HST Phase II Proposal Instructions for Cycle 12 (RPS2)
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| HST Phase II Proposal Instructions for Cycle 12 (RPS2) | |||
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Tables and Figures
Table 5.1: Internal Calibration Target Names
Table 5.2: Special External Target Names
Table 5.3: Instrument Configurations and Operating Modes
Table 5.4: Aperture and Field of View Names
The Visit and Exposure Specifications are used to define the proposed exposures for all the Scientific Instruments. While the number of parameters needed to define all possible instrument configurations is large, the Visit and Exposure Specifications has been simplified by using standard Instrument Configurations and Operating Modes to set most of the instrument parameters to default values. The rest of the exposure keywords are used to define parameters that usually change from one exposure to the next, such as filters, exposure times, and special scheduling requirements.
Before proceeding further, it is useful to define more carefully what is meant by an exposure and by a visit. An exposure consists of the events and data corresponding to a unique Exposure_Number in the RPS2 file within a given visit. The full description of an exposure is often called "the Exposure line", although in the RPS2 template it takes several lines to describe an exposure. Here we have adopted Exposure Specification as a term for this. Although many data samples (images or spectra) may result from a single execution of an Exposure Spec (due to the Instrument Configuration, Operating Mode, and Optional Parameters chosen), they are considered to be one exposure. The observer may specify multiple exposures on one exposure line by entering an integer greater than 1 for the Number_of_Iterations keyword (see 5.14 "Number of Times to Iterate the Exposure [Number_of_Iterations]"), and these exposures will be obtained consecutively (except for possible interruptions by Earth occultations, guide star acquisitions, and SAA passages). Exposures defined within a visit will be obtained consecutively and in the order specified within that visit.
A visit is an exposure or series of consecutive exposures, with overheads, on a given target, and may consist of the following parts:
- Guide-star acquisition (to point HST at the target)
- Target acquisition (to place the target in an instrument aperture)
- Science exposure(s) (to obtain the data)
- Instrument overheads (to set up the instrument and read out the data)
- Instrument calibrations (if more than the standard calibration is required)
If the visit lasts more than one orbit, it will continue with the following for each subsequent orbit:
- Guide-star re-acquisition (to keep HST pointed and locked after Earth occultations)
- Science exposure(s)
- Instrument overheads
- Instrument calibrations
Whenever one of the following occurs, a new visit must be defined:
- A change in target position of greater than 1 degree. (Contact your Program Coordinator for details regarding solar system objects that move more than about 30 arcsec during the observation and thus are likely to require multiple sets of guide stars).
- Repeated, periodic, or other time-separated observations with an interval between exposures such that one or more empty visibility periods (orbits with no exposures) would otherwise be required.
- Required change in spacecraft roll orientation.
5.1 Visit Number [Visit_Number]
Visit numbers provide a method for unique labeling of visits. The visit number should be a positive integer between 1 and 99. If you have more than 99 visits in your program, please contact your Program Coordinator. (Visit numbers are actually base 36 values ranging from 01 - ZZ.)
5.2 Visit Priority [Visit_Priority]
This field is required for visits in Pure Parallel (those with a Proposal_Category ending in /PAR) and SNAP programs. This field does not apply to primary exposures or programs.
Pure Parallel Visits
The priority should be a positive integer between 1 and 999. This is a number giving the scheduling priority for the given parallel visit, with higher numbers having higher priority. If a primary pointing matches the target of two or more visits in a parallel program, the system will schedule the highest-priority parallel visit that will fit into the opportunity. Therefore, to allow maximum use of long opportunities, visits designed for longer opportunities should have higher priority. No two parallel visits in a program should have the same priority.
SNAP Visits
The priority must be "H," "M" or "L," corresponding to High, Medium and Low. The default is "M," and the number of H values may not exceed the number of L values.
5.3 Visit-level Special Requirements [Visit_Requirements]
A variety of visit-level Special Requirements may be entered; these requirements apply to all exposures in the visit (exposure-level Special Requirements are discussed in Chapter7, Special Requirements [Visit_Requirements and Special_Requirements]). These requirements will be interpreted by the computer software that is used to schedule the observations; therefore it is absolutely essential that the specific formats shown in Chapter7, Special Requirements [Visit_Requirements and Special_Requirements] are followed precisely. If none of the allowed Special Requirements appears to be sufficient, it is permissible to describe the requirements with a text explanation using the Visit_Comments keyword. You should contact your Program Coordinator prior to entering such a comment in your program.
Several of these Special Requirements require the use of limited resources or may impose serious constraints on the scheduling system (e.g., ORIENT, CVZ, BETWEEN). These Special Requirements should be used with care.
The visit-level Special Requirements are described in detail in Chapter7, Special Requirements [Visit_Requirements and Special_Requirements]. If more than one Special Requirement is needed for a visit, they should be separated by a space, carriage return, or semi-colon, but not by a comma.
