The image insertion method determines how the scheduler will determine the "best" times to carry out an observation request. The four available image insertion methods may be selected using the opt, asap, alap, and mix keywords, whose meaning has been previously discussed:

• If none of these keywords is present, the scheduler will use the keyword which is specified in the user's profile under "Image insertion method."

• If one of these keywords is present, it will be used instead of the default keyword:
  • The opt keyword specifies that observations should be made at the highest possible altitude. For example,

    2003 QF70; opt

    is a request for observations of asteroid 2003 QF70, made by the default user. The default number of exposures specified in the default user's profile is being requested, and they should be taken as close to the meridian as possible. The other options for this request are all taken from the default user's profile.

  • The asap keyword specifies observations made at the earliest possible time. For example, the request

    2003 QF70; asap

    is identical to the previous one, except that the observations would take place at the earliest possible time.

  • The alap keyword is analogous to asap, with observations being made at the latest possible time.

  • The mix keyword tells the scheduler to try to achieve a trade-off between maximum altitude and minimum slew time in moving between the requested target and the next target. The relative importance of slew time minimization in this trade-off is specified in the scheduler configuration file.

Specifying the minimum altitude limit

If the minimum altitude limit for the exposures belonging to a given observation request is not specified explicitly, the default minimum altitude specified in the user's profile would be used. Although this may be adequate for many requests, the user may wish to specify a non-default altitude limit. This is done using the alt keyword:

NGC4698; alt>50

This would be interpreted as a request for observations of NGC4698, made by the default user. The observations would be carried out using the default options specified in the default user's profile, except that the minimum altitude limit would be 50 deg.

Note: Regardless of the minimum altitude limit specified in an observation request, no observations will be scheduled at altitudes and azimuths which are below the horizon line specified in the scheduler configuration file. Click here for more details about modeling of horizon lines.

Specifying the maximum |hour angle| limit

If the maximum |hour angle| limit for the exposures belonging to a given observation request is not specified explicitly, the default maximum |hour angle| specified in the user's profile would be used. Although this may be adequate for many requests, the user may wish to specify a non-default hour angle limit. This is done using the HA keyword:

NGC4698; HA<60

This would be interpreted as a request for observations of NGC4698, made by the default user. The observations would be carried out using the default options specified in the default user's profile, except that the maximum |hour angle| would be 60 min (which means that observations would be carried out when the object is at some hour angle between -60 and +60 min.

Note: Regardless of the maximum |hour angle| limit specified in an observation request, no observations will be scheduled at hour angles which violate the minimum and maximum |hour angle| limits specified in the scheduler configuration file. These limits represent safety slew limits for the telescope, so they should never be violated by any observation.