Introducing: ScopeHunter

This is something I was busy with the last couple of months: ScopeHunter.

It’s a internet search engine for optical instruments. It checks quite an amount of auction- and biddingsites and internet forums related to astronomy and photography with a buy/sell section.

If you’re looking for a telescope, microscope, webcam or a DSLR camera, you don’t have to search the web yourself.
ScopeHunter does all the work for you. You can even subscribe to a RSS feed to get regular search results.

Happy hunting! πŸ™‚

Astronomy YouTube channels worth checking

The years when YouTube was only a place where you could only find videos from kittens and fail videos containing people with skate boards crashing into fences are long gone.
Okay, these videos are still uploaded but things really got rolling when they introduced channels.
Since then numerous channels about all kinds of topics, like astronomy, exist.

For me, YouTube is a great source of information about my hobby.
In the last couple of years I subscribed (and unsubscribed) a lot of astronomy related channels and I would like to share a couple of them, which I really like, with you.

If you have another tip for a cool astronomy YouTube channel to check out, please put them in the comments.

Eyes on the Sky
Eyes on the Sky by amateur astronomer David Fuller brings you a weekly, 5 minute show about what’s up in the sky for this week.
Besides that he gives tips how to star hop to certain objects and occasionally you’ll see him wearing a wig for Astronomy Theatre πŸ™‚
A recommended channel for the novice but also for advanced amateur astronomer.
Oh, and don’t forget to check his website for background information and links to videos with astronomy tips like alignment, getting orientated and sun observation to name a few.

Universe Today
This channel, hosted by Fraser Cain, publisher of the astronomy and space news site Universe Today, covers every week a astronomy related topic.
Topics vary from How big is the Solar System to What is a Quasar?

Space Fan News
A weekly news show hosted by Tony Darnell (and sometimes by Scott Lewis) recapping the week with astronomy and space news.
Complex topics are explained in a simple, almost in layman terms, and entertaining manner.

Deep Sky Videos
This is one of the many high quality YouTube channels maintained by video journalist Brady Haran.
Deep Sky Videos covers the objects from the Messier catalogue, the telescopes in Chile and La Palma and other astronomy related topics.
Deep sky objects are explained by professional astronomers so you know what you’re looking at, next time you point your scope into its direction.

Astronomy Shed
Not that active as it was before, Astronomy Shed hosted by Dion Heap gives you the latest astronomy gadgets and explains you stuff you need to know about your telescope.
Topics like polar alignment and mirror collimation are explained in detail.
This channel really got me going again after my 20 years astro break.

Houston Haynes
I found this channel, hosted by Houston Haynes, when I was about to buy my Coronado PST solarscope.
Videos with valuable information about solar observation and solar imaging using a webcam.

Miscellaneous channels
Here are some channels where I’m subscribed to which aren’t astronomy specific but I really want to share with you.

Sometimes scientific, sometimes philosophical and sometimes food for thought: VSauce by Michael Stevens.

Do you like those BBC documentaries or old The Sky at Night episodes? Check out UKAstronomy.

The documentary channel for all your Space & Universe, Science & Technology and Nature documentaries in HD: The HDdocumentaryChannel.

Making a cheap dew controller using a LED dimmer

After short circuiting a 12 Volt hair dryer which I used for dew prevention at a starparty a few months ago, I thought it was time to get a real dew controller and a dew heater for my scope.
An average dew controller costs more than 100 Euro (or US Dollars) which is, in my opinion, quite expensive for something that only controls voltage between 0 and 12 with a potentiometer.

One or two years ago, ‘rwagter’ a user on the Dutch Astroforum, came up with the idea of using a cheap 12 Volt LED dimmer as a dew controller.
After that I’ve seen numerous dew controllers using this LED dimmer created by people on the Dutch Astroforum and Stargazers Lounge.
I’m not a electronics buff at all, but after reading how people had built their own, I would give it a try.

The dimmer costs about 4 US Dollars each on eBay, and most of the time shipping is free.
After ordering, you’ll need to have some patience because delivery from Hong Kong can take 4 or more weeks.
Just search on eBay for 12 Volt LED dimmer and find the one that resembles the picture above because that’s the one you’ll need for this DIY project.

For my DIY project I’m using 2 dimmers and each dimmer outputs to 2 channels.
You can connect a dew heater on each channel, so in my case I can connect 4 dew heaters.