5.4 On Hold Comments [On_Hold_Comments]
If you have requested via the Special Requirement ON HOLD that a given visit be placed "on hold" (which means that the visit will not be scheduled until you have cleared the hold), then indicate why the visit is on hold, and how the hold is to be released. Examples of On_Hold_Comments are:
- Target of Opportunity
- Waiting for Early Acquisition data from visit <number>
- Waiting for non-HST data [to be obtained <date>]
- Conditional if <text>
- Conditional on <exposure-list> if <text>
- Select <number> of <exposure-list>
5.5 Visit Comments [Visit_Comments]
The comments field shoud be used only to record observing notes; it should not be used to specify scheduling requirements. Comment lines are not interpreted by the software, but are maintained in the database and do appear on printouts of the programs. Please contact your Program Coordinator prior to inserting comments to make certain there is no other way to specify the information. An Example of a Visit_Comments is:
5.6 Exposure Number [Exposure_Number]
Exposure numbers provide a method for unique labeling of exposures within a visit. The line numbers must be positive, monotonically increasing (but not necessarily consecutive) unique integers; floating-point numbers are not allowed. The smallest exposure number permitted is 1, and the largest is 999.
Note that exposure numbers for coordinated parallels must be sequential; see 6.3 "Coordinated Parallels".
5.7 Target Name [Target_Name]
Normally, the name of an astronomical target from the Target List should be entered. In the case of certain internal calibration sources, a special code must be entered. In general, calibration observations will be requested only rarely, since most calibrations will be carried out by STScI (see the Call for =s).
Due to scheduling constraints, fixed external targets and solar system targets may not be used in the same visit. Also, none of the external calibration targets (EARTH-CALIB, ANTI-SUN, ORBIT-POLE-NORTH, ORBIT-POLE-SOUTH) may be used in the same visit with another external target.
5.7.1 Astronomical Targets
The target name should be entered exactly as it appears in the Target List (see 3.2 "Target Name [Target_Name and Alternate_Names]"). Only the prime target name (Target_Name) should be used; do not use the alternate names (Alternate_Names).
5.7.2 Special Targets
If an internal calibration observation is requested on the Visit and Exposure Specifications, one of the specific "target" names in Table 5.1 must be entered. The calibration source should not be entered in the Target List. See the Call for Proposals for discussions of the routine calibrations that will be performed by STScI. See the Instrument Handbooks for further details of the calibrations for each instrument.
Table 5.1: Internal Calibration Target Names
WAVE CCDFLAT
The special external targets listed in Table 5.2 may be specified in the Target_Name without including them in the Target List.
Table 5.2: Special External Target Names
Specific astronomical objects used as external calibrators (e.g., standard stars) should be entered in the Target List and Visit and Exposure Specifications as normal exposures, and the suffix -CALIB should be appended to their names, as discussed in 3.2.4 "Special Targets".
5.8 Instrument Configuration [Config]
Enter the Instrument Configuration to be used. The available choices are listed in Table 5.3, along with the corresponding Operating Modes that may be entered in "Opmode" (see 5.9 "Operating Mode [Opmode]"). Legal Apertures, Spectral Elements, and Optional Parameters are uniquely determined by the choice of the Instrument Configuration and Operating Mode. Detailed descriptions are provided in Part B of these Instructions and the Instrument Handbooks.
Table 5.3: Instrument Configurations and Operating Modes
WFPC2 IMAGE STIS/CCD ACQ, ACQ/PEAK, ACCUM STIS/FUV-MAMA or STIS/NUV-MAMA ACCUM, TIME-TAG FGS POS, TRANS NIC1 or NIC2 or NIC3 ACCUM, MULTIACCUM NIC2 ACQ ACS/WFC or ACS/SBC ACCUM ACS/HRC ACQ, ACCUM
5.9 Operating Mode [Opmode]
Enter the Operating Mode to be used. Table 5.3 lists all possibilities. See the Instrument Handbooks for a detailed discussion of each Operating Mode.
5.10 Aperture or Field of View [Aperture]
The desired aperture or field of view of the Scientific Instrument should be entered as defined in Table 5.4 below. However, observers are cautioned that not all combinations of Apertures, Operating Modes, and Spectral Elements are available. See the Instrument Handbooks for details.
Table 5.4: Aperture and Field of View Names
WFPC2 STIS FGS ACS NICMOS Wide variety of FOVs are available; refer to Chapter9, Wide Field Planetary Camera 2 (WFPC2) See Chapter10, Space Telescope Imaging Spectrograph (STIS) 1 2 3 See Chapter12, Advanced Camera for Surveys (ACS) NIC1, NIC1-FIX, NIC2, NIC2-ACQ, NIC2-CORON,NIC2-FIX, NIC3, NIC3-FIX
5.11 Spectral Element [Sp_Element]
The desired Spectral Element(s) should be entered. Spectral Elements include filters (F), gratings and grisms (G), echelles (E), prisms (PRISM), polarizers (POL), and mirrors (MIRROR). The names of the filters, gratings, grisms, and echelles include the wavelength of the approximate midpoint of the bandpass, in nanometers. More than one element may be specified, if necessary, using a comma to separate them (after confirming that the different elements can be used simultaneously, e.g., that they are not on the same filter wheel). Possibilities are listed in Part B of these Instructions and are described in the Instrument Handbooks.
