All Sky Camera Project
Construction Notes

Page Created: 2003 August 27
Home Image Gallery Design Notes Construction Notes Link Notes SCO
Our all-sky camera went live on 2005 March 17th, a St. Patricks Day Thursday. It is intended to catch large, bright meteors (aka bolides) in the hopes of determining if they ground and if so where, in the further hopes of gathering samples.

Construction Notes

  • 2006 January 29 - the 5 watt heating coil somehow turned into a 10-20 watt heater and killed off the 100 amphour deep cycle battery we had running it. There was a 110vac-12vdc 12 watt charger and a 2.2watt solar panel trying to keep it charged and they were not enough. So it was disconnected a few days ago and we are attempting to rehabilitate the battery. Still no movement on better motion sensing software, or on more light sensitive cameras or on wider angle lenses.
  • 2005 December 05 - installed 5watt heater system inside dome. Last years experience with 1 watt and 2 watt resistor systems showed that 2 watts was not enough. This time around we used nichrome wire wrapped around the inside dome perimeter. Approx 50" of wire gave us 29 ohms of resistance. V=IR at 12vdc gives us I=V/R=12/29=0.41 amps Watts=VA=12vdc*0.41A = 4.9 watts. This is run off the observatory battery which is on a 12watt charger.
  • 2005 Aug 29 - tried out RainX on the dome to make water droplets run off more.
  • 2005 August 12 - See All construction images. Installed newer P4-1700 MHz workstation with ms winnt2000 and linx fedora core 3 dual booting. We use windows now to access the two USB webcams and will use linux once we can get those drivers up and running. The 12" plastic domes arrived and we rebuilt the allsky camera system using a camera on the inside of the dome and mounted it atop the 8' 4"x4" post. There was sticky foam weatherstripping put down under the dome flange, to get a better moisture seal and keep rain out. A silicon bead was put down inside the dome itself in case moisture did get in. A USB webcam was placed inside and mounted on a wooden stand to point straight up, with the top of the webcam pointed north. The field of view of the webcam is not large (not yet measured but probably around 30-40 degrees). This webcam is being used to evaluate software and test the rest of the system. The webcam cable goes through a hole and into a junction box mounted under the platform. The junction box also contains cables for 12vdc for use in heaters to be used to heat the dome to prevent dew, condensation and melt snow. It also contains a composite video cable in case we use a different camea in the future. Immediately we noticed condensation inside the dome with the sun shining on it early in the morning with a lot of humidity. Down came the dome and two 2" diameter holes were drilled in the base of the platform under the dome and covered with nylon insect netting set in silicon. This so far has made the condensation go away. The heaters are also not yet in place. Earlier this spring we determined that 3 watts of heating was not quite enough for the inverted camera and mirror system. We will see how much it takes with the dome system.
  • 2005 July 19 - Removed the workstation from the observatory. This will give us the chance to replace the 3gb drive with a 20 gb drive and move from Windows NT2000 and the homewatcher software to Linux Fedora Core 4 and the motion software. The new 12" plastic domes have arrived as well and we will start construction on the new all sky camera this weekend. The wireless networking was not so reliable so we will be looking at laying a new cat5 cable from the house to the observatory to another high speed switch to allow the laptop and or another workstation to go out there.
  • 2005 July 09 - Shut down the observatory computer as temperatures inside were reaching 40deg C and above.
  • 2005 May 08 - took down the mirror tripod system and camera to replace the lens with a 4mm lens on loan. It would not focus and the low light PC164C camera started acting up, so the entire cam was offline for the last few weeks. We started testing today a low end webcab (labtech $20 usb1.1) with a 2m extension cable running under homewatcher, winnt2000. The webcam does a much better job at exposure compensation but not so good at low light condition, but we will see how it works tonight.
  • 2005 March 26 - after a night of -10 deg C we had the mirror frost over again. 3 hours of sun later, the frost was still on the unlit side. Need more heating power as 3 watts is not enough
  • 2005 March 25 - several days of data gathering and we have come to the point of deciding that the design is fundamentally flawed. We are not getting images of any stars at all, even though the camera without the mirror can pick up all of the stars in the Big Dipper, and most in Orion. With the mirror all we see is the moon, much bigger than it should be. Probably this is due to a less reflective-than-we-thought plastic based mirror.
  • 2005 March 22 - cleaned off the mirror, still not a great optical reflection, it being a plastic mirror we think. 1.44 watts of heating is not nearly enough as the entire surface frosted over last night. Will hook up 2nd resistance heater tonight. Re-Oriented the camera so that up is north. In addition, we'll probably rewire the section on the platform itself. Currently the video and power cables connect to the camera inside the PVC tube. Whenever you try to do any maintenance on the platform, you need to undo the top cover, unplug the cables, then pull the platform down. The top of the camera system is almost 12-13 feet above the ground. What we'll probably do it add a one meter video cable and 1 meter power cable to run down to a junction box under the platform. Then you just need to unplug the camera power, camera video and mirror heater power connections at about 7 feet above the ground, and remove the platform.
  • 2005 March 20 - We don't seem to be getting the performance out of this system that we were expecting. Images of the moon appear overexposed and more circular than a 1/4 moon should be. In addition, no stars are appearing on the every-30-minutes images and neither did Jupiter (mag -2.4). There is some scum on the mirror leftover from the snow/frost and we'll try cleaning it off Monday night.
  • 2005 March 18 - platform came down as some snow and frost covered the unheated mirror. Remove 1.5" from each tripod leg to allow the camera to close in on the mirror more. Realigned the camera inside the PVC, moved the two heaters inside the mirror to allow more power cable length. Remounted on the post and was able to connect one heater power cable (1.5watts). Rechecked focus and it seems to be at infinity.
  • 2005 March 17 - built the tripod support structure out of 1"x2" pine, created a wooden collar out of a 2"x4" with a 2" hole cut in it. We had previously measured the camera height above platform surface by plugging the camera in live and moving it around while watching the monitor and when the correct height was found, giving us full mirror coverage, we measured the camera lens a height above platform number and got about 27". This will be particular to your specific camera and lenses.

