as drawn by the armball

Reinvigorated astrophotography with a dSLR

After about 10 years of indecision, I finally bought a digital SLR camera. The Pentax K-r. A colleague at my astronomy society had one so I was aware of its capabilities. The first requirement was to be able to use my existing collection of K and KA lenses that date back to the 1980s. The K-r is very backward compatible in this regard. One feature used in the model choice was interval shooting for time-lapse. This will give me the ability to survey the night sky for an extended period in my aurora hunts. The jpeg image at right is one frame from a test run at interval shooting. 28mm lens aimed at a truck hubcap to make a fish-eye image, ISO 1600, 15 second exposure at F2.8. On later inspection 30 seconds or a higher ISO value would have been better. Also after about 2 hours dew descended on the mirror ending the show. Click on the image for a more detailed view. It is a mirror image with South at top, West to the right. Crux is just visible in the upper centre portion.

I'll see if I can upload the short time-lapse movie later.

I want to do Bulb setting and long exposures, but where is the cable release? One thing with the new cameras is the absence of a cable release socket. Pentax insist on an IR remote control (at additional expence of course), but I found that my old Sony VCR remote controls index search button will fire off the shutter. You have to set up remote control in the cameras menu first so that one button push will open the shutter then a later button push will close it. Easy.

So now I am ready to try some guided long exposures, but as expected with all new adventures in astronomy, it has rained for three days now. Hmm.

Radio tinkering with Jupiter in mind

In 2008 I wrote about my attempts to record radio outbursts from Jupiter but was plagued by severe background noise around 20-22Mhz.
This year I've cut dipoles to test 24 and 28Mhz looking for a quiet region of the spectrum. 28MHz proved the quietest.
The Moxon antenna (http://www.moxonantennaproject.com/) for 10 metres was my choice. 28.5 MHz had been quiet at night during the winter so was chosen as the band. A beam antenna for this frequency is not to large and unwieldy, and I have a very quiet background. However, the Jupiter storm signals are even weaker up at this band, so there is still a challenge ahead.
Once the antenna was built I was committed for the season. Come spring the sunspot levels had increased and the ionosphere activated to allow long distance DX transmission by ameteur radio operators on the band I was using. The band was now often  crowded in the evenings.  This narrowed the time window of operations but didn't prevent it.
Using predictions from the Kochi National College of tech http://www.kochi-ct.ac.jp/cgi-bin/jupiter/jup.cgi website to choose when to listen, I recorded the speaker sound from the (1984 vintage) Sony ICF7600D radio with the voice recording function on my Mp3 player. This allowed up to 8 hours recording in a file about 130MB in size. Once the file was transferred to the computer it could be played back at the predicted time segment for analysis. Various surges and swishes in the hiss can always be heard but only once (for Dec 4) have I heard ker-ash type sounds expected. I still have another month of available time windows before Jupiter is too low in the evenings.
Is the Moxon any good? I've heard good amateur DX from the Netherlands, Germany, UK, USA, and Taiwan. While on a signal if I turn the antenna about 180 degrees there is a definite decrease in signal strength. So it functions as  a true beam antenna with front to back ratio!
For Jupiter, so far I'm not convinced that it has worked. I am now planning  wire Yagi beams for lower bands, maybe around 19Mhz where the jupiter storm signal should be stronger. If I can find a spot near there that is quiet enough.