Estimation of the target dedicated time for an AOT

In this section we present a method to estimate the target dedicated time which is the total time including overheads necessary to execute a given AOT. The method is based on the AOT logic as of August 1, 1996. Since the logic (and therefore the time estimates) may change at any time during the mission, the time calculations presented here should be regarded as rough estimates probably good to within 20 sec per AOT.

When selecting the integration time one should be aware that the integration time can only be commanded by powers of 2 sec (32, 64, 128 ... 2048 sec). After estimating from the information presented in Section 4, one should round to the nearest power of 2 sec. The AOT logic always takes the nearest higher power of 2 sec in case a S/N is requested.

The next steps should be taken for each AOT:

• determine the AOT to be used and determine whether fine pointing mode (FPM) or raster mapping mode (RMM) should be used;
• look up in Table 8 under the proper column the fixed overhead time;
• for PHT03, PHT17, PHT18, and PHT19: add for each additional filter 20 sec for filter wheel overheads (i.e. no extra time for the first filter);
• for PHT22, PHT37, PHT38, and PHT39: add for each additional filter 10 sec (no extra time for the first filter);
• for PHT04: add 10 sec per aperture;
• in case of FPM: add the total integration times for each filter, in case of rectangular or triangular chopped mode multiply the on-target integration time by 2, in case of saw-tooth chop multiply by 3;
• in case of RMM: add the integration time per raster map determined from the integration time per raster point, the number of pointings, and the duration of the slews (see Sction 6.3.3);
• in case of PHT05 or PHT25: multiply the on-target intergration time by 2 to account for the heated FCS measurement;
• in case of FPM and if a heated detector is used: add 90 sec for each heated detector except P2 when both detectors P1 and P2 are requested in PHT03 (see previous section);
• in case of RMM and if a heated detector is used: add 160 sec for the first map and 70 sec for each additional map;
• in case of FPM: add for each detector requested 35 sec for the FCS measurement (caveat: see Section 6.3.4)
• in case of RMM: add for each map 70 sec for the FCS measurements (caveat: see Section 6.3.4);
• for PHT05 and PHT25: add 270 sec for the optional dark measurement;
• for PHT05 and PHT25: add 130 sec for the optional cold FCS measurement;
• for PHT40 in FPM: only add the total integration time to the value in Table 8;
• for PHT40 in RMM: add the raster map time to the value in Table 8;
• in case of concatenation add 20 sec (see Section 6.3.5), for solar system targets 300 sec, otherwise 180 sec for the spacecraft to slew to the target.