TW Horologii — Variable Star in Horologium
Good (52/100)
Observe
1Physical Properties
Magnitude
5.74
Range
5.52 - 5.95
Period
270 days
Variable Type
Semi-Regular Variable (Late-type Giant)
Spectral Type
C5II
Star Color
Deep ruby red
(B-V 2.28)
2Position & Identifiers
RA
03h 12m 33.2s
Dec
-57° 19' 18.0"
Constellation
Horologium
(Hor)
HR
977
HIP
14930
HD
20234
Variable ID
TW Hor
Querying VizieR catalog...
3How easy to follow?
Magnitude
5.5 – 6.0 mag
Amplitude
0.4 mag
Period
270.3 d
Type
SRB
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 | V. hard+ | V. hard | V. hard |
| 50 mm finder 50mm finder | Hard+ | Hard+ | Hard+ |
| 150 mm telescope 150mm scope | Hard+ | Hard+ | Hard+ |
Easy
Medium
Hard
Very hard
Impossible
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
Out of reach for typical amateur telescopes, even at Bortle 3.
4Visibility
Set a location in User Settings to see visibility data.
Best season
Oct – Dec
(peak: Nov)
5Light Curve
6Comparison Stars for TW Hor (5.5–6.0)
Nearby stable stars for estimating brightness (AAVSO)
Loading comparison stars…
Explore
7
Size Comparison
Querying VizieR for stellar data…
8
Compare Stars
9
Spectral Classification
10
Hertzsprung-Russell Diagram
Loading HR diagram…
11
Stellar Lifecycle
12
Blackbody Spectrum
13
Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
14
Stellar Fusion
Discover
15Stellar Notes
SRb 5.52 - 5.95V, about 158d.
Also classified C7,2 (N0).
Survey Image
Loading survey image…
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.
Explore Nightbase
Related knowledge, tools, and stories — no observation planning required.
Arthur Eddington
1919 eclipse expedition confirming general relativity; first theory of stellar interiors; the Eddington limit
Biography
Variable Stars — A Guide for Observers
A practical guide to visual observation of variable stars: estimating magnitudes, finding comparison stars, recording data, and contributing to science with AAVSO.
Article
Horologium
Mythology, bright stars, and deep-sky highlights.
Constellation
