When is the best time to observe 17 Hydrae?

17 Hydrae is best observed from December through February, with peak visibility during January when it transits around midnight in the Northern Hemisphere.

Where is 17 Hydrae located in the sky?

17 Hydrae lies in the constellation Hydra at right ascension 08h 55m and declination -07° 58′.

What telescope do I need to split 17 Hydrae?

Splitting 17 Hydrae requires an aperture of roughly 100 mm or larger — the components are separated by about 4.0″ at magnitudes near 6.7. Larger apertures and steady seeing help resolve the pair cleanly.

17 Hydrae — Double Star in Hydra

Magnitude 6.7^m DoubleStar Hydra (Hya) Visible

Star Map + List + Plan Star Hop

Observe

1Physical Properties

Magnitude 6.67

Spectral Type A2m

Star Color White (B-V 0.22)

Distance 815 ly

2Position & Identifiers

RA 08h 55m 29.6s

Dec -07° 58' 16.0"

Constellation Hydra (Hya)

HR 3553

HIP 43822

HD 76369

SAO 136408

Flamsteed 17 Hya

Double Cat 7093

SIMBAD

3How easy to split?

Primary 6.7 mag Companion 6.9 mag Separation 4.0″

Sign in and configure your equipment and default location to see a personalized row.

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

Set a location in User Settings to see visibility data.

Best season Dec – Feb (peak: Jan)

5Multiple Star System

Separation 4.0″

Companion Mag 6.9

Companion Sp A7m

Position Angle 4°

Star Colors A: White B: Yellow-white

Discoverer STF1295

Notes

Binary with HR 3552. Colors for combined light. Blended mag., 6.08V. Levato indicates spectral classes G5III+A0V, both | vsini =<50k/s.

Separation over time

Measured 1782 → 2021 (239 y)

Separation drift 5.0" → 4.0" (-1.00")

Rate -0.0042" / y

PA drift 357° → 4° (+7°, +0.029°/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.