A scheduler configuration file is divided into several sections. The various parameters which may be specified in each section are explained below and in the next pages.

Parameters of the scheduling algorithm

PARAMETERS OF SCHEDULING ALGORITHM:
  Enable download-while-slew? (yes/no)                                yes
  Maximum motion of asteroids during exposure (pixels):               3.0
  Maximum motion of comets during exposure (pixels):                  1.2
  Optimal motion between exposures (pixels):                          4.0
  Cut-off for motion rates (pixels/min):                              0.01
  Tolerance for interval between exposures of a given target (%):     20.
  Maximum shift for scheduled times (min):                            12.
  Maximum number of primary insertion attempts:                       300
  Spacing between primary insertion attempts (sec):                   100.
  Maximum number of secondary insertion attempts:                     20
  Stepsize for optimal spacing enforcement (sec):                     3.
  Relative importance of slew time optimization (%):                  30.
  Maximum Sun altitude (deg) in the evening:                          -15.
  Maximum Sun altitude (deg) in the morning:                          -15.

This section specifies parameters which determine the behavior of the scheduling algorithm:

• Enable download-while-slew? If you answer yes to this question, the scheduler will assume that the download of each exposure is carried out simultaneously with the telescope slew to the next target. This may yield significant time savings depending on your typical exposure times, download times, and slew times. This option is only available if the telescope is controlled by ACP using the MU image acquisition script. If you answer no to this question, the scheduler will assume that the image download and slew to next target do not overlap in time.

• Maximum motion of asteroids during exposure. When the exposure time for a given observation request is not specified by the user, it is chosen by the scheduler as the longest standard exposure time specified in the user's profile during which the object does not move more than the number of pixels specified in this option. Sufficiently slow minor planets (and targets outside the solar system) will be observed with the longest standard exposure time listed in the user's profile. Setting this parameter to 3.0 pixels is usually adequate to ensure that even fast moving NEOs do not produce trailed images regardless of their rate of motion (of course, an object which moves several pixels during the shortest standard exposure time will produce a trailed image, but this can only be avoided by defining another, shorter standard exposure time). Note that the maximum displacement specified in this option does not apply to comets, for which a different value may be specified (see below).

• Maximum motion of comets during exposure. This parameter is analogous to the previous one, but applies only to comets. Its suggested value (1.2 pixels) is smaller than the corresponding value for minor planets (3.0 pixels) to prevent "blurring" of the photometric center of comets, which may lead to inaccurate position measurements.

• Optimal motion between exposures. For observation requests involving an image sequence of type mot, the time interval between successive observations of the target is chosen by the scheduler so that the target moves approximately the number of pixels specified in this option between successive images. The suggested value (4.0 pixels) is usually adequate to ensure that the displacement of minor planets and comets is readily perceptible when blinking the images, yet not so large that it becomes difficult for the eye to follow its motion from one image to the next. In practice, each target will not move exactly the number of pixels specified in this option between successive images. A tolerance about this "optimal" displacement is specified in another option.

• Cut-off for motion rates. This is the smallest rate of motion (in pixels/minute) of a target for which the scheduler will try to ensure an optimal time interval between successive exposures (see previous option). For targets which are slower than this minimum rate of motion, scheduler will act as if the rate of motion were equal to the minimum value, and choose the spacing between exposures as described in the previous option. The suggested value of this option is 0.02 pixels/min. A target which moved at this rate would take almost 2 hours to move by a minimal visually detectable distance (2 pixels), and a sequence of 3 or 4 optimally spaced images would take from 4 to 6 hours, a time comparable to (and in many situations longer than) the time interval during which the object remains at a sufficient altitude to be observed. For such a very slow target, it is often more reasonable to reobserve it on a subsequent night than to wait for hours between successive observations on a single night.

• Tolerance for interval between exposures of a given target. When processing an observation request involving an image sequence of type mot, the scheduler will choose the time interval between successive images of the target so that it moves a number of pixels between (1 - r/100)d and (1 + r/100)d, where r is the tolerance specified in this option (expressed as a percentage), and d is the optimal motion between successive exposures of a target. When processing an observation request for which the interval T between successive exposures has been specified by the user, the scheduler will ensure that the actual interval between exposures of the target is between (1 - r/100)T and (1 + r/100)T.

