As part of the 2009 International Year of Astronomy our Colleagues at the Kuffner Sternwarte Observatory in Vienna produced a light meter that could be used to monitor light pollution. More details on the project and the meter are available at lightmeter.astronomy2009.at (use login Guest and IYA2009).

There are three stations in Ireland. One in Monasterevin (I’m not sure if it is active), one on the roof of the physics building in Trinity College Dublin, and the one I maintain in South Dublin.

Station Location:
long: -6.11
lat: 53.27
height: 95m
Raw Data: cademuir.data.11.2010


As part of the 2009 International Year of Astronomy our Colleagues at the Kuffner Sternwarte Observatory in Vienna produced a light meter that could be used to monitor light pollution. More details on the project and the meter are available at lightmeter.astronomy2009.at (use login Guest and IYA2009).

There are three stations in Ireland. One in Monasterevin (I’m not sure if it is active), one on the roof of the physics building in Trinity College Dublin, and the one I maintain in South Dublin.

Station Location:
long: -6.11
lat: 53.27
height: 95m
Raw Data: cademuir.data.10.2010


As part of the 2009 International Year of Astronomy our Colleagues at the Kuffner Sternwarte Observatory in Vienna produced a light meter that could be used to monitor light pollution. More details on the project and the meter are available at  lightmeter.astronomy2009.at (use login Guest and IYA2009).

There are three stations in Ireland. One in Monasterevin (I’m not sure if it is active), one on the roof of the physics building in Trinity College Dublin, and the one I maintain in South Dublin.

Station Location:
long: -6.11
lat: 53.27
height: 95m
Raw Data: cademuir.data.09.2010


I have some data that I need to come up with a way to graph. I’m using the Light Pollution from Thüringer Landessternwarte, Tautenburg, Germany and our friends at Kuffner-Observatory, Vienna, Austria. I have this unit hooked up to take a reading every second. It records the temperature, and data from three light meters, one designed to capture low levels of light which is of interest to us for light pollution (plotted logarithmically below). Anyway the units for these are all different and I cant see a way to plot them all on the same graph with rrdtool. In practice I probably don’t want to plot them all, but I do want to overlay mathematical models on the graphs. For example to plot the altitude of the sun and/or moon altitude and phase on the graph to see how that correlates to the light meters.

So any suggestions on what I can use to create these? Data is in a mysql database; need to be able to script the graph generation also.

By the way Dalkey got down to -6.3C during December, and snow on the ground does seem to cause an increase in light pollution. It’ll be interesting to compare some of this against an identical sensor on the top of the physics building in Trinity and if we can get it, air pollution data for the month. Basically we’d expect the increased albedo to increase light pollution, but snow has a reputation of clearing particles form the atmosphere so perhaps with less particles the light pollution is somewhat reduced. Lots of questions to answer :)

Heres the basic data for most of December to give you an idea at what I’m lookng to merge:

Woke up to a garden full of the little fellas today. Plenty around the estate too. Not a great photo but you get the main features. I noticed the local mistle thrush getting very worked up about them suddenly appearing on its turf! More info from Birdwatch Ireland.

24. December 2010 · Write a comment · Categories: General · Tags: ,

TED: Derek Sivers: Keep your goals to yourself

This video from TEDGlobal 2010 confirms something I have always felt. The warm fuzzy feelings you get when you tell people what you are going to do, gets interpreted by your brain as a reward for doing it, or at least for making steps towards your goal. You have done nothing, but your mind feels it has made some progress. I suspect we’ve all been here. I certainly have!

What I didn’t realise was that this not only be detrimental to your progress but can actually stop you achieving your goal. It can even stop you starting your goal!

Whats less clear is how telling people affects your goal after you are on your plan to achieving it. For example if your goal is to run a marathon, how does say sharing your running times and distances with friends affect your performance? Or sharing how much weight you have lost? Does the pat on the back from your peers cause you to sit back or does it force you to proceed and improve I wonder?

In any case I wont be telling you my new year resolutions! And if you have any it seems best if you don’t tell me, at least not until you are actually on the way to achieving your goal.

Here’s what the arch looks like today:

Under those 8 inches of snow you would see a roof. The roof itself is made from a red ‘coroline’ bituminous sheet from B&Q. It supported by the frame that you could see in the previous blog post; the support isn’t designed to hold much weight but it seems to be doing ok with the snow. And overall has a bit of a chinese feel to it.

