KPO

KPO Scientific Work
By far the most work done at KPO is development of the control systems rather than actually using the telescope! However occasionally it does get used for its intended purpose and provides useful data for scientific analysys.

Photometry Of Binary Stars

When we had the C14  in the observatory we recorded a fair amount of data with our Optec photometer in semi-automated mode. This meant choosing a target to observe ourselves, giving the software a bunch of observing parameters and letting it go. Data acquired at KPO during this period has appeared in various scientific papers. We aim to do this again at some stage possibly using CCD technology instead.

Minor Planet Occultations

Using our recently commissioned video camera we have been able to record a few of these events where a minor planet (aka asteroid) passes in front of a star causing the star to apparently dim to the brightness of the minor planet for a few seconds. When several observers in different locations record the timing of these events the position, size and even shape of the object can be determined.

In the past this has been quite difficult to do accurately because of the human factor in timing or the sensitivity of the instrument when taking samples fast enough to be useful. 10 samples/second is the bare minimum that is useful and our photometer is simply not sensitive enough to see down to 10th magnitude unless it is integrating over 10 seconds.
Our very first successful recording of an event by video was actually quite technically challenging because the expected magnitude drop was only 0.2 magnitude - pretty much impossible to detect visually.

On the left is an example screenshot from the video. Apart from the on-screen display, every other frame looks identical. The dot in the near-centre of the frame is the magnitude 9.3 asteroid Fortuna.

Information about how we got the on-screen display in the instruments section.
However when the video is processed using a photometry technique (comparing the amount of brightness in a small circle where the star is with the amount of brightness where the star isn't) the brightness of the star dims very slightly yet unmistakably.

The graph has been vertically exaggerated to highlight the effect of a drop in the mean from 3500 to 3100 for nearly 30 seconds.

Grazing Lunar Occultations

These happen when the moon passes in front of star in such a way that the star appears to skim along the edge of the moon, disappearing behind the lunear mountains and re-appearing again. This supposedly helps in mapping lunar mountains. This is another good candidate for video astronomy.

The image on the right is somewhat uninspiring vidcap of the lunar limb just before a star disappears (the star is just visible a a dot about 1cm from the moon). Click on the image for a short mpg of the 2-second disappearance behind a mountain. There was wispy cloud during this event just to make things worse. The star went behind a second "wider" mountain a bit later in this particular event.

Given that the moon is extremely bright and the star is magnitude 6, it is quite tricky to capture an event like this because of the limited dynamic range of a video camera. This is the reason why the moon has been banished to the corner of the frame as much as possible so the camera doesn't automatically reduce the exposure and render the star invisible.

Video grazing occultation.

Lunar Occultations

There is probably little value in in lunar occultations now days since it only really helps confirm the predicted position of the moon - something which is well known from other methods now. However, occasionally, the moon goes in front of "interesting" things which is kind of interesting to watch if nothing else.

Jupiter re-appears from behind the moon.
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