Inputs

Input Coordinates

The user may enter the input coordinates or resolve a Target Name using the Resolve Name button.

Coordinate System

Select the coordinate system for specifying the column direction. The Resource Cost Calculator supports the following choices:

Equatorial (J2000) - Equatorial w/ Julian epoch J2000
Ecliptic (B1950) - Ecliptic w/ Besselian epoch B1950

Coordinates

Input a set of coordinates in the format of the selected coordinate system or resolve a target name which will set the RA/Dec coordinates in J2000. The supported coordinate ranges are listed below.

EQUATORIAL - RA - Right Ascension, given in either sexagesimal or decimal format. Sexagesimal values are specified as "hh mm [ss[.ss]]" (that is, hours and minutes are required, seconds and fractions of seconds are optional). The range for RA is:
Sexagesimal 00 00 00.00 to 24 00 00.00
Decimal 00.00 to 360.00
EQUATORIAL - Dec - Declination, given in either sexagesimal or decimal format. Sexagesimal values are specified as "sdd mm [ss[.ss]]". The range for Dec is:
Sexagesimal -90 00 00.00 to 90 00 00.00
Decimal -90.00 to 90.00
ECLIPTIC - EL - Ecliptic Longitude, given in either sexagesimal or decimal format. Sexagesimal values are specified as "hh mm [ss[.ss]]". The range for EL is:
Sexagesimal 00 00 00.00 to 24 00 00.00
Decimal 00.00 to 360.00
ECLIPTIC - EB - Ecliptic Latitude, given in either sexagesimal or decimal format. Sexagesimal values are specified as "sdd mm [ss[.ss]]". The range for EB is:
Sexagesimal -90 00 00.00 to 90 00 00.00
Decimal -90.00 to 90.00

Enter a valid target name and click the Resolve Name button. This will query the catalog[s] specified in the Name Resolver field.

If one, and only one entry is found, the coordinates will be displayed in J2000. If no entry is found or more than one entry is retrieved, the user will be asked to modify the Target Name and try again.

Name Resolver

Name of the service or services that will be used to resolve the target name when the Resolve Name button is pressed. The services will be chosen in the specified order. For example, "NED/SIMBAD" will first search for the target name in NED and then, if the name was not found, in SIMBAD.

Proposed Exposure Time

The total exposure time in kiloseconds for requested observation of this target.

Science Instrument

Specifies which detector will be on the optical axis during the observation. The choices are: ACIS-I, ACIS-S, HRC-I, or HRC-S.

Required Chip Count

Required Chip Count for ACIS Instruments. Valid input range is 1 to 4.

If an HRC Instrument is selected, the Chip Count is defaulted to zero.

Constraints

The addition of a constraint (or multiple constraints) will increase the final resource cost. When stepping through each day of the cycle and determining the visibility of a target, the constraint is taken into account. If the constraint makes the target not visible on a day (e.g., a window, roll, uninterrupt, or phase constraint) that target will get a score of 0 on that day. Otherwise, the visibility score for the target is divided by a number based on the difficulty of the constraint. The more difficult the constraint, the larger the dividing number and the lower the score for a given day.

Uninterrupt Constraint

Value indicating that the science can only be optimized if the observation is interrupted as little as possible.

Options are: Y (Yes, required), N (No). The default is 'N'.
'Y' indicates that the science goals can only be achieved if the observation is not interrupted.

Observations >180 ksec will have to be interrupted due to the satellite orbit. If the uninterrupted flag is checked, the observations are constrained such that the pieces will be observed as contiguously as possible, and certainly in adjacent spacecraft orbits.

'Uninterrupted' and 'Split Interval' observations are mutually exclusive.

Split Constraint

Value indicating whether, if the observation is split into shorter segments during scheduling, all parts must be completed within a defined interval.

Options are: Y (Yes, required), N (No). The default is 'N'.

Split Interval
Relative Time Interval between segments of the observation if it is split during scheduling; all segments of the observation are to occur within this interval, from the beginning of the first to the end of the last. Valid range is: Split Interval >= Proposed Exposure Time and < 731 days.

'Uninterrupted' and 'Split Interval' observations are mutually exclusive.

'Grouping' and 'Split Interval' observations are mutually exclusive.

Coordinated Observation

Must this observation be coordinated with that of another observatory? Value indicating that the Chandra observations are to be coordinated with another observatory.

Coordination Window
Time Interval for coordinated observations. Valid range is 0.0 - 364.0 days.

Phase Constraint

Phase Dependent Observation. Value indicating that the observation is to be performed only within a specified phase range for a periodically-varying target.

Options are: Y (Yes, required), N (No). The default is 'N'.

