Blog

Meteor Antenna
17th February 2016 - 0 comments
Over the Christmas break I was reading up on using distant FM radio stations to detect and count meteors. The technique is called forward scattering. It makes use of the reflection of distant FM signals from meteor plasma trails. Meteors create momentary plasma trails at altitudes ~100km, which reflect in the ~100MHz range for up to 1-2 seconds. Fortunately there are a few gaps in the local FM bands and I could identify some distant potential radio stations with power outputs ~80 kW. So I built a tunable and very directional Yagi-Uda antenna. First I wanted to hear it for myself before setting up a computer, so for a few nights I listened to the hiss of an empty FM band for 1-2 hours at a time in the very early morning and then finally 2 seconds of rock music, then it was gone. I was tuned to a rock station in Canberra (467 km NE) - the signal had been reflected back from space by a meteor trail somewhere over the Australian Alps. I've now set up a computer to do the listening and shifted the focus to more distant stations in Rockhampton QLD, which is 1,686 km N-NE of my home, and picking up meteors over central NSW.
Planets 2016
17th February 2016 - 0 comments
I am gearing up for Jupiter, Mars and Saturn for early March, mid May and early June respectively. In particular Mars will be larger and well positioned for Southern observers and imagers.
Globular Cluster Listing Update
20th December 2015 - 0 comments
I've finally got around to linking the Globular Cluster Index to the individual images. I see that I have missed posting several clusters that I have imaged, so I will look over my hard drives and fill in the gaps. Where missing I have noted "pending" and linked to the gallery page for the interim. Also with Summer here, I will have a chance to capture the few that I have not imaged, e.g. M79 in Lepus and NGC3201 in Vela. I hope this set of images, which are scaled to 14' unless otherwise noted, will be useful to you if you are hunting for any of these clusters. I have observed all of these through my 16" and there is more variety than you may first suspect, with variation in size, brightness, degree of resolution, concentration and colour, and of course surrounding star fields. Tightly cropped images that are overexposed at the core tend to look pretty similar and often don't resemble what you see in the eyepiece.
Visit Mars
13th August 2015 - 1 comment
Through April 2014 Mars was in opposition. I captured well over 100 images of the red planet through the Celestron 9¼", most of them in IR. That generated a huge amount of processing work, which I had attended to from time-to-time since then. I am now close to setting up a new page "Visit Mars". Mars has a very small globe so rather than having still images showing a globe only 150 or so pixels across, I have been building animated GIFs that show off the main surface features of the planet.
Southern Globular Clusters now posted
13th August 2015 - 0 comments
Back in 2013 I imaged over 30 globular clusters that are visible from my back yard, i.e. 37.5° South. I posted a few on celestronimages.com but most sat on the hard drive. I finally set aside a few evenings and finished the processing, with a faster computer now, and have set up a page in my Gallery for Globular Star Clusters. Most images are posted at a fixed scale of 14' across. All the classic circumpolar clusters that you can't see in the North are there including NGC104 and NGC362 in Tucana, NGC2808 in Carina, NGC6397 in Ara and NGC6752 in Pavo. And of course ω Centauri. Anyway have a look. I plan to add another dozen, though all the biggest and brightest are done. Incidentally M13 is too far North for me so that is missing from the set.
Updating older images
05th August 2013 - 1 comment
I'm reprocessing my older images with Registax 6. Images dating back a few years were processed by Registax v5 or v4 and often with single point alignment. Registax 6 gives final images that are sharper over a much wider field. The atmosphere can distort otherwise sharp frames - sometimes it looks like regular waves rolling across the face of the Moon. The effect is more pronounced in red light vs IR and so with the older software, the IR images often looked sharper. As Registax 6 addresses this type of distortion really well, I have now found that processed red light images in particular have been improved and are usually better than images captured in IR.