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Sunday, November 18, 2007


Comet 17P/Holmes is still putting on a good show. I mounted my camera on the front of our 36 inch Spacewatch Telescope again last night and took this image of the comet. The camera was in a spot I had lots of trouble getting to, so I had a devil of a time centering and checking focus, but I managed to get the focus right. I had to crop this image so that it appears more like an image with about a 500mm focal length since the comet ended up in the lower corner of my frame. Did I mention that the camera was mounted in a spot that I had trouble getting to? Oh, yeah, I did..... Anyway, the comet sits right next to the brightest star in Perseus - Alpha Perseus (Mirfak) which is to the upper left of the comet in this image. The comets nucleus is visible to the bottom right of the almost but not quite circular coma. To the upper left of the nucleus is a complex dust structure that is slowly blowing away from the comet, pushed by solar wind and if the image were deep enough, we would see a complex tail structure of fine dust and gas extending off the frame to the upper left. This image was taken at 190mm focal length with an exposure of 60 seconds at f/6.3, ISO 400.
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Tuguldur said...

another nice view! The diffraction spikes of the Mirfak make the image even more nice!

Why didn't you do some dark frames, you could easily terminate those ugly noises in the data! :)

As for that equatorial mount, I told you to get one of them!!! It will be really worth for you!

Right now I am also imaging the comet from my backyard, will post the images tomorrow. You make a single 1' exposure with f/5.6 lens piggybacked on a big guy, I do tons of 1' exposure, darks and flat frames, a lot of processing, periodic error compensation.... but still we get almost the same results... I want to get to the Tucsonian dark skies or Arizonian will be correct!

BTW, why don't you post your imaging setup with 36"? that would be a funny scene. I hope you can borrow someone's camera, though.

Frank Taylor said...

Hey Jim, nice photo!

Now, where is your placemark showing Comet Holmes in Sky, and a placemark for where you took the picture from? Yes, I'm a Google Earth fanatic. :-)

Jim said...

I used the in camera auto-dark subtract and I actually have several images of the comet which I intend to co-add once I get a chance. I think I've got 5 or 6 one minute exposures. What program do you use to combine your images, Tuugii? I was going to load them into IRAF.... I'd take lots of darks, but I'd need to take them at about the same temperature as the exposures and I was too busy at the other telescope. I could make flats from all the rest of the images I took the same night. I have at elast 100, I think.... I did take some images of the setup I had last May just before my shutter broke and it was similar this time, around - without the camera itself, though.