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NGC3718 insane integration time project tips


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Hi guys.

Not too long ago I posted this photo of NGC3718 in luminance.LRM_EXPORT_985103005766127_20190404_190217015.thumb.jpeg.d52710ad6a387b513a194521ef125cb6.jpeg

I really like this target and the fact that is crossing the meridian very close to zenith made me enrol into a project that I never tried before. 

I wanna add as much data as possible until the begining of May when I get my new refractor.

If I'm lucky to have the clear skies with no moon around, I'm hoping to have at least 40 to 50 hours of data at the end of the project.

So far I have 15 hours of luminance, 1 hour and 50 min for each of the R, G and B and 7 hours of Ha.

I'm using my QHY183M, Baader Neodymium for luminance, Baader Ha,RGB, SW 130pds with x0.9 coma corrector.

My skies are supposed to be bortle 6 at Zenith. I live on the outskirts of London.

Any tips would be greatly appreciated. 

Thanks.

Emil

 

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Looking at the graph, am I right in thinking that I might have to expose more on the red filter than the other 2?

Or would it be better to increase the gain on the red filter?

I'm shooting at unity gain at the momen which is 11 for the QHY183M.

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There is Ha but it doesn't look terribly interesting to me. Isn't it going to be little different from the red, but fainter?

It does look as if more blue might help the colour balancing.

Like you I love this galaxy and your long integration is giving you a superb result. An excellent project.

Olly

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25 minutes ago, ollypenrice said:

There is Ha but it doesn't look terribly interesting to me. Isn't it going to be little different from the red, but fainter?

It does look as if more blue might help the colour balancing.

Like you I love this galaxy and your long integration is giving you a superb result. An excellent project.

Olly

I found a really nice photo of this galaxy on APOD that is absolutely superb and I'm mostly guided by the way it looks in that photo. 

(https://apod.nasa.gov/apod/image/1308/NGC3718_HaLRGBpugh.jpg)

NGC3718_HaLRGBpugh.jpg

I will never get that result but I'm doing my best with what I have from my location.

I was planning to shoot the same amount of R,G and B and then shoot some more of a certain colour if needs be.

Edited by emyliano2000
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What happened to your 200mm scope? There's not so much around those 2 galaxies. A 200mm mirror would gather more than 2 times the amount of light.

Edited by alexbb
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22 minutes ago, alexbb said:

What happened to your 200mm scope? There's not so much around those 2 galaxies. A 200mm mirror would gather more than 2 times the amount of light.

I sold it and bought a 10" quattro instead but I just couldn't get it to work with the qhy183m and sold that one too to get some money for a 4" refractor. ?

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1 minute ago, emyliano2000 said:

I sold it and bought a 10" quattro instead but I just couldn't get it to work with the qhy183m and sold that one too to get some money for a 4" refractor. ?

A-ha! Then I believe you only have one option. Shoot as much as you can. If I were you, I'd shoot as much luminance as possible and worry less about the RGB ratios.

BTW, nice image already!

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Lovely image! A very good start.

You can use that 33 hours 17" astragraph image by Martin Pugh from a very very dark (Bortle 1-2) site as a reference but do not get dissapointed if you cannot reach that level of resolution from your site near London.

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45 minutes ago, gorann said:

do not get dissapointed if you cannot reach that level of resolution from your site near London.

Oh, no definitely. Not expecting anything as close to that but gonna do my best. My dead line is the 13th of May. Hopefully I'll have a few clear moonless nights until then. This weekend would've been so good if that big bright ball in the sky wasn't there. ☺

3 clear nights in a row. ☺

 

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On 12/04/2019 at 13:13, emyliano2000 said:

Looking at the graph, am I right in thinking that I might have to expose more on the red filter than the other 2?

ZWO developed rgb filters that are optimised for the cameras spectral response, meaning that R is wider than b which is wider than g. 1 s exposure for each filter should give the same adu count, when imaging a neutral source.

If your filters are equally wide for each band, you should expose red and blue more than green. But since the galaxies have more detail in the blue region, it makes more sense to shoot more blue (longer exposures?). But if I were you, I'd check wether the blue master shows more detail than the L master in the outer regions. If that's so, consider adding blue to the L master. You'd need an awful lot of blue to make that work.

Btw, great image so far. Good luck with what ever you decide on next.

Which refractor will be coming your way in May?

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7 minutes ago, wimvb said:

ZWO developed rgb filters that are optimised for the cameras spectral response, meaning that R is wider than b which is wider than g. 1 s exposure for each filter should give the same adu count, when imaging a neutral source.

If your filters are equally wide for each band, you should expose red and blue more than green. But since the galaxies have more detail in the blue region, it makes more sense to shoot more blue (longer exposures?). But if I were you, I'd check wether the blue master shows more detail than the L master in the outer regions. If that's so, consider adding blue to the L master. You'd need an awful lot of blue to make that work.

Btw, great image so far. Good luck with what ever you decide on next.

Which refractor will be coming your way in May?

Thanks for the advice.

Blue is next on my list, looking forward to see if it looks better than L.

I'm getting a AT106 loaded with a moonlite focuser and high resolution stepper motor.

A friend bought it for me in the US and he's bringing over in May when he's coming to London.

Emil

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8 hours ago, ollypenrice said:

Martin Pugh and Paddy Gilliland both found strong blues in the spiral arms. I'd like to go back and try to find this because, in the data I have, I didn't find it.

 

Another project for the twin TEC rig perhaps?

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46 minutes ago, emyliano2000 said:

Oh, I would love to see that!

So would I!

A couple of months ago I started drawing up a list of potential galaxy targets for the TEC/QSI690 rig that Steve and Barry have at E-EyE - when I checked the list this morning NGC 3718 (& NGC 3729) was the first thing I had put on the list. Olly has the same FOV with the Atik 460 side of the twin TEC rig.......

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33 minutes ago, MrsGnomus said:

So would I!

A couple of months ago I started drawing up a list of potential galaxy targets for the TEC/QSI690 rig that Steve and Barry have at E-EyE - when I checked the list this morning NGC 3718 (& NGC 3729) was the first thing I had put on the list. Olly has the same FOV with the Atik 460 side of the twin TEC rig.......

Then we shall! I have a reasonable but lower resolution image in the can. This could serve as a base for a better colour layer and then we'd welly the luminance. Woo Hoo!

Olly

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