How long after sunset to start imaging?

[GrantEb]

Hi all

Probably a stupid question, but when is it OK to start imaging after sunset?

I have been starting at around 7PM lately. Is this to early or to late?

Thanks

Grant

[simon hicks]

Hi Grant,

It depends when sunset is, i.e. where you live and where you are imaging in the sky. But lets assume its in the UK and you are imaging near the zenith, then I would start a bit earlier. I actually like to start imaging about an hour after sunset.....though I might not use the first few frames. At least it gets everything set up, downloading and stable....plenty of time to get things right.

The best thing is to look at the histogram of each image as it is acquired, which is easier if you download straight to a laptop. As you flick from one image to the next you will see if the peak is moving to the left, i.e. the sky is getting darker. It will usually move to the left at the begining of the session and then settle down to a low value....and then start moving to the right again when the moon starts to come up, or hazy clouds appear, or the sun rises again.

The consistently dark ones are the ones to stack.

Cheers

Simon

[GrantEb]

Thanks Simon. Hopefully I can give that a go tonight.

Cheers

[brantuk]

Grant - try this link :

Sky View Cafe - Astronomy - Star Charts and Ephemeris

It's yet another planetaria but with extra info. The "insolation" tab tells you all the different types and times of darknesses throughout the year. You can allways check it before you start the camera rolling

[GrantEb]

Thanks, that looks very useful.

[Earl]

You can use the time, to take Flats, get some darks etc

[Bizibilder]

Try:

Astro Events for UK based locations

And pick a place near to yourself. It gives "Amateur Dark" times - which are a useful guide. It is updated daily, I think. You will see in the RH column the dates in the summer when it doesn't get "Amateur Dark" at all from some sites !!!

[GrantEb]

Thanks for that. I am around 6pm, earlier than I thought.

Cheers

[Photosbykev]

tongiht @ 53 degrees the sun is 18 degrees below the horizon just after 6pm assuming the sky is clear that's when I'll start playing.

Probably worth setting up a static camera looking east as well later in the evening and shoot continuously to capture any geminids that arrive early

[GrantEb]

The clouds look to hit me by around 6pm, typical. Good luck to the rest of you for clear skies.

[FraserClarke]

I usually start about 10 minutes *before* sunset, taking narrowband flat fields (telescope shaded from the setting sun of course).

For taking imaging data, I usually wait until ~12 degree twilight (sun 12 degrees below horizon). There is a bit of an improvement from 12->18 degrees, but you need a good dark site for it to be important. If you're dealing with a lot light pollution, or the moon is up, it probably won't make a significant difference. The extra 20-30 minutes of data certainly won't make your images worse

The points about using the time to debug the system is very good too