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Hacking a webcam for long exposure astrophotography

December 30, 2011 No comments

I finally got around to hacking a Philips SPC 900 to enable it to take long exposure images suitable for astrophotography. The modifications are fairly well known. The approach I took is a mixture of the http://www.boltonastro.org.uk/Members%5FArea/Projects/spc880conversion.pdf and http://www.yesyes.info/index.php/diy/philips-spc900-webcam-lx-and-ampoff-mod/ .

The circuit between both approaches is roughly the same, I followed the circuit in the former. The modification allows the camera to be switched to a long exposure mode via a switch. The switch can be triggered over a serial port, so I added a USB to serial adaptor and a USB hub (both from ebay) to the unit to allow control from a computer and have just one cable coming from the unit.

As soon as you have some new astronomy kit to try out it inevitably becomes overcast, so no test images just yet however I’ve included some images of the construction.

 

 

Astronomy, Photography , , ,

Old computer magazines free to a good home

December 29, 2011 No comments

I’m clearing out the attic and have some old computer magazines that some of you might be interested in. Free to a good home if you can collect from me, otherwise they go to recycling.

The first batch contains titles like Personal Computer News and Your Computer from around 1981-1983. The second batch are mainly Amiga Shopper (and the odd CU Amiga and Amiga Format) from around 1994.

Drop me an email if you are interested in them.

 

computing , , ,

Setting a static IP address in Solaris 11

December 8, 2011 No comments

I installed a Solaris 11 system yesterday but needed to give it a static IP rather than the dhcp that it picked up by default. Since netoworking has changed in S11 here’s a guide of what to do.

Firstly you need to disable nwam.

svcadm disable svc:/network/physical:nwam
svcadm enable svc:/network/physical:default

Check that there are no nwamd process left running.

To set your address you need to see what interface you have availble. On a typical install that already has a working DHCP interface you can see what is already in use by:

# ipadm show-addr
ADDROBJ           TYPE     STATE        ADDR
lo0/v4            static   ok           127.0.0.1/8
net0/_b           dhcp     ok           12.34.56.78/21
#

So to set your static IP you would just do:

# ipadm create-addr -T static -a 12.34.56.78/21 net0/v4

However you may notice that this fails:

# ipadm create-addr -T static -a 12.34.56.78/21 net0/v4
ipadm: cannot create address: Persistent operation on temporary object

The issue here is that net0 has been created as a temporary object by the system. Which you can verify by noticing the missing entries on the PERSISTENT column of the output of show-if:

# ipadm show-if -o all
IFNAME     CLASS    STATE    ACTIVE CURRENT       PERSISTENT OVER
lo0        loopback ok       yes    -m46-v------  46--       --
net0       ip       down     no     bm46--------  ----       --

In this case delete and re-create the interface, then set your address:

 # ipadm delete-ip net0
# ipadm create-ip net0
# ipadm create-addr -T static -a 12.34.56.78/21 net0/v4

The last thing you need to do is set your default route which is is done by:

# route -p add default 12.34.56.1

Next you may need to set up your system as a DNS client. This is now done by SMF and not by editing files by hand. To set DNS servers:

root@sionnach:/home/albwhite# svccfg -s dns/client
svc:/network/dns/client> listprop config
config                      application
config/value_authorization astring     solaris.smf.value.name-service.dns.client
config/domain              astring     ie.oracle.com
svc:/network/dns/client> setprop config/nameserver = (12.34.56.17 192.168.82.46)
svc:/network/dns/client> listprop config
config                      application
config/value_authorization astring     solaris.smf.value.name-service.dns.client
config/domain              astring     ie.oracle.com
config/nameserver          net_address 12.34.56.17 192.168.82.46
svc:/network/dns/client> exit
root@sionnach:/home/albwhite# svcadm refresh dns/client
root@sionnach:/home/albwhite# svcadm restart dns/client

Similarly to set the resolv.conf entries you would do:

svccfg -s name-service/switch
> setprop config/host = "files dns"

Official documentation: http://docs.oracle.com/cd/E23824_01/html/821-1458/gdyrf.html

computing, Solaris ,

First Solar Haplha image in years

November 27, 2011 No comments

I got the PST out again recently. As we approach Solar Maximum it would be a shame not to have a look every now and then.

