Help with UHC-S filter

Questions and answers about processing in StarTools and how to accomplish certain tasks.

Help with UHC-S filter

Postby Jaume » Sat Jun 02, 2018 9:21 am

Hi
Last night I did some photos (200 pictures , ISO 800, 20”) of NGC7380 whit my Nikon DSLR and the Baader UHC-S filter for light pollution.
I used DSS for stacking like I read in some tutorials, and approximately 150 pictures were staked.
At last, I have a fit file, that I open with Star tools. Then I use BIN (75) -> Autodev -> Crop-> Wipe (using Mask with Lasoo for the nebula) -> Vignetting ( Dark anomaly filter 5 pixels) -> Do
After that the image is fine. But I can’t see the nebula.
The I Use Develop, sliding until 90-92%.
The nebula is not in the image but I’m sure that is in there.
What can I do? Can you Help me?
Thanks
Jaume
 
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Re: Help with UHC-S filter

Postby admin » Sun Jun 03, 2018 5:29 am

Jaume wrote:Hi
Last night I did some photos (200 pictures , ISO 800, 20”) of NGC7380 whit my Nikon DSLR and the Baader UHC-S filter for light pollution.
I used DSS for stacking like I read in some tutorials, and approximately 150 pictures were staked.
At last, I have a fit file, that I open with Star tools. Then I use BIN (75) -> Autodev -> Crop-> Wipe (using Mask with Lasoo for the nebula) -> Vignetting ( Dark anomaly filter 5 pixels) -> Do
After that the image is fine. But I can’t see the nebula.
The I Use Develop, sliding until 90-92%.
The nebula is not in the image but I’m sure that is in there.
What can I do? Can you Help me?
Thanks


Hi there, welcome to the StarTools forums! :text-welcomewave:

Your problem is most likely that NGC 7380 is extremely faint. From a light polluted location and using just 20" frames, chances are that you simply did not get enough signal.
If you're just getting started, and depending on your location and light pollution, I would try some other, easier objects first. E.g. M42, M8, or the Carina nebula if you're in the Southern hemisphere.
That said, if you definitely feel the signal is there, feel free to share your stack with us here (e.g. through Dropbox, Google Drive or similar).

Clear skies!
Ivo Jager
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Re: Help with UHC-S filter

Postby Jaume » Sun Jun 03, 2018 6:53 pm

Hi
Here are the pictures stacked with DSS
https://drive.google.com/file/d/1EWrQwN ... sp=sharing


And the same pictures stacked with Nebulosity
https://drive.google.com/file/d/1onYWmK ... sp=sharing

Thanks for your help
Jaume
 
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Joined: Thu May 31, 2018 12:49 pm

Re: Help with UHC-S filter

Postby admin » Mon Jun 04, 2018 4:13 am

Hi,

Thank you for uploading. I just had a look at the data.
Unfortunately, it is as I feared; there is simply not enough signal in your stack.
Most of all though, you need to take flats; they are not optional, especially when you go for very faint objects like these. Any faint nebulosity you might have recorded is overwhelmed by uneven lighting and vignetting.
My original advice still stands - if you can't go longer than 20 seconds (I see some field rotation in your subs, correct?) cut your teeth on easily acquired objects such as M42, M8, M31, etc.

I hope this helps & wish you clear skies!
Ivo Jager
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Re: Help with UHC-S filter

Postby Jaume » Mon Jun 04, 2018 4:48 am

Thanks for your help!
Jaume
 
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Joined: Thu May 31, 2018 12:49 pm

Re: Help with UHC-S filter

Postby almcl » Tue Jun 05, 2018 9:27 am

In addition to following Ivo's expert advice, you are not quite on target. Image below (from Astrometry.net) shows NGC 7380 is just out of frame on the right. If you can get it centred you may find that the Wizard can be picked out?
Attachments
plate solve.jpg
plate solve.jpg (60.71 KiB) Viewed 133 times
Skywatcher 200P with an astro modded Canon 700d, cls ccd filter, field flattener, guided by QHY 5Lm, PHD2
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