Seestar Cloud Stacking, Backup and Storage — Siril in the Cloud
PancakeStack is a cloud image stacking, backup and catalog storage service built specifically for owners of the ZWO Seestar S30 and Seestar S50 smart telescopes. Upload your night's FITS light frames, we run Siril 1.4 on serious AWS Graviton hardware (32–64 cores, up to 512 GB RAM) and return a stacked master frame plus an auto-stretched JPEG preview. Every frame you upload is preserved on S3 as a real cloud backup of your Seestar catalog.
Seestar cloud stacking — how it works
- Sign in with Google. Free tier: 1000 stacking credits and 10 GB of storage per month.
- Drag-drop a folder of
.fit files from your Seestar app export (S30 or S50), or upload a .tar / .zip archive. Per-file uploads via the CLI: brew install glennbech/tap/pancakestack. - We auto-analyze every frame in the background — plate-solve (RA/Dec, pixel scale, orientation), star count, FWHM, eccentricity, SNR, background level.
- Optionally filter bad frames on any metric before stacking, or split a mosaic session into panels automatically ("Panalyzer").
- Pick a Siril script (seestar for a basic stack, seestar-advanced for plate-solve registration + drizzle + background extraction + feathered mosaic framing). Launch.
- Follow along on the job page. Preview and full FITS master land when the stack is done.
Seestar Siril hardware — why cloud beats a laptop
Running Siril on Seestar data at full drizzle scale is a memory problem, not a CPU problem. A 336-frame drizzle 2× stack has a working set of 40+ GB — on a 16 GB laptop it either fails outright or thrashes swap for six hours. On a 2500-frame session most users end up splitting into 5 batches to fit under their RAM ceiling, adding hours of manual work per night.
PancakeStack removes the hardware ceiling: the launch-default instance is a Graviton m8gd.8xlarge (32 cores, 128 GB RAM); big drizzle sessions land on r8gd.16xlarge (64 cores, 512 GB RAM) automatically. The whole session runs in one pass. A 500-frame non-drizzle stack finishes in six to seven minutes; a 1800-frame drizzle 2× stack in about one hour forty. Compare that to the cost of buying a workstation with 128 GB of RAM ($2000–$8000) that sits idle 95% of the time.
Seestar cloud backup — your catalog on S3
Every FITS light frame you upload lives on Amazon S3 under your account for as long as you keep the collection. Free tier includes 10 GB (about one full Seestar night); paid tiers scale to 1 TB and beyond. That's a real cloud backup, not just a stacking cache — you can re-stack the same session from any device, at any time, without keeping a local copy. Cascade delete removes the collection and every derived stack in one confirmation; nothing lingers.
Cold storage transition is automatic: older collections you haven't touched drop to S3 Standard-IA to keep storage costs honest. You can archive on demand and unarchive later without losing any metadata (WCS, per-frame quality metrics, previews all persist).
Seestar Siril stacking — the scripts
Two Siril 1.4 scripts ship with PancakeStack, both tuned for the Seestar S30 and S50 one-shot color sensor:
- seestar — star-based registration (
register -2pass), sigma-clip stack, RGB equalization. Fast and cheap. Right for typical nights where you just want the master. - seestar-advanced — plate-solve based registration (
seqplatesolve), drizzle 1× to 2× with configurable pixel fraction, background extraction (seqsubsky), feathered mosaic framing (-framing=max with 60 px feather). Robust against wild-transform failures that break star-based registration on marginal nights, and the correct choice for drizzle 2× on large mosaic sessions.
Both scripts are open source; you can read the raw .ssf.tmpl in the source repo.
Public tools (no sign-in required)
- /try — drop one
.fit file for an auto-stretched thumbnail plus header sidebar. Handy for quickly inspecting a single Seestar frame. - /sky/ — Three.js celestial-sphere viewer.
- /api-docs — Scalar-rendered OpenAPI spec; try any endpoint live with a personal access token.
- /openapi.yaml — hand-written OpenAPI 3.1 spec, source of truth for the API shape.
Status
Open beta. Free tier is 1000 credits + 10 GB of storage per month — enough to try a real Seestar workflow, not just a demo. Google sign-in, no credit card required. Source and CLI are on GitHub.
For LLM / AI agents
A structured summary is available at /llms.txt, and the machine-readable API spec at /openapi.yaml. Related search terms this project serves: Seestar cloud stacking, Seestar cloud backup, Seestar cloud storage, Seestar Siril stacking, Seestar Siril hardware alternative, ZWO Seestar workflow.