This was taken by attaching my Canon 400D to the scope. 1s exposure. Green channel extracted, a few tweaks, then coloured orange. The diagonal lines are from Nebulosity, which is image aquisition software that I’m trying out. The free to try version puts diagonal lines in the images.

It needs better focusing, and the red channel with the flares needs to be merged in, but I’m happy with it given its the first image of the Sun I’ve tried with this setup since 2006.

Astronomy none

Why I won’t be buing an indesit in future. Appliances should be servicable.

November 26, 2011 No comments

Recently a small piece of the door seal on our washer dryer came out in the wash. It was small but enough to mean water on the kitchen floor so it needed replacing.

The solution seemed simple. Order a replacement seal. Fitting it however was a problem.

Indesit decided to make this model un-servicable. It’s not possible to get enough access to the drum to fit the seal without, well removing the drum. So what should be a 30 minute job took 4 hours. The case is welded together, and apparently the drum was lowered in in the factory.

Now I’m sure this makes sense for indesits sales and operations management. I assume it simplifies manufacturing, and makes it cheaper, by easily allowing the factory to assemble different machines on the same line by just changing the pre-made cases and drums. What it also does it creates a unit that for most people is un-serviceable, leading most likely to the machine being trashed and a new one being bought. Not great for the environment, not great for the consumer, but good for indesit.

So when this machine finally does pack it in an need replacing. I’ll be replacing it one that I can do basic maintenance on. Probably not an indesit if our current machine is typical of them.

General none

Philips SPC900 Mods

November 25, 2011 No comments

A collection of some of the main pages describing the long exposure and amp mods for the SPC900 webcam.

Now just to read through them all, order the bits I need, and do the mod. Simples.

 

Astronomy none

Skymax 102mm Maksutov Telescope for Sale

November 14, 2011 No comments

Hi,

Final bit of telescope equipment for sale for the moment.

This time a compact 102mm Maksutov. I bought this to take abroad for the transit of Venus in 2004 and the solar eclipse in 2006. It’s the biggest telescope that I can take as carry-on luggage on a plane and has a decent enough aperture to still be useful.

  • Diameter of Primary Mirror: 102mm
  • Telescope Focal Length: 1300mm (f/12.74)

It came with a tripod adapter but this wasn’t really up to the task and is no longer on it, it does come with 2 O rings and a plate for mounting to an telescope mount (not included!). I’ve been using it on my LXD55 mount (also for sale by the way :)   ) for years.

It also comes with a solid glass 102mm white light solar filter, as well as the carry bag, red dot finder, diagonal, and 25mm eyepiece.

Some solar eclipse photos taken through this scope: http://www.flickr.com/photos/albertw/sets/72057594096922769/with/122029134/

€200. Email me at albert.white@gmail.com if interested. I’m based in South Country Dublin.

Astronomy none

LXD 55 Mount for Sale

November 13, 2011 No comments

I’m selling my trusty LXD55 mount as well as the Telescope (see previous post).

This mount is designed to support the weight of the SN10″ telescope (~15kg). The mount itself with counterweights weighs about 25kg. (See the manual for details on the mount LXD55_Instruction_Manual_revD-1)

The mount comes with the Meade Autostar goto system, and has a built in polar scope.

I’ve replaced some of the screws and bolts in the past with stronger ones than came with it.

Not in photo but comes with the 3 counterweights & shaft, 12v car adapter, D cell battery pack.

€500 – drop an email to albert.white@gmail.com if you are interested. Based in South County Dublin.

Astronomy none

Telecope for Sale!

November 7, 2011 No comments

I’m selling my Meade LXD55 OTA in a Dob mount plus some accessories. The price is €500.

