BJ3A
50 cm multispectral, China's Beijing-3A satellite — wide swath for sub-meter
When to use
- Stereo capture for DSM generation
- Wide-swath captures (23.5 km — wider than most 50 cm sensors)
- Cost-effective alternative to MAXAR for sub-meter work
When it's the wrong fit
- Customers with regulatory restrictions on Chinese data
- Sub-50 cm resolution needs
Processing levels
Five processing levels. Levels 1–3 are applied by default on every order; pansharpening (4) runs automatically when the sensor has a panchromatic band; mosaicking (5) runs automatically when the AOI spans multiple scenes. Specify any level explicitly if you need to override the default.
| L | Output | What's applied | Status |
|---|---|---|---|
| 0 | Raw | Digital numbers (sensor counts) with no calibration or geometric correction. Delivered as unprojected GeoTIFF with sensor metadata. | On request |
| 1 | Orthorectified | Geometric correction onto a DEM. Every pixel sits at its true ground position. Customer-supplied GCPs accepted at no extra cost. | Default |
| 2 | Surface reflectance | TOA radiometric correction plus atmospheric correction. Output is the actual fraction of light reflected by the ground, comparable across dates, sensors, and sun angles. | Default |
| 3 | Pansharpened | Gram-Schmidt fusion of panchromatic and multispectral bands. Spectral ratios preserved for downstream analytics. | Default |
| 4 | Mosaicked | Seamless multi-scene composite over the AOI with ML cloud/cirrus masking and custom seam-line path-finding. Applied automatically when the AOI spans more than one scene. | Default* |
*Mosaicking applies when the AOI spans more than one scene. Single-scene orders skip it.
Water masks, tree masks, glint handling, lidar-aligned reflectance, aquatic atmospheric correction, region-tuned models — anything your downstream pipeline requires. Quoted with the order.
DSM (digital surface model) and DTM (digital terrain model), priced per area. This sensor supports stereo capture, required for elevation products.
Specifications
| General | |
| Provider | 21AT (Twenty-First Century Aerospace Technology) |
| Country | China |
| System type | Satellite |
| Product type | Multispectral |
| Availability | Tasking and catalog |
| Available since | 2021 |
| Sensor | |
| Resolution | Panchromatic: 50 cm · Pansharpened: 50 cm · Multispectral: 2 m |
| Bit depth | 8-bit, 16-bit |
| Swath width | 23.5 km |
| Off-nadir range | Up to 45° |
| Constellation | 1 satellite (Beijing-3A (BJ-3A)) |
| Orbit | Sun-synchronous, 500 km |
| Revisit | Every 4 days — in practice 4–8 days |
| Acquisition modes | Mono, Stereo (tasking) |
| Reference | |
| CRS | Geographic-WGS84 |
| Positional accuracy | < 10 m CE90 absolute |
| Processing levels | Primary/Georectified with TOA radiometric processing; Level 4 upon request |
| Tasking and catalog conditions | |
| Minimum AOI width | tasking 3 km wide · catalog 3 km wide |
| Minimum charge area | tasking 70 km² · archive 25 km² |
| Geographic restrictions | Chinese ground station coverage. Geographic restrictions in some areas. Some government and defence customers cannot use Chinese imagery for regulatory reasons. |
Spectral bands
| Band | Designation and wavelength |
|---|---|
| Blue | 450-520 nm |
| Green | 520-590 nm |
| Red | 630-690 nm |
| NIR | 770-890 nm |
Delivery manifest
Each order delivers as a single archive containing the following files.
bj3a_[order_id].zip
├── data/ 4 band files, GeoTIFF, 8-bit
├── metadata.xml acquisition parameters, calibration coefficients
├── metadata.txt human-readable summary
├── masks/ cloud, transparency
├── thumbnails/ PNG previews
└── overviews/ JPEG quicklook
Compare with
Closest alternatives by resolution and product type.
| Spec | BJ3A | Göktürk-1 | Jilin-1 | KOMPSAT-3 |
|---|---|---|---|---|
| Resolution | 50 cm | 50 cm | 50 cm | 50 cm |
| Provider | 21AT (Twenty-First Century Aerospace Technology) | IMPROSAT (Turkish Air Force) | Chang Guang Satellite Technology (CGST) | SIIS (KARI) |
| Country | China | Türkiye | China | South Korea |
| Type | Multispectral | Multispectral | Multispectral | Multispectral |
| Availability | Tasking + catalog | Tasking + catalog | Tasking + catalog | Tasking + catalog |
Spectral indices
87 spectral indices are compatible with BJ3A. The most-used: NDVI,EVI,NDWI,SAVI,GNDVI,MSAVI. See the full spectral profile for the complete list and band mappings.
Ready to order BJ3A?
Browse the catalog, place a tasking order, or request a custom processing pipeline through the Geopera portal. We respond to quote requests within one business day.