Read OpenNGC's addendum, so the Pleiades and the Large Magellanic Cloud are on the map

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OpenNGC keeps the objects no NGC or IC number covers in a second file, addendum.csv, with the
same 32 semicolon-separated columns as NGC.csv. The ETL only ever fetched NGC.csv, so the
brightest deep-sky object in the sky, the Large Magellanic Cloud (V 0.29), was missing while
the Small one was drawn, and so were the Pleiades (M45), the Hyades, the Horsehead and the
Coalsack. fetchDeepSky now fetches the addendum beside NGC.csv, caches it as
openngc-addendum.csv, and runs its rows through the same loop.

Of its 64 rows, 27 pass the existing filters: all 22 named or Messier rows except M40, which
OpenNGC types as a double star, and M102, typed as a duplicate of M101; plus seven anonymous
open clusters brighter than V 9 (H05, H20, H21, Mel071, Mel101, Mel105, MWSC3171). deepsky.json
goes from 463 to 490 objects (galaxies 73 -> 85, clusters 294 -> 306, nebulae 96 -> 99), with
no existing record changed. Messier coverage goes from 106 to 107 of 110. 340 of the 490 have
a distance: the Pleiades 135.8 pc and the Coma Star Cluster 85.9 pc from their parallaxes;
the Hyades and the Local Group dwarfs honestly have none.

validateDeepSky now requires the Andromeda Galaxy and the Small Magellanic Cloud from NGC.csv,
the Large Magellanic Cloud and the Pleiades from the addendum, and at least 107 Messier
objects. Both checks were run against the real catalogue with the addendum removed: the ETL
fails on "Deep-sky object ESO056-115 is missing", and with the required list emptied, on
"Only 106 Messier objects were produced".

In the app, on the dev server: 490 sprites. The Pleiades sprite lies 0.00182 deg from Alcyone
(0.00183 deg from the published coordinates); the LMC 18.4209 deg from Canopus and 26.8215 deg
from Achernar (18.4209 and 26.8215 published); the Hyades 2.2591 deg from Aldebaran (2.2591).
The twelve labelled deep-sky objects now open with the Large Magellanic Cloud and the
Pleiades and include Brocchi's Cluster, in place of h Persei, chi Persei and NGC 2516.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

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This commit is contained in:

Senrokai

2026-09-24 20:59:39 +02:00

co-authored by Claude Opus 5.5

parent 74b93a0428

commit c01d3ec2bc

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