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# Is a dark site worth it?

23 replies to this topic

### #1 Huangdi

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Posted 31 March 2020 - 02:19 PM

I've been wondering about SQM, Bortle, and all that dark site stuff and thinking about whether it's worth it for me to image at a dark site.

The drive there is roughly 30 minutes and it's steep uphill (from 350m elevation to 1150m). My SQM readings from my garden are ~20,5 (So it's basically the low end of Bortle 4) and the dark site is ~21,3 (So it's Bortle 3).

With all the fuss of setting my stuff up in the dark (I usually can't go before it's dark) and having to leave a few hrs before sunrise because of sleep I wonder whether it's actually worth it to go there.

Let's take a look at the following scenario.

At home I can start imaging (sky brightness wise) at 9pm up until 5 am, that equals to roughly 8 hours of integration time.

At a dark site, I could start imaging at around 10pm until 3 am, that equals 5 hours.

So my question is, will these three lost hours of data surpass the increased SNR from a dark site? Do you know any articles/posts that can help me understand the actual science behind sky darkness? I am intrigued by it...But I've been struggling to find a proper formula to calculate the SNR improvement your sky darkness gives you, so help me out on that please!

Edited by Huangdi, 31 March 2020 - 02:19 PM.

### #2 SteveInNZ

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Posted 31 March 2020 - 02:37 PM

I had exactly the same question. DM is Darkness multiplier.

DM = 2.512^(DarkSQM - BrightSQM)

DM = 2.512 ^ (21.3 - 20.5) = 2.512 ^ 0.8 = 2.1

so 5 hours at the dark site is equivalent to 10.5 hours at home.

Steve.

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### #3 sg6

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Posted 31 March 2020 - 02:37 PM

Yes it is worth it.

If for nothing else other then to try it and decide for yourself.

Better then asking other peoples opinions.

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### #4 Huangdi

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Posted 31 March 2020 - 02:44 PM

I had exactly the same question. DM is Darkness multiplier.

DM = 2.512^(DarkSQM - BrightSQM)

DM = 2.512 ^ (21.3 - 20.5) = 2.512 ^ 0.8 = 2.1

so 5 hours at the dark site is equivalent to 10.5 hours at home.

Steve.

That sounds good! Do you have any source on this ?

Yes it is worth it.

If for nothing else other then to try it and decide for yourself.

Better then asking other peoples opinions.

I'm a big fan of trying out things But if I try it out, I will need power for my gear which isn't cheap to get. And if it turns out, that I only get a tiny improvement, then I'd rather not spend that money.

### #5 nitegeezer

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Posted 31 March 2020 - 02:46 PM

I would suggest going to a dark site when you can stay a few days. Do brighter targets at home and save the really faint stuff for the dark site. When you go to the dark site, take additional optics with you, even if it is just a pair of binoculars, the view alone makes it worthwhile.
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Posted 31 March 2020 - 03:08 PM

From my imaging at different sites I find it quite worth it.

### #7 TOMDEY

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Posted 31 March 2020 - 03:18 PM

If you intend to actually look up at the sky, when you get there... even momentarily... it will most certainly be worth it!    Tom

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### #8 gezak22

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Posted 31 March 2020 - 03:29 PM

Dark skies completely ruined me. I used to shoot exclusively from a dark blue zone. One night I wanted to see what I could achieve from my green zone backyard and the results were so underwhelming that once it became impractical to drive to the dark blue zone, I completely got out of the hobby.

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### #9 Exnihilo

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Posted 31 March 2020 - 04:00 PM

Well, for moon, planets, and double stars, its not necessary to go to a dark sky site.  But for everything else, dark skies are obviously preferred.

### #10 Huangdi

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Posted 31 March 2020 - 04:05 PM

Dark skies completely ruined me. I used to shoot exclusively from a dark blue zone. One night I wanted to see what I could achieve from my green zone backyard and the results were so underwhelming that once it became impractical to drive to the dark blue zone, I completely got out of the hobby.

