laurence
5286a2e81b
The scripts that processed the NGC 5128 session of 2026-07-21 previously lived inside the data directory and addressed it with absolute paths. Code and data are now separated: the code lives here, and a session is located at runtime through the ASTRO_SESSION environment variable. layout.py is what makes that work. It maps a FILENAME to the subdirectory that file belongs in, using the same rules the session directories are organised with, so a script can go on asking for 'master-Red.fit' or '_stars.npz' without any call site knowing the directory structure. Anything unrecognised resolves to the session root, which is visible and correctable rather than silently wrong. restructure.py reorganises a flat session directory into that layout. It is idempotent and dry-run by default. The 50 session scripts are kept as they were run rather than tidied into a library. They were written in sequence as the work went along, several of them by parallel agents, and they show it - but they are the honest provenance of a published set of results, and the productionised pipeline should be able to reproduce those results exactly. Verified before committing: all 51 files compile without warnings, and verify_core.py, closeup.py and triptych.py were run end to end against the reorganised session, correctly finding inputs across calibrated/, stacks/masters/ and final/ and writing outputs back to the right places.
91 lines
3.1 KiB
Python
91 lines
3.1 KiB
Python
"""Fetch a published globular cluster catalogue for NGC 5128 (Centaurus A) from VizieR.
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Primary catalogue: J/MNRAS/469/3444 table "gc" -- Taylor, Puzia, Ferrarez et al. 2017,
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MNRAS 469, 3444, "Survey of Centaurus A's Baryonic Structures (SCABS) II":
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3210 globular cluster candidates with ugriz photometry over ~1.55 deg^2 centred on Cen A.
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Fallback: J/AJ/143/84 (Harris+ 2012, 833 new GC candidates).
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Writes _cena_gc_ref.npz with keys:
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ra, dec : degrees, J2000 (ICRS)
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vmag : Johnson V estimated from SDSS g,r via Lupton (2005):
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V = g - 0.5784*(g-r) - 0.0038
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gmag,rmag: SDSS-like g and r from the source catalogue (NaN where missing)
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prob : Taylor+ 2017 GC membership probability (0-1), higher = more likely a GC
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"""
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import numpy as np
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from astroquery.vizier import Vizier
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from astropy.coordinates import SkyCoord
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import astropy.units as u
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import layout
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OUT = layout.path("_cena_gc_ref.npz")
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RA0, DEC0 = 201.365, -43.019
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# field half-widths in arcmin for a 43' x 29' frame
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HW_RA, HW_DEC = 21.5, 14.5
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def col(t, name):
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if name not in t.colnames:
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return None
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return np.ma.filled(np.ma.asarray(t[name]).astype(float), np.nan)
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def report(ra, dec, label):
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dra = (ra - RA0) * np.cos(np.radians(dec)) * 60.0
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dde = (dec - DEC0) * 60.0
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sep = np.hypot(dra, dde)
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infield = (np.abs(dra) <= HW_RA) & (np.abs(dde) <= HW_DEC)
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print(f" {label}: {len(ra)} rows")
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print(f" RA {ra.min():.4f} .. {ra.max():.4f} "
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f"(span {(ra.max()-ra.min())*np.cos(np.radians(DEC0))*60:.1f}')")
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print(f" Dec {dec.min():.4f} .. {dec.max():.4f} "
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f"(span {(dec.max()-dec.min())*60:.1f}')")
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print(f" sep from centre: median {np.median(sep):.1f}' max {sep.max():.1f}'")
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print(f" inside 43'x29' field: {infield.sum()}")
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return infield
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def main():
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v = Vizier(row_limit=-1)
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cid, tname = "J/MNRAS/469/3444", "J/MNRAS/469/3444/gc"
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print(f"Fetching {tname} (Taylor+ 2017, SCABS II)")
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try:
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tabs = v.get_catalogs(cid)
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t = [x for x in tabs if x.meta.get("name") == tname][0]
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except Exception as e:
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print(f" FAILED: {e}")
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return 1
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# RAJ2000/DEJ2000 are sexagesimal strings in this table
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sc = SkyCoord(np.asarray(t["RAJ2000"], str), np.asarray(t["DEJ2000"], str),
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unit=(u.hourangle, u.deg))
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ra = sc.ra.deg
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dec = sc.dec.deg
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g = col(t, "gmag")
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r = col(t, "rmag")
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prob = col(t, "Prob")
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good = np.isfinite(ra) & np.isfinite(dec)
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ra, dec, g, r, prob = ra[good], dec[good], g[good], r[good], prob[good]
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# -1.0 is the catalogue's "no photometry" sentinel -> NaN
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g = np.where(g <= 0, np.nan, g)
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r = np.where(r <= 0, np.nan, r)
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# Lupton (2005) SDSS -> Johnson V
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vmag = g - 0.5784 * (g - r) - 0.0038
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report(ra, dec, tname)
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print(f" vmag finite: {np.isfinite(vmag).sum()} "
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f"range {np.nanmin(vmag):.2f} .. {np.nanmax(vmag):.2f}")
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print(f" prob >=0.5: {(prob >= 0.5).sum()} >=0.9: {(prob >= 0.9).sum()}")
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np.savez(OUT, ra=ra, dec=dec, vmag=vmag, gmag=g, rmag=r, prob=prob)
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print(f"WROTE {OUT}")
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return 0
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if __name__ == "__main__":
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raise SystemExit(main())
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