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Tips and learned experiences from purely mobile astrophotography ~50 darksite imaging trips


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Well, most of the time i dont actually go to a dark site, but just a site. But that sounds silly so i will call it a darksite trip even though the destination was Bortle 6 or 7. Over the past 2 years i have gone out with my scope roughly 50 times and thought it a good point to reflect on what i have learned to do and not do while imaging at a darksite. Plenty of mistakes were made and (i hope) learned from, so i am writing out a list of good practices and things to avoid so that others could minimize frustration and lost nights under dark skies. I have streamlined my setup process to a point where there are never any surprises and i am collimated, polar aligned, all software running, all trinkets on the scope and guide calibrated within 30 minutes of striking the tripod down. Bringing this time down is essential in getting the most out of a darksite trip, as time that you spend fumbling in the dark will result in no images and will just frustrate you, leading you to avoid these trips.

Purely mobile astrophotography without a backyard is perfectly doable even with quite heavy kit if you plan ahead and get used to it, for example i am currently imaging with an 8'' newtonian and an AZ-EQ6, so around 60kg of stuff with everything packed. The only real requirement for astrophotography is in my opinion a car and of course being in shape enough to handle the gear. (and the cost of course, but you dont have to spend as much as i have).

Most of the trip happens before you decide to go out, in the form of research and planning, so here are my tips for that.

 

1) Before even thinking of going to a darksite:

Make sure you have a good quality power supply! Most "dumb" battery solutions drop below 12V well before they actually run out of juice, making your kit unstable (especially in cold weather, dont bother when -20). I recommend pouring good money for a power supply that can supply stable 13.6V for the entire night.

Dry rehearse everything from packing the stuff into easy to carry bags or boxes and setting the gear up at home. If you cant do it easily at home you absolutely wont be able to do it free of frustration out in the cold and dark of night. If you have been imaging from the comfort of your own backyard you may have forgotten how to do some things, or have not given any thought on how to carry the stuff as it is relatively easy to carry even heavy stuff a couple of meters outside. Give significant thought on how you are planning on carrying your mount, which for most quality EQ mounts will be over 15kg of steel in an awkward chunk. Pack spares of as many pieces of small and easy to carry kit you may need, like cables that can easily break during transportation (pack them separately from heavy stuff to avoid this), fuses for your cigarette lighter plugged devices (the tip has a fuse!). Obviously dont bring a spare scope or a spare mount or something like that. If those break, time to pack up and go home.

 

2) Where to go?

Absolutely, definitely dont EVER go out with the intention of darksite imaging to a place you have not visited before! Have done that, wont do that again. You might find lights where you thought there were none, roads not winter maintained, or just something that makes the spot a no-go. Just check it before hand.

If you dont know of a local darksite that is well documented and you are familiar with, you need to do some research. https://www.lightpollutionmap.info/ Is a good resource for rough sky quality estimates. Do be aware that this is not set in stone and should be used as just a general idea of sky quality. Try to look around google maps street view mode around dark areas you want to travel to to find a spot that you could easily drive to and set up a scope in. After you have some ideas, drive to the site after dark before actually going imaging and check that it actually works for you. Google maps may be outdated and there may be street lights or new construction that has brightened the area, you wont know unless you actually physically go there at night. Pay attention to things other than darkness too, for example which directions are free of trees, obstacles and such. For example if north is covered you need to plan how to polar align without access to Polaris. Easy to do with many software out there, but almost impossible if you just figure it out when actually setting up! If the area is very open, like the edge of a field or an opening in a forest or something keep in mind that there may be wind. Try to gauge whether there is too much wind and dont bother using the location if the forecast has any significant wind in it to avoid a useless trip.

 

3) Target research

You HAVE TO know what you will be imaging before you go out or you will waste time looking at planetarium apps or imaging a sub par target. Knowing the target location already, keep in mind that some azimuths may be covered with obstacles (if they were in the spot you chose) and choose a target that is elsewhere. You may need to choose multiple targets for the night if your primary target gets too low in the sky as the night progresses. Also have secondary targets in mind if for some reason you find that you dont want to image the primary target. Reasons could be something like light haze making the data worse than what you want/have already gathered or poor seeing making a difficult target not work out. Be aware of where the Moon is and dont bother imaging your main target if the Moon is close to it. Just plan a target somewhere else in the sky for these situations.  Once you have the targets in mind, set them up as sequences before heading out. I use NINA and have a library of sequences that have exposure lengths, dithers, guiding, platesolving etc all set up and all i have to do is click "start sequence" and the scope does its thing. I have named the sequences ending in - Rotation 90 or something like that so that i know what rotation the camera needs to be in. Before accidentally shooting for half a night so that half the target is off screen (never done that...)

