astronomy

Moon at Sunset by Conor Cunningham

Our lunar friend, rising in the east as I flew from Trondheim to Oslo

A work related errand saw me heading to Trondheim on a day trip a couple of days past, but unlike most work trips, this one afforded me a rather delightful site on my return flight. The weather had been tip top all day in Trondheim; sunny and about -1 Celcius, and as luck would have it, my flight was departing just as the moon rose.

As is at on the tarmac looking east, I could seen the top of the moon summit some of the local mountains. A quick think and I realised that this would make for a nice view as I was flying south and sitting in a window seat on the left of the plane. Quickly however, I realised that the only camera I had was my Samsung S5 mobile phone. Not the greatest of low light shooters, I tried to take a picture of moonie, only to quickly notice, as did my fellow passengers that I had left the flash on. Eejit. a few shots with the steadiest hand I could manage allowed me to get one or two usable shots.

One thing which is apparent in the photo, but isn't done justice by it, is the moon's light on the surface. It was a delightful sunset orange and it moved quickly across the surface, relative to my position on the plane. As you can see, the moon and its shadow are overexposed and there was no manual control on the camera, and hence, no way of saving the details.

I might be up there next week again, but I won't be so lucky to capture the moon during sunset then (bloody Earth, Moon orbital system!).

Tarantulas in Space by Conor Cunningham

NGC 2070, aka the Tarantula Nebula

It's been a while since I posted something spacey, so a couple of weekends ago whilst out with one of my astronomy clubs, I set about programming a remote telescope to take a picture of NGC 2070, otherwise know as the Tarantula nebula. To do this well, one needs a good telescope, a highly accurate tracking mount (to counter the Earth's rotation) and a nice camera. In this case the setup cost somewhere upwards of 80 000 USD and needless to say, I don't have that burning a hole in my pocket so I rent such a beast through iTelescope.net.

Enough of the rambling. The image comprises of 30 images, each five minutes of exposure. The camera is monochrome and 12 of the images are capturing 'white' light, six were capturing blue light, 3 for red light and 3 for green light.

The images are then stacked together to form master luminance, red, green and blue images, which are eventually all combined together into the relevant luminance and colour channels and then processed using advanced imaging techniques in software such as Pixinsight and Photoshop.

The Tarantula nebula is, as best I understand it, an area of star birth where gas and dust fall together under their gravity and eventually, fusion starts. It's about 160 000 light years away, but if it were as close as say Orion's Nebula, it would cast shadows on the night side of Earth! Bloody wow!

So after many hours of work, the above image was the result. I hope you like it!

Shooting for the Stars: Astrotrac TT320X-AG by Conor Cunningham

I'm a bit of geek, no two ways about it. Science is cool and I reckon I can prove it, too. The proof is the night sky and all it takes to perform the experiment is to lie flat on your back after dark on a clear night (the further you are from city lights, the better). How you end up on your back is up to you but I can attest to  walking out of a pub in Oslo on an icy winter's evening can have one vertical in less than a second. After peeking up for a bit you'll notice satellites streaking across the sky, meoteors before they evaporate entirely or become meteorites (meteoroids in space, meteors in our atmospehere, meotorites once they hit the deck), plenty of stars and if you're lucky some planets, too. Depending on how you look at it, you may be lucky enough to see the moon, too.

Moonie. As seen from Oslo, Norway

But I digress. The point I'm trying to make is that if you take a picture of the stars for less than a few seconds, you probably won't see them in your picture. Take a picture longer than a few seconds and you'll see them, but they probably won't be round. The reason is because the earth spins and the stars (for the all intents and purposes) don't move. That's why we see them going across our sky.

Stopping the Stars

Well, we can't, but we can track them. That's where the Astrotrac TT320X-AG (boring name, great device) comes in. I picked it up when I was in London a few weeks ago at European Astrofest. In short, the Astrotrac allows us to follow the stars in the night sky whilst our shutters are open. By aligning the central axis of the Astrotrac with the Earth's axis so that it can rotate the camera at the same rate as the Earth's rotation, albeit it in the opposite direction (there is a setting for both northern and southern hemispheres).

Last night was the first clear night since the night before, but the night before was the first clear night since around the new year. With that in mind and the forecast gloomy, I loaded up the car and headed into a carpark on the outer edge of Oslo's forests. Unfortunately there were a few too many skiers with headlamps in the area, then some learner drivers arrived with their instructors to use the area for lessons on night driving. Not a good start.

Well, it's only a test. I setup the tripod, mounted the three way head, then the astrotrac, polar aligned and put the camera on its ballhead and started to shoot. The alignment wasn't too bad, but not fantastic either. My biggest problem however was by far and away the light pollution from Oslo which effectively ruled out shooting south or west. North was my best bet so I pointed it north, framed the Plough/Big Dipper. I chose 30 seconds, ISO 800 and f/4 with a 24 - 105 @24mm.

Best viewed in full screen.

The big dipper is on the right just to the right of the streak (a satellite most likely) in the sky

Tips for Shooting the Night Sky

A tripod. No ifs or buts. The sturdier the better. A fast lense will of course help, the more light the better. ISO of between 800 - 1600. The higher you go the more noise you'll get, but the shorter the exposure time the less star trails you'll see (unless of course you use an Astrotrac!). Finally, you will need a remote trigger so that you don't shake the camera when you press the trigger. If you don't have a remote trigger, use a 2 or 10 second delay on the shutter. It's also worth considering mirror lockup (live view works just as well), too, if you really want to keep the vibrations to an absolute minimum.

Finally, for focus, I turn on live view (if you don't have it, don't fret) find the brighest star, point my camera at it, turn on manual focus and then turn on zoom in 10x and focus as accurately as I can. If you don't have live view (which I didn't until recently) you can use a dioptrix or simply your eyes.

Good luck!