2x 12 Volt LED dimmer
1x lighter plug for connecting to a powertank
4x RCA chassis mount (female)
2x 5mm red LED (diffuse)
2x LED holders (plastic)
2x 2200 Ohm resistors
1x casing to put it all in
some cable

A soldering iron
A drill to drill holes in the casing
Nice to have: a Multi meter

dewc_componentsThe LED’s and the resistors are not mandatory. I thought it would be fun to see the LED light dim when using the potentiometer πŸ™‚

Total costs (including the 2 dimmers) was 30 Euro.
You can reduce the costs by using only 1 dimmer, a smaller case or just by re-using the dimmer case.
The case and the lighter plug (I bought a fused one) were the most expensive: both around 8 euro.

Building the dew controller is pretty straight forward.
The first 2 connectors on the dimmer are 12 volt input (V- and V+), connectors 3 and 4 are output (V+ and V-).
Power from your power supply goes into the input and the output connects to a RCA connector.
The only thing you need to keep track of, are the + and the – connections.

I’m using 2 channels per dimmer, so if you want to do that too, you’ll have to connect them in parallel.
That’s really it.

If you want to add some LED’s, take a look at this picture (courtesy of Gina/Stargazers Lounge):
ledsThe only thing what’s wrong in this picture, is that the input and output connections of the dimmer are switched.
Got me puzzled for a few seconds.

Here is the result of a Saturday afternoon drilling and burning my fingers by the soldering iron.


Now I’ll have to wait for clear skies and loads of dew πŸ™‚

Remote control your GoTo telescope mount using a Raspberry Pi and SkySafari

SkySafari is a great astronomy app for smart devices like the iPhone, iPad and Android.
The SkySafari Plus and Pro versions add the possibility to remote control your GoTo telescope mount using the special SkyFi adapter.
This adapter sends serial (RS-232) commands, received with a wireless connection, to the handset of the GoTo mount.
Using SkySafari in combination with SkyFi increases the number of objects you can observe and current events in the sky (like comet PANSTARRS at the moment) are found easily this way.

I was wondering if it would be possible to create something like SkyFi using the Raspberry Pi.
And yes, it is possible. Quite easy actually!

What do you need?

  • Raspberry Pi configured with a working network connection (wifi preferred, of course).
  • USB to Serial cable.
  • GoTo telescope mount
  • PC Serial to GoTo handset cable. Shipped with your GoTo mount.
  • SkySafari Plus or Pro
  • Basic Linux knowledge

Now how are we to receive the commands from SkySafari?
This is done by the Serial To Network Proxy (ser2net).

Install ser2net:

sudo apt-get install ser2net

Add the following line, using your favorite text editor, at the end of the ser2net configuration file (/etc/ser2net.conf) which contains the port where ser2net is listening on:

4000:raw:0:/dev/ttyUSB0:9600 NONE 1STOPBIT 8DATABITS

In this case, I chose port 4000. You may choose another port but be sure it is between 1024 and 65535 and does not conflict with any other daemons listening on the same port.

Restart the ser2net service with the new configuration:

sudo /etc/init.d/ser2net restart

Next, configure your telescope in SkySafari.
My setup has a SkyWatcher SynScan GoTo on a EQ3-2 equatorial mount.
Be sure to enter your setup and don’t copy my settings bluntly πŸ˜‰


The IP address in the picture above corresponds with my Raspberry Pi. Of course, you should enter the IP address of your Raspberry Pi.
Same goes for the listening port. I’m using port 4000.
If you configured a different one for ser2net, enter that one.

After that is done, you should try to connect SkySafari with your mount in the Scope menu and you’re off to go!

Light pollution Cinema

I admit, looking at images made by the ISS crew or time lapse movies made by orbiting satellites of our planet at night can be quite beautiful and stunning.
Back on Earth, that beauty is nothing more than pollution. Light pollution.

Light pollution is becoming a real issue. Astronomers are not the only ones trying to alarm the government because of the disappearing dark skies (when was the last time you saw the Milky Way when you looked up?) but also biologists and people involved with health care blowing the whistle for people to get aware.

A great documentary about light pollution and the search for darkness is The City Dark.
After watching this documentary, I was quite shocked about the impact light pollution has on human health and the habitat of wild animals.

Not a documentary but, as they call it, a public service announcement about the problems and solutions of Light Pollution is Losing the Dark.

