When is the best time to observe Iota Bootis?

Iota Bootis is best observed from March through May, with peak visibility during April when it transits around midnight in the Northern Hemisphere.

Where is Iota Bootis located in the sky?

Iota Bootis lies in the constellation Boötes at right ascension 14h 16m and declination +51° 22′.

What telescope do I need to split Iota Bootis?

Splitting Iota Bootis requires an aperture of roughly 60 mm or larger — the components are separated by about 38.8″ at magnitudes near 4.8. Larger apertures and steady seeing help resolve the pair cleanly.

Iota Bootis — Double Star in Boötes

Observable Double Star Excellent (66/100)

Sep: 38.8", Companion: mag 7.4

Magnitude 4.8^m DoubleStar Boötes (Boo) Visible

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1Physical Properties

Magnitude 4.75

Range 4.73 - 4.78

Period 0.6 hours

Variable Type Delta Scuti (Low Amplitude)

Spectral Type A9V

Star Color Yellow-white (B-V 0.20)

Distance 68 ly

2Position & Identifiers

RA 14h 16m 09.9s

Dec +51° 22' 02.0"

Constellation Boötes (Boo)

HR 5350

HIP 69713

HD 125161

SAO 29071

Bayer Iota

Flamsteed 21 Boo

Variable ID Iot Boo

Double Cat 9198

SIMBAD

3How easy to split?

Primary 4.8 mag Companion 7.4 mag Separation 38.8″

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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

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Best season Mar – May (peak: Apr)

5Light Curve

6Multiple Star System Triple C: optical

Components 3 (triple)

Component IDs AB

Separation 38.8″

Companion Mag 7.4

Companion Sp K0V

Position Angle 33°

Star Colors A: Yellow-white B: Orange

Discoverer STFA 26

Notes

AB CPM? B is K0V.

Separation over time

Measured 1779 → 2023 (244 y)

Separation drift 37.6" → 38.8" (+1.20")

Rate +0.0049" / y

PA drift 37° → 33° (-4°, -0.016°/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.