Here are some large images I produced in the process of writing an article on ‘Imaging the Sun in Narrowband’ for the December 2014 issue of Astronomy Now.
The first is a 3-part mosaic taken with a 100mm f/9 telescope, a vertical slice of Sun. Lack of IR blocking of this image has reduced the H-alpha contrast and put the sunspots back in. I was avoiding using the Lunt blocking filter, which has the defect known as ‘rust’. (Kudos to Lunt that they have offered to replace it free, though it is an old piece of equipment, but I haven’t got the replacement yet.)
The second is a three-part mosaic with the Lunt LS60T, which gets the whole disk in. I hit on a very successful IR blocking method here. This was to use a 2″ Baader 35nm H alpha filter, that I sometimes use for deep-sky imaging, in the imaging train as a blocker.
Click once or twice to get images full-size. The first won’t fit on most screens.
Here’s a white light whole disk image from the 8th and a more detailed IR image from the 22, that I produced in the process of doing an article for the November ‘Astronomy Now’.(Click to enlarge.)
I thought I should take Jacques with a longer focal length than I used on August 05 with the Hyperstar, so I imaged it here with my 100mm f/9 refractor at prime focus with a Canon EOS 400D (as it’s inconvenient to remove the QHY8 CCD camera from the Hyperstar).
A couple of things went wrong with this image. Firstly the exposure I chose was too long: there is noticeable drift of the comet in 2 minutes at this image scale, so it is not as round as it should be. Secondly, it clouded over after I had only got 6 subs.
I have tried stretching the image and inverting it, as I did before, but there is no evidence of a tail here at all (though this is a much better calibrated image than the Hyperstar one).
Processing was in Nebulosity 2, and Photoshop CS4 using GradientXterminator and Neat Image plug-ins.
(Click to enlarge)
This was sufficiently low when it got dark that I had to start cutting the hedge back to get at it with the 100mm refractor in the main observatory. This scope with a DSLR at prime focus framed it well. (Click twice to enlarge fully)
Here’s Comet Jacques from last night. 20 one minute exposures stacked on the comet.
There are some colour gradients in the background that I haven’t been able to correct, I possibly need need better flat fields.
No trace of a tail in this image, though people have imaged a faint tail from darker sites.
I think this is the nicest dark-sky comet we have had fore a long time, possible since Holmes. It was just visible in 10×50 binoculars, and in a 100mm refractor it was a very nice sight.
Update: 7 August
On Richard Miles’ suggestion I tried radically stretching the image. I also inverted it and made it mono, and lo and behold, a tail is visible, to the right (west).
Here is the result of my Jupiter imaging early last night. Ropey seeing, but something salvaged. Two different presentations of the same data: the RGB shows truer colour, but the LRGB gives better contrast.
Seeing not so good as on the 10th, but as usual I’ve eked something out here using the LRGB process with L=R. Click to enlarge.
Here’s some further images from December 10, but the other end of the day. These were taken well before culmination, which was good because after midnight the sky, which had been stable for some time because of high pressure, fogged over. Click to see full size.
I had a busy night; seeing was unusually good for this location. Ian Sharp reported exceptional seeing in Sussex as well, but Damian Peach, in a different part of Sussex, reported poor seeing, strangely.
First row are RGB composites. Second row are the same data but presented using an LRGB process, which gives more contrasty results, but worse artefacts. Third row are Infra-red images at 742nm, with Callisto just emerged from occultation in the second one.
In total, 24 one-minute videos were processed to give this set. Click twice for full-size.