I've managed to enhance some jet detail in my Holmes image of 31 Oct by subtracting a Gaussian blurred version of the image from the original. The original was 25 minutes of exposure (50 x 30 sec).
http://homepage.ntlworld.com/the_shelleys/photos/holmes_jet_detail.jpg (http://homepage.ntlworld.com/the_shelleys/photos/holmes_jet_detail.jpg)
Excellent again - this really is interesting stuff... Well done - John
I've just discovered the IRIS RGRADIENT command:
http://www.astrosurf.org/buil/us/iris/comet/comet.htm (http://www.astrosurf.org/buil/us/iris/comet/comet.htm)
But this seemed to create too many artifacts in the image for my liking.
But I've reprocessed the above image with a variation of the technique to produce this:
http://homepage.ntlworld.com/the_shelleys/photos/holmes_jet_detail2.jpg (http://homepage.ntlworld.com/the_shelleys/photos/holmes_jet_detail2.jpg)
This would appear to show "jets" behind the comet and fainter large structures out to the edge of the coma. I don't think these are artifacts but I could be wrong. But I don't know how to interpret this.
Brilliant images Mark, have you tried to apply a Bas Relief filter to the image, this usually does something similar without removing and artificial flat.
Chris
P.S. 10/10 for being able to use IRIS :-)
That makes an interesting comparison with today's APOD:
http://antwrp.gsfc.nasa.gov/apod/ap071105.html
I now have enough images to begin to show the evolution of structures inside the coma. All images are the same scale i.e. 2x2 binned before cropping. The images show differing amounts of noise because of the differing total exposures in each case. If I had known then, how I would analyse the data now, I would have shot more data ...
It helps if you squint at the images!
29 October:
(http://homepage.ntlworld.com/the_shelleys/photos/holmes_jets_20071029.jpg)
31 October:
(http://homepage.ntlworld.com/the_shelleys/photos/holmes_jet_detail2.jpg)
4 November:
(http://homepage.ntlworld.com/the_shelleys/photos/holmes_jets_20071104.jpg)
Mark
These really are interesting images. Facinating to know if these are real jets or processing artifacts. Would you mind if I passed them onto someone in the Astronomy Dept at UCL to comment?
They are real jets. They compare well with other images i've seen. The comet is actually developing a visible tail at the moment (although a faint one) that has shown up on some deep images I have seen on other sites.
http://hubble.heim.at/holmes-2.htm
Quote from: Jim on Nov 08, 2007, 09:56:09
Would you mind if I passed them onto someone in the Astronomy Dept at UCL to comment?
By all means, Jim. I'd be interested in their response.
Hi Mark
I showed these to Dr Francisco Diego at UCL. He was very impressed with the pictures and said in his view the jets were real. He did ask why the pics had star trails, did you combine pics from different nights?
I'm guessing he tracked the comet nucleus and that will be why the stars are trailing.
Mike is right. For the 31 Oct image, I took 50 x 30 sec exposures over a period of 90 minutes and then stacked them to track the comet. The comet was moving relative to the star background, hence the trailing.
In fact I actually took many more images but most were not suitable for stacking because my mount (the standard CG5) was being used unguided.
Another APOD showing similar detail: http://antwrp.gsfc.nasa.gov/apod/ap071113.html
Some Hubble space telescope images have been published. One has been enhanced to give it a weird "bow tie" appearance:
http://www.spacetelescope.org/news/html/heic0718.html (http://www.spacetelescope.org/news/html/heic0718.html)
Hare are some excellent images and animations of Holmes jets taken from an observatory in the Pyrenees.
http://www.picdumidi.eu/ (http://www.picdumidi.eu/)
They're the best I've seen so far.
Oh the advantages of having a big scope on the top of a mountain... ;)