Observations for 20 July 2013
Grand's average interval is close to eight hours, so it is in a pattern where it is erupting at the same time of day, every day. Unfortunately, the times of day seem to be the worst possible-- shortly before dawn, right after sunset, and the middle of the day. So there are no true nighttime eruptions, but the lighting is poor for two eruptions, and the benches crowded for the third.
At least the first two eruptions of the day continued the run of two-burst eruptions. And the midday eruption did have a Vent overflow delay to explain why it took so long.
The third eruption started right after sunset, so the water column was still visible. Around the 11m mark, Grand's activity slowed down like it was going to stop. Then, after about 20 seconds, it picked back up and Grand continued, finally ending at 12m59s. So we got a long single burst, but couldn't even make it to a full thirteen minutes. Then Vent and Turban quit almost immediately, instead of their usual vigorous play for a minute.