College of the Rockies (COTR) in Cranbrook BC

COTR Observation Station: Some Calibration and Technical Info:

The College of the Rockies Astronomy department has a Sentinel IV AllSky Meteor camera running under WSentinel video capture software ver 1.1.11. The College is located at Cranbrook BC, in the SouthEastern corner of BC. Our Camera coordinates are N49° 31′ 03.1″, W115° 44′ 37.1″, at an elevation of 940.0m (within 10cm).

The Sample Photo shows what our black and white rooftop camera sees, the lights of Cranbrook to the West, along the bottom of the photo. There are some red beacons flashing on the surrounding mountains, the one at 12 o’clock position marks roughly North (about 3 degrees True). The double-beacon at the 1:30 position marks a TV/Cell Tower at 309 degrees. The fisheye lens can view all around the horizon. The twin pine trees at the 7 o’clock position are in the College’s South parking lot. There’s a exhaust vent that shades the camera from some bright lights over to the East. Although the housing has been leveled to within 0.3 deg, the camera is tilted 5 degrees inside, and results in an elliptical rather than a circular horizon. The ratio of major to minor axes is 1.10.

We use a Starlight B/W CCD, a HiCam HB-710E [http://www.hicam.co.kr/main/710.htm] ultra-low light-level (0.0003 lumens) video camera (with 1/2” CCD sensor, 768×494 effective pixels), with the Rainbow L163VDC4P fisheye lens (1.6~3.4mm F1.4 – with mechanical auto-iris). Video is fed to an ATI All-in-Wonder video capture card on a Windows XP computer at 640×480 pixels, 29.97 frames/second. There’s about 18 hot pixels in the CCD sensor, so those are not all stars shown in the photo. Available is a photo of the inside of the lenscap revealing the hotpixels. This is normally used when you’re “stacking” the video frames and want to subtract out the hotpixels and background levels. Hot Pixels in the Sony CCD sensor PNG file.

Photo Reference Points: in the photo there is a flashing dot at the 12 o’clock position that marks 3 degrees true. In the photo, note the top of Woodteck Hill has a rotating beacon. This hilltop is located at N 49°34’18”; W115°44’22”; at elevation of 3,421′(1,043m). From the college, this would be 6.0 km away at a bearing of 2.9 degrees, altitude 1.0 degrees up from the horizon.

Photo was taken at 18 May 2011 at 23:30:52 Mountain Daylight Time. Starmap generated by Meade Autostar Suite Astronomers Ed ver 3.19 2005

The pair of tower beacons at the 5 o’clock position, their centre point bearing 309°, are located 5.25 km distant at an elevation of 4,000 feet. The television tower is marked at 100 feet tall. Thus a total of about 4,100 feet (1,250m) at an angle of 3.0 degrees up from the horizon. Found on an older topographical map, 82G/12 dated 1980, 1:50,000 Scale, at N49°32’47”, W115°48’00”. The newer topographical maps don’t show the towers. The photo was taken 18May2011 at 23:35:50 MDT, and superimposed on a Autostar Suite 3.19 starmap adjusted to show the horizon at that time and location. At that time, the star Elnath in Auriga is located at (alt +3.0 °, az 312.8 °) The beacons are the same altitude as Elnath, at +3.0 degrees. No correction has been made for atmospheric refraction.

Time is synchronized to a College Network time server (since the end of August) and stays within 0.1 second of world time. Previous to that, it was slow by up to a minute.

Our AllSky camera was supplied by Richard Spalding of Sandia National Labs, in New Mexica, USA. Dick Spalding’s all-sky-all-the-time camera development is described at http://www.sandia.gov/LabNews/LN11-29-02/labnews11-29-02.pdf.

For more info, contact Rick Nowell at nowell@cotr.bc.ca