NGC 6781 Planetary Nebula

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menardre
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NGC 6781 Planetary Nebula

Unread post by menardre »

I really wanted to try an image something in Sagittarius, like Pete imaging M20. Like Pete, I have trees on the South side of my observatory so I can only image that part of sky for a few weeks in the summer, and it is only above the trees for a few hours. The problem is that the first quarter Moon was directly in the way. So, I reverted to using my favorite book, "The Night Sky Observers Guide" to try and find an interesting object far enough away from the Moon.

I found NGC 6781, which is a really nice planetary nebula in Aquila.

The last time I imaged I found I had difficulty with 4 minute images. The stars were bloated - obviously due to guiding issues. I found that the SVX130 refractor had slipped in its cradle and threw the entire rig way out of balance. I spend some time rebalancing.

For tonight session, I used 11 inch SCT and ZWO ASI2600 for imaging and SVX130 and ZWO ASI290 for autoguiding. The weather man predicted only scattered clouds (ha). I was able to start imaging at 9:06PM. I hoped to be able to image until early morning, but weather and equipment had other plans.

At about 10:30PM I noticed that autoguider had stopped. Also the focuser would not cooperate. It took a while but I finally found that the power cable to the Pegasus Power Box had come apart. Also, the serial-USB cable from the OPTEC focuser box had problems (intermittent connection). It took me a while to get everything back in order and restarted imaging around 10:55PM... I was able to capture a few more images and then clouds crept in, covering the sky. So I took flats and shutdown around 11PM. I was able to collect 43 images using 2 minute subs binned 2x2 with a gain of 100.

I saved the session data just in case I wanted to resume imaging the same object at a later date.

I processed using Pixinsight and found a much better result than I expected. I do not think that more integration time would have produced an appreciably better image.

Roger

Attached is the full frame version and a cropped version. There is also a third image where I used a star reduction process -- not really sure which I like best.
NGC 6781 Master_ABEdiv_Autocolor_ArcSinH_NXT_EzSR_EzMask_HTbg_Curves_MLTsharp_MLTsharp.jpg
NGC 6781 Master_ABEdiv_Autocolor_ArcSinH_NXT_EzSR_EzMask_HTbg_Curves_MLTsharp_MLTsharp.jpg (2.18 MiB) Viewed 391 times
NGC 6781 Master_ABEdiv_Autocolor_ArcSinH_NXT_EzSR_EzMask_HTbg_Curves_MLTsharp_MLTsharp_crop.jpg
NGC 6781 Master_ABEdiv_Autocolor_ArcSinH_NXT_EzSR_EzMask_HTbg_Curves_MLTsharp_MLTsharp_crop.jpg (673.57 KiB) Viewed 391 times
NGC 6781 Master_ABEdiv_Autocolor_ArcSinH_NXT_EzSR_EzMask_HTbg_Curves_MLTsharp_MLTsharp_SR_Crop.jpg
NGC 6781 Master_ABEdiv_Autocolor_ArcSinH_NXT_EzSR_EzMask_HTbg_Curves_MLTsharp_MLTsharp_SR_Crop.jpg (497.32 KiB) Viewed 391 times
Roger M.
Celestron CPC1100 EDGE, Stellarvue 130T refractor dual mounted on iOptron CEM120 on permanent pier mounted in Observatory. Imaging camera ZWO ASI2600 OSC, guide camera Lodestar or ZWO ASI290MM.
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AstroGeek
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Re: NGC 6781 Planetary Nebula

Unread post by AstroGeek »

I like the third one, with the star reduction, cropping, and fantastic colors.
Nice work, Roger.
Steve L
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menardre
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Joined: Tue Jan 17, 2012 6:09 pm

Re: NGC 6781 Planetary Nebula

Unread post by menardre »

Steve

Thanks. I agree. The reduced stars just seem to highlight the nebula more.

Roger
Roger M.
Celestron CPC1100 EDGE, Stellarvue 130T refractor dual mounted on iOptron CEM120 on permanent pier mounted in Observatory. Imaging camera ZWO ASI2600 OSC, guide camera Lodestar or ZWO ASI290MM.
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