Epoch (MJD)
For Phase Dependent observations, the reference date (MJD) corresponding to a phase of 0.0. Observations will be made at an integral number of Periods from this date, plus offsets as needed to locate the observations within the specified phase range. The reference date must be within 5 years of the current date.
Period (days)
The period in days characterizing the target variability.
Minimum Phase
Minimum phase in the variable phenomenon to be observed. Values must be between 0 and 1.
Minimum Phase Error
Tolerance in the minimum phase. This parameter sets how precisely the phase range will be covered. Values must be between 0 and 0.5.
Maximum Phase
Maximum phase in the variable phenomenon to be observed. Values must be between 0 and 1.
Maximum Phase Error
Tolerance in the maximum phase. This parameter sets how precisely the phase range will be covered. Values must be between 0 and 0.5.
Unique Phase
If a phase constrained observation is split and the observations end up in different phase windows, do the split observations need to sample unique parts of the phase window, or can they overlap?
Options are: Y (Yes, sample unique parts of phase window), N (No, they can overlap).

Pointing Constraint

Value indicating that the final pointing information/offsets need to be modified based upon the roll angle.

Options are: Y (Yes, required), N (No). The default is 'N'.

Group Constraint

Logical value indicating whether the observation needs to be observed within a relative time range with other targets in this proposal.

Options are: Y (Yes, required), N (No). The default is 'N'.

Maximum Time Interval
Relative Time Interval for grouping observations; all observations are to occur within this interval, from the beginning of the first to the end of the last. Valid range is 0.0 - 364.0 days.

'Monitoring' and 'Grouping' observations are mutually exclusive.

'Grouping' and 'Split Interval' observations are mutually exclusive.

Monitor Constraint

Logical value indicating whether the observation needs to be observed more than 1 time.

Options are: Y (Yes, required), N (No). The default is 'N'.

Exposure Time
Exposure time in kiloseconds allocated for each observation. The total of the exposure times must equal the time specified in the Total Observing Time field.
Minimum Time Interval
Minimum interval from the end of the preceding observation to the beginning of the current observation in days. Valid range is 0.0 - 364.0 days.
Maximum Time Interval
Maximum interval from the end of the preceding observation to the beginning of the current observation in days. Valid range is 0.0 - 364.0 days.
Split Interval
Relative Time Interval between observations if they need to be split; all observations are to occur within this interval, from the beginning of the first to the end of the last.
For Monitor series observations, valid range is: Split Interval < Maximum Time Interval - Minimum Time Interval

'Monitoring' and 'Grouping' observations are mutually exclusive.

Window Constraint

Logical value indicating a window constraint exists for this observation.

Options are: Y (Yes, required), N (No). The default is 'N'.

Start Time
The time in UT specifying the earliest observation start time.
Stop Time
The time in UT specifying the latest observation end time.

Field Input:

Browsers that support the Calendar Widget (e.g. Safari v14.1+, Firefox v93+, Chrome v20+ )
- The widget will pop-up to aid in selecting the date-time in the format:
  mm/dd/yyyy hh:mm:ss.sss [AM|PM]
  Note: Depending on the specific browser being used, some time fields may need to be manually set.
Browsers that do not support the widget (e.g. Firefox versions below v93)
- Users should manually enter the date-time in the following format:
  YYYY:DOY:HH:MM:SS.sss (DOY = Day Of Year)
  Note: The Dates application in this toolkit can help with obtaining Year and DOY from a calendar date.

Roll Constraint

Value indicating a roll constraint exists for this observation.

A roll constraint translates directly into a constraint on the day and time when an observation may be carried out. It should only be specified for cases in which a specific attitude is required to meet scientific objectives.

Options are: Y (Yes, required), N (No). The default is 'N'.

Roll Angle and Roll Tolerance
The spacecraft roll angle and roll tolerance (defined as the half-range and assumed symmetric) for the observation. Valid range is 0.0 - 360.
Is 180 Rotation OK?
Logical value indicating whether a 180 degree rotation of the roll angle is acceptable. The default is 'N'.

Results

Resource Cost

The normalized resource cost to Chandra for any target.

The resource cost is an estimate of how difficult a given observation would be, based on (at the very least) the location of the target in the sky (its visibility) and the length of the exposure. Constraints are also taken into account and increase the resource cost of a target. The more difficult the constraint, the larger the final resource score will be. In cases where the proposed observation cannot be performed as specified (e.g., long, uninterrupted ACIS exposures) the resource cost calculator may return the value "Inf", indicating an infinite resource cost. In this case the user must consider whether they can reduce the constraints on the observation (e.g., by removing the uninterrupt constraint) while still meeting their science goals.

The total RC budget for a given cycle is available in the Call for Proposals. For further details regarding the Resource Cost numerical value, please refer to the CfP at:
https://cxc.harvard.edu/proposer/CfP