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Eridanus, a dim constellation that is always overshadowed by it's brighter neighbors. These include Orion, Taurus, Monocerous and Canis Major. But these objects have many features of interest. Orion has the beautiful awe-inspiring Orion nebula, Taurus with incredible naked eye open clusters such as the Hyades and the Pleiades ( Subaru cluster ), Monocerous and its wealth of Nebulae and last but not least Canis Major with incredible Messier objects and it's beautiful gem that happens to be situated in the Great Dog's jaw, Sirius A and B.

But what about the faint, long constellation of Eridanus the river? Does it have anything to show our eyes and optical equipment? Indeed it does and some objects in it are very underrated indeed. Lets take a look at these objects in this very mysterious constellation.


BINARY STARS: We start our list with 63 Eridani, a magnitude 3.9 star situated in the gap between Lepus and Eridanus. It and its companion have a separation of 1.1 arc seconds, It will be a challenge for small telescopes. It is situated in a place where there are no bright stars around it.

32 Eridani: A beautiful binary star I stumbled across last night through my telescope! This lovely double has a topaz yellow primary and a sapphire colored secondary with superb contrast. They are 7 arc seconds apart and are at a distance of 300 light years away and are of +4.8 and +5.6 magnitude. Kind of like Beta Cygni for larger telescopes!

55 Eridani:  Also known as Struve 590 is a dim yet pretty pair of stars, The primary star at +6.7 magnitude is a deep yellow color and the secondary is a deep blue shining at magnitude +6.8. They are separated by 9 arc seconds.

Keid/Omicron2 Eridani: A triple star system 1 degree away from Beid or Omicron1 Eridani. The primary star is of magnitude +4.4 and the B star is of +9.5 magnitude 104 arc seconds away. while the C star is magnitude +11.2 and 9 arc seconds from the B star.

Acamar: Acamar is a pair of stars seperated by 8 arc seconds.


DEEP SKY OBJECTS: Sadly there is only one deep sky object of interest and that is the Witch Head Nebula. Located in between Rigel and Cursa ( Beta Eridani ) it appears as 160 x 60 arc minutes in size. It gets it's blue color from Rigel.


VARIABLE STARS: The only variable star I know that changes quite a bit in magnitude is Lambda Eridani which changes from magnitude +4.2 to +4.4 over a period of 0.7 days.


INTERESTING STARS: Epsilon Eridani: At a mere 10.5 light years away, this is the tenth closest star to Earth. This lovely yellow star shines at +3.7 magnitude and appears to be a part of a small triangle along with a +6.3 magnitude star and a + 7.3 magnitude star. the 7th magnitude star is actually a nice binary with the secondary star shining at magnitude +8.6 separated by 130 arc seconds.

Zibal/ Zeta Eridani: This star may not have any interesting features or facts, but last night when I was observing it with my telescope when suddenly a HUGE fireball crossed it and scared the living daylights out of me! So keep a close eye on Zibal!


Hopefully you can observe these objects and find alot of interest in Eridanus. If I missed anything please leave a reply since I live in the Northern hemisphere I might have missed some of the more southern objects.


Thanks for reading


A budding astronomer.



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So that's what it is supposed to look like. There is also the Eridanus Loop (Sharpless 245), but you are forgiven for not listing it.... very few people have spotted any sight of it.... I have tried several times from dark sites, but to avail. Nice collection of other types of objects!


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Hello Peter, Like I mentioned in the post I may have left out some objects. But I'm very surprised how little pictures there are of this nebula! It only took me 15 seconds of scrolling to find a picture of something unrelated. To that with the Orion Nebula it would probably take 10 minutes!


A budding astronomer

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