Final answer:
A secondary eclipse does not affect the transit depth, which is determined only during a primary transit when a planet crosses in front of a star. The transit depth remains consistent, and secondary eclipses provide other information but do not change this measurement.
Step-by-step explanation:
The effect of a secondary eclipse on the transit depth involves a different phase of observation compared to the primary transit. While the primary transit occurs when a planet moves in front of the star from our perspective, a secondary eclipse refers to the instance when the planet passes behind the star, temporarily blocking its emitted light.
During a secondary eclipse, the light curve will show a decline as the planet is eclipsed by the star, but this event does not affect the transit depth associated with the primary transit. The transit depth is quantified by the amount of light blocked during the primary transit, and its measurement remains the same regardless of a secondary eclipse. The secondary eclipse can be used to gather additional information about the planet's atmosphere and orbital characteristics but does not alter the primary transit depth measurement.
For a star half the size of the Sun with an Earth-sized planet, the transit depth would still be calculated based on the ratio of the planet's size to the star's size during the primary transit. It is not directly influenced by a secondary eclipse event.