Which error arises when a 18th-century navigator uses a sextant without correcting for index error?

💡 Explanation

When a sextant's mirrors are not perfectly parallel at zero degrees, index error is present because the apparent altitude of a celestial body is shifted. This causes systematic error in altitude readings. Therefore, the altitude is typically underestimated, rather than introducing longitude or declination errors, which stem from other sources.

• Which mechanism prevented early atmospheric Newcomen engines from achieving higher cycle rates?
• Which outcome occurred when the chinampa system experienced increased salinity in pre-colonial Mesoamerica maize cultivation?
• Which structural weakness, common in medieval timber-framed buildings, arises from uneven settling of the foundation?
• Which observational distortion complicated astronomical calculations performed using astrolabes during the medieval era?
• Which effect occurred due to Ibn al-Haytham's improved lens grinding techniques used for early reading stones?
• Which error corrupted celestial altitude measurements when using a medieval astrolabe during maritime navigation?