Re: The Feasibility and Application of Observing Small LEO Satellites with Amateur Telescopes

From: Carlos Bella via Seesat-l <seesat-l_at_satobs.org>
Date: Fri, 6 Feb 2015 11:08:37 -0200
The biggest problem will not be the magnitude limit but the angular resolution,
an allsky with a 180ยบ FOV has a resolution close to a full Moon diameter per
pixel. This makes the most satellites undetectable below a sufficient
magnitude to saturate a reasonable number of pixels in order to register their
trail (like ISS, Tiangong, Iridium and another flares superior to a
considerable negative magnitudes).

One solution is to create a similar CAMs system with DSLR using cameras with
smaller FOV (~20 to 50 degrees) positioned side by side in order to obtain
images of contiguous areas of the sky, which results in a high resolution
allsky.

But in this case would be more feasible to invest in a high sensibility
(low lux) CCTV cameras that have a much lower cost than the DSLR cameras.

To compare, on average, with my WATEC 902H2 Ultimate camera equiped with a
0.98 F/Stop lens and FOV of 40 degrees I got around 8 records of satellites
tracks by night (I can capture more but actually the capture software was
not configured for this) and several other sats/space debris flares and
flashes depending of the camera pointing position and atmospheric seeing. The
average magnitude limit of my camera is currently 5.5

Some observatories use DSLR cameras to Allsky, but to observing the weather,
auroras, eclipses and others wide angle events or effects:

- http://westactonastro.com/dslr-allsky.html
- http://www.beskeen.com/projects/allskycam/allskycam.shtml
- http://kho.unis.no/DSLR_Cameras.htm

Regards
Carlos


2015-02-05 23:23 GMT-02:00 George Herbert via Seesat-l <seesat-l_at_satobs.org>
:

> You may be able to do a liquid crystal shutter for exposure times >> the
> action time, which is ms to tens of ms.
>
> For normal photography no, for astrophotography including this?  Should be
> yes.
>
> George William Herbert
> Sent from my iPhone
>
> On Feb 5, 2015, at 3:08 PM, Sheldon Cooper via Seesat-l <
> seesat-l_at_satobs.org> wrote:
>
> >> Sounds like something similar to what is used at observatories for all
> >> sky viewing of weather conditions. Depends a lot on the camera and the
> >> optics used but I doubt if you will get fainter than magnitude +6 - more
> >> likely around mag +4 or so. Good luck.
> >> Greg
> >
> > That's exactly what gave me the idea and made me wonder if that method
> had ever been used as a UNID/lost track fence. I don't plan to do it myself
> as I'm definitely not located in a dark sky area. One reader emailed to say
> that DSLR mechanical shutter life might be an issue with all-night short
> time exposures taken nightly.
> >
> > On the viewing problems of the PDF at the thesis link:
> >
> >
> http://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=2148&context=theses
> >
> > I have had none viewing it within the Chrome browser or using the
> stand-alone Foxit reader.
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Received on Fri Feb 06 2015 - 07:09:40 UTC

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