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Ha horsehead minus guiding

MartinB

By MartinB
in Imaging - Deep Sky

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MartinB

MartinB

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Got in at 10.00pm last night just in time to set up for HH. I want to image this with my new GSO newt but the stars were twinkling away so my I decided on a shorter f/l and used an ED80 with 0.8 reducer/FF. The guiding wasn't working - the guide cam led was indicating a guide signal but nothing was getting through to the mount. The x axis showed a lovely PE curve +/- 4 arc secs. I am hoping it is the guide cable at fault. The plan for 20min guided subs was quickly changed to 10min unguided.

Just Ha last night. If the weather plays ball and I get a pass out hope to do the colour tonight

18x10mins unguided, QHY8 and astronomic 13nm Ha filter. Captured with Maxim and processed in PS. Cropped a little since I thought Horsie looked a bit lonely in the full size version.

9842_normal.jpeg

(click to enlarge)

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steppenwolf

steppenwolf

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Martin, as you know, I use the same optical train as you and the same size sensor and I too cropped my image of this object taken last night for the same reason - perhaps we should combine your Ha data with my RGB data!

This is a nice shot but can we see it without the false red and just as a greyscale?

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MartinB

MartinB

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Here is the mono Steve. Have rotated it a little as well.

Thanks Helen. Needed to go longer than 10mins eally using Ha with the OSC, nothing like as sensitive as the H9. The histogram curve is really skinny.

9843_normal.jpeg

(click to enlarge)

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centroid

centroid

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A nice basis on which to build Martin, with a good SNR.

What's the cause of the halos around the stars?

I know that Mike (yfronto) has struggled with this problem, but your image was captured with the ED80, and not a 'newt' :?

Dave

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MartinB

MartinB

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but of course the like the Mono best ehheheheheh .

Rog :)

Now there's a surprise :)

What's the cause of the halos around the stars?

Dave

Dave, the halos aren't down to the scope design. I think they are due to light reflecting off the chip cover back to the reflective Ha filter and back onto the chip. I think they are very dependent on the spacing between filter and chip which is why some people get them and others don't. I've never had a problem with other set ups. I might have to do some experimenting with the placement of the filter drawer but options are a bit limited.

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Psychobilly

Psychobilly

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Smashing Image ....

I get 2 hours of this region between the trees and eagerly await it every night I'm out all the other targets are fitted around soem time on this region but haven't been able to get any substantial data on it yet.

Is something is ever so slightly out of square as well...as all the halos are in the same direction.

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MartinB

MartinB

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Very slightly Billy, probably due to a slight tilt of the chip in relation to the filter. Thse reflections are usually slightly off centre because of the exageration produced by the distance the light has to travel before getting back to the chip, around 60mm in my case.

Here is an interesting article which explains the effect.

http://www.astrodon.com/articles_faq/articles_faq/press_release:391,355,49

Very nice shot of the HH & Flame area Martin, the halos do seem to be an Astronomik trait and it has been suggested that an extra IR cut will get rid of them.

I think it is any reflecting filter Mark - dichroic/interference. I have an IR cut filter in between the QHY8 and my filter drawer. It think the solution is to try altering the spacing...although I quite like the halo around Altinak and the other 2 tiddlers could easily be dealt with in PS

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MartinB

MartinB

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Thanks guys

Ten minute unguided subs wow, that shows how much attention to detail you pay in your setup :)

It's really a tribute to the EM200. The polar alignment scope is a work of art, it gets you incredibly close to the NCP in just 2 minutes and the PE doesn't really show up at short focal lengths.

Will look out for that email Bazza thanks

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RobH

RobH

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Great image of the area Martin.

The halos are filter reflections, I get them too but have to live with them as I can't change the filter/chip distance using a filter wheel.

I was very interested to see an image with a QHY8 and a H-alpha filter as I'm considering, amogst other options, getting a Hyperstar and QHY for the 14inch. What has been putting me off until now is that I assumed I wouldn't be able to do much in narrowband with it.

How much do you have to increase your exposure times compared to the H9 when using the OSC?

I would guess that with the 14 at F2, I'd still be looking at reasonable short subs.

Cheers

Rob

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MartinB

MartinB

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The QHY8 just can't compete with the H9 for capturing Ha Rob. If I manage to recover the data on my hard drive I might be able to find some comparison subs taken with the H9. Having said that it doesn't do too badly and with the speed of the hyperstar you would be onto a winner. The problem with the F2 imaging is that the angle of incident light compromises interference filters and shifts the band pass. You shouldn't really use anything less than 13nm and the new Baader 35nm filter would probably be a better bet. SteveL is the guy to talk to.

OSC is obviously the camera to go for with the hyperstar.

I have some colour data now for this image although the chip has become blighted by a multitude of dark splodges, not sure where they have come from. The idas which is also a reflective filter hasn't produced any halos.

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