About the Daily Satellite Passes App

On this page

What the app does
How to use the app
Download formats
Time zone information
Limitations
Acknowledgements

What the app does

This app contains information about the flight paths of the most popular public good satellites used by researchers in academia and public and private sector organisations in Australia.

For a given date, the app:

• determines start and end times when a specific satellite is visible from a selected ground station in the ANGSTT network (i.e. the time interval when an antenna at a specific location can be used to download data from the satellite)
• filters the satellite paths that intersect with a user-defined location (i.e. the daily passes that capture data for the specified area of interest)

How to use the app

Selecting satellites

1. Click the satellite icon:
2. Click the checkboxes next to the satellites of interest.
3. Close the pop-up window by clicking the 'X' icon or grey area outside of the window. The content will be refreshed based on your selection.

By default, only a single satellite (TERRA) is selected for calculating timings and footprints.

Only one footprint at a time can be viewed on the map, but all footprints are included in the downloadable GeoJSON file.

Selecting a date

1. Click the calendar icon:
2. Click on desired date.
3. Close the pop-up window.

Information is available for a single day only. Selecting all combinations of satellites and stations over a 24-hour time range can generate over 400 results.

Selecting the time interval and time zone

1. Click the clock icon:
2. Adjust slider to display the desired time range.
3. Optional: select the desired time zone.
4. Close the pop-up window.

By default, the applied time filter is 8am-6pm.

Selecting stations

1. Click the location icon:
2. Click the checkboxes next to the stations of interest.
3. Close the pop-up window.

By default, only a single downlink station (Alice Springs) is selected for calculating timings and footprints.

Filtering results by a user-defined location

1. Click the location icon:
2. Click the checkbox next to 'Select location'.
3. Type in the latitude and longitude coordinates and close the pop-up window. Alternatively, close the pop-up window and select a point on the map
4. The footprints that intersect with the chosen location will be displayed automatically.
5. To switch off this option, repeat steps 1 and 2 above.

Download formats

The flight path information can be downloaded in a tabular format (csv file) or as footprints in GeoJSON format for use in GIS software.

Both download options (csv and GeoJSON format) are displayed in the UTC time zone regardless of the time zone you select.

CSV

1. To download the csv file, click the 'table' icon in the top right corner:

GeoJSON

1. To download the GeoJSON footprint, click the ‘footprints’ icon in the top right corner:

Time zone information

The displayed date and time range are relative to the time zone.

There are four time zone options:

• AEST, Australian Eastern Standard Time
• ACST, Australian Central Standard Time
• AWST, Australian Western Standard Time
• UTC, Coordinated Universal Time

The default time zone corresponds to your browser location, but you can select any of the above time zones.

Example

If you are located in Eastern Australia, the reference time zone applied to all calculations will be Australian Eastern Standard Time (AEST). The ‘day’ starts at 0:00 and ends at 24:00 +10 hours relative to UTC.

However, if you select ‘UTC’ as a reference time zone, the ‘day’ starts and ends 14 hours earlier than the AEST time zone.

Limitations

• The timing and footprints of satellite overpasses are calculated in the browser based on the parameters specified in a two-line element set (TLE) from SpaceTrack.org. These parameters are updated once a day and are republished by Geoscience Australia as a free service (link).
• The timings and footprints are relevant for a selection of ground stations in the ANGSTT network (i.e. operating on the Australian continent only). Some ground stations are omitted, such as those operating in Antarctica.
• Satellite overpass timings and footprints are accurate only within a few days of the current date. The information should be used with caution for dates lagging or exceeding the current date by more than 10 days.
• 'Start' and 'end' times indicate the earliest and latest time a particular satellite is visible from a given location. They are based on the location’s altitude and minimum angle the antenna can see over the horizon. That angle is set between 2 and 5 degrees for different stations to better reflect actual acquisition capabilities of each ground station.
• A satellite may be visible from a particular ground station, but it does not mean the station is used for, or is capable of, transferring the data acquired by that satellite. E.g. no data from the Sentinel constellation of satellites is downloaded by the ANGSTT network of ground stations.
• Calculated 'start' and 'end' times may not precisely reflect actual acquisition schedules of individual ground stations in the ANGSTT network. The differences could be due to:
1. stations not having the capability of downlinking the data from a particular satellite
2. stations not having the capacity to downlink data from multiple satellites at the same time (hence only higher priority satellites are scheduled for downlink to a particular station)
3. ground station operators adjusting the acquisition time to accommodate satellites passing in quick succession and/or to limit data acquisition over the open ocean
4. for various operational purposes, operators specifying different parameters to those used as input into calculations in this app

Acknowledgements

This application is written in HTML5 and JavaScript.

It uses third party data and open source libraries, including:

• TLE information from SpaceTrack.org
• ground station locations from angstt.gov.au
• base map by OpenStreetMap contributors
• jquery
• jquery UI
• leafletjs
• momentjs
• momentjs timezones
• satellite.js
• jspredit
• vector3djs
• latlon-ellipsoidal.js
• latlon-vincenty.js
• dms.js
• ResizeSensor.js
• ElementQueries.js
• dataTables.js