The mirrors were the secret part of the garden. Two ikea mirrors that we had in the kitchen. The idea is that it should look as though its a gateway into another garden. What you are actually seeing is the one bit of orange on my kayak that isn’t covered in snow.

edit: I suppose I should mention a bit more about the mirrors. They are regular mirrors and not any fancy protected garden mirror. Behind them is a wooden frame so that the mirrors are not right against the concrete. They are held in place by a pieces of wood in front of them at the top and bottom (the top one is visible above). Then the edges and the wood holding them in place are filled with silicone. That should, in theory, allow the mirrors & wood to move a little with temperature variations to stop them cracking and also give them a bit of protection from rain. So far its worked well, no signs of moisture damage or cracks and its quiet even on stormy nights.

A couple of months back Min went on holidays to the UK for a week. While she was away I brought my Mum to a local nursery to buy some plants. While there she found a honeysuckle plant and I thought it would make a nice addition to our garden to cover up wall that prior to that only had ivy growing on it for 15 years. I’m sure it looked nice back when the garden was well maintained but it was a mess when we moved in.

Then I remembered Min saying that she’d like a rockery, and that’s when what should have been a simple little project grew legs. A quick glance through any gardening book will tell you how not to make a rockery. Don’t just throw a few stones on the ground, plant a couple of dwarf conifers, sprinkle a bit of gravel and call it a rockery – its not one. It also became quickly apparent that making a tiny rockery wouldn’t work in the garden, it would need to basically take up the area along the wall. After clearing out the plants that were there and getting rid of the pesky ivy this is what the area looked like:

I decided that I needed this to be a slope. And it needed better drainage than it currently had. So it all got dug out and broken bricks and gravel were put in at the base and then the topsoil piled back on top.

Next came the problem of rocks. Since I had a week to do this (well 2 days off work actually) I had to take what I could find. A local stone merchant just happened to have a basket of sandstone so I bought that along with some broken sandstone slabs that he had. I didn’t get a keystone unfortunately, and I still don’t have one – that is something that will need to be acquired.

The bare wall had been annoying me though. The honeysuckle would cover it eventually but the garden would still just be a rockery slope with a climber behind it. How about putting a feature in the wall in the middle to break up the wall and generate something interesting? The honeysuckle could have one side and I could put something like a Japanese maple on the other side (ok not a climber but big enough to cover the wall in time; and hey I can always put another climber in). After a bit of though I decided to go with a Chinese style gate arch, I could use the slab pieces to create a rough staircase through the rockery and by using the low plants on that it would eventually look like an overgrown stair with the bigger plants on the side.

The problem here is that Chinese archways are hard to come by in garden shops. Not that I wanted to buy one, I just wanted to copy one! After going through many webpages on chinese architecture and more importantly looking at what materials I had readily available in the local DIY and garden stores I came up with a way to make the arch. Here’s how it started off, complete with the basic sandstone outcrop.

The bamboo poles and wicker trellising come from B&Q. The rest of the wood is mostly from the old skirting board I had left over when the oak flooring went in to the house. See what I mean about it really needing a keystone? I’ll have to source one in the spring, or go looking for a decent sized sandstone laughing buddah!

That’s roughly the state it was in when Min came home. Despite time off work bad weather meant I didn’t get much more done.  Since then though I’ve got the ‘secret’ component done, extra topsoil in, and even a few plants! I’ll go over that in future posts – the whole thing is under about a foot of snow at the moment and I’ve no pics of it.

Apparently DIY stores are looking for €40 for snow shovels! Sod that. Bit of wood and half a plastic lid of an old compost bin and its sorted!

OK so its not the most elegant but it works well!

I came across a strange little networking problem earlier today.

The client in question had needed to be rebooted earlier in the day. The server had had no changes made to it. The problem only started occurring after the reboot of the client.

We had an NFS directory on the server that the client’s subnet had access to. However when we tried to mount the directory (via the automounter) it failed with a permission denied error. I should point out at this stage that the client is multihomed, that it it has several network interfaces onto different subnets and only one of these was allowed to access the share.

A little snooping showed that while the requests were mostly going out from the correct interface, some packets were coming out on an interface for another subnet. This shouldn’t occur since there is only one route packets can take out and its through the default router on the main interfaces subnet. It turns out however that we have 3 default routers on this machine – all active. This is likley a remnant of how the machine was installed, we copy in a defaultrouter file with multiple entries and since hosts usually only have one interface the rest get ignored. In the case of this system though the interface had been manually added over time and the routes were not activated, until the reboot then they all became active.

This meant that the system had 3 interfaces to contact the server on, but that the server would only authorise one of these interfaces. Since the interfaces had routes to the server the portmapper (rpcbind) was happily mapping ports on interfaces that we’d rather it didn’t.

Delete the routes, and delete the defaultrouter entries, restart rpcbind, and all works again.