• If this value is 0 (zero), the time series will consist of exposures taken in direct succession (so that the interval between successive exposures will be approximately equal to the sum of exposure time plus camera download time).
• For positive integer values, this field specifies the number of seconds between exposures. The scheduler does its best to ensure that exposures are equally spaced. The scheduler is usually set to 15% tolerance, which means that the actual interval between exposures will be within +/-15% of the user-specified value. The variations in the interval between exposures arise because the scheduler may insert observations of other targets between two successive exposures belonging to your time series (remember, at Tenagra each user pays for his/her total exposure time, not for a contiguous block of telescope time; any idle telescope time between exposures belonging to your time series may be used to perform other observations, possibly requested by other users). These +/-15% variations in spacing between exposures should not affect the statistical significance of the time series results.
• If the value of this field is -1, the scheduler chooses the time interval between successive exposures of the target according to its rate of motion, so that it moves a few pixels between successive exposures; this is convenient for detection purposes, and also ensures that meaningful rates of motion in R.A. and Dec. can be estimated from measured astrometric positions of the target. As discussed above, the spacing between exposures can vary by +/-15% with respect to its optimal value.

1. Note that if you specify a spacing which is smaller than the sum of exposure time plus camera download time for the specified resolution and frame size, it will be physically impossible to carry out your time series with the specified interval between images. If your desired time interval between exposures is small, you may wish to set the value of this field to zero so that the exposures will be taken in succession.
2. Time series may sometimes be interrupted by automatic "focus breaks" which occur at approximately 1-hr intervals for checking/adjusting telescope focus. These focus breaks normally take only 1-2 minutes.
3. When you request more than 4 exposures, the time interval between some of the exposures belonging to your time series may be longer than the interval you specified in this field. This sometimes occurs when other observation requests are scheduled in the intervals between the images belonging to your time series.

1. Dates are referred to universal time.
2. Nighttime in Arizona always starts at most a few hours after 0:00 UT, so each night at Tenagra can be uniquely identified by its UT date.
3. When the two date fields are the same, your observation request will be submitted to the scheduler for that night only.
4. The observation requests for each field in a mosaic are treated independently by the scheduler. If your window of opportunity spans more than one night, different fields may be observed on different nights.

The above is a hypothetical attempt to recover the periodic comet P/1996 R2, using a mosaic of five full fields of view (14.8 x 14.8 arcminutes) of the 32-inch telescope. The partially overlapping fields are arranged along a line passing through the nominal topocentric ephemeris position of P/1996 R2 (computed using the ephemeris provided by the Minor Planet & Comet Ephemeris Service); the line is oriented at position angle 152 degrees and moves with the comet. The central field of the mosaic is centered at the nominal ephemeris position at the time it is observed. The other 4 fields-of-view have suitable fixed offsets with respect to the nominal ephemeris position at the time they are observed, so as to cover a segment of the user-specified uncertainty line. The exposures will be of full resolution (0.87"/pixel), and will use the R filter. Each of the five fields in the mosaic will be imaged three times. The time interval between successive exposures of P/1996 R2 will be automatically determined by the scheduler so that it moves a few pixels in that time interval. The request will be attempted between 2003 Sept. 29 and 2003 Oct. 1 UT. If for some reason the request is not carried out on 2003 Sept. 29 UT, it will be attempted until 2003 Oct. 1 UT; we will stop retrying if the request is carried out. The observation requests for each of the five fields are treated independently by the scheduler, so that different fields might be observed on different nights between 2003 Sept. 29 and 2003 Oct. 1. Since the repeat field (columns 81-83) was left blank, the request will not be repeated. Since the moon exclusion radius (columns 85-87) was left blank, the default value of 5 deg around the full moon (scaled down for other moon phases) will be adopted.

The above is a request for a photometric single-night time series consisting of up to thirty 180-sec exposures of asteroid 2003 RW11 with the 32-inch telescope. Successive exposures in the series will be separated by approximately 600 seconds. The exposures will use 2x2 binning (1.74"/pixel), will only use the central 7.4 x 7.4 arcminute field of the CCD chip (256 x 256 pixels), and will be taken with the V filter. Each exposure will be centered at the topocentric ephemeris position of 2003 RW11 (computed using the ephemeris provided by the Minor Planet & Comet Ephemeris Service); if the object is moving fast, the telescope will follow it along the night, so that it is always centered in the CCD field (provided the available ephemeris is accurate enough). Since the dates are equal, and the repeat field (columns 81-83) was left blank, the time series will be attempted only on 2003 Sept. 25 UT. Since the moon exclusion radius (columns 85-87) was left blank, the default value of 5 deg around the full moon (scaled down for other moon phases) will be adopted.

Note: Observations of photometric reference stars should be requested using the format for non-solar system objects.

The above is a request for monitoring of minor planet (50000) over a 120-day period starting on 2003 Sept. 25, using the 32-inch telescope. On every night in this period, a single 300-sec exposure in the R filter is requested. This exposure will not be binned (0.87"/pixel) and will use the full 14.8 x 14.8 arcminute field of the CCD detector. The image will be centered at the ephemeris position of (50000) (computed using the ephemeris provided by the Minor Planet & Comet Ephemeris Service). The exclusion radius around the full moon was set to 45 deg, and will be scaled down for other moon phases.