That's awful! I've imaged at very dark skies before, but I didn't use my equipment so I'm kind of scared of the difference haha

I would suggest going to a dark site when you can stay a few days. Do brighter targets at home and save the really faint stuff for the dark site. When you go to the dark site, take additional optics with you, even if it is just a pair of binoculars, the view alone makes it worthwhile.

That sounds wise!

I guess I'll give it a go and perhaps borrow a battery to power my stuff. If I save 50% of the time then that sounds like a good compromise...

### #11 Hawkdl2

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Posted 31 March 2020 - 04:14 PM

If you are in some sort of hurry to collect data or want only the very best data, and you have the time to travel and the money to burn on power equipment, and don't mind sleeping in your car or on the ground while your gear does its thing, etc., then absolutely .  But you'll notice the equations don't say that you cannot come close to the same final image with regular-people skies, it just takes 2x the data.  So if you aren't in a hurry to capture data, don't want to spend the time traveling, prefer to sleep in your bed while you image, and would prefer not to spend the extra to set-up and power at a dark site, I don't see it's worth it - notwithstanding doing it for the joy of being in a dark site.  Better?  Absolutely! Worth it? Depends on your values and priorities.  Necessary to generate fantastic images? Absolutely not.

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### #12 Huangdi

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Posted 31 March 2020 - 04:44 PM

If you are in some sort of hurry to collect data or want only the very best data, and you have the time to travel and the money to burn on power equipment, and don't mind sleeping in your car or on the ground while your gear does its thing, etc., then absolutely .  But you'll notice the equations don't say that you cannot come close to the same final image with regular-people skies, it just takes 2x the data.  So if you aren't in a hurry to capture data, don't want to spend the time traveling, prefer to sleep in your bed while you image, and would prefer not to spend the extra to set-up and power at a dark site, I don't see it's worth it - notwithstanding doing it for the joy of being in a dark site.  Better?  Absolutely! Worth it? Depends on your values and priorities.  Necessary to generate fantastic images? Absolutely not.

You're saying that even if I have the same amount of exposure (lets say 10hrs dark site, 20hrs at home), the dark site image would still show a good improvement due to lacking LP or whatnot?

I have the time, don't mind sleeping in the car but money is always an issue I would love to see a comparison of this, but I doubt that anyone actually did it.

So the question remains, how much better is the image quality at a dark side, assuming the SNR is the same.

### #13 gezak22

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Posted 31 March 2020 - 05:06 PM

...

So the question remains, how much better is the image quality at a dark side, assuming the SNR is the same.

Even if someone were to give you a number, it will not be whole story because. For example, a 25% difference in SNR may seem marginal, but that 25% may mean the difference between capturing IFN (or a faint nebula) and not capturing it.

The best thing you can do is to try it out yourself. 30 minutes (1 hour round trip) is a small price to pay for an experimental answer to your question. My round trip was 2 hours, and it was more than worth it.

### #14 Huangdi

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Posted 31 March 2020 - 05:21 PM

Even if someone were to give you a number, it will not be whole story because. For example, a 25% difference in SNR may seem marginal, but that 25% may mean the difference between capturing IFN (or a faint nebula) and not capturing it.

The best thing you can do is to try it out yourself. 30 minutes (1 hour round trip) is a small price to pay for an experimental answer to your question. My round trip was 2 hours, and it was more than worth it.

Yeah that's the plan! I guess I'll do a comparison for everyone who will think about this after me

### #15 drd715

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Posted 31 March 2020 - 05:31 PM

That sounds good! Do you have any source on this ?

I'm a big fan of trying out things But if I try it out, I will need power for my gear which isn't cheap to get. And if it turns out, that I only get a tiny improvement, then I'd rather not spend that money.

Buy an extra battery that will fit your car. If you decide the dark site is too much trouble then use the battery in your car. Or put the new battery in the car and use the old one on site.

