The Crab Nebula

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The Crab Nebula

Postby Aratus » Wed Dec 20, 2017 2:29 pm

I find the supernova remnant 'Crab Nebula' difficult to see through a telescope, let alone image. It is fairly small too. I managed 10 x 1 min exposures using the ZWO. Each one barely showed a grey oval. However stacking them, and using a bit of processing brought out this image.
Image
The exploded star's atmosphere has been reduced to these filaments which are the inner part of the nebula, and can be seen in this image. There is a fainter outer edge to the nebula which I have never been able to image. The Crab Nebula is certainly a very different kind of object from the usual nebula and star clusters.
I use an 11" Celestron SCT (CPC 1100) on an equatorial wedge, housed in a 2.2m Pulsar observatory. I use a ZWO ASI1600MC and Canon 500D for imaging.
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Re: The Crab Nebula

Postby andrewscomputers » Wed Dec 20, 2017 5:08 pm

Hi Aratus I like the detail,did you use autoguiding on your telescope as I have got to give it a go,as I can only do 15 seconds on my images at the moment,before I encounter star trails.
Andy
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Re: The Crab Nebula

Postby Aratus » Wed Dec 20, 2017 10:50 pm

With an alt-azimuth you are limited to a minute or less dependent on the objects position in the sky.

With an equatorial mount it is technically possible to guide for hours. The reality is that it needs to be very accurately aligned even to get precise alignment for even a few minutes. The other problem is the gearing of the mount which has its own imperfections. At the moment I try to get the mount alignment as close as possible using a star drift method. I also use the periodic error correction facility on the mount to minimize that problem. In this case I also used a focal reducer which also reduces the effect of any movement. I can normally get some success up to 120 seconds using this method, which is sufficient for all the targets I've gone for so far.

I've never tried auto-guiding, but I understand that if it can be set up properly, it can give good results.
I use an 11" Celestron SCT (CPC 1100) on an equatorial wedge, housed in a 2.2m Pulsar observatory. I use a ZWO ASI1600MC and Canon 500D for imaging.
Aratus
 
Posts: 790
Joined: Tue Jan 12, 2016 2:17 pm
Location: East Lincolnshire

Re: The Crab Nebula

Postby andrewscomputers » Wed Dec 20, 2017 11:04 pm

Hi Aratus thanks for the reply,I am going to have a go with autoguiding on my Eq5 mount and see what happens to see if I can increase my exposure time.
Andy
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Re: The Crab Nebula

Postby Aratus » Thu Dec 21, 2017 1:00 pm

I'd be interested to know which equipment you are going use - and eventually how well it worked.
I use an 11" Celestron SCT (CPC 1100) on an equatorial wedge, housed in a 2.2m Pulsar observatory. I use a ZWO ASI1600MC and Canon 500D for imaging.
Aratus
 
Posts: 790
Joined: Tue Jan 12, 2016 2:17 pm
Location: East Lincolnshire

Re: The Crab Nebula

Postby andrewscomputers » Thu Dec 21, 2017 1:36 pm

Aratus wrote:I'd be interested to know which equipment you are going use - and eventually how well it worked.

Hi Aratus I am going to use an Altair 60mm guidescope with my gpcam mono camera as it has an st4 port to my goto system.Then I am going to use Phd2 which I have already on my laptop and control everything WiFi from my shed with 15 meter usb leads so that I don't touch the mount and see what happens as I am still experimenting at the moment.Then use my gpcolour to take the images whilst controlling my autofocuser.
Andy
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Re: The Crab Nebula

Postby Aratus » Thu Dec 21, 2017 4:26 pm

So how does it work? Does the guide-scope camera connect to the goto mount directly or via the laptop?
I use an 11" Celestron SCT (CPC 1100) on an equatorial wedge, housed in a 2.2m Pulsar observatory. I use a ZWO ASI1600MC and Canon 500D for imaging.
Aratus
 
Posts: 790
Joined: Tue Jan 12, 2016 2:17 pm
Location: East Lincolnshire

Re: The Crab Nebula

Postby andrewscomputers » Thu Dec 21, 2017 4:55 pm

Aratus wrote:So how does it work? Does the guide-scope camera connect to the goto mount directly or via the laptop?

Hi the guide-scope camera connects st4 to st4 on the goto mount and the usb cable connects to my laptop for the phd2 system,so hopefully can keep it tracking on the star.
Andy
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Re: The Crab Nebula

Postby Aratus » Thu Dec 21, 2017 5:14 pm

I see - thank you. I did buy a guide-scope with the hopes of trying manual and automatic guiding. Since I was able to get acceptable results without guiding, the idea sort of got lost. (I've now loaned the guide-scope out to the 10 year old son of a friend to try out as a general telescope over the winter!) I'll be interested to find out how you get on.
I use an 11" Celestron SCT (CPC 1100) on an equatorial wedge, housed in a 2.2m Pulsar observatory. I use a ZWO ASI1600MC and Canon 500D for imaging.
Aratus
 
Posts: 790
Joined: Tue Jan 12, 2016 2:17 pm
Location: East Lincolnshire

Re: The Crab Nebula

Postby andrewscomputers » Thu Dec 21, 2017 5:33 pm

Hi Aratus I will let you know how I get on when I get a clear night again Happy Xmas and New year.
Andy
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