PSF Guard 0.7 made stacking resumable. The 0.9 series makes that more useful across a whole season: different nights can use different calibration masters, a curve shows what additional frames are buying, and processing settings survive coming back to the project later.
The current release is 0.9.5, released September 9. Here are the changes I’d start with.
Each night gets its own calibration
A target can span several nights, with flats taken at different times or after a change to the optical train. PSF Guard now divides a stack into calibration sessions and applies each session’s masters as it integrates. Flat matching also accounts for recorded rotator angles.
You can mark calibration frames as usable only before or after an optical change. That gives a dust cleaning or camera adjustment an explicit boundary in the library. A project’s Calibration report shows the matching sessions, missing calibration types, and nights relying on older flats.
The stack’s Calibration control offers Auto, Force on, and Off, with overrides per channel. The calibration library documentation explains the matching rules and what happens when a usable master is missing.
Is another hour helping?
Stack cards now chart measured signal-to-noise growth as frames accumulate. For equal, known exposures, the chart also shows the square-root improvement ideal averaging would produce. Capture order shows how the session developed; quality order helps explore the value of keeping additional frames.
The curve stays with the resume checkpoint, so adding another night extends
the same history. Mixed or missing exposure lengths still produce a measured
curve, but do not receive an unsupported projection. The CLI exposes the same
analysis through psf-guard stack-snr for folders outside a catalog.
Processing the stack preview
With RC-Astro’s standalone CLI installed and licensed on the machine doing the processing, stack previews can use BlurXTerminator, NoiseXTerminator, and StarXTerminator. Star removal keeps separate starless and stars outputs, each with its own stretch and FITS download. The original integration stays intact.
In 0.9.5, these steps are also available per linear input channel when making a color stack. Applied results, tool versions, and editor settings return after a reload, and reverting a result is remembered too. Setup details are in stack previews.
Tidying the catalog and the integration
Alternate target names can now be merged from Overview, and selected exposures can move to an existing or new target or project from Grid. Each operation shows a preview before Apply. Files and grades stay in place; Target Scheduler plan counts follow the new grouping.
The release also fixes two ways a frame could appear twice: a scheduler sync arriving after an import or upload, and a calibration file imported again after being moved. Both now recognize the existing frame.
Completed stacks revisit early samples to reject bright transient trails that slipped through while the accumulator was still young. Low coverage and overlapping trails can still leave artifacts. Older stacks and checkpoints rebuild once to use the corrected processing.
Downloads
Get PSF Guard 0.9.5 or browse the full 0.9.0 release notes for the broader update, including the sensor inspector and client pairing. psf-guard.com has the guides; the Software page links the rest of the astronomy tools.