Wednesday, 31 December 2014

Lovejoy emerges from the South

Our skies are graced with another comet. It is a bit difficult for us to see in the North at the moment, but will move out of the low misty southern skies in a few days. Here is my first serious attempt at getting pictures of it. I just used a 400mm lens at f/6.3 and took 40 shots of 30 second exposure on a tracking mount (Dec 29 11pm). There is a hint of a tail there and while it doesn't look much now there is more to come from this icy rock.

Saturday, 15 November 2014

The Outer Gas Giants

After a successful forecast of reasonable seeing conditions in the UK (i.e. low 300 mbar geostrophic wind) I spent an evening at the observatory trying to aim a telescope so as to focus Neptune, then Uranus on a 6mm CCD chip. Despite the new mount being excellent at tracking this took some time, and it wasn't helped by the mount insisting on doing a meridian flip just before starting imaging. The 9.25 inch SCT 'scope was cooled, Neptune showed a disk in the eyepiece, and high magnification was achieved with an extended 2x barlow, to reach about 6m focal length. The only non-optimal factor was the collimation being out, which was clearly seen during a later image of Gamma Andromedae. I explored a range of objects until the corrector plate dewed up too quickly.
So I managed to capture video of: Neptune at 3x, Uranus at 4x, close-ups on Cleomedes and Aristarchus/Vallis Schröteri (which were low down and shaky), and longer exposures of the core of M31 (not shown) and NGC 7662 - the "blue snowball" planetary nebula. It was a lot of fun trying this all out freezing on a patio in a dark field, alone with the entirety of space!

Sunday, 5 October 2014

Little Planet of Waveney Mountain

I went to a local hilltop near the student residences in order to try and get a 360º panorama of the sky with my Canon 18mm lens, on a moonlit night. 'Waveney Mountain' is named after the former residences, which are themselves named after a local river and 'mountain' is a little joke among folk round here. After loads of practice with Hugin, a long pause (a few months) and several attempts at stitching the pictures last night, I have finally got something I'm happy with. I had to manually choose the control points that each pair of neighbouring images shares, and there was still a problem with a black wedge appearing in the place of one of the images. Hugin is great for remapping the pictures onto a stereographic projection but doesn't quite get what looks right, so I got it to remap the problem picture and pasted it in myself in Photoshop. A quick bit of clone brush to fill in the panorama gaps that I'd inadvertently missed and here's the result. Now I can do this, I'm tempted to get a nodal ninja tripod and a wider angle lens. Astrophotography can so easily be quite a costly hobby, but this was pretty inexpensive and a great idea to test out during moonlit season.

Wednesday, 3 September 2014

An re process of an old favourite

This is a quick and crude process of some stacked images of the Horsehead nebula. I took them through the 20 inch with the Canon 1000D (with the A-mod) in February 2013. I've just used the amazing Hugin software to assemble this mosaic of 4 images and tweaked it in Maxim, then applying a Digital Development Processing routine. It just looks stunning so I had to post it straightaway. The contrasting colours here make such an aesthetically rich faraway thing!

Wednesday, 20 August 2014

Zubenelgenubi gets some guests!

While testing my planetary imaging demo for the talk I'm giving next month (see: ) I spotted Saturn and Mars setting in the South West. I got a snap and looked at the image and spotted a star. I then ran across the field with the tripod to get a pic of the planets above the dome and observatory. So not such a 'far away thing'. It's one of those mind-blowing distance ratios. I also caught Andy walking back to the observatory who came back telling me the star was alpha Librae - aka Zubenelgenubi, my favourite star name! So from top to bottom we have Saturn, Zubenelgenubi (alpha-2 and alpha-1 next to it) then Mars. A beautiful scene I realised when processing it to bring out the faint details, giving pleasing pastel shades on the sky. Just 1/4" second exposure at ISO 1600, I had to turn the gamma down again as blogger overdoes it!

