How we estimate times and indicative values

An operational estimate describes a process of ours: the time we expect between payment confirmation and the documents being available. It depends on how the system is working at that moment and it can change.

An indicative astronomical value describes a calculation instead: how high the star sits, which direction to look, which part of the year it rises highest. The calculation is documented and repeatable, but deliberately simplified.

We keep them apart because their sources of error are unrelated. A slower preparation does not make a coordinate less correct, and a simplified computation has nothing to do with a processing queue.

Estimated preparation time: a few minutes after payment confirmation. It can vary and is not guaranteed.

Where the estimate comes from: the designed automatic sequence — assigning the star from the internal catalogue, freezing its scientific data, generating the PDFs included in the offer and verifying the assets before publishing them — that is, from the number and kind of steps the system performs. It does not come from a measured average or percentile: we do not record a historical distribution of these times, so we cannot say how often the estimate holds.

Any of those steps can take longer, and when that happens the system retries rather than delivering an incomplete document. If preparation or the checks run long, we email you as soon as the documents are available and there is nothing for you to do.

• What it represents: the expected order of magnitude of the automatic sequence, not a measurement.
• What it depends on: star assignment, document generation, asset verification.
• When it does not hold: when a check does not pass first time and the run is repeated.

• Delivery questions in the FAQ →

The star's altitude and direction from the place you entered are computed with standard spherical astronomy: Julian date, local sidereal time, hour angle.

The computation deliberately ignores atmospheric refraction, nutation, aberration, annual parallax and proper motion. That is a stated choice: it is meant for finding the star on a first evening, not for pointing an instrument.

Typical accuracy stays well within half a degree. Near the horizon refraction alone can shift the apparent altitude by up to about half a degree, and we do not model it — which is why a low star may appear a little earlier or later than the guide suggests.

• What it represents: an approximate position for finding the star by eye or with binoculars.
• Main assumption: no atmospheric correction is applied.
• When it is least reliable: near the horizon, and under bright or clouded skies.

• Methodology and sources →

The star's distance is not estimated. It is published only when the measurement holds against a fixed rule: the parallax must be positive and its relative error must stay below twenty per cent.

When a measurement does not clear that threshold we do not offer an approximate figure; the document states that the distance is not known with sufficient reliability. An honest line is worth more than a number that does not hold.

This is a rule with a numeric threshold, not an operational estimate. We describe it here precisely so the two are not confused.

Catalogue identifiers, coordinates and parallax come from the SIMBAD astronomical database, distributed by the Centre de Données astronomiques de Strasbourg. Using a public source does not mean that source endorses this commercial service.

The data consulted for your star is frozen when the documents are created. If the catalogue changes later, your document stays as you received it, together with its consultation date.

The place coordinates are the ones you enter in the configurator. Choosing a different place changes the times and directions the guide suggests, not the star.

• Sources, licences and consultation dates →

We publish no punctuality percentage, service level or historical average: we do not measure them, and such a number would be invented.

We do not guarantee naked-eye visibility: it depends on magnitude, season, location, horizon, light pollution, weather and equipment.

We do not present astronomical values as precise pointing data, and we do not turn an estimate into a contractual commitment. Contractual commitments live in the terms of sale.

• What you are really buying →