Examples of the Spectral Element designations are the following:
5.12 Central Wavelength or Range if Grating or Prism Used [Wavelength]
If a linear ramp filter, quadrant filter, grating, or prism is to be used, the central wavelength should be entered. NICMOS exposures do not require a central wavelength or range.
Wavelengths should be expressed in Å in the observed frame (but the units should be omitted). Use vacuum wavelengths below 2000 Å, and air wavelengths above 2000 Å.
For STIS exposures, the central wavelength must obey one of the legal spectral element/wavelength combinations given in Table 10.2: Supported Central Wavelengths for STIS Gratings.
5.13 Optional Parameters [Optional_Parameters]
The Operating Modes of the instruments frequently have parameters that may be adjusted. The default parameter values that have been defined for the various Instrument Configurations and Operating Modes can be overridden by entries in Optional Parameters. See the instrument chapters in this document and the Instrument Handbooks for descriptions of the Optional Parameters.
If more than one Optional Parameter is entered, they can be separated by commas. The format that should be used is <parameter> = <value> (for example, BINAXIS1=1, BINAXIS2=1). If no entry is made, the default value will be used (e.g., BINAXIS1=1 would be used in STIS/CCD ACCUM Mode; see Section 10.4).
5.14 Number of Times to Iterate the Exposure
[Number_of_Iterations]Enter the number of times the defined exposure is to be iterated; enter 1 if only one execution of the exposure is desired. Typical reasons for iterating an exposure are to monitor temporal changes in a target or to keep CCD exposures short to minimize blooming by a bright star. If more than one execution is requested, the iterations will be obtained in a contiguous fashion. Also note that for STIS, these iterations can be interrupted by an autowavecal. The autowavecal can be suppressed; see SEQuence <exposure-list> NON-INTerruptible.
5.15 Time per Exposure [Time_Per_Exposure]
Enter the exposure time for each separate exposure, using units of either hours (H), minutes (M), or seconds (S). Do not combine H, M, and S on the same line (i.e., use 90M rather than 1H 30M). It is important that observers consult the Instrument Handbooks, and the tools on the STScI web pages.
Note that the exposure time is the total time for one execution of a defined exposure. Multiple executions may be specified by entering a value for Number_of_Iterations (see Section 5.14), or with certain Special Requirements. The exposure time entered may be divided among many subexposures, samples, or spectra, depending on the Instrument Configuration, Operating Mode, and Optional Parameters. Generally, the exposure time is used only for the collection of photons, but there are exceptions for which instrumental overheads are included in the exposure time. For details, see the specification for each Operating Mode in Part B of these Instructions. In the normal case, the exposure time entered may be used to obtain a single image, to obtain a series of spectra (ACCUM spectra with STIS using PATTERN, for example), or to perform a complex, autonomous target acquisition.
Routine calibration exposures will be performed by STScI. If special internal calibrations are required for your program, consult the Internal Calibration Target tables in Part B of these Instructions for information about what exposure times to use.
Use the Target Acquisition sections of the Instrument Handbooks and STScI web tools to estimate exposure times used for acquisition exposures.
Exposure times may be changed during scheduling by STScI in order to place exposures in observing windows defined by orbital constraints (Earth blockage, passage through the SAA, etc.) and to improve overall efficiency; the exposure-level Special Requirements EXPAND, MAX DUR, and MIN DUR (see "" for details) can be used to control these changes in exposure time. If no preference is specified by the observer, changes to exposure times will be such that the exposure time is not changed by more than about 20%; note that increases, as well as decreases, in exposure time are possible.
Target acquisition and peakup exposure times are not altered during scheduling.
5.16 Exposure-level Special Requirements
[Special_Requirements]A variety of exposure-level Special Requirements may be entered; these requirements apply to individual exposures in a visit (visit-level Special Requirements are discussed in Chapter7, Special Requirements [Visit_Requirements and Special_Requirements]). These requirements will be interpreted by the computer software that is used to schedule the observations; therefore it is absolutely essential that the specific formats shown in Chapter7, Special Requirements [Visit_Requirements and Special_Requirements] are followed precisely. If none of the allowed Special Requirements appears to be sufficient, it is permissible to describe the requirements with a text explanation using the "Comments" keyword. You should contact your Program Coordinator prior to entering such a comment in your program.
Several of these Special Requirements require the use of limited resources or may impose serious constraints on the scheduling system (e.g., RT ANALYSIS, REQ UPLINK). These Special Requirements should be used with care.
The exposure-level Special Requirements are described in detail in Chapter7, Special Requirements [Visit_Requirements and Special_Requirements]. If more than one Special Requirement is needed for a visit, they should be separated by a space, carriage return, or semi-colon, but not by a comma.
5.17 Exposure-level Comments [Comments]
Information that cannot be made to conform to the required formats may be entered as a comment. Comment lines are not interpreted by the software, but are maintained in the database and do appear on printouts of the programs. Comments should be used sparingly, if at all. They are intended only for the small number of programs whose requirements cannot be met with standard and supported features. Please contact your Program Coordinator before entering comments that would affect the execution of an expposure.
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