Plan an imaging weekend’s storage before the first exposure

Budget separately for the files you capture, the space your processing workflow creates and a second copy of your originals. Start with the imaging-session storage calculator, then check its estimate against actual files from your camera and a small processing trial. The useful decision is whether each destination has enough free space for its own job.

A weekend folder should also tell you what belongs together without requiring you to remember Friday night’s settings on Sunday morning. A modest naming scheme and a short session note are easier to maintain than an elaborate archive you abandon halfway through the trip.

Count what you will save

Make a capture list for each night: target, planned light-frame count, file format and calibration files you expect to save. Include test exposures and replacement frames in a separate allowance. Storage planning concerns every saved frame, including those you later reject.

If you have planned only a desired integration time, first turn it into an exposure count. Our guide to choosing sub-exposure length explains how a short trial informs that choice. Keep pauses and the available imaging window separate from the arithmetic of saved exposures.

Measure a representative saved file using the settings you intend to use. If you change camera mode, dimensions or format, measure another sample. Do not substitute the size of a preview image for the acquisition file.

N.I.N.A.’s imaging settings distinguish the saved format, compression and destination folder. Its documentation also explains that compression takes additional saving time while reducing file size. Check your actual configuration before relying on a previous session’s measurement. N.I.N.A. imaging documentation

Use the calculator as a first estimate, and write down the assumptions beside the result. If its inputs cannot represent a mixed session directly, calculate the groups separately and add them together.

A hypothetical two-night budget

Suppose, purely as a worked example, that you plan 120 light frames on each of two nights. Your measured sample files are 50 MB each. You also intend to save 100 calibration frames of the same assumed size across the weekend.

The calculation is:

• Lights: 240 × 50 MB = 12,000 MB.
• Calibration files: 100 × 50 MB = 5,000 MB.
• Original capture total: 17,000 MB, or 17 GB using decimal units.

If you choose a 25% capture allowance for extra saved frames, the capture allocation becomes 21.25 GB. That percentage is an illustrative planning choice, not a camera requirement or a guarantee of sufficient space.

A second complete copy of that allocation needs another 21.25 GB on its destination. Together, the two allocations total 42.5 GB across the two locations. Neither number includes processing intermediates, existing files or unrelated computer use. Keep units consistent when comparing these figures with your computer’s free-space display.

This example deliberately uses measured file size rather than a camera specification. Replace every assumption with your own figures before making a storage decision.

Give processing its own space budget

Do not assume that room for the originals means room to stack them. Siril’s script tutorial calls for a processing disk with space for several times the original images. It describes intermediate files being written into a process directory and recommends copying source images into the working structure while retaining a backup elsewhere. Siril script-processing tutorial

Before travelling, run a small representative batch through your intended workflow. Record the input size and the largest working-folder size you observe. Include the stages you actually expect to use. Treat this as a rehearsal, with additional headroom, rather than a universal multiplier for every future project.

Write the resulting processing allowance against the processing drive. If acquisition and processing share a drive, add their simultaneous needs there. A spacious backup destination does not increase free space on the computer doing the stacking.

Make capture folders and processing folders distinct

A practical original-data structure is a weekend folder containing one folder per observing night, then target and frame type. Add a short text note identifying the camera settings and calibration groups. Use the camera calibration checklist to decide which settings need recording; this storage plan does not establish which calibration files are suitable.

For N.I.N.A. users, folder and filename patterns can contain changing keywords and fixed text, with a preview in the settings. Separate patterns can be specified for flats, darks and biases. Test those previews and save a few sample frames before the weekend. N.I.N.A. file-pattern settings

Then prepare a separate processing workspace that follows your chosen software’s requirements. Siril’s manual workflow uses a working directory and descriptive sequence names, and it can create sequences from existing FITS files using symbolic links. A sequence link is not an independent backup. Avoid treating renamed files or an extra folder on the same drive as your second copy. Siril manual pre-processing tutorial

Finish each night with a short handover

Record the last completed target, saved frame counts, changed settings and any interrupted sequences. Copy the originals to the second destination, compare folder counts and sizes, and open representative copied files before relying on that copy. These checks are practical checks, not proof that every byte is intact.

Keep originals while you establish that the processing result and backup are usable. Identify temporary working files explicitly before removing anything. Siril’s documented process folder has a defined role in its script workflow; a folder with a similar name in another workflow may contain something different.

Your final pre-trip check is straightforward: each drive has a written allocation, each saved frame has a predictable home, and a trial has demonstrated the route from capture to processing to a second copy. Revisit the budget whenever the capture settings or workflow change.