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Scripts and code for DESI Survey Operations
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Tile 3395 from 20240811 has low THRUFRAC values on P1/P2/P3 #204

Closed LNapolitano closed 2 weeks ago

LNapolitano commented 2 months ago

Tile 3395 is currently marked as unsure due to thrufrac alerts related to low exposure time as can clearly be seen on the attached QA sheet.

Additional information shared on slack by Anand: the two exposures are 247522-3, taken from 00:06 to 00:48:

247524 4951 SCIENCE 00:48 1266.3 DARK 0-9 ok ok ok ok ok - - 247523 3395 SCIENCE 00:28 1112.8 DARK 0-9 ok ok ok ok ok - - 247522 3395 SCIENCE 00:06 1208.8 DARK 0-9 ok ok ok ok ok - -

the nightlog mentions clouds:

00:06 [07:06] Exp. 247522- Good - First SPLIT of the tenth DARK tile 3395, correction move: 3.4 micron, Survey speed variable between 30% and 80% as fine clouds pass through, no issues with the data. (SO) Tile 3395, Exptime: 1208.78, Airmass: 1.10, Sequence: DESI, Flavor: science, Program: DARK

00:28 [07:28] Exp. 247523- Good - Second SPLIT of the tenth DARK tile 3395, correction move: 3.4 micron, Survey speed up to 80% again, no issues with the data. (SO) Tile 3395, Exptime: 1112.81, Airmass: 1.08, Sequence: _Split, Flavor: science, Program: DARK

the grafana plots for transparency + survey speed show a drop at that time (attached screenshot)if useful, here are the b/r/z thrufrac values for the two exposures:

Table.read("/global/cfs/cdirs/desi/spectro/redux/daily/exposures/20240811/00247522/exposure-qa-00247522.fits", "PETALQA") ["PETAL_LOC", "BTHRUFRAC", "RTHRUFRAC", "ZTHRUFRAC"]

    PETAL_LOC BTHRUFRAC  RTHRUFRAC ZTHRUFRAC 
    int16    float32    float32   float32  
    0  0.9558431 0.9934089  0.9828018
    1 0.80612034 0.8655604  0.8398901
    2  0.7772591 0.8320261 0.80464345
    3  0.8329367 0.8896742 0.85450953
    4 0.96630466 0.9430628   0.940925
    5  1.0361375 1.0321798   1.084696
    6  1.1930491 1.1293575  1.1565788
    7  1.1751591 1.1102453   1.137546
    8  1.1619656 1.1303558  1.1441573
    9  1.0952247 1.0741291  1.0542518

Table.read("/global/cfs/cdirs/desi/spectro/redux/daily/exposures/20240811/00247523/exposure-qa-00247523.fits", "PETALQA")["PETAL_LOC", "BTHRUFRAC", "RTHRUFRAC", "ZTHRUFRAC"]

    PETAL_LOC BTHRUFRAC  RTHRUFRAC  ZTHRUFRAC 
    int16    float32    float32    float32  
    0  0.9230686 0.97155917 0.94972503
    1  0.7602825  0.8280579  0.8014233
    2  0.7920688  0.8376865  0.8208937
    3 0.89362687   0.931959 0.91757005
    4  1.0115296   0.974123  0.9868406
    5   1.057972  1.0534825  1.1160134
    6  1.1845658  1.1254636  1.1499221
    7  1.1724463  1.1165701  1.1357466
    8  1.1422725  1.1107304  1.1063292
    9  1.0621675  1.0503678  1.0155352

20240812-Tile3395

Screenshot 2024-08-12 at 10 09 20 AM

schlafly commented 2 months ago

Looks likely cloudy here to me. https://data.desi.lbl.gov/desi/users/raichoor/main-status/spacewatch/spacewatch-20240811.mp4 . Let's go ahead and call it bad; if there's 30% differential extinction there will be other issues. @akremin , @abhi0395 , could we mark tileid 3395 on 20240811, expid 00247522, 00247523 as bad? Thanks!

schlafly commented 1 month ago

Pinging this outstanding issue.

geordie666 commented 1 month ago

@akremin: Could you please mark these exposures as bad?

schlafly commented 2 weeks ago

Can we reprocess these tiles as well?

akremin commented 2 weeks ago

I have marked exposures 00247522 and 00247523 on 20240811 as bad and purged all the data for tile 3395 on that night. It has not been observed since, so there was no reprocessing to do.

geordie666 commented 2 weeks ago

I updated the tiles-specstatus file for tile 3395 and am closing this issue.

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