help please, poor images last night

[TiffsAndAstro]

so i imaged ngc 6604 and ic 1396 last night and got almost just stars, almost no nebula. i've culled subs, search for cloud, used different flats, just stacked lights and can't for the life of me work out what's wrong.

maybe frosting on the glass of my camera? histogram view of a stack below. histogram seems less extreme than normal. could there have been a layer of thin cloud or could this be extremely bad seeing, maybe? it seemed pretty clear until about 1230am.

maybe someone can discern a problem from these? its not a huge deal, just want to make sure i haven't messed something up before next clear night in a few years time. 

 

 

 

 

[Elp]

You do realise the past few days the moon has been low but nearly 100pc phase right? And you're imaging OSC without a filter.

High thin cloud could also do it though your star size will be affected by it slightly.

[Vroobel]

Did you believe the forecast last night? My one showed fully clear sky, no high, mid or low clouds, but I could see Vega only. Did you check the sky before imaging? 

 

[TiffsAndAstro]

16 minutes ago, Elp said:

You do realise the past few days the moon has been low but nearly 100pc phase right? And you're imaging OSC without a filter.

High thin cloud could also do it though your star size will be affected by it slightly.

Hmmm, moon looked about 50% but was pretty close to NGC 6604, so it could be that. I did look at the moon and thought it looked nice and very yellow....

Ic1396 was further away but maybe not 90d away.

I've shot with worse looking moons and not noticed anything as extreme as this, but maybe I was lucky?

[TiffsAndAstro]

1 minute ago, Vroobel said:

Did you believe the forecast last night? My one showed fully clear sky, no high, mid or low clouds, but I could see Vega only. Did you check the sky before imaging? 

 

Lol yes I checked sky. Did a couple of polar alignments between 930 and say 1130. I could see stars. Admittedly I could only see vega from about 1230. I packed up at 1

was it worse cloud then my eyes could tell? That's far from impossible

[Elp]

5 minutes ago, Vroobel said:

Did you believe the forecast last night?

Mine said clear by 11, was it??? Ended up packing it all away again.

[TiffsAndAstro]

5 minutes ago, Vroobel said:

Did you believe the forecast last night? My one showed fully clear sky, no high, mid or low clouds, but I could see Vega only. Did you check the sky before imaging? 

 

Also I literally have 4 apps on my phone. My favourite is still the Flo one, even though it retrospectively improves its predictions

[Elp]

I wouldn't rule anything else out but whenever I've been to a dark site, even at 50pc the moon blots out half the sky, so it'll cause all sorts of issues with OSC imaging. It's one of the reasons I primarily do mono, clear skies all too often coincide with near full moons. The moon was near 90pc phase yday.

Edited August 17 by Elp

[TiffsAndAstro]

1 minute ago, Elp said:

Mine said clear by 11, was it??? Ended up packing it all away again.

For me it was clear from 930 and I was polar aligned about 915.

I do seem to struggle identifying if there's a thin layer of cloud though

[Elp]

Once I setup I couldn't even PA as clouds sweeped in. Waited around 15 mins, managed it, but cloud everywhere. Experience tells me to pack away, wasn't going to wait until the new forecast 1am clear spell for 1 hour odd imaging.

[TiffsAndAstro]

Just now, Elp said:

I wouldn't rule anything else out but whenever I've been to a dark site, even at 50pc the moon blots out half the sky, so it'll cause all sorts of issues with OSC imaging. It's one of the reasons I primarily do mono, clear skies all too often coincide with near full moons.

Ok I think I've checked everything else, so I'll put it down to moon.

Dnb filter should be here in 5 days ish...I got the 2" 7nm and a third filter holder for £120 all inc

[Elp]

You still have to plan around it, it'll play havoc with your o3 signal, but you might get away with it and capture something if it's near opposite end of the sky.

Edited August 17 by Elp

[TiffsAndAstro]

Just now, Elp said:

Once I setup I couldn't even PA as clouds sweeped in. Waited around 15 mins, managed it, but cloud everywhere. Experience tells me to pack away, wasn't going to wait until the new forecast 1am clear spell for 1 hour odd imaging.

Atm if it looks 33% possible to image for minimum 2 hours I'll set up at 9 while still daylight and be 3ppa at 930.

[Elp]

Wait until winter, you'll be laughing, but your extremities won't.

