Beneath every Vedic chart Tempora computes is the same astronomical engine: Swiss Ephemeris, the gold-standard library derived from NASA's JPL ephemeris. Tempora pairs it with the True Pushya Paksha ayanamsa for sidereal alignment and Whole Sign houses per Indian convention. Each choice is deliberate, documented and fixed across the calibration. This piece walks through the astronomy, the ayanamsa, the house system, and what precision at this layer actually buys.
Swiss Ephemeris is a high-precision astronomical computation library maintained by Astrodienst, the Swiss astrology platform, since 1997. It computes planetary positions, lunar nodes, asteroids and house cusps for any date and location, accurate to arc-second precision over a date range of approximately thirteen thousand years (13,200 BCE to 17,191 CE in the long file set).
The library is derived from JPL DE431, the long-arc planetary ephemeris produced by NASA's Jet Propulsion Laboratory. JPL DE431 is the same ephemeris used for spacecraft navigation, occultation prediction and other applications where arc-second-level accuracy is operationally required. Swiss Ephemeris compresses the JPL data into a format suitable for real-time computation on consumer hardware while preserving the underlying precision.
Astrodienst publishes the source code and the ephemeris data files. The library is free for non-commercial use and licensed for commercial use through a small fee that supports continued maintenance. It is the standard astronomical layer across professional astrology software (Astrodienst's own AstroWeb, Solar Fire, JHora, Parashara's Light, and others) and across academic-adjacent astrology research.
Tempora uses Swiss Ephemeris through the pyswisseph Python bindings. Every planetary position the calibration engine reads is a Swiss Ephemeris call against the documented date, time and location. The astronomy is therefore identical to what any other Swiss Ephemeris user would obtain for the same inputs.
Three alternatives Tempora considered and rejected.
Hand-computed positions from classical tables. The traditional Indian astrology curriculum includes hand-computation of planetary positions from sidereal tables. The skill is preserved in the academic Jyotish tradition. As a primary computation source for a research framework, however, hand computation introduces small errors at every step that compound over thousands of computations. A 0.1° drift on the natal Moon shifts nakshatra-boundary cases. Tempora's framework cannot absorb that level of computational noise without invalidating the small-orb signatures.
Commercial closed-source astrology software. Several commercial Indian astrology platforms (Parashara's Light, JHora and others) compute charts to comparable precision and many use Swiss Ephemeris under the hood. The downside for Tempora's purposes is that a closed-source layer cannot be embedded in a public reproducibility chain. A reader running Tempora's open calibration engine cannot run a closed astrology platform's planetary-position output as the input to that engine.
Built-from-scratch ephemeris computation. Re-implementing planetary computation from first principles is a research project of its own. Astrodienst has spent decades on Swiss Ephemeris; reproducing the work would consume years and produce something necessarily less validated than the existing standard. The framework's leverage is in calibration, not astronomy. Adopting the standard library frees that engineering time for the calibration work.
Swiss Ephemeris is therefore the rational choice. Open source, validated against JPL, used across the field, and transparent enough that a reader can verify any single planetary position independently.
Sidereal Vedic astrology requires choosing an ayanamsa, the offset that converts a tropical zodiac longitude (anchored to the vernal equinox) into a sidereal one (anchored to the fixed stars). The ayanamsa is approximately 24° in 2026 and increases by about 50 arc-seconds per year due to precession of the equinoxes.
Several ayanamsa systems exist in active use. Each anchors the sidereal zodiac to a slightly different reference point.
| Ayanamsa | Anchor | Approximate value 2026 |
|---|---|---|
| Lahiri Chitrapaksha | Spica (Chitra) at 0° Libra sidereal | ~24.20° |
| True Pushya Paksha (PVRN Rao) | Pushya at the centre of the Pushya nakshatra | ~24.10° |
| Krishnamurti (KP) | Empirically tuned for KP-system event timing | ~24.16° |
| Raman | Raman's rectified Lahiri | ~22.56° |
| Fagan-Bradley | Western sidereal anchor (Aldebaran) | ~25.05° |
The differences between systems are small in absolute terms (within about 1° in 2026) but operationally significant for nakshatra-boundary cases and for any signature with an orb tighter than 4°. A natal Moon at the boundary between Punarvasu and Pushya nakshatras under Lahiri may sit clearly inside Pushya under True Pushya Paksha, or vice versa. The choice of ayanamsa changes the reading.
