Best time for imaging?

[BrendanC]

I'm setting up a spreadsheet of objects I'm interested in, and when's best for me to image them.

I'm using Stellarium to find each object to decide whether it's visible from my location.

However, I'm not sure what to list as the 'best' time. Options are:

• When we hit astronomical darkness and the object is as LOW as possible - because that gives me the most time to capture it as it moves across the sky throughout the night
• When we hit astronomical darkness and the object is as HIGH as possible - because that gives the least amount of atmospheric distortion BUT also less time with the object because it's already traversed half the sky
• Or something else entirely.

To take M42 as an example: where I live, towards the end of January, astronomical darkness is at around 6:30pm, and that's about when M42 becomes visible in my garden, at its lowest point. However, toward the end of February, when darkness is at about 7:30pm, it's at its highest. So which of those would be better to add to my spreadsheet as 'the best' time to think about imaging it?

Is this even making sense?

Any/all comments welcome, including ones telling me I'm not making any sense.

[tomato]

You will get better results when the object is higher in the sky but on the other hand if you only take images at this point it will take you quite a long time to gather a lot of data, especially in the UK.

From your equipment list in your signature I assume you are using a DSLR, so you are capturing colour data all at the same time, so not much choice to be had on when you capture individual colour channels.

My own take on this is Imaging time is so scarce in the UK that once it is properly dark, start imaging your subject and don’t stop until you either get too tired to continue or the object goes behind a tree or the neighbour’s house. You can always delete the sub standard subs later. Faint Deep Sky Objects (which is most of them) generally require total integration times in hours rather than minutes to capture good detail and colour.

[CloudMagnet]

It really does depend on the object I think. You dont want it to cross the meridian unless you want to do a merdian flip. A way I do Orion is to image M42 for the first half of the night, then when it crosses the merdian, flip the scope and do the Flame nebula- you get both in the same night

Otherwise, I plan my targets by normally looking at when they will rise above any obstructions (houses, trees) and then start imaging from there. If you are doing a full night, then the seeing will averge out over the time anyway. If you pick a target starting at maxium height, then the seeing will just get worse as the night goes on for a lot of targets so it makes little difference I think.

[endless-sky]

From my personal experience, I would start shooting only at astronomical darkness and when the object is at least 25° above the horizon (depending on the subject, of course, there might be objects that are never above 25°, but then are also limited by houses/trees).

Here is a link to a good online planner: https://telescopius.com/

Enter your location and desired date and then click on "Targets" and "Deep Sky". It will tell you what will be available, when, and give you an altitude vs time curve for each object of interest. You can also filter the object list (object type, magnitude, size, etc.). I find it really useful!

[BrendanC]

Lots of food for thought, thanks everyone.

I've come across Telescopius before, wasn't quite sure how to use it but I might give it another go off the recommendation here.

[BrendanC]

Hmmmm. Telescopius is rather good isn't it? In fact, it's pretty much exactly what I've been trying to put together!

I might abandon my foolish home-brewed approach and use Telescopius instead.

[endless-sky]

I am glad you liked it! I also like all the customization that you can achieve using the filters and the options. And it's also nice that you can choose the objects based on a specified value of degrees over the horizon, for at least a certain amount of time. Another nice feature is the FOV calculator: you specify sensor dimensions and focal length and you see how big - or small - each object will look like on your photographs, for a given camera and lens/telescope combination.

[BrendanC]

It's actually amazing. I've just spent an hour being amazed by it. I love that it integrates with Stellarium and APT too.

Basically, all the data and tools I've been creating myself, have been done much better in Telescopius!

The only gripe is that it keeps forgetting the aperture of my scope which I've set as 5 inches but it keeps changing it to 8 inches. Still, I really like it. Definitely my new toy.

I think I just didn't 'get it' before because it is a little daunting, as is so much of the astro software and sites. But after trying to do this myself, I suddenly understand what it's all about.

And it's free. 

Nice recommendation, thanks.

[endless-sky]

I just checked to make sure: if you register and log in, you can save all your favorite configurations for the FOV calculator!