# FAQs

### I never received an account invitation email. What should I do?

Please check your spam inbox. If you still don't see the invitation email, reach out to <support@hydrosat.com> for assistance.

### I received my temporary password, but I see an error when I try to connect to the API. What's happening?

You may encounter a `500 Internal Server Error` if you attempt to connect to the API without first resetting your temporary password.     &#x20;

To reset your temporary password, please follow the instructions [here](/overview.md#getting-started-with-hydrosat-data).

### Can I browse the catalog even if I haven't ordered any data?

Yes! Please email <support@hydrosat.com> requesting a demo account.&#x20;

You can also check out our Open Data Program, which you won't need an account to access.

### What is STAC?

STAC stands for "SpatioTemporal Asset Catalog". It's a standardized framework for indexing, cataloging, and describing geospatial data. It makes Hydrosat data easier to work with, especially if you're integrating it with data from other sources.

### What do the different assets in a STAC item represent?

Each STAC item includes several assets representing the individual data and metadata files associated with the scene. Items from different collections have different assets, as defined below and on our [Product Details](/product-details.md) page.

<details>

<summary>vz-viri-l1a</summary>

<table><thead><tr><th width="214">Asset</th><th width="392">Description</th><th>File Type</th></tr></thead><tbody><tr><td>BLUE</td><td>Blue band digital number (DN) values</td><td>COG</td></tr><tr><td>GREEN</td><td>Green band DNs</td><td>COG</td></tr><tr><td>NIR</td><td>NIR band DNs</td><td>COG</td></tr><tr><td>RED</td><td>Red band DNs</td><td>COG</td></tr><tr><td>REDEDGE1</td><td>Red edge 1 band DNs</td><td>COG</td></tr><tr><td>REDEDGE2</td><td>Red edge 2 band DNs</td><td>COG</td></tr><tr><td>REDEDGE3</td><td>Red edge 3 band DNs</td><td>COG</td></tr><tr><td>QUALITY_ASSURANCE</td><td>Radiometric saturation mask</td><td>COG</td></tr><tr><td>PREVIEW</td><td>Full-resolution RGB preview image</td><td>COG</td></tr><tr><td>THUMBNAIL</td><td>Low-resolution RGB thumbnail </td><td>PNG</td></tr><tr><td>METADATA</td><td>Ancillary metadata file</td><td>JSON</td></tr></tbody></table>

COGs from the vz-viri-l1a collection are provided at the resolution of the VIRI sensor (\~30 m).

</details>

<details>

<summary>vz-liri-l1a</summary>

<table><thead><tr><th width="214">Asset</th><th width="392">Description</th><th>File Type</th></tr></thead><tbody><tr><td>LWIR1</td><td>LWIR 1 band digital number (DN) values</td><td>COG</td></tr><tr><td>LWIR2</td><td>LWIR 2 band DNs</td><td>COG</td></tr><tr><td>QUALITY_ASSURANCE</td><td>Radiometric saturation mask</td><td>COG</td></tr><tr><td>PREVIEW_LWIR</td><td>Full-resolution LWIR preview image</td><td>COG</td></tr><tr><td>THUMBNAIL</td><td>Low-resolution thumbnail </td><td>PNG</td></tr><tr><td>METADATA</td><td>Ancillary metadata file</td><td>JSON</td></tr></tbody></table>

COGs from the vz-liri-l1a collection are provided at the resolution of the LIRI sensor (\~70 m).

</details>

<details>

<summary>vz-l1b</summary>

<table><thead><tr><th width="214">Asset</th><th width="392">Description</th><th>File Type</th></tr></thead><tbody><tr><td>BLUE</td><td>Blue band digital number (DN) values</td><td>COG</td></tr><tr><td>GREEN</td><td>Green band DNs</td><td>COG</td></tr><tr><td>NIR</td><td>NIR band DNs</td><td>COG</td></tr><tr><td>RED</td><td>Red band DNs</td><td>COG</td></tr><tr><td>REDEDGE1</td><td>Red edge 1 band DNs</td><td>COG</td></tr><tr><td>REDEDGE2</td><td>Red edge 2 band DNs</td><td>COG</td></tr><tr><td>REDEDGE3</td><td>Red edge 3 band DNs</td><td>COG</td></tr><tr><td>LWIR1</td><td>LWIR 1 band DNs</td><td>COG</td></tr><tr><td>LWIR2</td><td>LWIR 2 band DNs</td><td>COG</td></tr><tr><td>QUALITY_ASSURANCE</td><td>Radiometric saturation mask</td><td>COG</td></tr><tr><td>CLOUD_MASK</td><td>Mask indicating cloud, cloud shadow, and snow or ice</td><td>COG</td></tr><tr><td>PREVIEW</td><td>Full-resolution RGB preview image</td><td>COG</td></tr><tr><td>PREVIEW_LWIR</td><td>Full-resolution LWIR preview image</td><td>COG</td></tr><tr><td>THUMBNAIL</td><td>Low-resolution RGB thumbnail </td><td>PNG</td></tr><tr><td>METADATA</td><td>Ancillary metadata file</td><td>JSON</td></tr></tbody></table>

COGs from the vz-l1b collection are provided at 30 m resolution.

