| Right Ascension | 19 : 52 : 28.3 (h:m:s) |
|---|---|
| Declination | +01 : 00 : 20 (deg:m:s) |
| Distance | 1,450 (ly) |
| Visual brightness | 3.48 .. 4.39 (mag) |
| Period | 7.177 (days) |
| Spectra type | F6..G2 Ibv |
Eta Aquilae was the first Delta Cephei, or Cepheid variable to be recognized, in 1784 by the English amateur astronomer Edward Pigott (Pigott 1785) - even shortly before Delta Cephei was found (by his friend and neighbor John Goodricke). At that time, it was still counted to the now extinct former constellation Antinous, thus named Eta Antinoi.
Eta is one of the brightest Cepheids known; it varies in brightness between 3.7 mag in its maximum and 4.5 mag near its minimum with a period of 7.17644 days. It also varies its spectral type over this period, between G2 and F6 Ib. As all Cepheids, it is a supergiant star. At its presumable distance of 1,450 ly, its apparent visual magnitude corresponds to an absolute magnitude of -4.76 to -3.85, or about 6000 solar luminosities near its maximum and 2500 near its minimum.
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