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Old 18-12-2016, 11:00 AM
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ZeroID (Brent)
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Ngc 300 ?

How much exposure is needed to image NGC300 ?
I did nearly 2 hours last night through the Lunt 102mm, F7 and the 1200D at ISO 1600 with 80 second exposures. Did a quick stack and the galaxy is barely visible, seems to need quite a few more hours.
I understand it's a face on galaxy so surface brightness is a lot lower but I had to really push it with Photoshop to see anything at all.
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Old 18-12-2016, 01:58 PM
glend (Glen)
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Before i commit to a long run on a new target i do some single test exposures at various duration and gain (or ISO) settings. As i use SGP to image, it will stretch a pre-view of each test frames. I find that helps.
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Old 18-12-2016, 06:01 PM
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ZeroID (Brent)
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Quote:
Originally Posted by glend View Post
Before i commit to a long run on a new target i do some single test exposures at various duration and gain (or ISO) settings. As i use SGP to image, it will stretch a pre-view of each test frames. I find that helps.
Hi Glen, BYEos just shows it on a single frame OK but I would have thought 111 minutes of exposure would give me something to stack.
The 80 second exposure time is my high limit for LP management, it was a pretty good night transparency wise. Sculptor from a previous run came up easily within 90 mins of exposure but it is more edge on and denser.

Trouble is now I'll have to wait till another clear night comes along and that's not likely for a while.

Such is life I guess ...
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Old 18-12-2016, 06:08 PM
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Atmos (Colin)
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NGC 300 has a pretty low surface brightness so it doesn't much like LP
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Old 18-12-2016, 08:30 PM
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Camelopardalis (Dunk)
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Yeah I took a shot of NGC 253 a week or so ago and it wasn't even funny compared to shots from a dark site. It almost wasn't there
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Old 19-12-2016, 11:42 AM
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Quote:
Originally Posted by Camelopardalis View Post
Yeah I took a shot of NGC 253 a week or so ago and it wasn't even funny compared to shots from a dark site. It almost wasn't there
New name for that Galaxy, 'The Invisible Galaxy'.

Just need to start extending my astroimaging repertoire a bit. Having a long history of technical problems limiting my attempts and to finally get a system working reasonably well I need to find new targets and challenges. Looks like this is one of them.

With Auckland's LP, the weather and my limited sky options sometimes the choices I have are restricted. Sculptor is getting too low in my west already, the sky is still quite light till well after 9pm. The south eastern options are no good, LP. I have to wait till they get over the SCP into the south western sky to do anything there. I struggle with anything higher than Mag 8. Sculptor and Sombrero have been my staple due to mag and orientation giving me best results.

Patience required, other brighter targets will be back over the year. I can wait.
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Old 19-12-2016, 06:27 PM
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Camelopardalis (Dunk)
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Yeah LP is a challenge! Are you already using some kind of LP filter? Might not help much if your local LP is broad spectrum...
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Old 19-12-2016, 10:23 PM
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I remember trying ngc300 with my ED100 and abandoning the project. Then I tried with an 8" F4 Newt and got better results. But you need dark skies with good transparency.

Here's mine from October. 8" F4, 486 x 30 second subs. Here's a single unstretched 30 sec sub to compare. Unmodified Pentax K-5.
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Old 21-12-2016, 07:42 AM
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ZeroID (Brent)
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Dunk > No filters used, it would extend exposure times out to something stupid. I process the LP out with levels\curves then noise reduction.

Kevin > That figures, I can just see a slight blur on the stacked images !!

So another clear night last night, had a go at NGC 55, couple of hours at ISO 3200. Haven't processed anything yet as I crashed in bed around midnight. Not good for a working week ...

I may get stupidly brave and see if I can balance the 10" F5 Serrurier Newt up there, that should fix the sucker !!
Or the 8F8 ....
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Old 21-12-2016, 04:52 PM
markas (Mark)
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The surface brightness of NGC 300 varies from ~18-19 Mag/square arcsec near the centre to ~24+ at 11 arcmin from the centre. If the sky background is 18.5, as it is from my suburban Melbourne location, then this object is going to be extremely difficult.

From a good dark sky site (SQL 21.4) with a 10" f/3.6 scope a reasonable image is gettable. The image included here is 80min L binned X1 and 3 hours RGB binned X2; camera Moravian G2-8300.
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Old 22-12-2016, 10:22 AM
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ZeroID (Brent)
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Quote:
Originally Posted by markas View Post
The surface brightness of NGC 300 varies from ~18-19 Mag/square arcsec near the centre to ~24+ at 11 arcmin from the centre. If the sky background is 18.5, as it is from my suburban Melbourne location, then this object is going to be extremely difficult.

From a good dark sky site (SQL 21.4) with a 10" f/3.6 scope a reasonable image is gettable. The image included here is 80min L binned X1 and 3 hours RGB binned X2; camera Moravian G2-8300.
NOW you tell me ...
Had better success with NGC 55 but that still needs a lot more photons. Went back to NGC 253 and added another 90 mins to my existing frames. That is starting to show a lot more detail and colour so I think I'll go back to that for a while and perfect my techniques a bit more while it's viewable.
Still having intermittent weird guiding problems. I ended up doing 30 sec exposures unguided last night and getting excellent results, Metaguide is just not playing ball very well and PHD2 keeps crashing out at start.
The tribulations of it all ...
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Old 22-12-2016, 10:42 PM
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That's one of the reasons why I like unguided imaging Brent. I don't have the patience for computer drama as well as scope and cloud drama.
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Old 23-12-2016, 05:56 AM
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On the previous computer which unfortunately died, guiding worked well with PHD2. I could be calibrated and guiding within 5 minutes. Newer computer seems to not like the software for some unknown reason. I'll run the Windoze updates during Xmas break and see if it fixes the problem. At least the unguided session has told me it isn't a mount or alignment problem.

Anyone using Metaguide got a list of their normal settings so I can compare ? I find it a messy and non intuitive piece of software.
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Old 26-12-2016, 09:03 PM
torsion (Bram)
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Hi Brent,
Sorry to hear about your troubles.

I am using Metaguide and it works great. I am using it with QHY5L-ii with an OAG at prime focus behind a 9.25HD, on a iOptron iEQ45 (via ASCOM through a general HUB). I am using the latest Metaguide version, but still use EZPlanetary in broadcast mode (also I have it set to Bin2x2, hence the large pixel size in the metaguide settings). Attached are my settings.

Hope this helps.
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Old 27-12-2016, 11:21 AM
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ZeroID (Brent)
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Hi Bram, thanks for that.
Your settings are quite different from mine but so is your setup but at least it gives me some ideas to play with. If I can understand your settings I can possibly interpret mine better.
For the time being I have added a laptop to the mix running the new PHD2 software (the advantages of a permanent Ob setup and spare PC's) and for good measure 're-engineered' the guide scope mechanicals.
Now to wait for the clouds to clear .. and I didn't even spend any $$$ .... Sheesh !

All the best for the New Year.
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Old 27-12-2016, 10:27 PM
torsion (Bram)
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No problem. Let me know which settings you have trouble with!

All the ones in red are (incl pixel width and height) related to the guide calibration, so you should check they are coreect for your setup.

The values for the mount (guide rate etc) are mount specific, and are similar to those in PHD. The dec angle is obtained through your ASCOM mount connection, or you can enter it manually, it doesn't need to be exact.

I usually run at 8 frames per seconds (eg. ~125ms per frame).

Good luck, and happy new year!

Cheers,
Bram

Last edited by torsion; 27-12-2016 at 10:28 PM. Reason: Typos
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