</details>

<details>

<summary>vz-l2</summary>

<table><thead><tr><th width="214">Asset</th><th width="392">Description</th><th>File Type</th></tr></thead><tbody><tr><td>BLUE_SR</td><td>Blue band surface reflectance</td><td>COG</td></tr><tr><td>GREEN_SR</td><td>Green band surface reflectance</td><td>COG</td></tr><tr><td>NIR_SR</td><td>NIR band surface reflectance</td><td>COG</td></tr><tr><td>RED_SR</td><td>Red band surface reflectance</td><td>COG</td></tr><tr><td>REDEDGE1_SR</td><td>Red edge 1 band surface reflectance</td><td>COG</td></tr><tr><td>REDEDGE2_SR</td><td>Red edge 2 band surface reflectance</td><td>COG</td></tr><tr><td>REDEDGE3_SR</td><td>Red edge 3 band surface reflectance</td><td>COG</td></tr><tr><td>LWIR1_BT</td><td>LWIR 1 band brightness temperature</td><td>COG</td></tr><tr><td>LWIR2_BT</td><td>LWIR 2 band brightness temperature</td><td>COG</td></tr><tr><td>LWIR1_EMIS</td><td>LWIR 1 band emissivity</td><td>COG</td></tr><tr><td>LWIR2_EMIS</td><td>LWIR 2 band emissivity</td><td>COG</td></tr><tr><td>LST</td><td>Land surface temperature</td><td>COG</td></tr><tr><td>LST_UNCERTAINTY</td><td>Land surface temperature uncertainty</td><td>COG</td></tr><tr><td>QUALITY_ASSURANCE</td><td>Radiometric saturation mask</td><td>COG</td></tr><tr><td>CLOUD_MASK</td><td>Mask indicating cloud, cloud shadow, and snow or ice</td><td>COG</td></tr><tr><td>PREVIEW</td><td>Full-resolution RGB preview image</td><td>COG</td></tr><tr><td>PREVIEW_LST</td><td>Full-resolution LST preview image</td><td>COG</td></tr><tr><td>THUMBNAIL</td><td>Low-resolution RGB thumbnail </td><td>PNG</td></tr><tr><td>THUMBNAIL_LST</td><td>Low-resolution LST thumbnail</td><td>PNG</td></tr><tr><td>METADATA</td><td>Ancillary metadata file</td><td>JSON</td></tr></tbody></table>

COGs from the vz-l2 collection are provided at 30 m resolution.

</details>

### I only see thumbnail assets for certain scenes. Where's the rest of the data?

You have full access to the scenes you've ordered and thumbnail access to the rest of the catalog.

### What do the different values in the cloud mask mean?

The cloud mask encodes information about clear or cloudy conditions present within each pixel.&#x20;

Specifically, the cloud mask contains bit-packed pixel values; each pixel value is a decimal representation of binary strings, in which each bit represents a different condition.

For simplicity, we recommend using the look-up table below. The table displays common pixel values and their meanings.&#x20;

<table><thead><tr><th data-type="number">Value</th><th data-type="checkbox">Clear</th><th data-type="checkbox">No data</th><th data-type="checkbox">Cloud</th></tr></thead><tbody><tr><td>0</td><td>true</td><td>false</td><td>false</td></tr><tr><td>1</td><td>false</td><td>true</td><td>false</td></tr><tr><td>2</td><td>false</td><td>false</td><td>true</td></tr></tbody></table>

If you see a value of 2 in the cloud mask, for example, this would indicate cloudy conditions.

You can also review our how-to guide on using the cloud mask for additional information.

### How can I use Hydrosat data with Google Earth Engine?

We recommend using the [Google Earth Engine Python API](https://developers.google.com/earth-engine/guides/python_install) along with the [xee](https://github.com/google/Xee) extension to smoothly integrate the two data sources.

### I want to learn more about Hydrosat's data products. Where can I find more information?

You can find additional details in our product guide. Please reach out to your organization point of contact if you don't already have this document.


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