Tempora uses True Pushya Paksha, the ayanamsa championed by P V R Narasimha Rao. The reason is structural. The Pushya-anchored framework aligns the nakshatra boundaries with the dasha mathematics Tempora calibrates against; the dasha sequence (Vimshottari) is itself anchored to the Moon's nakshatra at birth, and an ayanamsa that places the nakshatra boundaries cleanly is the natural input. The choice was made before the calibration was run, and the calibration is locked to it. Switching ayanamsa now would require re-running the entire calibration on the new positional data; the lift figures published in the current table are specific to True Pushya Paksha.
This is a substantive choice and Tempora is not asserting it as the only defensible choice. Lahiri is the official Government of India ayanamsa and has wide currency; Krishnamurti is preferred by KP practitioners. A reader who prefers a different ayanamsa can rerun Tempora's open calibration with that ayanamsa and observe how the lift figures move. The framework is robust to the choice in the sense that the methodology applies equally; the specific numbers are conditional on the ayanamsa.
The choice of sidereal over tropical is upstream of the ayanamsa choice. The tropical zodiac anchors 0° Aries to the vernal equinox. The sidereal anchors to the fixed stars and is offset from the tropical by the ayanamsa.
Western astrology uses the tropical zodiac. Vedic astrology uses the sidereal. The choice is not arbitrary; the dasha mathematics, the nakshatra system, the navamsa divisional charts and the classical Indian techniques all assume sidereal definitions. A natal Sun in tropical Aries can be sidereal Pisces in 2026; the dasha lord that activates depends on which framework is used.
Tempora's framework is sidereal because the techniques the framework operationalises are sidereal. The forward calls cite Mars-Rahu conjunction signatures that depend on sidereal positions, dasha states that depend on sidereal Moon nakshatra, and stellium-activation patterns that depend on sidereal sign membership. A tropical-framework version of the same calibration would produce different signatures, different lift figures, and different forward calls. The two are coherent within themselves but they are not the same framework.
The third structural choice is the house system. Houses divide the celestial sphere into twelve segments relative to the local horizon and meridian at the moment and place of the chart. Several house systems exist, each cutting the segments differently.
| House system | Cusp definition | Use |
|---|---|---|
| Whole Sign | Each house occupies one full sign; the rising sign is the entire 1st house | Hellenistic and Indian Vedic standard |
| Placidus | Time-based unequal cusps; the most common Western system | Western tropical practice |
| Bhava Chalit | Indian variant where cusps are computed at the midpoint of each sign | Some Indian practitioners use Bhava Chalit alongside Whole Sign |
| Equal House | Each house is exactly 30° from the ascendant degree | Compromise between Whole Sign and Placidus |
Tempora uses Whole Sign. This is the older documented system and the canonical Indian Vedic convention. The dasha system, the divisional charts, and the karaka-based reading techniques are all defined in classical Indian texts using Whole Sign.
The audit cycle of May 2026 included an explicit check on house-system consistency across the corpus. All articles referenced Whole Sign; no article referenced Placidus or Bhava Chalit. Where house placement appeared to drift between articles (the audit caught this on one mundane case study), the drift was traced to a chart-identity question rather than a house-system question. The house-system layer is locked.
The May 2026 audit cycle on the corpus caught a precision incident worth documenting because it illustrates exactly what the ephemeris layer protects against.
The Russia February 2028 forecast article had been published with a peak-transit date of 5 February 2028 cited in the body and 20 February 2028 cited in the disposition. The Mars-Rahu conjunction signature on the Russia 1991 chart drives the article's central forward call. When the audit reran the engine over the cited window, the actual peak (closest approach) returned 6 January 2028 at 1.0° in Capricorn. By 5 February the conjunction had separated to over 30° and was no longer within signature orb. The narrative date and the engine date were thirty days apart.
Two failure modes had compounded. The original article had cited a peak date sourced from a manual transit calculation that did not match the engine. The publication had not run a cross-check between narrative and engine. The audit caught both. The reconciliation: the article was superseded with a Section 3 that documents the engine return as of January 2028, retires the February peak claim, and walks through what the corrected window looks like. The forward call's falsifier and event-shape window were preserved; the transit-shape framing was rebuilt against the engine.
This is the kind of drift that an ephemeris layer protects against only if the layer is actually used. Swiss Ephemeris is precise; the audit discipline is what ensures the precision propagates from the engine into the published article. Without the cross-check, the precision sits in the engine while the article drifts.
