Analyst guide · Geolocation & Tracking
Direct answer: Compare only valid observations of normally lit locations when assessing new darkening. Distinguish image-supported change from a field-confirmed electricity outage.
A practical verification workflow
- Establish the baseline and identify cells that were normally lit. A place already dark in the baseline is not evidence of a new outage merely because it remains dark.
- Apply the current quality mask before counting. Cloud-obscured or otherwise invalid cells should remain unknown rather than being reassigned to dark or unaffected.
- Calculate changed cells and area using the declared pixel size. Show the valid-comparison denominator so a percentage can be reproduced.
- Compare imagery with independent infrastructure or field records. Label the subset that has confirmation instead of making every image anomaly a confirmed service failure.
A separate worked illustration
A fictional tile has 40 normally lit cells, but clouds hide ten of them in the later image. If six of the thirty valid cells darken, the observation is six darkened cells among thirty valid comparisons. The ten obscured cells cannot be used to imply either working power or confirmed failure.
The common reasoning error
Palette colours are display choices, and darkness has more than one possible cause. Keep the measured image change narrower than a causal outage claim unless independent evidence supports that cause.
Keep an auditable analyst note
Record the question, source identifier, original observation, conversion or calculation, and the narrow conclusion it supports. Separate a confirmed fact from an inference and from information that is still unknown. Keep the original timestamp or unit alongside any normalized value so another reader can reproduce the reasoning.
Practise with the related case
Operation Nightlight Mask: Interpret an Outage Image applies this skill in a fictional evidence packet with five graded objectives. This guide explains the method, not the hidden answer key. Case evidence and entities are invented; the separate illustration above is not a substitute for reading the dossier. Sign-in is required to use the case terminal.
Questions readers ask
Should cloud-obscured cells be counted as dark?
No. Their current state is not validly observed.
Can independent outage records strengthen an image finding?
Yes, when they match the relevant place and time; report the confirmed subset explicitly.
Reporting context and further reading
NASA Gandak River flood observations · 2026-10-02. This primary-source reporting provides recent topic context only. It is not evidence that the invented case happened, and its publication date may differ from the incident dates described.
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