[meteorite-list] 2011 MD Animation

From: John Hendry <pict_at_meteoritecentral.com>
Date: Tue, 28 Jun 2011 13:21:02 -0500
Message-ID: <CA2F84AF.E598%pict_at_pict.co.uk>

Thanks Richard I get it. I think my Nikon DSLR can be set to perform a
similar technique for noise reduction using a dark frame subtraction with
the dark frame getting an equal "exposure" time as the image to be
processed.

John

On 28/06/2011 12:43, "Richard Kowalski" <damoclid at yahoo.com> wrote:

>Hi John.
>
>What you are seeing are not "companions" but instead are imaging
>artifacts called "hot pixels". They are pixels that have a non linear
>response and are normal. Astronomical imagers usually use a technique
>called "Dark Frame Subtraction" to remove these hot pixels from the
>image. I imagine Yure had some reason why he didn't "apply the dark".
>
> Another technique to reduce hot pixels is to lower the temperature of
>the imaging chip that as the response of these pixels becomes more linear
>again as the chip gets colder. Many use a combination of both cooling and
>dark frames. Professional observatories cool our cameras so cold that we
>don't have these hot pixels and don't need to this step during image
>processing.
>
>Hope this helps.
>
>
>--
>Richard Kowalski
>Full Moon Photography
>IMCA #1081
>
>
>----- Original Message -----
>From: John Hendry <pict at pict.co.uk>
>To: Richard Kowalski <damoclid at yahoo.com>; meteorite list
><meteorite-list at meteoritecentral.com>
>Cc:
>Sent: Tuesday, June 28, 2011 8:04 AM
>Subject: Re: [meteorite-list] 2011 MD Animation
>
>I'm counting what appear to be 17 fainter companion objects in parallel
>trajectories. Is that what I'm looking at or is it some sort of video
>artefact? If they are companions can their size be determined
>approximately from the relative brightness or by some other means?
>Thanks,
>John
>
>
>On 28/06/2011 01:24, "Richard Kowalski" <damoclid at yahoo.com> wrote:
>
>>I got a few positional images of this object with our 1.5-m (60") on Mt.
>>Lemmon last night, but Jure Skvar? at the ?rni Vrh Observatory in
>>Slovenia obtained one of the nicer time lapse animations of the asteroids
>>motion against the background stars.
>>
>>
>>He writes on his Youtube page:
>>
>>"The images for this animation were taken using a 60-cm telescope from
>>the ?rni Vrh Observatory on the night of 26 July 2011. Each exposure
>>was of 15 seconds. The telescope was tracking on the asteroid, changing
>>the rate of tracking between exposures. The entire sequence lasted
>>about 4h40m, during which 635 exposures were made. At the time the
>>asteroid was less than 200000 km from Earth. At the closest approach
>>some 15 hours later the distance was about 20000 km."
>>
>>4 hours, 40 minutes of imaging the NEO until his dawn, compressed down to
>>43 seconds. Enjoy
>>
>>
>>http://www.youtube.com/watch?v=p-pv18xDWCY
>>
>>
>>--
>>Richard Kowalski
>>Full Moon Photography
>>IMCA #1081
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Received on Tue 28 Jun 2011 02:21:02 PM PDT