Swiss Ephemeris with fixed ayanamsa and fixed house system is the floor of the framework. It does not produce predictions on its own. What it provides is a deterministic input layer: any reader running the same Swiss Ephemeris call against the same date and location obtains the same output. This makes the calibration above it auditable. When the audit catches drift, the drift is in the calibration narrative or the article body, never in the astronomy. That is the property the ephemeris layer is buying.
Forward calls are dated. Each call cites a window in which one or more high-lift signatures are predicted to fire, with an explicit observable signal and a falsifier condition. The astronomy determines what the engine returns for that window. The calibration determines whether the signature's lift figure clears the publication threshold. The narrative determines how the call is described to a reader.
If the astronomy is uncertain, the rest collapses. A window cited as 1 February 2028 to 28 February 2028 means the Mars-Rahu signature should be at orb-active during that range. If the engine returns the actual peak as 6 January 2028, the cited window is wrong by a month and the call is unfalsifiable as stated. By using Swiss Ephemeris the framework removes the astronomical uncertainty: any reader can verify the engine return against any other Swiss Ephemeris implementation and confirm that the peak is where the engine says it is.
The orb on the signature determines how long the window stays open. A 6° applying orb on Mars-Rahu means the signature is active for the days while Mars is approaching Rahu within 6°, which is typically a window of about ten to fourteen days around peak. The window is therefore not a fuzzy month; it is an astronomically defined band, sharp at both ends, that the engine returns in seconds.
This is what calibrated lift framework needs at its base. The lift figures derived in the calibration article presuppose that the orb-active windows on event dates are correctly identified. If the astronomy drifts, the event-set scoring drifts with it, and the lift figures themselves become unreliable. Swiss Ephemeris fixes this.
A reader who wants to check a single planetary position from a Tempora article can do so in three different ways.
The simplest is to use the Astrodienst free chart calculator at astro.com, set the same date, time and location, and observe the planetary positions. This uses the same Swiss Ephemeris library and should match the Tempora engine output to arc-minute precision. The free Astrodienst tool is set to tropical by default; switch it to sidereal True Pushya Paksha (or to Lahiri and apply a small offset) to compare directly.
The second is to run pyswisseph locally with the same inputs Tempora's engine uses. The library is one pip install. A short script can call swe.calc_ut and swe.set_sid_mode and print the planetary positions for the same datetime and location.
The third is to cross-check against any other Swiss-Ephemeris-based tool: JHora, Solar Fire, the Astrodienst commercial product, or any of the Indian astrology apps that use Swiss Ephemeris under the hood. Output should match within milliarc-second tolerance because all of these tools share the same astronomical floor.
If the cross-check returns a different position from the Tempora engine, one of three things has happened: the inputs differ (date, time, location or ayanamsa), the local Swiss Ephemeris install is using a different ephemeris file set, or there is a bug in Tempora's engine that the audit did not catch. The first is most common; the third is what the audit cycle is designed to surface.
The astronomical layer has limitations that the rest of the framework inherits.
Time precision matters. A two-hour error in birth time shifts the natal Moon by approximately one degree. National-chart birth times are recorded to varying precision; some are recorded to the minute (Russia 1991 12:45 MSK), others to the hour (UK 1801 00:00 GMT, India 1947 00:00 IST). The framework inherits whatever precision the canonical record carries.
Ayanamsa is a choice not a measurement. No empirical procedure decides between Lahiri and True Pushya Paksha. They are conventions; the framework picks one and locks to it. A reader who prefers a different ayanamsa is free to rerun the calibration; the lift figures will move.
House cusps depend on the ascendant. Whole Sign sidesteps cusp uncertainty within a sign because every house is a full sign. Across sign boundaries, the ascendant degree at birth determines the lagna. A two-minute error on a fast-rising sign can flip the lagna; the framework's small-orb signatures inherit this sensitivity.
True nodes versus mean nodes. Tempora uses true nodes (the actual instantaneous Rahu-Ketu axis) rather than mean nodes (a smoothed monthly average). True nodes oscillate slightly around the mean; the difference can shift Rahu's position by half a degree on a given date. The Tempora calibration was run with true nodes throughout.
None of these limitations are unique to Tempora's framework. They apply to any astrology operation using the same astronomical library. What is different about Tempora is that the choices are documented and locked, and the audit catches drift if any of them is silently changed.
A standard astrology firm rarely publishes its astronomical layer. The reader does not know what ayanamsa was used, what house system, what node convention. Inputs and choices are silent; a reader cannot reproduce a chart from a published article without guessing.
