### How do you find the total time on source?

Posted:

**Wed Feb 12, 2020 1:14 pm**I have a large dataset that is the result of merging many uv datasets collected over the course of a few years. The information i want is quite basic but has proved difficult to get consistent accurate results from. I want to know how much time we have on the source over this period of time. We expect a value in the region of ~50h.

Does anyone have any ideas on why these all return different values? I assume they are all measuring slightly different things but without knowing what the differences are I'm not sure which value i should be using.

Thanks!

- When i tried taking the value of tau from uvspec with options=nobase,avall and an interval covering the whole period i got 4578.1min (572h)

When i did the same but with options=nobase i got 4578.1min (76.3h)

When i check the file with uvindex (as suggested here) I get (2295min) 38.25h. @Mark.Wieringa mentions that "You need to run this on a single source file too.". Is this to say that uvindex won't give an accurate result for a merged dataset and i should run it on individual datasets and sum the results?

When i log uvplt time vs amplitude and take the number of timestamps and multiply by the 10s integration length i get (140103min) 2335h (obviously incorrect)

When i log uvplt time vs amplitude and take the number of unique timestamps and multiply by the 10s integration length i get (1123.8min) 18.73h

When i take the number of correlations (5169911400) and multiply by the 10s integration, divide out the number of baselines (doesnâ€™t account for antenna dropouts) and the number of channels (6145) i get 6677min (111.28h)

I also attempted running gethd on the data set with in=PATH_TO_DATASET/inttime but it returned no errors nor values.

Does anyone have any ideas on why these all return different values? I assume they are all measuring slightly different things but without knowing what the differences are I'm not sure which value i should be using.

Thanks!