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### #16 nimitz69

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Posted 31 March 2020 - 05:36 PM

I've been wondering about SQM, Bortle, and all that dark site stuff and thinking about whether it's worth it for me to image at a dark site.

The drive there is roughly 30 minutes and it's steep uphill (from 350m elevation to 1150m). My SQM readings from my garden are ~20,5 (So it's basically the low end of Bortle 4) and the dark site is ~21,3 (So it's Bortle 3).

With all the fuss of setting my stuff up in the dark (I usually can't go before it's dark) and having to leave a few hrs before sunrise because of sleep I wonder whether it's actually worth it to go there.

Let's take a look at the following scenario.

At home I can start imaging (sky brightness wise) at 9pm up until 5 am, that equals to roughly 8 hours of integration time.

At a dark site, I could start imaging at around 10pm until 3 am, that equals 5 hours.

So my question is, will these three lost hours of data surpass the increased SNR from a dark site? Do you know any articles/posts that can help me understand the actual science behind sky darkness? I am intrigued by it...But I've been struggling to find a proper formula to calculate the SNR improvement your sky darkness gives you, so help me out on that please!

For me? No.  But you’re not me and the only real way to know it to do it for yourself.  Most people I know would kill for SQM 20.5 in their backyard  BTW  This is why I built an observatory in my backyard.

The hassle of packing up my gear, driving to the dark site, unpacking and setting up, followed by 4? 5? 6? Hrs of sitting alone in my vehicle doing exactly what during the session? Then packing up & driving home at 3am only to have to unpack my vehicle again when i get home.  No thanks.

This would also limit imaging to weekends since I still work M-F.

My backyard is 19.4 and there is a dark site 68 miles away at SQM 20.5 but its just not worth it.  I’ll gladly accept the increased capture time if it means I only have to walk 25’ to my observatory to image any time its clear ... YMMV

Edited by nimitz69, 31 March 2020 - 05:38 PM.

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### #17 tjz

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Posted 31 March 2020 - 05:40 PM

I image in 2 different locales: Bortle 5 suburbs and Bortle 3 rural. It's a 1.5 hour drive for me, but every time I image or observe on a moonless night there I wonder why I don't just move there permanently. It makes a huge difference in those faint targets. Especially during galaxy season where you can't do narrowband, it seems to me an hour in Bortle 3 is like 3 hours in Bortle 5. And just taking it in with bare eyes or binoculars while the equipment is busy is a huge treat.

Give it a try, I bet you'll be pleased!

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### #18 drd715

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Posted 31 March 2020 - 05:40 PM

If you are in some sort of hurry to collect data or want only the very best data, and you have the time to travel and the money to burn on power equipment, and don't mind sleeping in your car or on the ground while your gear does its thing, etc., then absolutely . But you'll notice the equations don't say that you cannot come close to the same final image with regular-people skies, it just takes 2x the data. So if you aren't in a hurry to capture data, don't want to spend the time traveling, prefer to sleep in your bed while you image, and would prefer not to spend the extra to set-up and power at a dark site, I don't see it's worth it - notwithstanding doing it for the joy of being in a dark site. Better? Absolutely! Worth it? Depends on your values and priorities. Necessary to generate fantastic images? Absolutely not.

Or you might find camping away from the stresses of town pleasant and get a small travel trailer to use at a remote site. Anything from a 4x8 bunk to a 14 foot egg. See www.fiberglassrv.com Good for hauling out the astro gear too and has a battery for the gear. Rig the inside for computer control of your scope and hide inside from the cold. When you are tired just stretch out for a nap.

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### #19 OldManSky

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Posted 31 March 2020 - 05:52 PM

I used to drive 1-2 hours for one-night sessions. Mostly because they were group outings, and I enjoyed the company very much. Now I have between Bortle 3 and 4 at home. To get to a 2, I’d have to drive 2 hours, and I couldn’t do that more than 1 or 2 nights a month. So I built a little observatory and I image from home nearly every clear night, even work nights. That beats a small improvement in darkness any day.

