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 Post subject: Re: Long-distance imaging with the Bradford Robotic Telescop
PostPosted: Wed May 29, 2013 7:08 pm 
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Ross, if you have not done so already I should buy a lottery ticket, good luck that they pointed at your co-ordinates exactly at the right time. Its a great image.

Any idea what the fuzziness is in the tail about a quarter distance from the comet head? It looks like aircraft trails as they begin to dissipate in the atmosphere. It must be a photographic effect. It shows up better on the negative version.

Regards


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 Post subject: Re: Long-distance imaging with the Bradford Robotic Telescop
PostPosted: Wed May 29, 2013 7:47 pm 
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bholmes wrote:
Any idea what the fuzziness is in the tail about a quarter distance from the comet head? It must be a photographic effect. It shows up better on the negative version.

When I play with the thresholds to accentuate them, they look a little like smears in the optical system:
Attachment:
File comment: BRT Job no. 198674
ccsmears.jpg
ccsmears.jpg [ 65.03 KiB | Viewed 6597 times ]
And the diagonal line to the South of the comet is probably an aircraft or satellite trail.


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 Post subject: Re: Long-distance imaging with the Bradford Robotic Telescop
PostPosted: Wed May 29, 2013 7:52 pm 
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Thanks Ross


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 Post subject: Re: Long-distance imaging with the Bradford Robotic Telescop
PostPosted: Fri Jun 14, 2013 3:53 pm 
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Want to image without getting your telescope out? Well this is real armchair astronomy and you get to hone your IRIS skills to boot.

Ross's post about the BRT came at an opportune time since I am wanting to get to grips with IRIS but don't have many decent images to play with. I took up the offer to try out the BRT and you can see what I ended up with on the Gallery. It was a couple of weeks before my image arrived and a day and a half to process it with much assistance from Ross but there was a lot of learning in that time so it will not take very long next time around - M100 is sitting there waiting to be processed.

If you like what you see then why not have a go. You will need to get the access details from Ross and we should have a workflow sheet ready soon to help guide you through the ins and outs of processing. The BRT scopes are going to have some annual maintenance anytime soon so there won't be any new images for a few weeks. This need not stop you from looking around the site and perhaps downloading some of the tens of thousands of images that are already there. There is even some basic processing available on the site, so have a go!

Good luck


Last edited by bholmes on Fri Jun 14, 2013 9:39 pm, edited 1 time in total.

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 Post subject: Re: Long-distance imaging with the Bradford Robotic Telescop
PostPosted: Fri Jun 14, 2013 8:08 pm 
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Yes, it's certainly a good way of practising your image-processing skills.
The data is rather different to what you'd get from a DSLR: the three colour-planes arrive as separate FITS files which need to be aligned and combined to form the colour image - and there's practically no light-pollution to remove! :D


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 Post subject: Cleaning the Bradford Robotic Telescope optics
PostPosted: Thu Jun 20, 2013 3:15 pm 
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The servicing team from the University of Bradford is now working on-site at Mount Teide, and they have been cleaning a year's accumulated muck off the front of their C14 OTA today:
http://ed-brt.blogspot.co.uk/2013/06/cleaning-telescope-optics.html
Amazing that my recent M17 image was taken through that lot!


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 Post subject: Re: Long-distance imaging with the Bradford Robotic Telescop
PostPosted: Sat Jun 22, 2013 6:17 am 
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I guess that explains all those smears on the negative of Panstarrs. It would be interesting to see what the flats look like taken through that lot.


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 Post subject: Re: Long-distance imaging with the Bradford Robotic Telescop
PostPosted: Wed Jul 03, 2013 8:06 am 
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I've put a copy of last night's presentation on processing BRT images in the Library section of our Members' Area:
http://www.boltonastro.co.uk/members2/index.php/fp/Members%E2%80%99-Presentations/Practice-processing-using-BRT-images/


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 Post subject: FLAT-tery will get you somewhere!
PostPosted: Fri Sep 20, 2013 8:22 am 
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I'm now able to answer Bernie's question about the diagonal streaks on my BRT Cluster Camera image of comet PanSTARRS from the end of May:
bholmes wrote:
Any idea what the fuzziness is in the tail about a quarter distance from the comet head? It looks like aircraft trails as they begin to dissipate in the atmosphere. It must be a photographic effect. It shows up better on the negative version.

I've since found that these artifacts are visible to some extent on all long-exposures from the Cluster Camera, both before and after its lens was cleaned during the servicing visit in June. And they appear on images taken with both Clear and Colour filters, so it must be something inside the lens, or the camera's sensor (or its glass window).

Now we know that these effects can be mitigated by the use of FLAT-field calibration, but there are currently no "flats" available from this camera. However I've just been experimenting with creating a "synthetic flat" from a number of long-exposure deep-sky images. I went through the BRT image archive and chose 23 of different targets which didn't contain any very bright stars or extended objects and used the "Make a Flat-field" process in IRIS to normalise them and form a median average:
Attachment:
File comment: Synthetic flat formed from 23x ClusterCam deep-sky images
brtcluster_old.jpg
brtcluster_old.jpg [ 36.79 KiB | Viewed 5586 times ]

I could then use this to calibrate my PanSTARRS image:
Attachment:
File comment: Original image with diagonal smears
beforeflat.jpg
beforeflat.jpg [ 134.15 KiB | Viewed 5586 times ]
Attachment:
File comment: Result of division by my synthetic flat
afterflat.jpg
afterflat.jpg [ 148.36 KiB | Viewed 5586 times ]

The extent of the comet's "anti-tail" shows up much better now! :D


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 Post subject: Re: Long-distance imaging with the Bradford Robotic Telescop
PostPosted: Tue Sep 24, 2013 11:05 pm 
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That makes a huge improvement Ross, excellent work in tracking down a solution, I know that the guys at BRT are very appreciative of your help.

Regards


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