Ptolemaic magnitude scale

E1022097

The Ptolemaic magnitude scale is an ancient astronomical system, originating with Claudius Ptolemy, that ranks stars by their apparent brightness in six broad classes from first (brightest) to sixth (faintest) magnitude.

All labels observed (1)

Label Occurrences
Ptolemaic magnitude scale canonical 1

How this entity was disambiguated

Statements (47)

Predicate Object
instanceOf astronomical brightness scale ⓘ
historical astronomical system ⓘ
stellar magnitude scale ⓘ
appliesTo fixed stars ⓘ
approximateDate circa 150 CE ⓘ
assumes stars grouped into discrete brightness classes ⓘ
assumesObserver average human eye under dark skies ⓘ
brightestClass first magnitude ⓘ
catalogueAssociated Ptolemy star catalogue ⓘ
linked to: Almagest
classificationBasis naked-eye visual impression ⓘ
classificationType visual brightness class ⓘ
classRangeLowerBound 1 ⓘ
classRangeUpperBound 6 ⓘ
comparedToModernScale qualitative rather than quantitative ⓘ
dataType ordinal scale ⓘ
developedBy Claudius Ptolemy ⓘ
linked to: Claudius Ptolemaeus
documentationLanguage Ancient Greek ⓘ
era 2nd century ⓘ
faintestClass sixth magnitude ⓘ
field astrometry ⓘ
astronomy ⓘ
hasMagnitudeClass fifth magnitude ⓘ
first magnitude ⓘ
fourth magnitude ⓘ
second magnitude ⓘ
sixth magnitude ⓘ
third magnitude ⓘ
historicalStatus superseded ⓘ
influenced Pogson magnitude scale ⓘ
modern logarithmic magnitude scale ⓘ
limitingMagnitude approximately sixth magnitude ⓘ
measures apparent brightness of stars ⓘ
apparent magnitude ⓘ
namedAfter Claudius Ptolemy ⓘ
linked to: Claudius Ptolemaeus
numberOfClasses 6 ⓘ
observationMethod unaided eye ⓘ
orderingPrinciple smaller magnitude number indicates brighter star ⓘ
originatedIn ancient Greece ⓘ
precision coarse ⓘ
relatedConcept apparent magnitude ⓘ
naked-eye limiting magnitude ⓘ
visual magnitude ⓘ
replacedBy Pogson magnitude scale ⓘ
logarithmic stellar magnitude system ⓘ
usedFor cataloguing stars ⓘ
ranking stellar brightness ⓘ
usedInWork Almagest ⓘ

How these facts were elicited

Referenced by (1)

Full triples — surface form annotated when it differs from this entity's canonical label.

Al-Sufi's Book of Fixed Stars → uses → Ptolemaic magnitude scale ⓘ