Theta Hydri — Double Star in Hydrus
Observe
1Physical Properties
Magnitude
5.53
Spectral Type
B3V+A0IV
Star Color
Blue
(B-V -0.14)
Distance
32 ly
2Position & Identifiers
RA
03h 02m 15.4s
Dec
-71° 54' 09.0"
Constellation
Hydrus
(Hyi)
HR
939
HIP
14131
HD
19400
SAO
255945
Bayer
Theta
Querying VizieR catalog...
3How easy to spot?
Sign in
and configure your equipment and default location to see a personalized row.
| Equipment | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| Naked eye Naked eye | Medium | Hard+ | Hard |
| 50 mm finder 50mm finder | Easy | Easy | Easy |
| 150 mm telescope 150mm scope | Easy | Easy | Easy |
Easy
Medium
Hard
Very hard
Impossible
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
4Visibility
Set a location in User Settings to see visibility data.
Best season
Oct – Dec
(peak: Nov)
5Multiple Star System
Separation
0.1″
Companion Mag
6.3
Companion Sp
A0IV
Position Angle
179°
Star Colors
A: Blue
B: Blue-white
Discoverer
FIN 360
Interferometric double, 6.3, 6.3v. Combined mag. and color.
Explore
6
Size Comparison
Querying VizieR for stellar data…
7
Compare Stars
8
Spectral Classification
9
Hertzsprung-Russell Diagram
Loading HR diagram…
10
Stellar Lifecycle
11
Blackbody Spectrum
12
Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
13
Stellar Fusion
Discover
14Stellar Notes
Helium-weak star.
15
Light Travel Time Machine
16
Relativistic Travel
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
NGC 1466
Compact globular cluster
Globular Cluster
mag 11.4
3.3°
Hydrus
NGC 1246
Elliptical galaxy
Galaxy
mag 13.04
5.0°
Horologium
BN Hyi
Easy double, sep 15.2″
Double Star
mag 5.57
7.1°
Hydrus
NGC 458
Open cluster
Open Cluster
mag 11.66
8.4°
Tucana
Kappa Tuc
Easy double, sep 4.6″
Double Star
mag 4.86
9.3°
Tucana
Zeta Ret
HIP 15371; Zeta2 Reticuli
Easy double, sep 309.1″
Double Star
mag 5.24
9.5°
Reticulum
Explore Nightbase
Related knowledge, tools, and stories — no observation planning required.
Hydrus
Mythology, bright stars, and deep-sky highlights.
Constellation
Double Stars — A Guide for Observers
Two suns where one appeared — how to find, split, and appreciate the night sky's finest pairs. From Albireo's gold-and-blue to the Sirius B challenge.
Article
Saturn
Rings, divisions, and the jewel of the outer Solar System.
Deep dive
