Draft:33 Hydrae
K-type giant in the Hydra constellation
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33 Hydrae (Ukdah III, A Hydrae) is a star in the direction of Hydra. It has a right ascension of 09h 34m 32.64s and a declination of −05° 54′ 53.3″. Its apparent magnitude is 5.56. Considering its distance of 681 light-years from Earth, its absolute magnitude is −1.04. It belongs to the spectral class K1III.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Hydrae[1][2] |
| Right ascension | 9h 34m 32.7s[1][2] |
| Declination | −5° 54′ 54″[1][2] |
| Apparent magnitude (V) | 5.56[1][2] |
| Characteristics | |
| Evolutionary stage | Red giant |
| Spectral type | K1III[1][2] |
| U−B color index | 1.13[1][2] |
| B−V color index | 1.16[1][2] |
| R−I color index | 0.41E[1][2] |
| Astrometry | |
| Radial velocity (Rv) | 1.13 km/s |
| Proper motion (μ) | RA: 13 mas/yr Dec.: mas/yr |
| Other designations | |
| BD-05 2840，SAO 136964，HD 82870，HR 3814 | |
| Database references | |
| SIMBAD | data |
Nomenclature
33 Hydrae is the star's Flamsteed designation. It also has the Bayer designation A Hydrae.
This star along with Tau1 Hydrae, Tau2 Hydrae and Iota Hydrae, were Ptolemy's Καμπή (Kampē); but Kazwini knew them as عقدة ʽuqdah (or ʽuḳdah) "knot".[3] According to a 1971 NASA memorandum,[4] Ukdah was the name of an asterism of four stars: Tau1 Hydrae as Uḳdah I, Tau2 Hydrae as Uḳdah II, 33 Hydrae as Uḳdah III and Iota Hydrae as Uḳdah IV.