Use Cases

The protocols proposed here are the foundation for the implementation of a service by observatories. A service is not to be confused with a tool, a service is an interface allowing the extraction of information via a query while a client performs the queries depending on the purpose of the tool.

For example, currently, observatories operate visibility tools which all have different user interfaces and output formats. Once the observatories offer a standardized service to extract visibility information, a mulitple visibility tool can be developed that uses the same queries for multiple observatories and display visibility for each observatory as a function of time. A demonstrator of such a tool can be accessed at:

http://integral.esa.int/toby

A much more complex application would be a multimessenger platform, and initial plans are outlined in this document from the ASTERICS project:

https://www.asterics2020.eu/sites/default/files/documents/asterics-d5.16.pdf

An important element to obtain approval from the IVOA, are use cases that demonstrate that the proposed standards are of common use. Some initial examples are given here.

1. Science Operations

a) Long-term planning

of a large number of observations for simultaneous execution with various observatories. Communication with mission planners is still needed, but conversion is much faster if:

    Visibility services are used for the observatories to identify a list of common visibility slots
    The long-term plan information for the various observatories is taken into account to identify time intervals that are not planned yet.

For each target, a list of time intervals when all observatories can observe and when they are also free can be generated.

b) Coordinate a fast-response Target of Opportunity campaign

Use visibility services to get list of common visibility slots

Priorities of planned observations in each involved observatory can be used to rank the common visibility slots to minimize scientific impact at least to those observatories providing priority information on planned observations.

On short notice, no free slots can be expected, but if priority flags are provided by each observatory, flexible observations that can be postponed can be identified as potentially feasible slots.

2. Following large observatories

A small observatory (or even private garden observatory) wants to follow observations of a large observatory without interaction: The observation locator service gives the information of scheduled observing times.

3. Multi-messenger Observations

Schedule multi-band observations with diverse constraints (e.g. ground-based only during night, space-based only during certain positions in the orbit) at a fixed phase of a binary systemw ith known orbital period: Visibility information from above can be folded with the ephemeris of the target to find out whether there is any coinciding times the desired phase can be covered by all facilities. If more than one possibility is found, planning information can be used to rank them.

4. Science Exploration

1. A scientist is interested in one particular target and wants to plan new observations without duplicating existing efforts: A query on target coordinates without any time limits to all participating observatories gives a list of performed and planned future observations giving an idea of the gaps that need to be filled.

2. A scientist is analyzing data of one observatory and wants to know whether other observatories observed the same target, possible even during the same time, e.g., silently followed: A multiple query on past observations of all participating observatories, filtered on target coordinates (and time interval if contemporaneous data are desired), gives this information.

3. A scientist wants to find all observations of Jupiter that were taken simultaneously with a radio and an X-ray telescope: A tool that takes the planet ephemeris as input makes queries for short consecutive time intervals and the respective sky coordinates to the radio and X-ray telescopes of interest. Positive output is recorded and simultaneous coverage can then easily be identified.