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It has been quite a while since I have been out doing any astrophotography and this night was not a particularly good one as the Moon was only 2 days from full. In preparation for the lunar eclipse, I decided to test the mount and polar alignment with a long exposure test. The clutch had been slipping on the RA axis but a friend was able to help me clean the gear grease from the washer and rubber which makes up the clutch. While this has helped, I am still having problems with the motor not turning the gears so there may be something loose inside the motor itself. After a few attempts, the motor started tracking and I started imaging. Average exposure was about 100 seconds at ISO800. The final stacked image was very blue, probably due to the light of the silvery moon :-) After doing a fairly nasty histogram stretch, more like a nip and tuck, I corrected the blue sky to black using the black/white point in Paint Shop Pro. I did not do any unsharp masking as all the stars looked great and quite natural in shape, size and colour. Heavy unsharp masking can create an unwelcome hotspot in the centre of each star.
As you can see, Merope's Nebula is visible, as well as some nebulosity around Maia. The stars are trailed very slightly but it does not interfer too much with the detail. Limiting Magnitude is estimated around Mag18.
We had a great evening of observing at Big Collin Picnic area, north of Ballyclare with the magificent Slemish mountain directly north of our location. The evening started well with a quick observation of Sunspot 649/656 and then on with the barbeque. The cloud started to come as soon as it got dark and was lingering up until 11pm. After this, it cleared up completely and we were left with just over an hour of beautiful dark skies (for this time of year anyway) and steady, still air. The usual favourites of M13, M27 which was quite beautiful and detailed, M57 which glowed brightly and the Perseus double cluster were the highlights. The rest of the time was spent lookng for Perseids which were infrequent but quite bright with some reaching Mag-7. This was the first time we have used the digital SLR for really long exposures, piggybacked on our 10inch LX200. The scope was setup fairly quickly but the polar alignment was very good and the stars stayted round. The biggest problem was focussing as looking through the viewfinder is very dark and small. The only way of focussing seemed to be by trial and error, using the preview and zoom to check each exposure.
80 second exposure showing Casseopeia, Andromeda and the top of Perseus. A satellite, Iridium 19, is also visible in frame.
The Andromeda Galaxy, the double cluster in Perseus and a thin layer of cloud in this 120 second exposure.
Cloud thickening and showing how light pollution even has it's effects on top of Big Collin. At the top right of the image you can see 2 bright stars of Ursa Major, Alkaid and the double star Mizar and Alcor which is split cleanly in this widefield image. At the bottom right is the satellite ERS-1. Details taken from Starry Night Pro. Exposure was 255 seconds.
After the cloud dispersed I left the shutter open for 100 seconds to capture this beauty of Casseopeia in the Milky Way along with the North American Nebula, the Dumbbell Nebula and Bronchi's cluster (the upside-down coathanger). There is a possible Perseid meteor to the right of the coathanger cluster. Click here for an annotated image.
Another long exposure of 132 seconds showing the depth to the Milk Way. NGC884 the Double Cluster in Perseue, M31 the Andromeda Galaxy with a possible Perseid in the lower left of the frame to the right of the small cloud.
Not giving up, myself and John McC went up to Slieve Croob only to be clouded out in thick fog. The night after we tried again and ended up somewhere outside Crossgar up a lane. There was a very heavy dew which made the use of the dew heater on the camera a necessity, but the skies were darker, though with some localised light pollution. An exposure of 589 seconds with some heavy processing to reduce the orange-ness from the image turned up with this... Again ,you can see the Double Cluster more bright than ever and M31. the constellation of Casseopeia is getting lost in the Milky Way.
Not until you start to image deep sky objects with long exposures do you realise how bad light pollution can be. Admittedly, the transparency was poor and the streetlights were making things worse, but when a 30 second exposure of sky is a bright orange, you DO feel like giving up altogether. Longer exposures would have been better but the tracking on the Vixen GP didn't seem to be as good as on previous occasions. The polar alignment may have been off slightly. I did do a dark frame but it turned out I didn't need to as the dark image was completely black with no noise apparent at ISO400 30seconds! Any visible noise is due to me trying to filter out the orange skyglow. This Canon 300D has great potential... The final image was corrected with north up, no mirror image was necessary. Image from Registax was histogram stretched, manually colour corected and a light unsharp mask was applied. Central star cluster was selected individually and gamma adjusted to brighten colours. In the original image, stars down to Mag17 are visible though, due to filtering the light pollution, stars are visible to approximately Mag13 in above images. Original frame showed structure to nearby NGC6207, IC4617 was just a dot.
Sunspot Group 655
I first observed this sunspot as it came round the limb a few days ago and it has developed progressively with small sunspots splitting in two and enlarging in only a matter of about 15 minutes. It's the first time I have been able to watch it happen in real time and is absolutely fascinating.
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