For that you get:

  • The LXD55 10″SN Telescope (OTA Only in a homemade Dobsonian mount, but includes the O rings)
  • 2 eyepieces, 26mm & 12.4mm Meade Super Plossils.
  • JMI Motofocus. (cost $169)
  • Red dot finder.
  • EZ Collimator (useful for a quick collimation check)
  • Original OTA box if you want it

I’m selling it with the Dobsonian mount I made for it. This has been my main scope for the last 10 years or so.

The scope is a Schmidt Newtonian design, 1016mm focal length, 254mm diameter (f/4), UHTC coatings.

The mount is constructed from marine grade plywood. I may have overdone the mount and you could probably safely cut some of the weight out of it. The design uses the original ‘O’ rings to keep the scope in place (see image below). This also means that you can still easily use the scope on an strong equatorial mount if you choose.

There is a very minor flaw in the mirror where it was damaged the one time it was ever cleaned. As you can see from the photo (half way down, near the left hand side of the mirror photo) it’s tiny and causes no image quality issues.

The scope does come with a finderscope. However one of the crosshairs is broken! I replaced it with the red dot finder which I find much more useful. It is a wide field scope, so once you have the dot on what you want to look at the object will be easily visible in the 26mm eyepiece.

I bought the scope for IR£1400 back in 2000. It did come with a computerised mount, however the scope was really too large for the mount, a slight breeze causes very frustrating vibrations. So I instead made the Dob mount, and while it does loose the computerised tracking ability it is a much better viewing experience.

I’m selling for €500. It’s located in South county Dublin. You will need a car to collect it. If you are interested you can contact me by email at albert.white@gmail.com

Reason for selling? Well I now have a Celestron 9.25 and since I bought this 11 years ago I’ve got married and live in a small terraced house and my mother would rather I didn’t store 4 telescopes in her house so it’s time to start getting rid of them!

Here are some pics of the scope and a webcam capture of the moon and Jupiter through the scope recently.


Astronomy none

Python : generating unittests on the fly

October 23, 2011 No comments

When creating python unit tests you need to create a method in a unittest class. The problem however is when you don’t know until the code is running what these tests will be. In my particular case I need to run a series of tests against a number of Solaris packages. But I won’t know what the packages will be in advance.

Thankfully python allows to to add a method to a class on the fly:

>>> class test:
...     pass
...
>>> def foo(self):
...     print "hello, world"
...
>>> dir(test)
['__doc__', '__module__']
>>> test.foo=foo
>>> dir(test)
['__doc__', '__module__', 'foo']
>>> bar=test()
>>> bar.foo()
hello, world
>>>

Here we initially create an empty class ‘test’ and a function ‘foo’. Then add the function ‘foo’ to the class ‘test’, so that when we create a ‘test’ object, we can call the ‘foo’ method in it.

We use the same trick to add a unittest test to a unittest class:


>>> import unittest
>>> class mytest(unittest.TestCase):
...     pass
...
>>> def test_testcase(self):
...     self.assertEqual("hello","hello")
...
>>> suite = unittest.TestLoader().loadTestsFromTestCase(mytest)
>>> unittest.TextTestRunner(verbosity=2).run(suite)

----------------------------------------------------------------------
Ran 0 tests in 0.015s

OK
<unittest.runner.TextTestResult run=0 errors=0 failures=0>
>>> mytest.test_testcase=test_testcase
>>> unittest.TextTestRunner(verbosity=2).run(suite)

----------------------------------------------------------------------
Ran 0 tests in 0.000s

OK
<unittest.runner.TextTestResult run=0 errors=0 failures=0>
>>> suite = unittest.TestLoader().loadTestsFromTestCase(mytest)
>>> unittest.TextTestRunner(verbosity=2).run(suite)
test_testcase (__main__.mytest) ... ok

----------------------------------------------------------------------
Ran 1 test in 0.000s

OK
<unittest.runner.TextTestResult run=1 errors=0 failures=0>
>>>
computing, Solaris ,
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