Docs · FAQ
FAQ
Privacy
Does the app upload my images or scan data?
No. Scanning is fully local. The only outbound network traffic is the optional weekly license recheck, which sends a license ID and an anonymous fingerprint hash — never image data, file paths, or scan results.
Does it read my image pixels?
No. Only FITS headers are read. The pixel arrays are never touched.
What is in the “fingerprint hash”?
A SHA-256 of (your OS username + a stable machine identifier + a salt). It is one-way and not reversible. We use it only to detect a single license being used on many different machines.
Performance
How fast is scanning?
On a local SSD, expect 1,000–4,000 frames/second. On a 1 GbE NAS, 200–500 frames/second. Bottleneck is small-file metadata, not raw bandwidth.
How big does the database get?
Roughly 1–2 kB per indexed frame. A 100,000-frame archive lands around 150–200 MB on SQLite.
FITS support
What FITS variants are supported?
Standard FITS (primary HDU, header-only read). Compressed (.fits.gz, .fz) is supported but slower. Multi-extension FITS is read for primary header only.
What headers are required?
None hard-required. Photon Ledger does its best with whatever is present. For full functionality, OBJECT, FILTER, EXPTIME, DATE-OBS should be set.
Licensing
Where does the license file go?
macOS: ~/Library/Application Support/photon-ledger/license.plic. Windows: %APPDATA%\photon-ledger\license.plic. Linux: ~/.config/photon-ledger/license.plic.
I work offline — will my license keep working?
Yes. The license is verified offline with an embedded public key. Once a week, when you're online, the app rechecks for revocations. If you're offline through a recheck window, the app extends a 24-hour grace period and keeps working.
How many machines can I use one license on?
One license is intended for the machines you personally use. There is no hard machine lock, but a license activating from many different fingerprints will be flagged and may be revoked.
NAS / Postgres
Will it work over SMB / NFS?
Yes. Read-only access to your FITS files is enough. Make sure the share is mounted before you scan.
How do I connect to PostgreSQL?
Pro only. In Settings → Database, switch the backend to PostgreSQL and provide a connection URL (postgres://user:pass@host:5432/dbname). The schema is created on first run.