Topic: GOES Spring 2018 Eclipse and Keep Out Zone/Stray Light Exclusion Schedules and Impacts

Date/Time Issued: February 12, 2018 1750 UTC

Product(s) or Data Impacted: GOES-16 (GOES-East) ABI and GLM data and GOES-15 (GOES-West) Imager and Sounder Data

Date/Time of Initial Impact: February 5, 2018 0415 UTC

Date/Time of Expected End: May 4, 2018 0545 UTC

Length of Outage: M-BSee details below

Details/Specifics of Change:

The Spring 2018 Eclipse and Keep Out Zone (KOZ)/Stray Light Exclusion (SLZ) schedules are now available on our web page at http://www.ospo.noaa.gov/Operations/GOES/eclipse.html

For your convenience, the eclipse schedules are provided in HTML, Excel (1997-2003 and 2007-2010), and Adobe PDF formats. The schedules are for both the Imager and the Sounder instruments for GOES-15 (GOES-West).

During eclipse season with the GOES-R satellite series Advanced Baseline Imager (ABI), stray light contamination is visible approximately 45 minutes before and after satellite local midnight (~0500 UTC for GOES-East) which is approximately 45 days before and after the vernal (March 20, 2018) and autumnal (September 22, 2018) equinox, in the form of a vertical beam of light that is more intense at the end closer to the Sun. Stray light contamination is often prominent in the images of visible and near infrared bands (bands 1M-bM-^@M-^S6), although it can also be discerned in band 7 images. This is a normal occurrence for the ABI.

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Stray light contamination and truncated swaths during the GOES-East Spring 2018 eclipse season will be apparent on ABI imagery:

- Starting February 5, 2018 from approximately 0415 UTC - 0545 UTC each day in the Southern Hemisphere until March 20, 2018.

- Starting March 20, 2018 from approximately 0415 UTC - 0545 UTC each day in the Northern Hemisphere until May 4, 2018.

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During eclipse season with the GOES-R satellite series Geostationary Lightning Mapper (GLM), M-Bsolar intrusion into the lens assembly will result in localized blooming (false events) and saturation (blind regions) in the data. These effects will occur daily around the same time as the ABI (0415 UTC - 0545 UTC). The daily effects begin with many false events at the limb, which cover regions of varying size and location as the eclipse features move across the field of view. The false events will peak during the beginning and end of the eclipse season (~end of February and mid-April) and the 20-second files will intermittently peak in size above 3-5 MB per file during false events, which is well above the average of ~0.3 MB per file.

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The increased number of false events can cause an overflow condition in the electronics which saturates the event processing. This saturation creates blind regions in the data outside of the areas impacted by the solar intrusion. The length of these temporary outages depends on the region, and is on the order of minutes. A blooming filter is being developed to remove the event spikes, although lightning detection outages will remain in the affected regions. A data quality product is under development to notify users of impacts during future eclipse seasons.

Contact Information for Further Information: ESPC Operations at ESPCOperations@noaa.gov or 301-817-3880 or SPSD User Services at SPSD.UserServices@noaa.gov

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Web Site(s) for applicable information:

See http://www.ospo.noaa.gov/Operations/GOES/eclipse.html for full eclipse schedules.

See http://www.ospo.noaa.gov/Operations/GOES/schedules.html for full GOES scanning schedules and scan sectors.

See http://www.ssd.noaa.gov/PS/SATS/messages.html for this and other satellite related messages.

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