ZTF DR18 lightcurves in parquet format. There are 1,174 field subdirectories, 
containing a total of 174,033 parquet files (one for each field / chip / 
quadrant / filter combination).

File content and format are documented in section 12c of the release notes:
https://irsa.ipac.caltech.edu/data/ZTF/docs/releases/dr18/ztf_release_notes_dr18.pdf

To read parquet using python/pandas:
https://pandas.pydata.org/docs/user_guide/io.html?#parquet

The parquet files can be verified on a Unix/Linux OS using:
"md5sum -c checksum.md5"

Total volume: ~ 6.0T

Lightcurve statistics in g-filter:
Number of lightcurves with >=  1 epoch :   1,488,194,151
Number of lightcurves with >=  2 epochs:   1,221,665,749
Number of lightcurves with >=  5 epochs:   1,010,499,155
Number of lightcurves with >= 10 epochs:     889,847,815
Number of lightcurves with >= 20 epochs:     765,998,171

Lightcurve statistics in r-filter:
Number of lightcurves with >=  1 epoch :   2,344,147,275
Number of lightcurves with >=  2 epochs:   2,006,756,363
Number of lightcurves with >=  5 epochs:   1,698,929,328
Number of lightcurves with >= 10 epochs:   1,517,399,765
Number of lightcurves with >= 20 epochs:   1,339,592,303

Lightcurve statistics in i-filter:
Number of lightcurves with >=  1 epoch :     863,074,487
Number of lightcurves with >=  2 epochs:     730,703,178
Number of lightcurves with >=  5 epochs:     623,708,714
Number of lightcurves with >= 10 epochs:     549,376,500
Number of lightcurves with >= 20 epochs:     456,827,796

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Last modified: 2023-06-14