As others have mentioned, I’d drive to a really dark site to stay there multiple nights, especially if it wasn’t just me but a star party kind of thing. I wouldn’t do it for one night and only a little better conditions.

Up to you.

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### #20 TXLS99

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Posted 31 March 2020 - 06:26 PM

For me, 20.5 vs 21.3 wouldnt be worth it. I'd rather add another hour of integration time at home to help make up the difference. Now for those that live in a more light polluted area, that have access to a dark site nearby, the difference is unbelievable.

Theres probably a fair amount of people that have never seen a comparison like this, so below are two single exposures of M31(no filters involved).  First one is from home Bortle 8 800iso and only a 30sec exposure. The second image is Bortle 4 800iso but at 90secs. Imagine how washed out that first image would have been at 90secs under that light polluted sky.

.

Edited by TXLS99, 31 March 2020 - 06:28 PM.

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### #21 DaveB

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Posted 31 March 2020 - 06:48 PM

I put up a ROR observatory a while ago, and I was deciding between my backyard (20.5) vs. a vacation home about 4 hours away with 21.75 skies. I opted for the backyard and I'm glad that I did because I would image every clear night, even when there was only a brief period of clear skies. See my Abin pages for the images under a 20.5 sky. I'm sure that my time under 21.75 skies would have been much more productive, but I more than made up for that with the total amount of imaging time in my backyard vs. what I would have accomplished at a remote site.

I recently moved to a home with 19.75 skies  but I still plan on imaging from here (currently waiting for another ROR to be built) rather than finding a dark site. People on here that image from more light polluted skies give me hope for what I can accomplish here. Note that I'll have a permanent setup. For me, the difference between having a permanent setup vs having to build / tear down ever night was much, much more of a positive factor rather than a dark sky vs a medium dark sky. (I would have no patience to try to image in a Bortle 3 sky or brighter.)

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### #22 calypsob

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Posted 01 April 2020 - 10:01 AM

If there are lights around your home and the 21.3 is remote, then 21.3 is worth it. Transparency drastically changes sqm so watch that closely, its only worth your time if its above average. Otherwise image from home if its even possible. Also, a few times I have forgotten to check the map and see if the blue ridge parkway is closed, this is where I image, that usually makes a wasted trip. 21.3 at zenith is very much worth the drive imo, its tough to get a good ifn signal below mag 21 and lp gradients with skies of 20.5 are terrible, my yard is usually 21.4, south is a giant light dome

### #23 ks__observer

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Posted 01 April 2020 - 10:25 AM

I had exactly the same question. DM is Darkness multiplier.

DM = 2.512^(DarkSQM - BrightSQM)

DM = 2.512 ^ (21.3 - 20.5) = 2.512 ^ 0.8 = 2.1

so 5 hours at the dark site is equivalent to 10.5 hours at home.

Steve.

+1

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### #24 CCD-Freak

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Posted 01 April 2020 - 10:32 AM

Or you might find camping away from the stresses of town pleasant and get a small travel trailer to use at a remote site. Anything from a 4x8 bunk to a 14 foot egg. See www.fiberglassrv.com Good for hauling out the astro gear too and has a battery for the gear. Rig the inside for computer control of your scope and hide inside from the cold. When you are tired just stretch out for a nap.

Sent from my SM-N950U using Tapatalk

Confessions of a Dark Sky Junkie.....I go to the dark site whenever possible and stay for as long as the sky stays clear.  The peace, quiet, solitude and the darkness are worth the trip alone.  Objects in the sky look better visually and are easier to process when imaging without the pesky glow of the city.   Comfort is king so I purchased a Casita which I named the Moonlight Manor.

Now if we could just get rid of the clouds and the Covid 19....Life would be good.

John

CCD-Freak

WD5IKX

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