    We mounted the camera inside a 2" PVC pipe 7" long. A standard 1/4"x20 bolthole was drilled through the PVC in the approximate area of the camera 1/4"x20 mounting hole was. We moved it up the pipe a little more to give the lens some protection from the elements, ie so that the lens surface was up a little ways into the PVC. A Nut on the inside to act as a lock and a nut on the outside to lock it in place.

    Some pink styrofoam was inserted into the gap around the lens and between the pipe to stop bugs and wind blown precip up into the pipe.

    We slipped the PVC into the wooden collar. The wooden collar as mentioned above, as two give us something adjustable for the pipe to move up and down, in case our measurements were off, and to give the legs something to attach to as well.

    Taped the cables down for now along one tripod leg and hooked into observatory system. Manhandled platform up to top of 4"x4" post and discovered that it is too high to safely work on. Went Live! Got some images (out of focus) of the moon. Camera not aligned and too high above mirror. Heating power cables too short to reach junction box.
    First Live Image 20050316 19:30:52

  • 2005 March 13 - Put in deck block and a 4"x4" pressure treated post and connected it to the observatory roll off roof infrastructure for stability. Ran a 25' RG-59 shielded composite video cable out from the computer to the top of the post, along with an 18 gauge 12vdc power cable from the observatory battery (a 70+ amp-hour deep cycle rechargable with a 110VAC trickle charger attached) to a power junction box mounted at the top of the post. The camera platform is coming along as well. We have the mirror mounted on a sturdy 1" think plywood with cork top, wired in two heaters, each consisting of a 100 ohm resistor which will generate 1.44 watts of heat to help keep the mirror from fogging/dewing up. Each of these heaters runs into a male RCA plug through the platform base and connect up to the 12vdc power inside the junction box.
  • 2004 February 13 - moved computer system in observatory, network connection and camera have been working flawlessly for some weeks now. The next step is to pick a preliminary location near the observatory and construct the mirror/camera platform. Will need 12vdc power feed for camera and heaters, and a shielded video composite cable.
  • 2005 January 08 - working 802.11g wireless networking connection up and running, tried many software packages, temporarily settled on homewatcher lite v2. One problem that has come up is when the camera aperture is wide open, bright daylight totally washes out the image.
  • 2005 January 02 - working Supercircuits PC64c low light B&W video camera up and running inside the observatory for now.. still need to get data transfer network connection up and running, motion detection software and an outside mount for the mirror and camera.
  • 2004 December 28 - working P3-500 workstation with ATI All in Wonder Rage Pro graphics card with an ATI breakout cable, out in observatory with an insulating bubblewrap cover over the workstation (like hot water heater insulators). Motherboard temp=12 degC, CPU temp = 40 deg C, with observatory temp at -5 deg C.
    For question or comments about this page /allskycamera/construct.htm contact us at kim or kevin (at) starlightcascade (dot) ca