[TiffsAndAstro]

Just now, Elp said:

You still have to plan around it, it'll play havoc with your o3 signal.

Yeah no Oiii but can still use the Ha. There's no odd/unusual companion to go with a Ha/Oiii filter like say Hb/He lol is there?

[TiffsAndAstro]

1 minute ago, Elp said:

Wait until winter, you'll be laughing, but your extremities won't.

I will be outside for only minutes as my rig will be so reliable I'll be asleep from 7pm to 7am

[Elp]

Think askar do the D2 an S2/o3 one. They all seem to concentrate on ha and o3 as these are the most common emissions and S2 also falls into red. The Optolong lenhance does hb/ha/o3, there's only a handful of targets with significant hb though.

Edited August 17 by Elp

[TiffsAndAstro]

9 minutes ago, Elp said:

Think askar do the D2 an S2/o3 one. They all seem to concentrate on ha and o3 as these are the most common emissions and S2 also falls into red. The Optolong lenhance does hb/ha/o3, there's only a handful of targets with significant hb though.

i was thinking i can't be only person with an osc who doesn't want to throw away half their photons when moons is out. all dnb filters have Oiii? a Ha/S might be cool ? Could maybe use that when moon is up and not throw away half my data. 

not going mono. at least for many many years. 

 

Edited August 17 by TiffsAndAstro

[Vroobel]

I still feel the hunger of data to process, but seriously, I matured up from the time when I was begging for a piece of the clear sky. The only thing I did last night was taking my main setup outside to cool it down, anything else I usually do within 10 minutes. I gave up and took it home around midnight. No stress at all, woke up rested. 🙂

 

[TiffsAndAstro]

7 minutes ago, Vroobel said:

I still feel the hunger of data to process, but seriously, I matured up from the time when I was begging for a piece of the clear sky. The only thing I did last night was taking my main setup outside to cool it down, anything else I usually do within 10 minutes. I gave up and took it home around midnight. No stress at all, woke up rested. 🙂

 

I have a set of sequences ready so I can zoom from one part of the sky to another. Not worked out well so far

[Elp]

21 minutes ago, TiffsAndAstro said:

i was thinking i can't be only person with an osc who doesn't want to throw away half their photons when moons is out

A lot of people don't attempt OSC when the moon is nearly fully phased. It depends on where in the sky you're imaging.

Ha/S2 filter wouldn't work as only your red pixels will pick up both together.

[TiffsAndAstro]

2 minutes ago, Elp said:

A lot of people don't attempt OSC when the moon is nearly fully phased. It depends on where in the sky you're imaging.

Ha/S2 filter wouldn't work as only your red pixels will pick up both together.

Yeah need something higher up. But not much into UV.

50% is still better than nothing. I wonder why I've not noticed this effect before though. Maybe was more subtle than last night.

I'm still 50% certain I've changed/broken something:(

[Stuart1971]

26 minutes ago, TiffsAndAstro said:

i was thinking i can't be only person with an osc who doesn't want to throw away half their photons when moons is out. all dnb filters have Oiii? a Ha/S might be cool ? Could maybe use that when moon is up and not throw away half my data. 

not going mono. at least for many many years. 

 

Not sure what you mean here..

Using a dual narrowband filter while there is a full moon, is ok, as long as you keep well away from pointing towards the moon, (not as good as without moon obviously) as for Ha/SII then as has been said this would be both in the red Chanel, you are much better with Ha/OIII in these conditions…

[TiffsAndAstro]

Just now, Stuart1971 said:

Not sure what you mean here..

Using a dual narrowband filter while there is a full moon, is ok, as long as you keep well away from pointing towards the moon, (not as good as without moon obviously) as for Ha/SII then as has been said this would be both in the red Chanel, you are much better with Ha/OIII in these conditions…

i was under the impression that the Oiii data taken under moonlight would be susceptible to the broadband reflected by the moon. 

so i was hoping for a supplementary filter that didn't involve Oiii and was worth using under moon light. but to be fair, this doesn't make much sense as there would then be 4 colours to work into the RGB spectrum for a final image

[900SL]

Dual narrowband is good if there is no moon and low to moderate light pollution.

Once you have a bright moon phase and/or B8/9 it can really mess up your Oiii channel if you are targeting near the moon (like in the same quadrant)

DNB should be good in B5 though. Not a lot of point in using it just for Ha, you are only using 1/4 pixels

Edited August 17 by 900SL