Sunday, 13 January 2013

Fifth moon of Jupiter

I finally found my fifth moon of Jupiter! It's called Himalia, and lives about a degree away from Jupiter in the sky. We recently opened our observatory to the public for three nights, and had clear skies for the last two. After the last people left the dome and were chatting downstairs I set to work obtaining more images of the star field near Jupiter. Unfortunately my Canon 1000D had had a slight mechanical problem, resulting in a brush hair being trapped in front of the sensor. The shutter open-close mechanism suddenly failed to move faster than 1/200" and I tried to clean it with a substandard optical brush. The calibration is a little out. The flat field needs to be updated and also the dark frames I used were from a warmer night. Depsite this, stacking 8 x 30" pictures gave me this interesting image, showing rays of light radiating from Jupiter...and a teency, tiny little dot that was not on the Palomar Observatory Sky Survey red plates. This is Himalia, an outer rock orbiting Jupiter way beyond the four big, bright Galilean satellites that were viewed by many folk earlier in the evening. Some of the visitors got a preview of Himalia on the back of my camera after I had tried to get a few early shots of it. The event was a great success, thanks to the weather holding out and our facilities having been well maintained.

Tuesday, 1 January 2013

A glimpse into Orion's depths.

At last! A snippet of clear sky between fast-changing clouds. Enough to grab a few 30 second exposures of a weird little nebula, IC 426. I turned to one of my to do lists on my phone, that contained unusual objects I wanted to image. I managed to get a moment after a short viewing session at the observatory to whack on my camera, focus on Alnilam, and run off some shots as I dodged the clouds. The moon was rising during the exposures, of which 12 were useful. I got home and processed in Deep Sky Stacker, using some old darks and flats, which I really need to update. Still I got this weird blue thing that looks a bit like the North America Nebula. All I saw on the back of the camera was a wavy line passing between the two brightish stars at centre and winding round like a river on a map. After processing, the rest of the nebula appeared, along with a few other patches. Judging from the colour, this looks like a reflection nebula. The nebula is located to the 'upper left' of the star Alnilam, and the orientation of the illumination seems to fit with Alnilam being the source. So as a first guess, this floating patch of dust could be part of the Orion Stellar Association about 900 light years away [need references].