Post by rjcobain on Dec 22, 2005 12:35:14 GMT
Hi all,
This is my first post to this message board. I have been lurking for a few days just to get a feel for things. I understand that some of you are curious about the meteor logging website that I have so I thought I would post a message explaining how it works. Forgive me for copying and pasting this info from another post I made on the ukastroimaging website but I am in work so I can't spend to long on this!
The equipment used can be put together relatively cheaply Basically you need a high sensitive security camera such as the watec 902h (dm2s also) or 120n. You don't need one of these mintrons that have lots of video frame integration built in as this is pointless for meteors. Then you need to get a very fast wide angle lens, such as the computar 6mm f0.8(!) or the 2.5mm f1 (I think). With this setup you can reach mag 4-5 in a 1/50 of a second, which is nice and comparable to an image intensifier. Image intensifiers are almost useless anyway because they don't last very long, cost the earth, and have low resolution.
Then you need a waterproof security camera housing so that you can monitor the sky constantly. This is part of the trick because meteors are quite rare and it is essential to monitor every night. The next crucial component is the software and computer capture hardware. The software I use is called UFOCapture and it is Japanese although the interface in English. This software will only capture video if something is bright and moving. Without the software you would have to capture the entire night of video and trawl through it all manually also you would need a very large harddisk.
sonotaco.com/
free version sonotaco.com/soft/index.html#ufcfr
If you look at the website you will see some amazing video of meteors brighter than this one and also rare objects such as sprites and blue jets. I have only ever captured one sprite with this system because to capture sprites you need to orient the camera towards the horizon, whereas my camera is pointing up in order to triangulate with Armagh planetarium who have a similar system. At last count we had over 60 simultaneous meteor observations. If anyone needs any help to get\use the software and hardware don't hesitate to email\PM me.
Anyway, once the meteors have been captured they are analyzed using another piece of software from the same author called UFOAnalyzer which, after being configured, will trace the meteor path backwards to see if it corresponds to any known radiant. Only radiants which are known to be active at that time of year will be considered. Different radiants have different allowed margins of error in the displacement from the centre of the radiant. When a meteor has been determined to have come from a particular radiant, an approximate calculation is made by the software which uses certain assumptions in order to give an approximate speed and height. Only if the meteor is thought to have come from a particular radiant will the calculations work. Even then they are very approximate. For instance the speed calculations for the Leonids were too high , 70+ km/s . According to Tolis Christou at Armagh observatory, objects within the solar system cannot exceed 72 km/s , although interstellar meteors are predicted to exist!
Also important to note is that the magnitude estimates are quite approximate due to the fact that the video signal only has 255 levels of brightness. Earlier data on the meteorlogni website was underestimating the brightness of meteors but now the estimates are better. Very bright meteors also tend to get overestimated.
After the meteors are analyzed, the data is output into a CSV file and copied to a backup folder. In order to get this data onto the website I wrote an application to do it automatically. All I do is right click on the folder for the evenings captures and the code will copy the CSV file to a SQL database, compresses the videos using VirtualDub and Windows VCM codec, and images using imagemagick and uploads the lot. Also the monthly log page is updated and a daily log page is created, and the top 10 brightest page is updated hopefully!! The meteor log pages are all actually XML files which are translated on the server into HTML.
Anyway I think this post is long enough! Here is a pic of the brightest Geminid that I captured this year. If you look closely at the video there are actually 2 Geminids! The peak was unfortunately clouded out here in Bangor so there were not as many meteors as expected.
This is my first post to this message board. I have been lurking for a few days just to get a feel for things. I understand that some of you are curious about the meteor logging website that I have so I thought I would post a message explaining how it works. Forgive me for copying and pasting this info from another post I made on the ukastroimaging website but I am in work so I can't spend to long on this!
The equipment used can be put together relatively cheaply Basically you need a high sensitive security camera such as the watec 902h (dm2s also) or 120n. You don't need one of these mintrons that have lots of video frame integration built in as this is pointless for meteors. Then you need to get a very fast wide angle lens, such as the computar 6mm f0.8(!) or the 2.5mm f1 (I think). With this setup you can reach mag 4-5 in a 1/50 of a second, which is nice and comparable to an image intensifier. Image intensifiers are almost useless anyway because they don't last very long, cost the earth, and have low resolution.
Then you need a waterproof security camera housing so that you can monitor the sky constantly. This is part of the trick because meteors are quite rare and it is essential to monitor every night. The next crucial component is the software and computer capture hardware. The software I use is called UFOCapture and it is Japanese although the interface in English. This software will only capture video if something is bright and moving. Without the software you would have to capture the entire night of video and trawl through it all manually also you would need a very large harddisk.
sonotaco.com/
free version sonotaco.com/soft/index.html#ufcfr
If you look at the website you will see some amazing video of meteors brighter than this one and also rare objects such as sprites and blue jets. I have only ever captured one sprite with this system because to capture sprites you need to orient the camera towards the horizon, whereas my camera is pointing up in order to triangulate with Armagh planetarium who have a similar system. At last count we had over 60 simultaneous meteor observations. If anyone needs any help to get\use the software and hardware don't hesitate to email\PM me.
Anyway, once the meteors have been captured they are analyzed using another piece of software from the same author called UFOAnalyzer which, after being configured, will trace the meteor path backwards to see if it corresponds to any known radiant. Only radiants which are known to be active at that time of year will be considered. Different radiants have different allowed margins of error in the displacement from the centre of the radiant. When a meteor has been determined to have come from a particular radiant, an approximate calculation is made by the software which uses certain assumptions in order to give an approximate speed and height. Only if the meteor is thought to have come from a particular radiant will the calculations work. Even then they are very approximate. For instance the speed calculations for the Leonids were too high , 70+ km/s . According to Tolis Christou at Armagh observatory, objects within the solar system cannot exceed 72 km/s , although interstellar meteors are predicted to exist!
Also important to note is that the magnitude estimates are quite approximate due to the fact that the video signal only has 255 levels of brightness. Earlier data on the meteorlogni website was underestimating the brightness of meteors but now the estimates are better. Very bright meteors also tend to get overestimated.
After the meteors are analyzed, the data is output into a CSV file and copied to a backup folder. In order to get this data onto the website I wrote an application to do it automatically. All I do is right click on the folder for the evenings captures and the code will copy the CSV file to a SQL database, compresses the videos using VirtualDub and Windows VCM codec, and images using imagemagick and uploads the lot. Also the monthly log page is updated and a daily log page is created, and the top 10 brightest page is updated hopefully!! The meteor log pages are all actually XML files which are translated on the server into HTML.
Anyway I think this post is long enough! Here is a pic of the brightest Geminid that I captured this year. If you look closely at the video there are actually 2 Geminids! The peak was unfortunately clouded out here in Bangor so there were not as many meteors as expected.
