When is the best time to observe Dabih?

Dabih is best observed from June through August, with peak visibility during July when it transits around midnight in the Northern Hemisphere.

Where is Dabih located in the sky?

Dabih lies in the constellation Capricornus at right ascension 20h 21m and declination -14° 47′.

What telescope do I need to split Dabih?

Splitting Dabih requires an aperture of roughly 60 mm or larger — the components are separated by about 205.2″ at magnitudes near 3.1. The companion is about 3.0 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Dabih — Double Star in Capricornus

HIP 100345; Beta Capricorni; 9 Capricorni

Observable Double Star Good (49/100)

Sep: 205.2", Companion: mag 6.1

Magnitude 3.1^m DoubleStar Capricornus (Cap) Visible

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About Dabih

Description

Dabih is a complex multiple star system at magnitude 3.08 in Capricornus. The naked-eye star is actually at least five components, with the two main pairs separated by about 3.5 arcminutes — easily split in binoculars. The brighter component is a yellow giant of spectral type F8, located about 328 light-years from Earth.

Observing Tips

Dabih sits at the western (head) end of Capricornus. Binoculars reveal it as a wide double star, with the two main components easily resolved. The constellation Capricornus is a faint zodiacal figure east of Sagittarius. Best observed August through November.

History

The name Dabih comes from the Arabic 'al-dhabih,' meaning 'the slaughterer,' referring to a sacrificial ritual. Capricornus is one of the oldest constellations, recognized as a sea-goat hybrid since Babylonian times over 4,000 years ago.

Fun Facts

Dabih is one of the easiest bright multiple star systems to split with binoculars — the two main components are separated by over 3 arcminutes, about one-tenth the width of the full Moon.

Observe

1Physical Properties

Magnitude 3.08

Spectral Type K0 :II: + A5:N

Star Color Orange (B-V 0.79)

Distance 326 ly

2Position & Identifiers

RA 20h 21m 00.7s

Dec -14° 46' 53.0"

Constellation Capricornus (Cap)

HR 7776

HIP 100345

HD 193496

Bayer Beta

Flamsteed 9 Cap

SIMBAD Wikipedia

3How easy to split?

Primary 3.1 mag Companion 6.1 mag Separation 205.2″

Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Easy	Easy
150 mm Newton 150mm Newt.	Easy	Easy	Easy
Celestron C8 (203 mm SCT) C8 203mm	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 Jun – Aug (peak: Jul)

5Multiple Star System 8 components D: optical

Components 8

Component IDs *

Separation 205.2″

Companion Mag 6.1

Companion Sp A0

Position Angle 266°

Star Colors A: Orange B: Blue-white

Discoverer STFA 52

Notes

Complex system with HR 7775, q.v. Component B, vsini 97k/s. Occultations indicate component A is multiple system: 4.0, | 4.3v sep. 0.0002", 4.8v at 0.022" and 6.7v at 0.0001". A also suspected astrometric binary, 3.07 F8V. Possibly also | two faint 13v components at 112" discovered by John Herschel.

Separation over time

Measured 1800 → 2016 (216 y)

Separation drift 205.5" → 205.2" (-0.30")

Rate -0.0014" / y

PA drift 268° → 266° (-2°, -0.009°/y)

Essentially fixed on human timescales — the same view your grandchildren will see.

Measured from the WDS observational archive. No orbital solution has been derived — most likely the period is too long to fit an orbit to the available measurement arc.

Eyepiece View

Telescope Eyepiece

32x Dawes: 1.9″ TFOV: 1.6°

Seeing

Scale Realistic = true angular size

A: 3.1 · B: 6.1 · Sep: 205.2″ · PA: 266° · N up, E right

Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″

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Spectral Classification

Hertzsprung-Russell Diagram

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Stellar Lifecycle

Blackbody Spectrum

Stellar Absorption Spectrum

Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.

Stellar Fusion

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15Stellar Notes

Spectroscopic Binary

HR 7776-7775 = AxBC. 1374.126d, K 21.9k/s, V0 -18.9k/s, msin3i 3.75, asini 376. Alternate orbit 1374.23d, | K 22.44k/s, V0 -18.95k/s, msin3i 3.63, asini 382.5. Might be eclipsing. vsini of sceondary 115k/s?

Spectral

Also classified G0III + B8V, K0II-IIIp + A0, B8V + K0II-III, or G8II + A0V:.

Alternative Names

Dabih. Beta1 = Dabih Major; Beta2 = Dabih Minor.

Remarks

Occultation diam. = 0.00305 - 0.00317". Diam. primary 0.0033".