Information: - For the crater , see Aristillus ( crater ) . Aristyllus ( fl . ca . 261 BC ) was a Greek astronomer , presumably of the school of Timocharis ( c.300 BC ) . He was among the earliest meridian - astronomy observers . Six of his stellar declinations are preserved at Almajest 7.3 . All are exactly correct within his over-cautious rounding to 1/4 degree . See discussion ( and lessons ) at DIO 7.1 1 p. 13 ( 2007 ) . Aristyllus was long mis - dated to c.300 BC ( which made his data look among the poorest of the ancients ) ; but when his correct date was found by least - squares ( Isis 73:259 - 265 ( 1982 ) p. 263 ) , it was realized that his star declinations ' accuracy was unexcelled in antiquity . His data suggest that he worked in Alexandria : see DIO 4.1 3 Table 3 p. 45 ( 2004 ) . A lunar crater , Aristillus , aptly near the Moon 's meridian and at a lunar latitude roughly equal to the terrestrial latitude of Alexandria , is named after him . - Timocharis of Alexandria (c. 320 260 BC) was a Greek astronomer and philosopher. Likely born in Alexandria, he was a contemporary of Euclid. - Alexandria (or ; Arabic: '; '; "") is the second largest city and a major economic centre in Egypt, extending about along the coast of the Mediterranean Sea in the north central part of the country. Its low elevation on the Nile delta makes it highly vulnerable to rising sea levels. Alexandria is Egypt's largest seaport, serving approximately 80% of Egypt's imports and exports. It is an important industrial center because of its natural gas and oil pipelines from Suez. Alexandria is also an important tourist destination. - Euclid ("Eukleids" ; fl. 300 BCE), sometimes called Euclid of Alexandria to distinguish him from Euclides of Megara, was a Greek mathematician, often referred to as the "father of geometry". He was active in Alexandria during the reign of PtolemyI (323283 BCE). His "Elements" is one of the most influential works in the history of mathematics, serving as the main textbook for teaching mathematics (especially geometry) from the time of its publication until the late 19th or early 20th century. In the "Elements", Euclid deduced the principles of what is now called Euclidean geometry from a small set of axioms. Euclid also wrote works on perspective, conic sections, spherical geometry, number theory and rigor. What entity does 'aristyllus' has the relation 'date of death' with?
The answer to this question is:
300 bce