 

4) Packing and traveling

Check that each piece of kit is packed, then check again and pack the thing you forgot the first time. Try to minimize setup time by preinstalling as many things as possible, like: Keep the imaging train intact and if possible attached to the scope. If not possible, keep the imaging train as one chunk that you thread/insert into the focuser. Keep the guide cam in the guide scope and don touch the focuser, keep your mini-PC and the cables connected to that in a neat package that you just unfold when on site etc. Driving for an hour to somewhere and figuring out that you left an important piece of kit home is not a good time (have done, will probably do again). Give some thought on temperature differences with your kit as you will probably need to spend some time cooling the scope down when you arrive. If its winter and there is a 40 degree difference between indoors and the imaging location, you need to take steps to minimize the cooldown time on the way there so that you waste as little time as possible. I carry my newtonian in an Oklop padded bag, which also unfortunately acts as insulation and the scope will still be almost room temperature after the drive. This is why i open the bag once its in my trunk to let it cool down faster and dont use the heater in my car at full. Obviously the heater needs to a) keep me alive and b) keep the windows clear, but other than that just wear a hat and gloves and you'll find a ready to use scope when you arrive instead of looking at tube currents for more than an hour!

You may also want to pack visual astronomy gear if you plan on doing that. If you think that you'll "do some visual if you have time", spoiler alert, you wont. You need to plan on doing visual or it doesn't happen, at least if you suffer from chronic astrophotography as badly as i seem to do. This is a good way to salvage a ruined night if there is too much wind for example, as your mount will perform well enough for visual purposes in wind that makes accurate imaging nonsensical.

The best way to prepare is to leave all of your kit prepacked at all times in their carrying bags and not put them up for temporary storage between trips. Difficult to forget something like this!

 

5) Set up and beginning imaging

Do this the same way every time so that there are no surprises. For me it is: Plug in the cooling fan on my mirror to the battery pack to win as much cooling time as possible while i set everything else up, set up the mount with rough polar alignment to the north, scope and gear on the mount, polar align with sharpcap pro (Or NINA if Polaris is not available), guide calibrate on as low a declination you can, but still preferably at a high altitude. Not possible for me at 60 degrees north, so usually i have to settle for Declination 10-30 targets. Once its done, start the sequence, focus etc and off it goes. DONT "test things out" or "adjust" guiding if you didn't plan on it. If you need to iron out an issue with guiding, plan the session for JUST that or you will be frustrated on the wasted time and probably still not get the issue fixed. Check guide logs later and try to make guesses on what to fix, its much easier than trying to ad hoc a solution to a minor issue. If you have a new piece of kit that need testing, expect to not get any imaging done and you'll be less annoyed in the end.

 

6) Rules and showstoppers

Sometimes the weather just does a 180 and clouds appear out of nowhere even when the forecast said it would be 100% clear for the whole night. Have a set limit on how long you are going to wait for the clouds to pass and stick with it. If you wait for 30 minutes and "its just about to get clear", well usually it isn't and the 30 minutes goes on and on and on. Depends on whether its a good spot and a long drive but usually i wait for an hour and at this point the forecast should have changed to the actual conditions and now its much more clear on what the weather will be like. If at that point i dont see the clouds ending soon i head back home. Much better than just waiting for gaps in the clouds for the whole night! Accepting defeat is much better than the demoralizing wait for the clouds to end for hours and hours on end, trust me on this one.

Equipment breakages would also be something to keep in mind. Lets say something breaks and you dont have a spare. Just go home and fix it later, dont try to fix an issue you didn't prepare for beforehand. If you planned well and a cable, fuse, or something else easily replaceable breaks then great, fix that and keep going. Software issues are the most common culprits in my opinion to keep in mind. If you didn't check that every piece of software works with the remote setup then its on you and something to fix for next time.

 

7) Ending the session

You also want to have a limit on how long you are staying. If you plan on sleeping through the night, make sure everything is set up so that it keeps doing its thing without the need for babysitting. If you are planning on heading home after imaging and not sleep through the night, then have a limit set in mind. If you image to the bitter end of sunrise when you didn't plan to you'll be grumpy and tired tearing down the kit and driving back home in the wee hours. What the limit is will depend on your sleeping habits of course, but try not to ruin your sleep schedule too much or you wont be doing these kinds of trips out of annoyance anymore.

 

8 ) Try to have fun!

Sometimes easy to forget 😅.

 

TLDR ( wrote a wall of text...): Planning, planning and more planning will make your trips more efficient and less annoying.

Any rules, ideas, or tips come to mind? Feel free to comment your own experiences!

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