Category Archives: Astronomy

Free Astronomy Observing Guides

Before these get lost in the ether (again!) I want to put them on my blog.

Some years back a few of us put together some observing challenge booklets for the Irish Federation of Astronomical Societies. I don’t think the certificates are still being offered but they are a great resource if you are stuck wondering what you should try and look at with your new telescope or binoculars!

Light Pollution Observations parser

I’ve created some code to do basic processing of light pollution observation files at

This came about from chatting to Prof. Brian Espey about processing the data from the SQM data loggers that he and others use around the country to monitor Irish dark skies and to assis the Dark Sky Places (and prospective places!).

Basically it does two things:

Continue reading Light Pollution Observations parser

Detecting Meteors from radio reflections

When I was in school, I remember being told that it was possible to tune an FM radio do a free frequency low in the band and during a meteor storm you could ‘hear’ when meteors struck the atmosphere as the FM signal from distant radio stations would be reflected back down from the ionised meteor trail. This may have been possible as back then there were plenty of high powered FM stations from Eastern Europe using a lower portion of the spectrum and receivers often went below the 88.5 that is the limit on the dial now. But I never heard anything. Over the years as my interest in meteors and radio was peeked I looked into it again, but the number of stations to use was dwindling and there were few artificial sources that could produce an audible ping. Continue reading Detecting Meteors from radio reflections

C9.25 tube wobbling

I’ve been having a problem over the past few months of the focus in my scope drifting unacceptably out of focus when imaging targets around the sky. Even when staying on same target for extended periods of time there was a noticeable shift. In some extreme cases the collimation also appears to be way off. This seemed to be a rather severe case of mirror shifting that larger SCT’s suffer from. The solution to which is to securely fix the primary mirror within the cell, usually by threading bolts into the mirror from the back of the scope. This seemed to fit the symptoms I was seeing, though some people did mention that I shouldn’t bee seeing this sever an effect with a relatively small scope. So yesterday I decided to disassemble the scope and see what the back of the primary was like and if it would be possible to secure it. It didn’t take me long to discover a more likely cause. Continue reading C9.25 tube wobbling

Imaging geostationary satellites

One of the people at our table at the COSMOS star party this brought up the topic of long distance radio communications and the use of geostationary satellites to facilitate such communication. The idea of trying to image some of these satellites then came up and we discussed the possibility.

So last night I decided to give it a go. Continue reading Imaging geostationary satellites

Analysing CCD characteristics and Determining minimum optimal exposure time.


My main interest st the moment is in minor planet astrometry, particularly of brighter Near Earth Asteroids. In order to get precise astrometry of these objects it helps if they are not moving in a single frame. Slow NEO’s can have rates of several arcseconds per minute so being able to take short exposures and stacking them is often required to get precise enough astrometry. It is possible to compute the minimum exposure needed for an asteroid by ensuring it’s movement does not exceed the FWHM of stars in your image, e.g. if an NEO is travelling at 4”/minute and you have a FWHM of 4” then an image one minute in duration will not show trailing. However it is also necessary to understand what the minimum exposure you can take with your setup is to minimise noise and maximise the signal to noise ratio. And it was necessary to understand the camera characteristics in order to make that determination. Continue reading Analysing CCD characteristics and Determining minimum optimal exposure time.