• The Author – Bart Busschots

  

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I’ve just missed two days of work and I may miss more because of an illness that has been around probably since the dawn of time, you’d think we’d have figured something out by now! We can go to the moon and wipe out entire continents with a single bomb but we still can’t cure the common cold.

Mind you if this birdflue thing turns out quite as bad as people are suggesting it might then maybe the common cold won’t seem quite so bad anymore.

OK, so you have a telescope and a collection of eyepieces ranging from 6mm up to 45mm but you have no idea how much the bloody things will magnify! Welcome to my world. I keep on forgetting how to do the calculation and what the focal lengths of the Astro2 telescopes are!

One might ask, ‘why are eyepieces labeled with focal lengths instead of magnifications?’. I mean it would be much easier if they did that, right? Unfortunately they can’t because the magnification is not just a function of the eyepiece but also of the focal length of the telescope it is used in. Hence, the same eyepiece will give a different magnification on different telescopes.

Astro2 have the use of two telescopes so that means that there are two focal lengths I’m going to have to start remembering:

• Meade 10" LX200 – 2,500mm
• Meade ETX90 – 1,250mm

Now that we have the focal lengths of the telescopes, how do we get the magnifications for each of the eyepieces?

M = f_o/f_e

Where f_o is the focal length of the objective (i.e. the telescope) and f_e is the focal length of the eye piece (make sure the two are in the same units, usually mm).

This means that the eyepiece I use most often for Astro2 events (26mm) gives a magnification of 96X on the big LX200 and 48X on the little ETX90. It also means that the maximum we can magnify for Astro2 events is about 415X and the minimum is about 60X with the LX200 and 30X with the ETX90.

Mind you it should be pointed out that there is a limit to how far you can magnify with any scope till the image quality just gets too poor to use and that maximum is approximately the diameter of the primary lens/mirror in mm so for the LX200 that gives us an optimum magnification of 250X (i.e. about a 10mm eye-piece) and for the ETX90 about 90X (i.e. about a 13mm eye piece).

At the moment Mars is making it’s closest approach to Earth for the next 18 years so Astro2 thought this was too good a chance to miss! The only slight drawback was that Mars wasn’t well placed for observation from the Physics Observatory until after midnight. However, I offered to run a Mars watch at 1am and to my great surprise I wasn’t alone! There were in fact over 20 other people braving the cold with me!

This was the first opportunity Astro2 had to use the physics department’s LX200 10" telescope. The conditions were not really ideal but we did nonetheless get a good look. We started off with a 15mm eyepiece giving a magnification of about 170X which allowed people to see some surface details while keeping the magnification low enough to keep the image nice and sharp. Once everyone had a look at the low magnification I changed to a 12mm eyepiece to increase the magnification to about 120X. At this stage the sky was getting very hazy and there was a good coating of dew on the corrector plate of the telescope but we could still easily see the black regions on the surface even though the image was quite fuzzy. I did try to up the magnification to about 280X with a 9mm eyepiece but that just wasn’t gonna happen in those conditions!

All in all I think people had a good time and I’m really encouraged by such a high turnout for an Astro2 event at 1am!

Now that the worst of the ‘browser wars’ finally seems to be behind us and now that JavaScript can easily communicate with servers to get data without page re-freshes via AJAX one has to wonder if there are any real uses left for applets. My conclusions would be that yes there are still some uses for applets on the web but they are few and far between. Anyone who uses an applet in this day and age should have a bloody good reason to do so because your browser should not have to load a JVM just to view a web page unless that JVM is providing something spectacular that actually adds something to your page and that cannot be done with the core web technologies (XHTML, CSS, JS, AJAX).

Read more

I was doing some NASTY SQL coding this evening (or squealing as Smiler would say) and I got bogged down quite a while trying to get DISTINCT and ORDER BY working in the same query. The PostgreSQL error message was not entirely clear and I must have misinterpreted it about 5 times before I finally figured out what it was so desperately trying to tell me!

Turns out that even if you don’t actually want to select the field you are sorting on in a query that uses the DISTINCT keyword you still HAVE to include it in your SELECT list or PSQL will have kittens!

BTW, I am aware that it is considered a ‘bad smell’ by some hard-core SQL programmers to use to DISTINCT key word and I generally agree with their logic (why go to the effort of selecting a load of extra rows that you are just gonna prune off in the end?). However, I can’t for the life of me figure out how to get rid of the DISTINCT in the query below, any insights you may have would be appreciated (looks at Bon)!

SELECT DISTINCT a.id AS assignmentId, a.name AS assignmentName, a.team_id AS teamId, 
  t.name AS teamName, a.completed AS assignmentComp, a.last_updated_at AS lastUpdated
FROM ((student_team st INNER JOIN teams t ON st.team_id = t.id) 
  INNER JOIN assignments a ON t.id = a.team_id) 
  INNER JOIN projects p ON t.project_id=p.id
WHERE a.completed='true'
ORDER BY a.last_updated_at DESC LIMIT 5;

This little guide is just a greatly padded out version of instructions I got from Misha but since we have quite a few Ubuntu users and quite a few Java programmers in MiNDS> this should come in quite useful.

