When is the best time to observe Kappa Delphini?

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

Where is Kappa Delphini located in the sky?

Kappa Delphini lies in the constellation Delphinus at right ascension 20h 39m and declination +10° 05′.

What telescope do I need to split Kappa Delphini?

Splitting Kappa Delphini requires an aperture of roughly 60 mm or larger — the components are separated by about 214.6″ at magnitudes near 5.0. The companion is about 3.6 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Kappa Delphini — Double Star in Delphinus

Observable Double Star Fair (33/100)

Sep: 214.6", Companion: mag 8.6

Magnitude 5.0^m DoubleStar Delphinus (Del) Visible

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Observe

1Physical Properties

Magnitude 5.05

Spectral Type G2IV subgiant

Star Color Orange (B-V 0.72)

Distance 125 ly

2Position & Identifiers

RA 20h 39m 07.8s

Dec +10° 05' 10.0"

Constellation Delphinus (Del)

HR 7896

HIP 101916

HD 196755

SAO 126059

Bayer Kappa

Flamsteed 7 Del

Double Cat 14101

SIMBAD

3How easy to split?

Primary 5.1 mag Companion 8.6 mag Separation 214.6″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Easy	Medium+
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

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Best season Jun – Aug (peak: Jul)

5Multiple Star System Triple B: optical

Components 3 (triple)

Component IDs AC

Separation 214.6″

Companion Mag 8.6

Companion Sp K2IV

Position Angle 101°

Star Colors A: Orange C: Orange

Discoverer STT 533

Notes

AB optical. B, 11.8v at 29". AC CPM, C is K2IV.

Separation over time

Measured 1852 → 2015 (163 y)

Separation drift 213.8" → 214.6" (+0.80")

Rate +0.0049" / y

PA drift 101° → 101° (+0°, +0.000°/y)

Slow change over generations — observable in lifetime comparisons.

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.