warning message and continues, assuming that the slew is actually over (which may not be true if there are problems with the telescope or the lower-level telescope control software).
corrTgtCoords. Set this to True if you wish that corrections for atmospheric refraction be applied to each target J2000.0 coordinate. Otherwise, set it to False.

Telescope slew limits

' TELESCOPE SLEW LIMITS
minAlt = 20.                          ' Targets below altitude minAlt (deg) will be skipped.
minHA = 30.                           ' Targets at |HA| < minHA (time minutes) will be skipped.
                                      ' This is zero for fork-mounted telescopes, and should be
                                      ' positive for German equatorial mounts like the Paramount
maxHA = 600.                          ' Targets at |HA| > maxHA (time minutes) will be skipped.
maxDec = +90.                         ' Targets north of declination maxDec (deg) will be skipped.  
minDec = -28.                         ' Targets south of declination minDec (deg) will be skipped.

minAlt. This parameter specifies the minimum altitude (in degrees) at which a target position can be in order to be considered "valid". If a target is at an altitude less than minAlt when the telescope is about to slew toward it, the slew is cancelled.

minHA. This parameter specifies the minimum absolute value of the hour angle (expressed in minutes of time) at which a target position can be in order to be considered "valid". If a target is at an hour angle H such that |H| is less than minHA minutes when the telescope is about to slew toward it, the slew is cancelled.

maxHA. This parameter specifies the maximum absolute value of the hour angle (expressed in minutes of time) at which a target position can be in order to be considered "valid". If a target is at an hour angle H such that |H| is greater than maxHA minutes when the telescope is about to slew toward it, the slew is cancelled.

maxDec. This parameter specifies the northernmost declination (in degrees) at which a target position can be in order to be considered "valid". If a target is at a declination north of maxDec when the telescope is about to slew toward it, the slew is cancelled.

minDec. This parameter specifies the southernmost declination (in degrees) at which a target position can be in order to be considered "valid". If a target is at a declination south of minDec when the telescope is about to slew toward it, the slew is cancelled.

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© 1999-2004 Paulo Holvorcem