Wednesday, 29 May 2013

Huge local elliptical galaxy hiding directly behind the Milky Way

The asterism Czernik 11 pictured here, lies within the myriad stars in Cassiopeia, a constellation with the Milky Way running through it. It acts as a signpost to the galaxy Maffei 1. All that's visible is a nuclear region of a nearby galaxy, appearing as a diffuse 11th magnitude glow, very difficult to find or see among so many stars. Here I stumbled across it in April, after looking at comet PANSTARRS. It is hidden directly behind the Milky Way's dust and 98.6% of its light is blocked by it. In near Infra Red it appears as a huge galaxy stretching up to 23 arc minutes and were it not in the plane of our Galaxy, we would be able to see it well in binoculars on a dark night.

Another go at M87's Back Hole Jet

Here is the central massive elliptical galaxy in the Virgo Cluster. M87 is huge and has an active nucleus (supermassive black hole) that is producing a visible jet as well as two much more distant radio lobes. The jet is detectable on fairly short exposure images, such as the 22 15-second exposures used to produce this image. The area in the photo includes two other galaxies of the Virgo cluster. I avoided using guiding, and rejected a few images with motion blur during the stacking (production of the final image).

The southern pinwheel from the UK.

This is the southern pinwheel galaxy, M83, taken from the northern latitude of 52½ºN. It was under 7º above the southeastern horizon when I got the 44 images of 30 second exposure. Using RAW mode on the modified Canon, and having gathered plenty of flats of darks has enabled me to divide out the light pollution background pretty well. A bit of gradient removal and digital processing gave me this reasonable image taken through a lot of atmosphere.

Sunday, 12 May 2013

Two spring galaxies and a supernova

This pair of galaxies are M66 and M65, which are on the left and the right respectively. They are located in the eastern part of the constellation Leo the Lion, just around the centre of the Lion's imaginary femur. In M65, there is a supernova which you can see below the nucleus of the galaxy, halfway to the edge and a little left. This apparent star is not usually there, and it was brightening in the days leading up to when I took this photograph on the evening of April 6th. I took it in the usual way, with my modified Canon 1000D on our society's 20 inch motorised Dobsonian, and stacking lots of 30 second exposures. I was careful with the calibration frames in that they were gathered during the previous twilight. I've processed the image a little more gently than usual and used a digital development algorithm to make the image look a little more like peering in a huge telescope. I'm amazed with the detailed structures I can see in these two fantastic galaxies.

Friday, 3 May 2013

Detection of Distant Aurora

I was getting aurora alerts on my phone and with activity having been raging at Kp=10 all day and evening I couldn't resist driving North of the City and going for a look just before bedtime. I set up the modified Camera on a tripod and took a few 30 second, wide angle shots. One short sequence shot at around 2300UT on May 1st, showed a noticeable change when I flicked through it. There were three red vertical beams where there hadn't been any 90 seconds ago. The glow below these on the actual pictures had a greenish hint to it, showing it may have been green aurora but it was too masked by light pollution for me to be satisfied I was seeing aurora, so I had an idea of a rather more scientific technique of image subtraction. I manually blurred and shrunk the images in paint shop pro and did a subtraction. On enhancing the contrast, and getting rid of a few noise artefacts I got this weird picture. It is a difference picture, so the yellowish cloud is where the cloud was advancing, and the darker blue cloud is where the cloud was. So... I managed to defeat the cloud and light pollution to reveal proof of aurora! What's more I decided to do a rough distance calculation. I estimate the top of the red aurora is 400km high, which is seen at 20º altitude. This leads to a distance 1200km, or a guesstimate of around 800km, allowing for curvature. The green and the red emission of aurorae come from atomic oxygen, but the red is from a higher energy, long lived excited state. This state's energy gets quenched by collisions with air molecules below 100km or so altitude, due to the higher density of the atmosphere.