Observe
1Physical Properties
Magnitude
6.02
Range
5.85 - 6.73
Period
120 days
Variable Type
Semi-Regular Variable (Late-type Giant)
Spectral Type
M5IIbS
Star Color
Red
(B-V 1.64)
2Position & Identifiers
RA
17h 56m 48.4s
Dec
+45° 21' 03.0"
Constellation
Hercules
(Her)
HR
6702
HIP
87850
HD
163990
Variable ID
OP Her
Querying VizieR catalog...
3How easy to follow?
Magnitude
5.9 – 6.7 mag
Amplitude
0.9 mag
Period
120.5 d
Type
SRB
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| Equipment | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| Naked eye Naked eye | V. hard+ | V. hard | Imp. |
| 50 mm finder 50mm finder | Medium+ | Medium+ | Medium |
| 150 mm telescope 150mm scope | Medium+ | Medium+ | Medium+ |
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
May – Jul
(peak: Jun)
5Light Curve
6Comparison Stars for OP Her (5.8–6.7)
Nearby stable stars for estimating brightness (AAVSO)
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Explore
7
Size Comparison
Querying VizieR for stellar data…
8
Compare Stars
9
Spectral Classification
10
Hertzsprung-Russell Diagram
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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 5.85 - 6.73V, 7.7 - 8.3p, 120.5d.
Technetium star.
Survey Image
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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
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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
Hercules
Mythology, bright stars, and deep-sky highlights.
Constellation
