First Light Guide #15: Messier 34

Messier 34

A detailed guide to finding / observing the open cluster

First Light Guides 14 graphicFirst Light Guides #15 is a detailed written and video reference to finding and observing the open cluster Messier 34 in the constellation of Perseus. The cluster is considered to be somewhere between the ages of the also-young Pleiades and Hyades star clusters, born some 200-250 million years ago. This guide is ideal for beginners, but many advanced amateur astronomers may find it useful. It is designed to help you locate this open cluster with almost any telescope. There is a video for how to find Messier 34 with a magnified finderscope, and a video for a red-dot finder to help anyone with any telescope locate the star.

Visitors who are new to this site may wish to get started here, while more advanced observers can search the First Light Guides by constellation, or by right ascension


Find Messier 34 in the sky

While Messier 34 contains some 400 stars, most observers will not see that many of them. However, the brighter members make several dozen (or more) of them easily visible in most telescopes. 

Here is how anyone with a small telescope can locate Messier 34 with a magnified finderscope:

Here is how anyone with a small telescope can locate Messier 34 with a red dot finder:

Observing tips:

Messier 34 is a wonderful open cluster to observe; often seen as a faint haze through many finderscopes, making it easy to locate once the observer knows where to starhop. But as with any deep sky object, begin with an eyepiece that provides low magnification to start, then increase it as your telescope and viewing conditions allow. 

As with any open cluster, the view will vary from observer to observer, but there are a half a dozen or so 8th and 9th magnitude stars that most anyone can see easily, with many more 10th and 11th magnitude stars that can be seen from most anywhere with little difficulty. 

The cluster is listed as being 35 arc minutes across - more than a half of one degree - but this includes some cluster members that are further out. Try bumping up the magnification to at least a medium-power range for your telescope to help darken the sky background somewhat. This can help in spotting more of the fainter cluster members. 

Useful filter(s): None needed or required.

What should I see?

A half a dozen or more 8th and 9th magnitude stars, with many more dimmer star members around a somewhat centralized area - see graphic below. 

Details of Messier 34

Approximate view of Double Cluster as seen at 38x-low power

Type: Open cluster

Distance: 1,500 light years, ± 2.0 

Apparent magnitude: 5.5 (integrated magnitude)

Diameter: 35 arc minutes

Right ascension: 02h 42m 6s

Declination: +42 46' 0"












Because telescopes and observers are all different, here are some alternate sketched/drawn views of Messier 34:

Jeremy Perez, 6" f/8 telescope at 37.5x

Eric C Graff, 6" f/6 telescope at 60x



The constellation: Perseus

General information about Perseus the Hero, where Messier 34 is located, can be found here.  This will help you know where to find the constellation in the sky and be able to locate and identify its brightest stars.

Name of constellation: Perseus

Abbreviation: Per

Genetive form: Persei

Common names: The Hero

Associated asterisms: No major ones

Original 48 of Ptolemy: Yes

Area by size: 615 square degrees

Relative size: 24 out of 88 (Serpens is next larger, Cassiopeia is next smaller)

First Light Guide objects: Messier 34, Double Cluster, Algol

Brightest stars, in order of magnitude 

First lists the Bayer designation, then the "traditional" star name (often Arabic, but not always - see each star's notes for details). Graphic shows constellation at zenith as if looking up with body facing north.

  • α (alpha) Persei (Mirfak) magnitude 1.79, is the 37th brightest star in the sky. It is 510 light years away from us. The traditional name is derived from the Arabic Mirfaq al-Thurayya, which means, "the elbow."

  • β (beta) Persei (Algol) is an eclipsing variable star of 2.1 that dips to 3.4 every 2.86 days. At maximum, it is the 59th brightest star in the sky. Traditional name is from the Arabic رأس الغول ra's al-ghūl : head (ra's) of the ogre (al-ghūl) - or "ghoul."

  • ζ (zeta) Persei is magnitude 2.84, and about 750 light years from Earth.

  • ε (epsilon) Persei is magnitude 2.88, and approximately 640 light years distant.

  • γ (gamma) Persei is an eclipsing binary system, with an combined magnitude of 2.93, and around 243 light years distant.

  • δ (delta) Persei is magnitude 3.01 and is 520 light years away.

  • ρ (rho) Persei is magnitude 3.39 and is 308 light years distant.