Basically this is the Debian way of installing the Sun JSDK so that it can be managed with dpkg and hence easily upgraded or removed at a later date.

Firstly, since Ubuntu IS a distribution of Debian really I will just refer to Debian in these instructions but the instructions also apply to Ubuntu and in fact it was on Ubuntu that I tested this. Also, these instructions assume that you are logged in as a user who has access to root via sudo.

The way this will work is that we will use a Debian package called java-package to turn the binary Linux installer we get from Sun (or IBM and others too) into a proper Debian package (.deb) and then we will use Debian’s package manager (dpkg) to install that Debian package.

The first step in the process is to install the java-package program that will allow us to create the .deb file. To do this simply type:

sudo apt-get install java-package

If you are asked for a password it is for sudo and you should enter your own login password.

The next step is to go to java.sun.com and download the Linux binary installer for the JSDK that you want to install. DO NOT DOWNLOAD THE LINUX RPM FILE!

The next step is to use java-package to turn this binary file into a Debian package, to do this move into the folder where you downloaded the binary file from java.sun.com.

NOTE, if you are doing this in the college on your machine for your 4th year project you will have to copy the binary file to /tmp and work from there because local root does not have access to your NFS mounted home directory.

For this step you will need fakeroot, if you don’t have it installed install it with apt-get like so:

sudo apt-get install fakeroot

Once you have fakeroot installed and you are in the right directory start the packaging with the command (replacing file_from_sun.bin with the actual name of the file you got from Sun):

fakeroot make-jpkg file_from_sun.bin

This will now appear to run the Sun installer but rather than installing it into your system it is extracting it to a temporary fake root file system and then creating the .deb file from the files in that fake file system. During this stage you will be asked to agree to the Java license agreement.

When the above command completes (will take a few minutes) a .deb file will have been created in your current folder. This is the file that we will now install with dpkg as follows (replacing name_of_deb_file.deb with the actual name of the .deb file created):

sudo dpkg -i name_of_deb_file.deb

And hey presto you are finished, when ever you want to get rid of that JDK all you have to do is (replacing name_of_deb_file_without_The_extension with the name of the generated .deb file but with the .deb extension left out, e.g. sun-j2sdk1.5):

dpkg --purge name_of_deb_file_without_The_extension

You can then install a new JSDK in the same was as described above or just leave your system Java free (heaven knows why you’d do something mad like that!)

So, you have a mac server running OS X and your boss tells you it needs to act as a mail server too. The HARD way to do things is to compile your own postfix and then manually configure it. If you are a Unix whiz then this will of course be the kind of stuff you do in your sleep but if you’re just a pleb like the rest of us then you will be interested in this neat bit of software.

Using Post Fix Enabler it took me a whopping 30 seconds to get my machine running properly as a mail server (note things were made quite a bit quicker by the fact that I had to use another server as a smarthost). Yes, it costs just under $10 but it is money well spent!

I had been warned that Bugzilla was a pain to install but when I read the instructions on their webpage I thought it all looked pretty simple, turns out it WAS a pain to install!

The trouble was caused by two things:

1. CPAN modules refusing to build on OS X
2. Bugzilla making ridiculous assumptions that just don’t stand up to reality, namely:
1. You will always want to use /usr/bin/perl
2. sendmail will always be in /usr/lib/sendmail

For details on how I resolved these issues read on.

Firstly, getting Perl to behave itself. The simplest solution to this problem is not to use Perl that comes with OS X but to use DarwinPorts or Fink to get Perl in order. I used DarwinPorts because I have had bad experiences with Fink and really like DarwinPorts. Anyway, it worked like a charm, all the modules I needed were available via DarwinPorts and installed with no issues at all. One thing to note is that this does not patch up the Perl in /usr/bin but rather installs a whole new Perl in /opt/local/bin. One slight annoyance was that to get DBI::MySQL I also had to install a copy of MySQL from DarwinPorts. This is fine because you don’t actually have to USE it, just have it there. As it happens the guys at MySQL have an excellent binary distribution of the MySQL server these days so there is no need to get it from DarwinPorts. I also already had other databases installed and running on my MySQL install so I was in no humor to have a second MySQL server running just for Bugzilla! The one complication here is that the default location for the MySQL socket in the DarwinPorts Perl is the location the DarwinPorts MySQL server uses and not the one the default MySQL server uses. Since I am not using this MySQL I had to tell Bugzilla not to use the default socket but the one I was actually using. You do this by editing localconfig. In my case I had to set the following:

$db_sock = '/private/tmp/mysql.sock';

Now, you can probably imagine how using DarwinPorts’ Perl caused the first of the assumptions made by the Bugzilla installer to break down. The Perl that comes with OS X is at /usr/bin/perl and is used by loads of stuff on the system (so I can’t replace it with a symlink to the right Perl), the Perl from DarwinPorts is at /opt/local/bin/perl. Although I explicitly ran the installer for Bugzilla with this Perl in the hope that it would be smart and realise that it should use that Perl for everything, it still set all the shebang lines to #!/usr/bin/perl and hence although Bugzilla passed the installer’s tests with flying colours, it crashed in a heap when you tried to use it because it went running off to the wrong Perl!

