Cycle 19 Call for Proposals

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 SNAP proposals the OS should describe a typical observation for one or a few of the targets. A complete and unique description of the target list should be provided in the ‘Scientific Justification’ section of the proposal (see Section 9.1).

•	For Long-Term Programs, the OS should include information for all the proposed observations, not just those requested in Cycle 19.

•	Parallel observations must be included in the OS, and marked as such using the relevant special requirement flags (see Section 8.16.11 and Table 8.1). For NICMOS, list all observations with all cameras which will be used for parallel observations.

•	Target acquisition observations (see Section 5.2 of the HST Primer) need not be included in the OS, unless they are themselves used for scientific analysis.

•

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).

Enter 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 4 exposures with the B filter and 2 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.

For all proposals, we are requesting additional scheduling information for your observations; note that this request does not apply to either observations of solar system or generic targets. The additional information will help STScI understand and assess the scheduling implications of your program. Be sure also to read Section 9.2, ‘Description of the Observations’, as that is the primary place for describing your observing strategy.

•	NO SCHEDULING CONSTRAINTS: setting this requirement means that there are no scheduling constraints on the Observation Block.

•

SHADOW: 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. Note that this requirement should not be used if low continuum background is required: in that case use LOW SKY instead.

•

LOW SKY: 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 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. Note that LOW SKY is generally incompatible with CVZ.

•

SAME ORIENT: 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).

•	ORIENT: 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.

•	BETWEEN: 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.

•

AFTER OBSERVATION BY: 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.

If 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.