|Space Telescope Science Institute|
|HST Call for Proposals and Primer|
8.16 Observation Summary (OS)The OS lists the main characteristics of the observations that you propose to obtain. In general you must include in the OS all the configurations, modes and spectral elements that you propose to use, and all the targets that you propose to observe. Configurations or targets that are not specified in the Phase I proposal, but are included in Phase II, may delay the program implementation, and may be disallowed. Note the following:
• For Long-Term Programs, the OS should include information for all the proposed observations, not just those requested in Cycle 21.
• Normal calibration observations that are often or routinely taken (e.g, fringe flats) need not be included in the OS. However, the OS should include any special calibration exposures of internal sources or external targets (see Section 4.3). Special internal calibrations should be listed separately from external calibration exposures. When these special calibrations require additional orbits, that should be specified and the orbits included in the total allocation. The need for these calibrations should be justified in the ‘Description of the Observations’ (see Section 9.2).The OS consists of individual ‘observation blocks’, each containing several separate pieces of information.
Observation blocks are numbered sequentially in the APT Phase I proposal form. Each observation block should include the items that are listed and discussed below in separate sub-sections.8.16.1 TargetSelect the target from the pull-down menu. The menu will contain all the targets you have entered on the “Targets” page.8.16.2 InstrumentSelect an instrument from the pull-down menu. The menu will contain all the available instruments. Only one instrument can be selected in each observation block.8.16.3 Instrument Setup(s)Under “Instrument Setups” click on “Add”. This will bring up a pop-up menu which will allow you to select the parameters for the observation (e.g., config, science mode, spectral elements).8.16.4 ConfigEnter the Scientific Instrument configuration. A pull-down menu shows the available and allowed options for the instrument you have selected.8.16.5 Science ModeEnter the science mode. A pull-down menu shows the available and allowed options (which depend on the choice of Configuration).8.16.6 CoronagraphyIf you are proposing coronagraphic observations with STIS, then set this keyword to ‘yes’. Coronagraphic observations with the ACS/SBC are not permitted (see Section 3.3.2 of the ACS Instrument Handbook).8.16.7 PolarizerIf you are proposing polarimetric observations with ACS, then set this keyword to ‘yes’. There is no polarimetry keyword in the proposal pdf file, but this sets the appropriate flag in the Phase I submission.8.16.8 Spectral ElementEnter the desired spectral elements (i.e., filters and gratings) using the ‘Spectral Element’ pull-down menus which show the available and allowed options (which depend on the choice of Configuration and Science Mode). Each Instrument Setup denotes a set of exposures with the same spectral elements. For example if you are taking four exposures with the B filter and two with the V filter, one instrument setup would give the B filter as the Spectral Element, and a separate instrument setup would give the V filter as the Spectral Element.If a COS or STIS grating is used, then first select the grating and subsequently give the central wavelengths in Angstroms for the exposures.8.16.9 OrbitsEnter the number of orbits requested (i.e., the sum of the orbits required for all the instrument setups in the observation block). Consult Chapter 6 of the HST Primer for instructions on how to calculate the appropriate number of orbits for your observations.8.16.10 Number of IterationsIf you require multiple sets of observations, enter the number of iterations (for example, if you will reobserve at a different time or if you have a large mosaic). This will automatically update the total number of orbits requested for the target.8.16.11 Special Requirement CheckboxesMark one or more of the special requirement checkboxes, if applicable. The meanings of the checkboxes are indicated in the table below. For Snapshot observations, only the ‘duplication’ checkbox is allowed.
8.16.12 Scheduling RequirementsFor all proposals, we request that you provide additional scheduling information for your observations; this request does not apply to observations of solar system or generic targets. The additional information will help STScI understand and assess the scheduling implications of your program. Be sure to read Section 9.2, ‘Description of the Observations’, as that is the primary place for describing your observing strategy.Set this requirement when all exposures defined in the Observation Block are affected adversely by geocoronal Lyman-alpha background emission, and therefore need to be obtained when HST is in Earth shadow. This requirement complicates scheduling and reduces HST observing efficiency, and must therefore have adequate scientific justification in the Phase I proposal. SHADOW is generally incompatible with CVZ. This requirement should not be used if low continuum background is required: in that case use LOW SKY instead.Set this requirement when all exposures defined in the Observation Block are affected adversely by scattered light (e.g zodiacal light and earthshine), and therefore need to be obtained with minimal sky background. The continuum background for HST observations is a function of when and how a given target is observed. Observations can be scheduled when the sky background is within 30% of its yearly minimum for the given target, which is done by restricting the observations to times that minimize both zodiacal light and earthshine scattered by the Optical Telescope Assembly (OTA). To minimize the zodiacal light, the scheduling algorithm places seasonal restrictions on the observations; to reduce the earthshine, the amount of time data is taken within an orbit is reduced by approximately 15%. The former complicates scheduling, while the latter reduces the observing efficiency of HST. Therefore, using the LOW SKY restriction must have adequate scientific justification included in the Phase I proposal. With this restriction, the zodiacal background light for low-ecliptic latitude targets can be reduced by as much as a factor of 4. Avoiding the earthshine at the standard earth-limb avoidance angle (see Section 2.3 of the HST Primer) can make a similar difference. LOW SKY is generally incompatible with CVZ.Setting this requirement means that all exposures defined in the Observation Block MUST be observed at the exact same ORIENT. This requirement is only meaningful if the observations are to occur in multiple visits (e.g. Number of Iterations is greater than 1, or if the Total Orbits is greater than 5).Enter the ORIENT range that all the exposures defined in the Observation Block must be observed within. If multiple ORIENT ranges are acceptable, then enter all values.Enter the range of dates that all exposures defined in the Observation Block must be observed within. If multiple BETWEENs are acceptable, then enter all values.Enter any timing requirements between Observation Blocks. Timing requirements between observations WITHIN an Observation Block do not need to be specified. This is intended to capture repeated visits with spacings of multiple days or greater, not timing requirements of less than 1-2 days.For Large and Treasury programs, we will contact the proposer within 1-2 weeks of the submission deadline if we need to verify our understanding of the appropriate scheduling constraints. As noted previously (Section 8.12), if a CoI is to serve as the contact for this verification, the Contact CoI keyword box should be set.8.16.13 Verifying Schedule ConstraintsIf you have specified any scheduling constraints, you are encouraged to use the APT Visit planner to verify that your observations are indeed schedulable. While it cannot check that the total number of orbits you have requested are available, the Visit Planner will at least confirm whether or not there are days during the cycle when your target(s) can be observed with your imposed scheduling constraints. In general, the more days that are available, the more feasible your program. This is particularly important for Large Programs. Detailed instructions for performing this verification can be found in the APT Help menu.If you find that any observation is not schedulable, and it is not scientifically possible to adjust any special scheduling constraints (e.g. a BETWEEN), then you can increase the scheduling opportunities by selecting the Increase Scheduling Flexibility flag in APT. Note that using this option may require you to ask for a larger orbit allocation, since setting the flag will reduce the orbital visibility for the observation; this reduced orbital visibility is automatically used for Large Programs. Detailed instructions for performing this verification can be found in the APT Help menu.