THEMIS Ground-based All Sky Imager Keogram, Level-1

Published by CDAWeb, THEMIS | National Aeronautics and Space Administration | Catalog Last Checked: September 09, 2026 at 12:12 AM | Dataset Last Updated: September 08, 2026

THEMIS Ground All Sky Imager Keograms for all observatories. Keograms are composed of thin images slices taken down the middle of all-sky images and graphed against time. Keograms allow for substorm analysis without the need for full sized raw images. The ASI stations each monitor a 170 degree field of view imaging the auroral oval at kilometer resolution. The ASI is comprised of a fisheye lens and CCD in a stainless steel enclosure topped with a transparent acrylic dome. Exposure control ranges from 5 s to 1 ms although the typical data rate is one image every 3 seconds. Silicone heaters keep the instrument within the nominal temperature range. During daylight hours a sun shades deploy to protect the CCD.

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Complete Metadata

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accessLevel	public
bureauCode	[ "026:00" ]
contactPoint	{ "fn": "NASA Space Physics Data Facility", "@type": "vcard:Contact", "hasEmail": "mailto:NASA-SPDF-Support@nasa.onmicrosoft.com" }
description	THEMIS Ground All Sky Imager Keograms for all observatories. Keograms are composed of thin images slices taken down the middle of all-sky images and graphed against time. Keograms allow for substorm analysis without the need for full sized raw images. The ASI stations each monitor a 170 degree field of view imaging the auroral oval at kilometer resolution. The ASI is comprised of a fisheye lens and CCD in a stainless steel enclosure topped with a transparent acrylic dome. Exposure control ranges from 5 s to 1 ms although the typical data rate is one image every 3 seconds. Silicone heaters keep the instrument within the nominal temperature range. During daylight hours a sun shades deploy to protect the CCD.
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identifier	https://doi.org/10.48322/a2pk-b377
keyword	[ "imageintensity" ]
landingPage	https://doi.org/10.48322/a2pk-b377
license	https://www.usa.gov/government-works
modified	2026-09-08
programCode	[ "026:000" ]
publisher	{ "name": "CDAWeb, THEMIS", "@type": "org:Organization" }
theme	[ "Heliophysics" ]
title	THEMIS Ground-based All Sky Imager Keogram, Level-1

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