1. Tropical or sidereal?
A Western tropical longitude and a sidereal longitude use different zodiac origins. They can produce different sign labels from identical birth details while each is internally consistent. Confirm the named zodiac and, for a sidereal result, the named ayanamsha. This project calculates only the twelve-sign Western tropical zodiac.
2. Did both tools calculate the same UTC instant?
Compare the local date, 12/24-hour interpretation, selected city, IANA timezone, historical UTC offset and final UTC instant. Common failures include choosing a same-name city in another region, applying today’s offset to a historical date, treating a fractional offset as a whole hour, or silently selecting one side of a daylight-saving fold.
For unknown time, also compare the rule. A tool that inserts noon is answering a single-instant question. This site evaluates the full valid local date for eligible planets and refuses to calculate Rising without a time.
3. Geocentric, topocentric or heliocentric?
The supported planetary outputs here are geocentric apparent longitudes: positions from the centre of Earth with the documented apparent-position corrections. A topocentric result uses the observer’s surface location and can differ, especially for the Moon. A heliocentric result is centred on the Sun and answers a different question. The coordinate origin and apparent/geometric setting should be compared before the numeric values.
4. Did rounding happen before sign classification?
Near a 30-degree boundary, early rounding can create an apparent sign change. For example, an unrounded value just below 30 degrees still belongs to the earlier sign even if its display rounds to 30°00′. This site classifies the full floating-point longitude first and formats degrees and minutes afterward. It also shows a boundary warning within 0.10 degrees of an edge.
5. Are the Ascendant conventions and limits the same?
Rising depends on the local horizon, coordinates, sidereal time, the chosen ecliptic convention and which eastern intersection is selected. Some products also couple the Ascendant to a house-system calculation; this one does not calculate houses. The current implementation supports latitude 66 degrees south through 66 degrees north and returns an explicit unsupported state beyond that verified range.
A reproducible comparison checklist
Capture non-sensitive technical facts rather than a screenshot containing birth details. Compare: zodiac system; body and coordinate origin; local date/time confidence; place coordinates; IANA timezone and offset; UTC instant or evaluated interval; engine/data version; unrounded longitude; and the rule used for missing time. If those match and the difference exceeds the documented tolerance, it becomes a useful correction report.
- Do not post a full birth record in a public support thread.
- A small degree difference is not automatically a sign disagreement.
- An interpretation disagreement is separate from a placement-calculation disagreement.