Comet E2 Jacques

A night at the observatory and a moonless clear spell coincided! Not wanting to waste the opportunity I wheeled the society's new iOptron mount out and set up the 9.25inch Schmidt with the help of a busy crowd. I put my modified Canon on the back of it along with a f/6.3 focal reducer. Time constraints meant a full perfect drift-align wasn't possible, so I limited exposures to 30 seconds to reduce any star trails. Auto-guiding is not quite ready with this set up yet, but once we get the equipment together, beautifully long exposures will become possible! During the 20 minutes or so it took to get 22 good exposures, Comet Jacques had slid past a star and moved quite considerably! This required a special star then comet stack in Deep Sky Stacker. The result had a fair bit of star ghosting in the direction of the comet's motion and there is still a small ghost of the comet's nucleus left in the image that I couldn't remove easily. Several runs through Carboni's horizontal and vertical banding removal routine got rid of the bias pattern noise in the camera sensor, but the faint ghost trails were still a little annoying. I tilted the image until these trails were horizontal and ran another horizontal banding removal routine on the image. Then I tilted it back. Above's the result, and below with the faint parts smoothed. Not too much exposure, but am I right in thinking there's a hint of a tail to the right at about 110º CW from vertical? The green emission in the coma ('swan bands' in the spectra) comes from the molecules C2 and CN and their positive ions.

Monday, 30 June 2014

Midsummer Planets

During the light nights of summer here in the UK, planets are an ideal target. Unfortunately, we are also rather far North for good planetary imaging, as they are low in the southern sky, but this didn't stop me. I used the new iOptron mount with the Schmidt Cassegrain 9.25 inch f/10. After attempting a focal length of 11.5m, I also tried cutting it back to 5m and got just as good results. With the imaging source colour webcam, I recorded video with a range of exposures of Saturn and Mars. The mount tracked well despite a quick manual align. I manually fused the long and short exposures of Saturn in Photoshop after trying out the "Merge to HDR function" with less success. So the photo includes moons (L to R) Dione, Rhea, Tethys and Enceladus - just, below the planet. Mars also had a distinct phase (88%) and is only 9.9 arc seconds tall (phase mask added). Vaguely visible are Mare Acidalium (top centre) and Mare Erythraeum (bottom) as the North pole is tilted toward us. Taken 22UT 24th June 14.

Monday, 19 May 2014

Cometary Conjunction

I managed somehow to get an image out of the 20 inch scope after its drive rebuild. It has been out of action for imaging for months. The drives are still in their development stages, and I'd disassembled my focal reducer adapter for that scope. I had to image in short exposures (20s) and pick the best 30% or so. It was an ideal photo opportunity with the 3.7 magnitude guide star χ Ursae Majoris, a degree from the brightening comet 2012 K1 PANSTARRS, and its usual companion, galaxy NGC 3677. Still, this lovely pairing made a great view and photo - they just fit in the frame. χ UMa is a little off the top of the field of view (around 30' across). This comet is worth watching as it passes by φ UMa and descends into the summer twilight and may become visible in the morning sky in autumn. It has moved a little (SW) during this images exposure time.

Saturday, 19 April 2014

Looking Inside the Pentagon of Auriga

The area in central Auriga featuring open clusters M36 & M38, IC 417 (around central star, phi Aurigae), IC 405 and IC410 - the flaming star nebula. About an hour's worth of 90 second exposures piggybacked on the top of my 8" through a telephoto lens with a modified Canon 1000D. Taken from Kelling Heath. There was a lot of mist and clagg in the air that night, so it's not bad! There are dark lanes and other patches of nebulosity lurking around this region of the milky way.

Wednesday, 12 March 2014

Jupiter - always interesting

I "videoed" Jupiter on the 8 inch Schmidt-cassegrain at the observatory tonight (11th March 2013). I got better results with just the 2x barlow than with 2 2x barlows. I was operating at f/20-22 (focal length just over 4m) and exposures of 1/54 of a second. I captured 2500 frames in 1min40, and stacked the best 1760 of them in Registax 6. The three moons made a beautiful triangle and Callisto cast a rare shadow on to the disk - something I noticed in the eyepiece, plus the red spot was in view. What chance! The Imaging Source (non-cooled) DBK colour camera was pushed into the scope and off I went. The moons to the right were (top to bottom) Europa, Io, Callisto - and you can see it is Callisto causing the shadow. Each moon seemed to have an independent motion to each other as the conjunction developed over the course of an hour or two.

