Moon phases and DSO observation

[N3ptune]

Hello

I am just checking something: At what point for you, the moon becomes an obstacle for watching the deep sky objects? Just to see up to which point it's possible to push the DSO observation with the moon.

Thanks

[Commanderfish]

Depends on sky transparency/ amount of moisture in the sky catching LP.  I'd say that the week around full moon (i.e. three days either side of full moon) is not worth bothering with for DSOs.  Maybe 4 days either side of full moon actually.

[N3ptune]

oki it's better then I thought. The transparency and moisture..RH is around 80% RH these day.  It's not going to be a DSO week end

[rockystar]

I find that even a 50% moon in the sky hinders DSO observing, but a 50% moon is only in the sky for 50% of the night, so check out the and set times also. But I'd say the same, 3 or 4 days either side.

But there are plenty of other targets - I've recently got into observing and sketching double /multiple stars on these nights: Not that I've been out this month!

[Knighty2112]

Yep, I wouldn't bother looking for any DSO's really 4 days before and after full moon. 

[DeepSkyBagger]

I agree with rockystar to a greater or lesser degree. I don't observe if there is a 50%+ Moon in the sky. It's worth noting, though that a 50% waxing moon is brighter than a 50% waning moon, because the 'left-hand' side of the moon is covered with darker maria, whereas the 'right-hand' side has far more bright uplands.

You need to experiment yourself.  See what you find acceptable personally.

[N3ptune]

Quote

50% waxing moon is brighter than a 50% waning moon

Oh i didn't know that! interesting thing to verify. Tonight it's going to be a waxing moon, the bad phase. (I am going to draw a sketch of a crater instead of watching the DSO's)

[acey]

10 hours ago, N3ptune said:

At what point for you, the moon becomes an obstacle for watching the deep sky objects?

When it's above the horizon. At a genuinely dark site, if your eyes are fully dark adapted, a rising crescent Moon is like a searchlight. I'm happy to arrive at my dark site maybe an hour before moonset, then by time I've set up and my eyes are adapting the Moon is sinking out of the way. But when it rises it's time for me to pack up - and enjoy looking at it coming up from the horizon into the brightening sky.

Having said that, if you're really pushed then it's still possible to view a lot of brighter DSOs under moonlight. A moonlit dark site is still in most cases darker than an average moonless suburban one. But if, like me, you prefer to save your energy for the best nights available, then plan your schedule around times when the Moon won't be seen.

[John]

For the best views of most DSO's, I find the moon always a hindrance if it's in the sky.

Of course you can see the brighter DSO's when the moon is around but you always know that the DSO would look a lot better when the moon is below the horizon.

When the moon is in the sky, I rarely do any serious DSO hunting.

 

 

[alan potts]

I am the same as John any Moon is a bad moon for this activity, in truth I don't even bother using my biggest scope much above first quarter unless it is for planetary views.

[Stu]

As Acey says, a lot depends on the darkness of your skies. If like Alan and others you have a nice dark site, the moon will make observing DSOs fairly pointless vs a pristine moonless night. If however your skies are fairly light polluted (and by that I mean proper light pollution, not just the odd street light here and there) then you will probably take any clear night you can get aside from a few night directly around full moon.

[N3ptune]

Thanks for all your answers,

The place where I go, it's in a yellow light pollution sector, near to a small city which is red. It's not perfect but it's not bad, on the other side (to the north) it's a national parc, a large green zone. 

I think ill go like Alan said, when the moon is less then a quarter... seems more secure.