• Maximum shift for scheduled times. Once the scheduler has allocated telescope time for an individual observation (image) of a target, the allocated time interval may be shifted in time in order to better accomodate subsequently processed observing requests, but the shift will not exceed the amount of time (in minutes) specified in this option.

• Maximum number of primary insertion attempts. When the scheduler processes an observation request, it considers a certain number of times during the observing run as prospective primary insertion points, that is, times when the first observation of the requested image sequence might conceivably be started. The number of primary insertion points is limited by the value specified in this option. If you increase the maximum number of primary insertion attempts, the scheduler will "try harder" to find a suitable time to start each observation request, at the expense of slowing down the scheduler's execution. If you decrease the maximum number of primary insertion attempts, the scheduler will run faster, at the expense of possibly missing some opportunities to allocate telescope time to certain targets.

• Spacing between primary insertion attempts. This is the time interval (expressed in seconds) between successive prospective primary insertion points (see previous option). The maximum time interval (in seconds) scanned for prospective primary insertion points is equal to the product of the values of this option and of the previous option. The suggested values (up to 300 prospective primary insertion points spaced 100 sec apart) mean that for each observation request, a time interval of up to 8.3 hours will be scanned for prospective primary insertion points. This time interval is comparable to the time during which a well-placed target would normally remain visible during a given night. When scheduling observations over time intervals which are significantly shorter than a full night, you might consider decreasing the spacing between prospective primary insertion points so that the maximum time interval scanned for prospective insertion points is comparable to the duration of the observing run.

• Maximum number of secondary insertion attempts. When the scheduler processes an observing request involving an image sequence of type mot, it will first choose the primary insertion point, that is, the time when the first observation of the requested sequence will start. If the requested sequence contains more than one observation, the scheduler will then choose the start time for the second observation of the sequence among a certain number of prospective secondary insertion points. If more than two observations have been requested in the sequence, once the second observation's start time has been chosen the scheduler will choose the third observation's start time among a certain number of secondary insertion points, and so forth, until time has been allocated for the whole requested image sequence. The number of prospective secondary insertion points is limited by the value specified in this option. Increasing the number of secondary insertion attempts means that the scheduler will "try harder" to find suitable times for the various observations, at the expense of slower execution.

• Stepsize for optimal spacing enforcement. After the scheduler allocates telescope time for an observation request, it may need to slightly adjust the start times of some previously processed observing requests to ensure that the corresponding image sequences have acceptable time intervals between successive exposures. When needed, this adjustment is made by shifting the start times of individual observations in time steps defined by the value of this option. The default value (3 sec) is probably adequate for most users.

• Relative importance of slew time optimization. When the scheduler chooses the start time of the first observation of a requested image sequence (consisting of one or more images of a given target), it tries to achieve a trade-off between maximizing the altitude at which the images will be taken and minimizing the telescope slew time which is spent when carrying out the observations of the target. The relative importance of both (often conflicting) goals is specified by the value of this option. A value of 0% would correspond to pure altitude maximization, while a value of 100% would correspond to pure slew time minimization.

• Maximum Sun altitude in the evening. This parameter is used for the automatic computation of the start time of an observing run. When running the scheduler, the start time of the observing run being scheduled is by default taken to be the time after the next sunset at the telescope's location when the sun reaches the altitude (expressed in degrees) specified in this option (strictly speaking, the previous rule applies when the scheduler is run at a time when the sun is above the horizon as seen from the telescope's location; if the sun is below the horizon when the scheduler is run, the same rule applies with "last sunset" instead of "next sunset"). A value between -13 and -15 deg is probably adequate for most users. This parameter should never be positive, to prevent accidental telescope pointing at the sun.

• Maximum Sun altitude in the morning. This parameter is used for the automatic computation of the end time of an observing run. When running the scheduler, the end time of the observing run being scheduled is by default taken to be the time before the next sunrise at the telescope's location when the sun reaches the altitude (expressed in degrees) specified in this option. A value between -13 and -15 deg is probably adequate for most users. This parameter should never be positive, to prevent accidental telescope pointing at the sun.