Canon 1000D piggy-back on 80ED

 
After months of anticipation, I hope it will deliver the promised kick-start to the appreciation of astronomy, by the wider public. 

To celebrate the first clear night (for me) of 2009, I thought I should do a first thing, too.

So I attached my newly purchased Canon 1000D digital SLR camera, to my Skywatcher refractor.  

The Canon was not actually looking through the telescope – I need to buy a Canon T-thread adaptor before I can do that.  This time it was just “piggy-back” (or afocal as the serious astronomers call it), to take advantage of the telescope’s motor-driven mount.  I was using the 18-55 mm zoom lens, the camera came with.

The weather is freezing (-5 degrees C) tonight and this made it tricky, but I managed to take some images of the constellation Orion (the Hunter).  

Constellation of Orion

It was splendid in the South.

I used a 30 second exposure for this shot (right).  I’m still getting used to all the hundreds of settings on the Canon and I felt it was fighting back, once or twice!  But I’m pleased with the results.

You can see the indication of the Orion nebula M42/43, below the three-star “belt” of Orion.  Also, follow the line of the belt downwards and left to see Sirius, the brightest star in our sky (apart from the Sun).  It’s barely above the horizon (and the hedge!) in the shot.

I will be giving a talk on the Winter night sky next Monday, to my local astronomy society.  I hope to make good use of this image and the others.

In mythology, Orion is said to be a hunter. The shape of the stars in the sky can be interpreted as a man, with a belt and sword, who is holding out a shield against the neighbouring constellation of Taurus, the Bull.

Constellation of Orion

However, from northerly latitudes in Summer, Orion is below the horizon at night and cannot be seen.

The main and easily recognised star pattern within Orion, is four stars in a rectangle which is bisected by the slanted “belt” of three stars.

In one direction, the belt points to Sirius, which is the brighest star in the sky and in the constellation of Canis Major. In the other direction, the belt points to the orange-red star Aldebaran in Taurus.

Orion is therefore a very useful “signpost” in the sky.

The “sword” of Orion, which appears to hang down from the belt, is actually a huge nebula (M42/M43), where stars are being created.

Each of the four main stars are bright and interesting.

Betelgeuse

The top left star (for an observer in the northern hemisphere) is the brightest. It is alpha-Orionis, called Betelgeuse.

Betelgeuse is noticably red-coloured to the unaided eye and is a red super-giant, variable star.

Its magnitude fluctuates between O and 1.3 every 6 years and it also pulsates in diameter from 300-400 times the size of the Sun. It is a true giant and it is 430 light years away.

Rigel

The bottom right star is Rigel and it is usually the brightest in Orion at magnitude 0.2. However, because of Betelgeuse’s variability, Rigel is designated beta-Orionis (not alpha-Orionis).

Rigel is a blue-white supergiant that is 800 light years away so it is nearly twice as far from Earth as Betelgeuse.

Bellatrix

The star at the top right (for Northern hemisphere observers) is a gamma-Orionis, called Bellatrix. It is a blue giant of magnitude 1.6

Saiph

The bottom-left star is Saiph, kappa-Orionis, at magnitude 2

The “Belt” of Orion

In some ways, the three stars which form the “belt” are the most interesting.

From left to right, they are zeta-Orionis called Alnitak (“the girdle”), then epsilon-Orionis called Alnilam (“string of pearls”), and lastly delta-Orionis called Mintaka (“belt”).

Alnilam is a blue super-giant, magnitude 1.7. It is 1600 light years away.

Both Mintaka and Alnitak are multiple stars.

Mintaka is an eclipsing binary with a period of 6 days. The pair is a magnitude 2.2-2.35 blue-white star with a magnitude 6 companion you can see in binoculars and small telescopes.

Alnitak is a tight pair of stars with magnitude 1.8 and 4. You need a good telescope to split them.

Sigma-Orionis

Just below Alnitak, is another multiple star, sigma-Orionis. It looks like a double star in binoculars, but a decent small telescope will actually show it to be four stars.

The “Sword”

As mentioned above, the Sword can be seen just under the belt.

It is a swirling mass of gas called the Orion Nebula, where stars are being born and it is excellent to observe through binoculars or telescope.

When Messier compiled his famous catalogue, he recorded this gas cloud as two separate objects, M42 and M43. Astronomers now believe them both to be part of the same cloud, although there is a dark area which makes them look separate, through a small telescope.

The “Trapezium”

In the centre of the Orion Nebula is the multiple star, theta-Orionis. Through a telescope, you can see a trapezium pattern of four stars.

It is believed that these stars have actually been created from the cloud of gas that is the Orion Nebula and that it is their light, that makes the Nebula glow.

Summary

As you can hopefully appreciate and see, the constellation of Orion is fascinating and well-worth some of your observing time, with binoculars or telescope.

It is known as “the Swan” because of its distinctive cross-shape in the sky. You can imagine it as a flying swan, with wings outstretched.

Cygnus has a declination of 29 degrees so it can be seen high in the sky to the south during the summer, from northerly latitudes. It is also visible to southern hemisphere observers.

Deneb

The brightest star, alpha-Cygni, is called Deneb (“the tail” from the Arabic).

Deneb is one of the brightest stars in our sky, having a magnitude of 1.2, in spite of it being 2000 light years away. Its absolute (or actual) magnitude is -7, which means it is 30,000 times brighter than our Sun.

Deneb is the most distant, first magnitude star.

Albireo

The double star Albireo (beta-Cygni), marks the head of the swan and it is a showpiece of the sky.

Look at it through a small telescope and you will see a pair of stars in contrasting colours. There is an amber star of magnitude 3, together with a blue-green star of magnitude 5. Beautiful!

The Milky Way

Cygnus lies in a particularly rich area of the sky for stars and clusters because we are looking here, into our own galaxy, the Milky Way.

On a dark and clear night, you can see with the unaided eye a “gap” in the Milky Way, to the side of Cygnus, called the “Cygnus Rift” or “Northern Coalsack”. It is not in fact a gap in the stars, but actually a dark area of dust produced by stellar explosions, that obscures our view of stars in this area.

Veil Nebula

Below the left arm (for northern observers) is an area of gas called the Veil Nebula. This is the remains of a supernova, or exploding star, from 30,000 years ago.

It is tricky to see without imaging the area, although you can see it under good conditions using a low-power telescope.

61-Cygni

This is a pair of orange dwarf stars, that are some of the closest stars to us (just 11 light years away). A good target for a small telescope.

The Coathanger

Below Albireo, towards the constellation of Aquila, is another good target for binoculars and small telescopes. It is not technically in Cygnus, but in the constellation of Vulpecula.

The Coathanger is a cluster of stars and the brightest ones, look just like an inverted coathanger.

Summary

For observers in the Northern hemisphere, the constellation of Cygnus make an interesting observation area. It is high in the sky, so you can see nice sights, even if the sky is not particularly dark.