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Astro Projects

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All Sky Camera Mark 7

Gina

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This is my latest generation of all sky cameras and based on the ASI178MM followed by ASI185MC CMOS astro camera and a Fujinon fish-eye lens of 1.4mm focal length.  Although rated at f1.8, this lens lets a lot more light through than this would imply.  Image capture is provided by a Raspberry Pi 3 in conjunction with INDI software.  This is used with KStars/Ekos client software running on a Linux Mint desktop indoors.  Communication is via Wi-Fi.  The Mark 6 ASC has proved inadequate after being in use for some time. 

This blog will describe the problems of the Mark 6 and report my progress in developing this new version.

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Camera temperature is gradually decreasing and now down past -12°.  Another FITS saved file converted to PNG in PI.  30ms exposure.

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Now why did I choose the longest day (shortest night) to test the ASC???  Well, I didn't choose it - it was just how it worked out ?  At least it's a clear night with few clouds.

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Gradually getting darker...  Exposure 3s and camera temperature -8.7°C.  Venus now showing in the south.  The small dot - the bigger splodge is the moon now overloading the image sensor.

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10s exposures and the camera sensor is warming up and approaching -5°C.

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Gina

Posted (edited)

Not long until sunset now...  well, Nautical Dark.  Actual sunset was 21:30 according to Clear Outside.  There is no Astro Dark tonight!

Edited by Gina

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Gina

Posted (edited)

The camera temperature is going down again - maybe the ambient temperature has dropped.  Camera temperature now -9°C.  Don't think I can see any hot pixels so I think I can say the new design has worked ?  Still some sky glow from the sun I think.

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Edited by Gina

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Gina

Posted (edited)

Taking 60s exposures now and camera temperature seems steady at around 10.5°C.  Gain still at 96.

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Edited by Gina

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Gina

Posted (edited)

Set up Ekos - KStars to take 250 60s exposures which should capture images until just before sunrise.  Camera temperature around -8°C.

A final image for tonight...

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Edited by Gina
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Image from 02:30 this morning.  Certainly not astronomically dark!  The Milky Way is visible though much better on a really dark night.  No processing has been applied to these images other than conversion from TIFF to PNG to post here, in PixInsight.

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Gina

Posted (edited)

Now the sun is up and an almost cloudless sky, I'm capturing an image every 10s with an exposure of 32µs and gain at 0.  Camera temperature of -12°C.  Could do with less cooling during the day but it needs some as with the camera thermally insulated it would get hot otherwise.  I think the only disadvantage of having full cooling is that it uses an unnecessary 20W of electricity.  It isn't causing any sensor cover glass icing or even misting though when I started 32µs exposures after the camera was off for a couple of hours and the temperature reached -20°C there was some misting round the edge.  I'll give this some thought but I want to get on with other projects.

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Edited by Gina

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Cropped screenshot from KStars FITS Viewer showing some clouds coming over now.

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Rather stringy cumulus clouds constantly coming over the sky.  Camera temperature now around -10°C.  Weather forecast predicts more cloud by midday.

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In the heat of the mid-day sun the camera temperature is -3.7°C.  I bet the "cooler" is pretty hot!!  Might go out and check.

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Some wispy high level cloud and some lower.  The things in the field next door near the bottom of the frame are cattle.  This lens gives more than 180° FOV - I think it's quoted as 185°.  Anyway, it goes below horizontal which I think is remarkable.

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Some photos of the ASC mounted on the roof.  The fixing is temporary and will be tidied up and improved.  I just wanted it up there to check out.

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A lot more wispy cloud gathering now so there may not be much doing tonight though the cloud could go away again, of course.

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UPDATE :- While the ASC is basically working with good nighttime cooling there are several things that want improving. 

  1. Mounting wants doing properly
  2. Driver that controls the cooling and dew heater doesn't seem to be working
  3. Camera cooling could do with two levels of cooling (full cooling not wanted in daytime)
  4. Needs WiFi setting up to reduce cables
  5. Power cable needs arranging so that roof can be opened with any chance of cable catching on anything

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Gina

Posted (edited)

On reading through this blog I see that several things have changed since starting it.  It is also a hotchpotch of various constructions and two different astro cameras and with little structure.  It therefore seems to me that I should start a new blog with just the construction details of this all sky camera (which I think should be called the Mk 8).  Another reason for starting a new blog is that this blog is a follow on from previous blogs and threads of earlier ASC versions and finding any actual information is well nigh impossible.  I found this when I tried to find how to change the WiFi settings.  That information is in one of the blogs/threads but no way of knowing which without a great deal of reading.

I propose to write a new blog with details of the current incarnation of my ASC with all the setting up information.  This may enable anyone else to make a copy if they wished.  That is the purpose of blogs - to spread information.  I don't believe I have accomplished this effectively.  It will also act as a reference work in case I need to alter anything.

Edited by Gina

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I've scanned this blog and preceding threads right back to the Mark 3 which used the Arduino rather than RPi and not found the setup info ?  It must be somewhere else!  Anyway, I'm leaving the ASC running overnight and will probably work on it tomorrow.

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