Tempora has chosen the opposite posture. The ayanamsa is named (True Pushya Paksha, PVRN Rao). The house system is named (Whole Sign). The node convention is named (true nodes). The library is named (Swiss Ephemeris via pyswisseph). Any single planetary position in any Tempora article is reproducible by a reader with access to the same library. The astronomy is not the firm's competitive contribution; it is the public floor on which the proprietary work sits.
What is proprietary is the calibration: the labelled event sets, the per-signature scoring functions, the lift table, the audit discipline. What is not proprietary is the astronomy. Drawing this line clearly is what lets the framework be auditable from outside while preserving Tempora's research investment in calibration. The astronomy is shared; the calibration is the firm's contribution.
Swiss Ephemeris is a high-precision astronomical computation library maintained by Astrodienst since 1997. It is derived from the JPL DE431 ephemeris produced by NASA's Jet Propulsion Laboratory and computes planetary positions to arc-second precision over a date range of about 13,000 years. It is the standard library used across professional astrology software and is the astronomical layer beneath the Tempora calibration engine. The library is open in source form for non-commercial use and licensed for commercial use through a small fee to Astrodienst.
True Pushya Paksha is the ayanamsa championed by P V R Narasimha Rao that anchors the sidereal zodiac to the fixed star Pushya at the centre of the Pushya nakshatra. Lahiri Chitrapaksha anchors to Spica (Chitra) and is the official ayanamsa of the Indian government's calendar reform committee. The two differ by about 0.9° in 2026. Tempora uses True Pushya Paksha because the Pushya-anchored framework aligns the nakshatra boundaries with the dasha system Tempora calibrates against. The choice is documented and the calibration was run with this ayanamsa fixed; switching ayanamsa would require re-running the entire calibration.
The tropical zodiac is anchored to the vernal equinox (the moment in spring when the Sun crosses the celestial equator northward). The sidereal zodiac is anchored to the fixed stars. The two are offset by the precession of the equinoxes, currently about 24° in the True Pushya Paksha framework. Western astrology uses the tropical zodiac. Vedic astrology uses the sidereal. Tempora's framework is sidereal because the dasha mathematics, the nakshatra system, and the classical Indian techniques that Tempora calibrates against are all defined in sidereal terms.
Whole Sign is the house system where each of the twelve houses occupies exactly one zodiac sign, with the rising sign forming the entire 1st house. It is the oldest documented house system, used in Hellenistic astrology and adopted as the dominant convention in Indian Vedic astrology. The alternatives Tempora considered are Placidus (Western standard, time-based unequal cusps) and Bhava Chalit (Indian variant where house cusps are computed at the midpoint of each sign rather than the boundary). Tempora uses Whole Sign per the canonical Indian sidereal convention; this is also the system used in the natal-chart records the calibration engine reads.
Planetary positions from Swiss Ephemeris are accurate to arc-second precision, which translates to date accuracy of better than one day for slow planets (Saturn, Rahu, Jupiter) and better than one hour for the Moon. The forward-call publication-window precision is therefore limited not by the astronomy but by the orbs Tempora chooses for signature activation, typically 4 to 8 degrees applying. The audit cycle of 9 May 2026 caught one date drift on a published article (a peak transit-date claim that was off by 30 days from the engine return); the fix was to recompute against the engine and publish the correction. The astronomy is precise; the discipline that catches drift between narrative and astronomy is what makes the precision usable.
Every dated forward call depends on knowing where the planets actually are on the cited date. If the astronomical layer drifts, the forward call drifts with it. By using Swiss Ephemeris with a fixed ayanamsa and a fixed house system, Tempora removes the astronomical uncertainty from the reproducibility chain. The forward call's pass-fail criterion becomes a function of the labelled signature scoring above threshold during the named window, with no ambiguity about where the planets were on a given date. Without ephemeris truth, the calibration math is rebuilt on shifting ground.
This article documents the astronomical layer Tempora Research operates above: Swiss Ephemeris with True Pushya Paksha ayanamsa and Whole Sign houses. Swiss Ephemeris is maintained by Astrodienst (astro.com); Tempora is an independent user of the library and is not affiliated with Astrodienst. The 2026-05-09 audit findings referenced here are summarised from an internal audit log maintained as part of Tempora's research-publishing standards. This article is a method-defining piece for the Tempora corpus and does not constitute scientific peer-reviewed publication. It does not constitute medical, financial, legal or professional advice. Article first published 2026-05-09 by Tempora Research.