Aurora borealis!

Yeah! I caught a glimpse of the Northern Lights for the first time this solar 'season' on Thurs 27 Mar 22UT. It was not too impressive aesthetically, but lovely to see the lights again. A colourless dim glow was hovering, detached from the horizon and for a time, a shaft of light appeared in the sky just beneath Cassiopeia. The advances in Camera technology (and mine is well out of date) meant an easy capture of the wonderful colours.
Here I've done a stack of 8 x 15s images pointing N, just N of Norwich. I stacked on the ground, not the stars, so they are trailed. The green, lower glow is from atomic Oxygen, i.e. O atoms, emitting during the decay from excited singlet S state to the singlet D state, an allowed transition. The red light, also from atomic O, is only seen at higher altitudes, where the air is much thinner, this would occur at lower altitude but the excited state causing it is knocked back down by collisions with other air molecules. This excited state is the singlet D mentioned above, the 'first' or lowest energy excited state, and it releases its red light with a time constant of about 107 seconds. This means it needs to avoid getting hit for about a minute, in order for it to have a change to spit out its red light. The reason for this slow time is because the transition from singlet D to the 'ground state' (triplet P) is forbidden, as the spin has to change from singlet to triplet, something not allowed by quantum mechanics.

Sunday, 9 February 2014

The Milky Way over the Bristol Channel. New processing.

I have had another go at processing the twelve 30-second (dark-subtracted jpeg) exposures that I took of the Milky Way setting over the Bristol Channel last September. I was not happy with the 8-bit look to the background subtraction and the lens-distortion. I used the beautifully complex free program hugin to correct for the barrel distortion of the lens and stack the images based on a spherical geometry. I had a long task, taking many hours to work out how to get the control points only on the stars. I eventually found a method for hugin to use to pick the control points, and it resulted in a beautifully stacked final image except it came out with a distorted perspective. So I stacked the shore images and recombined the image with the stars, and ran a background subtraction. The resulting processed image is much sharper but still with very slight trails from the individual 30 second exposures. I've reduced the scale to 0.25 here (jpeg), so the trails are barely visible. Altogether not bad for 12 minutes on a tripod perched on a windy clifftop.

Saturday, 25 January 2014

There's nothing like stargazing live

It's not live as we know it, Jim. It happened 11.4 million years ago. But - that's using our human concept of time. In reality time isn't a constant thing - there's no such thing as simultaneous. As far as I'm concerned, the recent supernova in the galaxy M82 has just happened, because all of us on Earth agree that its light has reached us in the last few days. That's good enough for me. Last night I was spurred on to get my 8 inch Meade LX10 SCT out of its box and onto its tripod positioned in my urban back yard. I popped in an eyepiece, focussed and swung it round to Ursa Major. After only 2 or 3 minutes of dark adaption I had seen the supernova with my own eyes. That was awesome but very quick. A near conversation on social media meant two other astronomers (whose blog links are here) had swung their kits round to image it. Thereafter I had a go at imaging it, with limited tracking and got a few 15 second exposures at f/6.3. I left it running and later did a stack of 75. A little blurry. Tonight I have selected the best 45 images out of 100 and used PIPP software to debayer and crop them around the galaxy. A quick stack in Deep Sky Stacker gave me a smooth image, and a DDP (digital development processing) gave this result. Much better than before, but only 11 minutes worth of data on a Canon 1000D is not gonna cut the mustard these days. Still I'm pleased to see it - so here it is. The society's telescope is currently unable to be used for photography, and we've been using it for stargazing live open nights, hence the lack of blog posts.