Stellarium Web shows a 3-4 minute discrepancy between myself and a distance learner

[lavatyper]

Greetings, I am using Stellarium Web to guide a group of online distance learners around the night sky. For the sake of limiting the scope of this discussion, let's assume that these distance learners are in the same time zone that I am in and live within 60 mi (100 km). I am in EDT.

One application of interest is to inspect the rise/set times for sky objects, such as the Moon, by looking at when the altitude is zero (or as close to zero as possible). Let's say that I ask the group to find when the Moon rises on a specific calendar date of this year. So, we all set Stellarium to the exact same location and we're all in the same time zone.

Most of the people in the distance group get the same rise/set time for that object on that day, to within about a minute. But I have one learner whose time is 3-4 minutes off, and we can't figure out why. We have exactly the same settings and we are both going to the same Stellarium Web webpage, to view the same object, on the same date, with the same location set. And when I say 3-4 minutes off, I mean, the time on Stellarium Web when the altitude of the object is zero happens to be 3-4 minutes earlier than what the other person's copy of Stellarium Web shows as the time at which the altitude is zero.

We're pretty exhausted on how to go any further on troubleshooting this, so, help. What's going on?

[10110111]

May be because that one device has atmosphere on/off setting differing from the other devices. This affects timing due to refraction.

[xalioth]

Please keep in mind that a 100 km distance difference toward east or west means well above 3 minutes of sunset/sunrise difference and it's not related to your timezone, but just because you live at different longitude!

[lavatyper]

Hi xalioth, but what if I and that person who live 100 km apart, but still in the same time zone, set our location to the same coordinates within that time zone (like, at a location in between where we live), will Stellarium Web show the same times?