Making a time-lapse of deep-sky objects

A lot of specialists and astrophotographers would probably look at me like: "whaaaaat?". Could that even be possible/realizable? Since I love challenges, here is a new one for me that is mind-boggling! Deep-sky objects (i.e. planets, galaxies, nebulae, or anything that needs magnification) are hard to capture without a telescope or a tracker. Fortunately I have the latter, a camera and a 500mm objective. But why try shooting a time-lapse of a deep-sky object? Well, firstly because it virtually does not appear anywhere on the web or literature (expect a few exceptions), secondly because I thought it could be exciting to combine deep-sky objects with real-size landmarks and thirdly because I might be crazy.

M31 - The Andromeda Galaxy

Well I am not that crazy since there are a myriad of time-lapse of the moonrise or moonset with a foreground out there! What if one replaced the moon with the Andromeda Galaxy (M31) or the Orion Nebula (M41), wouldn't it be beautiful? Yes of course, I thought. But it is very challenging, because of multiple factors.

1) It requires a lot of thinking before hand. The desired object has to move close enough to a foreground and for long enough to be interesting. You have to make sure of the time of the year, where your object is gonna pass... etc.

2) Tracking will not be an option, since it starts being interesting from 80-90mm focal length. The sense you choose has to have a fast glass, but shooting below f/2.8 will not be recommended (well if you can go below on your sense of course!) to get the least light abberation.

3) Stacking will not be possible: the object will of course not appear as in a Hubble-telescope picture and it might be a good idea to filter your light to get the most of the nebulosity. I am just getting started in this discipline, but so far I got very satisfying results without a filter. I can't wait to try out my new CLS filter on my canon and take a time-lapse of the Orion Nebula setting on the horizon!

4) If the horizon is your foreground, it won't be that interesting, because of the atmospheric pollution and bending. The objects will appear distorted and as if they were in a haze. Mountains could ideally be an excellent foreground as they are high.

My first attempt was the Andromeda galaxy and it was an accident! It is an excellent object to take a time-lapse of, because it is so bright! I shot the session on my sony a7r2 + metabones adapter + canon 100mm @ 2.8, 35'', tracked with iOptron Skytracker for 2 hours. Originally I wanted to stack the pictures together to get a clear shot of M31, but I had let the camera on for two hours, and a lot of tree branches got on most of the shots. I decided to put them together just for fun, and I actually liked it. Why not try with other things?

February 15th-16th, 2016. A big Aurora Borealis storm is coming and I am preparing for a night of wide-angle time-lapse. But this time around, I am also bringing long lenses! I want to try and take a time-lapse of M31 in the northern lights, as I knew that the galaxy was passing low enough on the horizon (where the lights would be in Denmark...) at around 1:00 AM, at the heart of the light show! I was amazed by the result, and I might be wrong but I have never found anything like it anywhere in literature. It's not like nobody has ever seen it, but it's more like nobody has ever tried to capture it, or at least publish it...

M31 Bombarded by the Aurora

I've tracked M31 for 1h30 as it was passing low on the horizon (the result is a bit fainter than expected, but still awesome to me!) with the same equipement, but for 20'' at ISO 1250, 150mm (the problem with northern lights is that they are so elusive that one needs to reduce the exposure time to get the most of them). I love the result and want to try it again soon! You can watch the time-lapse here:

It is just a start, but I need to practice and get better at it. I love combining deep-sky objects and time-lapses! I can't wait for the next winter to be able to develop my skills at this new discipline! Stay tuned for more exciting deep-sky object time-lapses! You can also watch a newer time-lapse sequence of M31 with the rock of Esterhøj, Denmark in the foreground in my video 'Into the Danish Winter' here.