I figured that if the shebang lines were not generated by setting them to the Perl running the installer then there MUST be a configuration option to allow you to specify what Perl should be used. I tried looking really hard but with no joy. I looked on the online documentation, no joy, I tried their mailing list, not even a reply so I took the bull by the horns and wrote my own Perl script to change all the shebang lines for me:

#!/opt/local/bin/perl

use strict;

print "\n\n";

# get the files in the directory
opendir(THISDIR, ".");
my @files = readdir(THISDIR);
closedir(THISDIR);

#loop through the files
foreach my $file (@files){
  # skip files that are not cgi files
  next unless $file =~ m/\.cgi$/;

  print "Processing file: $file\n";

  # get the contents
  open(CGIFILE, "$file");
  my @contents = <CGIFILE>;
  close(CGIFILE);

  # write it back out but with the correct shebang line
  open(CGIFILE, ">$file");
  if($contents[0] =~ m/^\#\!/){
    print CGIFILE "#!/opt/local/bin/perl\n";
  }else{
   print CGIFILE $contents[0];
  }
  for(my $i=1;$i < scalar(@contents); $i++){
    print CGIFILE $contents[$i];
  }
  close(CGIFILE);
}

print "\n\n";

This got Bugzilla up and running and talking ot the DB but desepite the fact that I had sendmail up and running on the server Bugzilla now had a hissy-fit each time you tried to add a bug or do anything that caused it to try to send an email. This is where the second retarded assumption made by the Bugzilla peeps was the culprit. firstly, their error reporting sucks donkey dick and was of no use at all so into the code I dived. After some poking around inside the source tree I figured the problem must lie within Bugzilla/BugMail.pm and sure enough in the last function of that file (line 868 of 876) I found this:

open(SENDMAIL, "|/usr/lib/sendmail $sendmailparam -t -i") 

Yup, they had hard-coded in the location of sendmail! Again, there is no way to set the location of sendmail in any config file I could find so I had to manually edit this line to look like this:

open(SENDMAIL, "|/usr/sbin/sendmail $sendmailparam -t -i")

Once that was done all was fine and Bugzilla is now working but I really shouldn’t have had to jump through so many hoops to get it working!

I won’t lie and say that I’m surprised Arnie vetoed the first ever gay marriage bill to make it to a US governor’s desk but I am still very disappointed. Arnie has chosen to over-rule the democratically elected representatives of California because he is afraid of the extreme right.

Interesting how people who claim to be strong proponents of democracy show their true colours when a decision goes against them. What is also interesting is the nice little U-turn the republicans have just done. When Mass. was forced to allow gay marriage by a court ruling Bush said it should not be up to courts to decide such important issues but up to the elected representatives of the people, now that the elected representatives of the people have tried to legislate for gay marriage the new republican line is that it should be a matter for the courts. Pity Americans seem to have too short of an attention span to see what their ‘government’ is at.

All in all yet antoher sad day for America, good-bye democracy, good-bye tolerance, good-bye equality.

I read Dave’s post about the historic act of decommissioning by the IRA this week so this stuff was on my mind and when I saw that Hearts and Minds was on this evening on BBC I felt I just had to watch it to get a Northern Irish perspective on all this. What I was made me very sad indeed, Unionists are not being led by competent, driven leaders with a vision of a bright future for the north, the are being followed down a dark alley to despair by their so called leaders who are too busy bickering amongst themselves to notice the momentous things going on around them.

This week the IRA ‘put beyond use’ a ‘massive’ amount of weapons and was witnessed to do so by a retired general of internationally recognized integrity and two priests of exceptionally high standing within Northern Ireland who are near universally accepted as men of extreme integrity. Further more, we have been told that the amount of weapons disposed of was in line with both British and Irish intelligence estimates of how much weaponry the IRA had. I mean this was a serious bit of weapons dumping, it even included anti-aircraft missiles for goodness sake! Just think of how much less weapons there are on this island today than there were this time last week and ask your self, can that be a bad thing?

The one thing that was obvious from watching the Unionist politicians today is that they are not man enough to stand up and say that this is a positive step for the people of Northern Ireland. Instead Paisley and his guriers are slinging mud at General John de Chastelain and at the two priests who witnessed the decommissioning. How very big of them! These people are telling the Unionists what they have claimed to be waiting on for years yet they don’t want to hear it anymore. Their last big excuse for not moving forward is gone. They are frantically scrambling to make that not be the case and to come up with new excuses but all it is doing is showing them up as being too scared of moving forward to take so much as one positive step.

The IRA have swallowed their pride and handed in their guns, maybe it’s about time big Ian swallowed his and said YES for once in his life!

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