I think we’ve all probably had one of those nights under the stars where everything has gone wrong and had the feeling of being completely unprepared for a clear night and getting ourselves in a mess. Well with the help of this post, hopefully you won’t end up in that situation. I’m going to explain my process for preparing for a night of astrophotography so you’re less likely to lose valuable imaging time and more likely to succeed!
Comment your favourite preparation tips below for others!
The Preparation Routine
Get set up as early as possible, preferably while it’s still light outside.
This gets trickier as the nights get longer in Autumn going into Winter. However, if you setup as early as possible, then you’re as prepared as you can be before starting your imaging session. For me this has become especially important as I’ve added more complexity to my rig with auto guiding, plate solving etc.
This means that when astro dark begins, I’m ready to start imaging straight away and have already ironed out any issues during setup, and therefore maximising my imaging time.
Polar align as early as possible.
Similar to the first tip. By polar aligning earlier, I’m able to do 2 things, 1. setup while it’s still reasonably light outside so I don’t trip over my gear, 2. Polaris is a very bright star, so by polar aligning early you can be certain you’ve aligned to the correct star as it will be the only one visible in your polar scope. Twilight is the best time to polar align.
Use Stellarium or other online resources to research what targets are good for your equipment.
I’m a big believer that your imaging gear shouldn’t hold you back. You can take great astro images by just using a tripod, DSLR and kit lens. However, there’s little point trying to image a tiny galaxy with a setup like that as you will barely be able to see it. That’s where Stellarium, or other planetary software can help.
Stellarium gives you the option of inputting your equipment details into it so you can frame up your targets and see what the field of view (FOV) looks like. That way, you know how well an object will appear within your FOV before you start imaging it. Stellarium will also allow you to plan your session properly, i.e. when will the deep sky object be high enough to start imaging, or when will it be too low etc.
Planning your sessions this way will maximise your imaging time.
Use the meridian line in Stellarium to see if you need to carry out a meridian flip during your imaging session.
The last thing you want is for your expensive astrophotography gear to hit your tripod legs. That’s why meridian flips* are so important. By turning on the meridian line in Stellarium and tracking your object, you can see whether or not you will need to do a meridian flip at any point during your session.
*the meridian is an invisible line in the sky going from North to South. As you track deep sky objects from East to West, if your target crosses the meridian during imaging, you will need to do a meridian flip.
You can also automate this by turning on auto-meridian flips if you use image acquisition software such as the ZWO ASI Air, NINA or Astroberry. Just be careful of cable snags, I’d always recommend standing next to your gear during a meridian flip, just in case.
Check the weather!
This one is too obvious right? Well sometimes it’s the obvious things we miss. In this day and age where there are so many apps to track the weather, it can often mean that if we’re sat on the sofa and an app tells us it’s cloudy outside, we believe it. Well I have lost count of the amount of times that all those apps have been wrong (I have 4 different weather apps on my phone, often contradicting one another).
We all know weather forecasts aren’t perfect, it’s even ubiquitous in the UK to assume that the weather forecast is wrong. However, if an app tells us it’s cloudy, we tend to believe it. It is always worth going outside and actually checking what the weather is doing, particularly if you’re just wanting to grab a quick shot of the moon!
Take calibration frames before imaging, or at least straight after if possible.
Often easier said than done. However, calibration frames are such an important part of the astrophotography data gathering process. The quality of your final image depends on them!
One of the key important factors about flats is that they’re taken using the same focus as your light frames. If you bring your equipment inside after imaging and think “I’ll take those flats tomorrow”, then you might find you accidentally knock the focus off, meaning your flats won’t fully match your light frames.
If you’re unsure how to take flat frames, I have a guide here.
If you have a cooled camera, why not setup a dark library for various temperatures and exposure times and just refresh it every so often. It can be such a time saver in the long run. Temperature matching your darks to your lights is crucial, so if not using a cooled camera, you really need to take them at the same time to ensure the temperature of the sensor is matched.
If you’re unsure how to take dark frames, I have a guide here.
These can actually be done at any time as they’re only capturing the noise pattern of your camera.
If you’re unsure how to take bias frames, I have a guide here.
By following these basic principles, you should be well prepared for each imaging session. This doesn’t mean that there won’t be any gremlins in your routine, like why is auto-guiding suddenly not working even though it’s worked every time for the last 2 years?! Seriously, these things do happen!