Listing event start and end times from time series

Hi,
I'm new to this group, and fairly new to Excel, so I'm hoping someone can help me with this.
I have no experience with Visual Basic, so I'm also hoping there may be a solution using Excel formulas.

I have a long time series that logs the presence of events. I'm hoping to get the start time for each event and the end time of each event.
The data is organized with one column of consecutive times (in 0.5 second increments, >10,000 rows) and the adjacent column is whether an event was present at that time.
If the event was present, there is a "1" for that time. If the event was not present, there is a "0" for that time.
The events last for several seconds (i.e. several rows of 1's).
So, the output that I hope to get is the start time and the end time of each event (the first "1" and the last "1" of each event).
I've attached a file with sample data and manually calculated results.

I'm using Excel 2021 on a PC.
I really appreciate any help!
Thanks!
-jeremy

Thanks! I’ve now corrected it to Excel 2021.

Put this formula in C2:

=IF(B2<>1,"",IF(OR(B1=0,B3=0),MAX(C$1:C1)+1,""))

then copy it down to the bottom of your data. Then you can use this formula in cell G2:

=IF(ROWS($1:1)*2>MAX($C:$C),"",INDEX($A:$A,MATCH(ROWS($1:1)*2-1,$C:$C,0)))

Copy it into H2, and edit the formula to remove the -1 (shown in red above), then copy both formulae down as far as you think you need them.

Hope this helps.

Pete