Image composed of a virtual collection of a kernel, operating system, and configuration.
Glance is the API-driven OpenStack image service that provides services and associated libraries to store, browse, register, distribute, and retrieve bootable disk images. It acts as a registry for virtual machine images, allowing users to copy server images for immediate storage. These images can be used as templates when setting up new instances.
NERC Images List
NERC provides a set of default images that can be used as source while launching an instance:
How to create and upload own custom images?
Beside the above mentioned system provided images users can customize and upload their own images to the NERC, as documented in this documentation.
Please refer to this guide to understand more on how can you get other virtual machine images to the NERC's OpenStack platform.