Made by the International Dark-Sky Association and Loch Ness Productions, which can watched and downloaded for free on the internet.
Special dome versions (for displaying in a planetarium or observatory) are available too.

Lichtvervuiling in Utrecht

Sorry, this post is in Dutch.

Afgelopen week ben ik een avondje op stap geweest met Stefan Speelberg, 2e jaars student aan de Hogeschool voor Journalistiek.
Zijn opdracht was het maken van een radio item van 3 minuten over lichtvervuiling en de overlast die amateur astronomen die hiervan ondervinden.

Hoe we de lichtvervuiling in de binnenstad van Utrecht en in een donkere omgeving ergens in de provincie ervaren, kan je horen in onderstaand radio item.

Nog even voor de duidelijkheid: dit item is niet echt op de radio uitgezonden geweest. Het was een studie opdracht van Stefan voor een fictief radioprogramma.

Using the Raspberry Pi for camera surveillance using Motion and cloud storage

February, 16th 2014
A fully updated post using BoxFS2 with oauth2 authentication.
The previous version of this post used an old version of BoxFS which is now obsolete because changed their API.

If you are looking for a cheap camera surveillance setup, the Raspberry Pi is a great solution.
It is small, easy to install and, most important, has low energy usage.
I own Model B (see the Raspberry Pi Wikipedia page for detail about the models) which uses 3.5 Watts.

There are several open source motion detection applications for Linux such as ZoneMinder and Motion.
Both programs are available through the Rasbian repository.
ZoneMinder looks like a real security control center with all those nice cam screens, but it’s too bloated and too CPU heavy for the Raspberry Pi.
Motion is more lightweight and doesn’t stress the CPU too much when processing 320×200 camera data.
With 2 IP camera’s my average load is less than 0.50 on my RasPi, which also serves as an caching DNS server.

For storage of the AVI video files which contain the captured motion frames, I use a free account. provides the same service as the popular Dropbox.
The reason for choosing is because Dropbox has no open source client. The Dropbox Linux client is closed source and has, at the moment, no support for ARM devices like the Raspberry Pi.
Furthermore the free account gives you 10 GB of free storage. Way enough to store home camera data for a couple of months.

is the weapon of choice to mount your account as a drive partition on your Raspberry Pi.
Some basic Linux knowledge is preferred.

Setting up BoxFS2
First, read the README file on the BoxFS2 site carefully for the needed dependencies πŸ™‚

Install the needed libraries from the command prompt:

sudo apt-get install libxml2-dev libfuse-dev libcurl4-gnutls-dev

Besides some libraries from the Raspbian repository, you’ll also need libapp and libjson.
Get the latest commits from boxfs2, libapp and libjson:

git clone
git clone
git clone

Compile libapp first, then libjson and boxfs2 last using make and sudo make install.
After installing make sure you run the command ldconfig to update links to the libraries for the operating system.
Forgetting this might give you some error messages about not found libraries.

The BoxFS2 binary will be installed in /usr/local/bin.

Creating a BoxFS2 config file
With the command boxfs-init you can create a config file for BoxFS2.
The configuration file will be placed in the directory .boxfs2.

Open an editor and the configuration file would look something like this:

# Conf file for boxfs
# edit to fit your needs.

# Put oauth2 tokens here:
token_file = /home/pi/.boxfs/token

# Set a valid mount point
mountpoint = /home/pi/
verbose = no
largefiles = no

# Configure the cache
cache_dir = /home/pi/.boxfs/cache
expire_time = 1440

# Configure your uid and gid below:
uid = 1000
gid = 1000
fperm = 644
dperm = 755

The mountpoint must be provided in either way. This can be an empty directory called /motion for example.

Also check the user id (uid) and the group id (gid) of the user you are using.
You can check this in the passwd file which is located in /etc.
In my case I’m using user pi which has user id 1000 and group id 1000.

To let Boxfs2 run as a non-root user you have to add your user to the fuse group:

sudo gpasswd -a fuse

If you won’t do this, the following error message will be shown:
fuse: failed to open /dev/fuse: Permission denied

Also the execute bit of the fusermount binary should be set:

sudo chmod +x /bin/fusermount

Forgetting this will cause mounting to fail with this error message:
fuse: failed to exec fusermount: Permission denied

Mounting your account using BoxFS
To start the BoxFS2 client, simply run this command from the home directory of your user:

boxfs -f .boxfs/boxfs.cfg

The first time you run boxfs, you will need to complete the authentication (oauth2) process and grant access to your account. It’s easy, just follow the instructions on the terminal and on your browser.

