Prime Time (-ish)

Today at 2:03:05, the date and time, if you write it in a particular form, is a string of the first six prime numbers: 02:03:05:07:11:13

This only works if you use DD/MM/YY format for the date, and not the American MM/DD/YY, or the more sensible YYYY/MM/DD format.

So, just after lunch take a look at the clock and ponder this celestial / mathematics alignment.

Spider Season

As autumn draws in we start to see more spiders around the house, what are they are why are there here?

The most commonly encountered UK house spider is Tegenaria Duellica, this cute little fellow:

Male T. Duellica posing artfully
Male T. Duellica, note the “boxing gloves”


I saw fellow because the great majority of these you’ll see are males – you can tell by the enlarged pedipalps at the front close to the body and eyes, making the spider look like it’s wearing boxing gloves. Females lack the boxing glove look.

The females are usually to be found in cooler outbuildings and attics in their flat funnel-likeĀ  webs. They wait for a male to approach and mate. The male will stay by the female, mating several times, usually dying and being eaten by the female in the process.

Tegenaria duellica web in the roof of a shed
T. duellica web in the roof of a shed, with spider in residence and corpses of victims adorning the walls.


The female will lay around 50 eggs in a collection of marble sized whitish-yellowish egg sacks – you’ve probably seen these in sheds and under floor boards. The female’s job is done and she dies (a small percentage live and will mate a second time).

Tegenaria duellica egg sack
Tegenaria duellica egg sack.


The eggs hatch when the weather warms up in early spring. the spiderlings take a year to 18 months to reach sexual maturity and start the process all over again.

Astrophotography & Star Trails

While trying to photograph meteors in the Perseids shower recently I ended up taking a lot of longish exposure photographs of the same patch of sky. I was hoping to catch a meteor or several shooting though the frame. Reviewing the photos when I got home I found I caught no meteors, indeed I saw none either, but I did have a set of images I could make a star trail image from.

The usual way to make star trail images is to load the separate images into layers in Photoshop or Gimp and them blend them together. I’ve since found a nice piece of software that automates this process, StarStaX. The following two images were generated with this software. I only had a small number of images usable for the stacking, and there were quite large gaps in time between image, so the results are not as great as they could be. This is not the fault of the software.

StarStaX Test 1
Stacking some star photos. Originals were 20s exposures with 5sec between images, hence the dotted look to the trails.
Some shorter exposures stacked. Was looking for meteors, but saw none. Camera must have moved, giving the jump in star positions. There’s at least one airplane / satellite trail in the stacked image.


Playing Radio

Last weekend a bunch of us from the Havering Amateur Radio Club decamped to a field at the Kelvedon Hatch secret nuclear bunker and set about trying to contact as much of the planet as possible by radio.

It was a good excuse to try out my new radio, an Icom 9100, and break out the big beams and linear amplifiers.

We had two HF stations, on 20m and 17m and one VHF station trying to work though some satellites.
A total of over 300 QSOs were logged, a good third of those using CW on 20m. There is a QSO map on line. Some photos of the event are on Flickr.

You’ve got to photograph a bug or two when you’re in a field. Here’s a ladybird larvae.
DSC_2392 - Version 2

The insides of things are beautiful…

…lets see what they look like.
These days I work with X-Ray systems. I’m just finishing up commissioning and testing of the latest one, so I’m using it to image various things.

This is a compact fluorescent lamp. At full size you can see the coils of tungsten wire in the electrodes in the glass spiral, you can also see some tiny droplets of condensed mercury at the end of the spiral. It;s this mercury that’s essential for the operation of the lamp, but is also what makes them (slightly) hazardous if the glass breaks.
Compact Fluorescent Lamp