2.2 KiB
Full-sky 2MASS PSC output
This directory is generated, not versioned. Create it with:
python3 scripts/download_2mass_psc_all_sky.py --plan
python3 scripts/download_2mass_psc_all_sky.py --download --workers 2
The acquisition uses fixed final integer indices: ra_index = 0..359 and
dec_index = 0..179. Each ownership cell is [ra_index, ra_index + 1) x [dec_index - 90, dec_index - 89) in ICRS degrees, except that dec_index=179
also owns Dec +90. To avoid polar over-fetch, each latitude band is acquired
through wider integer-RA cover sectors. A cover owns a disjoint run of final
tiles and its one-degree cone contains every point it owns; cone overlap is
therefore discarded by ownership rather than a whole-sky de-duplication table.
Raw responses and cleaning intermediates are in /tmp/2mass_psc_all_sky/ and
are deleted after each successful cover. .done/ makes reruns resume after
completed final tiles.
Downloads stay serial to be considerate of IRSA, while --workers N cleans up
to N already-downloaded covers in parallel. The queue is bounded to N, so
temporary raw/intermediate storage cannot grow without bound. Start with
--workers 2; increase it only if CPU and /tmp headroom remain available.
Each atomic output CSV uses the renderer's four-column CSV format and has a
name such as tile_ra129_dec109.csv, which means RA [129, 130) and Dec
[19, 20) degrees. For any coordinate, use
ra_index = floor(RA_deg mod 360) and
dec_index = min(179, floor(Dec_deg + 90)) to select the filename directly.
It applies the same three-band rd_flg/photometry selection and blackbody fit
as the sample processor. The downloader fails if an IRSA response reaches
--outrows, so crowded fields cannot be silently truncated. It deletes raw
tile tables after successful cleaning unless --keep-raw is passed.
The two existing fields imply roughly 15--17 GiB of cleaned CSV for the full
PSC. Their raw response rows imply 70--75 GiB if every source appeared once.
The cover grid uses substantially fewer cone areas than the old fixed-grid
fetcher, but retaining every overlapping raw response would still need roughly
190--210 GiB. The default bounded pipeline only needs up to --workers raw
responses and intermediates in addition to final output.