When the mount is successful, set the right permissions with the command chmod -r 755 <mountpoint>.

To check if everything is doing what it should be doing, go to your BoxFS mount point and try to create or copy some files.
For debugging I recommend to be logged in to your account with your browser to see if things are actually written in to the cloud storage.

Installing and configuring Motion

To install Motion just run this command:

sudo apt-get install motion

Be sure that your camera’s and/or webcams output a 320×200 (or 240) image and Motion is configured with the same resolution.
I’ve tried a resolution like 640×400 pixels, but the CPU load went sky high on the RasPi, so I’ve settled for a lower resolution.
The images generated by my camera’s are quite clear and useful, so I’m happy.
I have no experience over clocking the Pi in combination with Motion, but if you do, please share your findings in the comments.
Same goes for solving the above resolution problem πŸ™‚

Further configuring Motion is something you have to do on your own.
The on line manual is quite clear about the numerous settings which can be done.
Mailing an image snapshot or a simple message when motion is detected is just one of the many possibilities.
Oh, and don’t forget to set the path to your BoxFS2 mount point to store your videos πŸ˜‰

When you’ve got an mobile device, you can use the app to download an AVI file and watch it using a movie player which supports the file format.
Great when you’re on holiday for example, and want to know what’s going on at home.
And all of this without tamperingΒ  your firewall, keeping your home network closed and secure.

I hope this post helps you to set up your own budget camera surveillance system.
For less than 180 euro (that’s 2 decent IP camera’s and a RasPi) you’re all set to go.

The Registax 6 initialize error

In my previous post I wrote about using the Philips webcams with the Linux 3.0 kernel and problems which might occur.
Last week I had to opportunity to capture the planet Jupiter with my webcam and last night I felt like processing the AVI files using Registax 6.

I use Registax 6 on my Ubuntu laptop in a VirtualBox environment running Windows XP. Yeah, some applications just don’t work that good using Wine so I have to use Windows once in a while πŸ˜‰
Okay, so I clicked the Registax 6 icon and… ERROR The application failed to initialize properly (0xc0150002). Click on OK to terminate the application.


Looking at the Windows System Logs I noticed that some Microsoft Virtual C++ 9 (aka Microsoft Virtual C++ 2008) libraries weren’t found.
Registax was created with Virtual C++ and it seems that those libraries were damaged or deleted.

Downloading and installing the Virtual C++ 2008 Redistributable Package solved the problem.

Hope this helps if you ever stumble upon this error message.

Philips webcams and the Linux 3.x kernel

The Philips SPC900 and ToU Cam Pro II webcams are still very popular by amateur astronomers who want to try out some basic planetary astrophotography.
I happen to be such a person.
A few years ago I said farewell to the Windows operating system and started to use Ubuntu Linux.
I am still very pleased about my decision.

Last Friday was the first imaging session in a while.
Planet Jupiter was tracked by my mount, webcam was plugged into my telescope and connected to my laptop.
I started up my favorite capturing tool wxAstroCapture.
An over exposed image was displayed on my screen so I had to tweak around with the gain.

Bang! Kernel panic.

Using the sliders for controlling gain, brightness etcetera caused the operating system to crash.
After rebooting it happened again, thus so far an evening of webcam imaging πŸ™

Now what’s the cause of this?

Philips webcams use special drivers (PWC) to make them work under Linux.
Imaging software such as wxAstroCapture and Qastrocam-g2 use the Video For Linux (V4L) API to communicate with these webcam drivers.
Version 1 of the V4L API was included with the older 2.6 Linux kernel but was replaced with V4L version 2 when Linux kernel 3.x was introduced.
The current status of the webcam drivers is that they aren’t 100% compatible with V4L version 2 and causes, in my case, the OS to crash.

The solution is quite simple: switch back to a Linux 2.6.x kernel.
When booting your machine, choose in the GRUB boot menu the Previous Versions option.
Select a 2.6 kernel version to your taste and the machine will boot with this version.

If you try to use your favorite imaging tool, you’ll notice it works like a charm again.

My laptop runs Ubuntu 12.04 at the moment. I guess switching to another kernel version on other Linux distros with this similar problem will be just as easy.

Happy camming! πŸ™‚