DM-39140: add photodiode integration algorithm for use with CCOB #264
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…ter used with CCOB
| sum : `float` | ||
| Total charge measured. | ||
| """ | ||
| dt = self.timeSamples[:, 1:] - self.timeSamples[:, :-1] |
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I don't understand the indexing here, as I thought both timeSamples and currentSamples were 1-d arrays. Both python and numpy complain about this if I attempt to index a list or a 1-d np.array like this.
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I see that these are FITS table inputs, and not the 2-column ascii inputs I've used previously. I think that means there's a missing .flatten() that needs to be added in __init__ on lines 64 and 65 (unless this extra axis is intentional and I'm missing something). If these are flattened, I think this simplifies to the [1:], [:-1] indices that I would have expected.
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I had also thought that the extra axis was intentional, so wrote the code to account for that without flattening the arrays. I think it does make sense to flatten these arrays, but that will have downstream consequences, e.g., places like this.
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Ok, I'll add a separate ticket for that, as it's scope creep to do it here. DM-39338.
| # The .currentSamples values are the current integrals over | ||
| # the interval preceding the current time stamp, so omit the | ||
| # first value. | ||
| charge = self.currentScale*self.currentSamples[:, 1:] |
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I don't think I understand this scaling. From the two example photodiode files I've looked at, the current samples are all positive, so this inverts them all to be negative. I think that and the min/maxes below inverts the measurements, such that with my test photodiode (instrument='LSSTCam', exposure=3021120700810, collections="LSSTCam/photodiode" as it was the first to return a result from the butler) yields bg_current=-1.19e-7, return=3.50e-7, and np.sum(charge)=-1.12e-6 np.sum(-bg_current*dt)=1.47e-6. The index for my example also is selecting the points where current ~ -1.2e-7, while ~index selects those around -1e-12.
Have I somehow confused myself?
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The data from the CCOB uses a different ammeter than for the BOT data, and the sampled points have negative values for the intervals where the CCOB LED is on, and so differs from the BOT data in that regard. See instrument='LSST-TS8', exposure=202305122056562, collections="LSST-TS8/photodiode" in /repo/ir2.
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Ok, I was confused about the inputs then, and this makes the default value make more sense to me. The test TS8 photodiode I tried to look at must not have been ingested for some reason.
With a proper example, the values come out looking like I was expecting the first time, so I think that clears my confusion.
This will be used for TS8 and LSSTCam data taken at SLAC for Run 6 testing.