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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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I think I can just about make out The Milky Way in spite of a nearly full moon.  10s exposure, gain 288 gamma 25.59ff6353e40be_Screenshotfrom2017-11-0519-07-16.thumb.png.9fb0468029cdc117d7d081f62cb7d7b5.png

 

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Camera cooling is working very well - 20°C with cooling off and just 3°C with cooling on.  Dew heater is also on.

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I'm going to have to print the middle section of the casing in more than one part - there isn't enough on the print bed to hold it.

Edited by Gina
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Latest image and the last for tonight I think as there's probably no point in capturing images with a nearly full moon in the FOV.  This does show great promise for when the moon is out of the way though.  Several stars visible including the "W" of Cassiopeia.  Looks like clouds coming in from the SW so I wont leave the rig out all night without its casing to keep wet off the electronics.

59ff9adfa7059_Screenshotfrom2017-11-0523-05-31.thumb.png.da723160c49531317d89a892f16c8ff2.png

Edited by Gina
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Successfully printed the middle top section of the casing and glued the top part to it.  Here it is on the ASC.  There's plenty of room inside now! :D

5a00d8a080eb9_MiddleTop01.thumb.png.1893f650a173a33cb0d8448ffc7bfa6b.png5a00d89be16c3_MiddleTop02.thumb.png.ad1029586d8f49455c43f7ae709917fa.png5a00d8978a3c6_MiddleTop03.thumb.png.cc82c65a4835d0207d640843eb2dc351.png5a00d89316fc8_MiddleTop04.thumb.png.38666914871774e663563ca8861941e5.png5a00d88de3292_MiddleTop05.thumb.png.14cd9f627adbe852df8db2d93d22b642.png

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Designed and printed the middle bottom which is just a cylinder and also designed and now printing the bottom part of the casing that attaches to the pipe.

5a01de42b10ef_Bottom01.png.e11d2b295904617bb8b10933fb28bb85.png

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The rain has stopped and the sun has come out so I've put the rig outside on the guttering.  Here's an image.  I'm having a problem with the white balance - I just can't seem to get it right.  I don't know what's changed as it seems fine at first.

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Turned on auto white balance for both red and blue.  It is a red sunset but the image shows everything red whereas the trees and grass are still green.

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More work on the casing.

Bottom part printed and fitted into middle part satisfactorily.  (Upside down view.)
5a021421d3a13_Bottom02.thumb.png.87fcf428ba6ebb2eba2e0d23398d4d80.png

Bottom part cleaned up - the cone didn't print properly so I've repaired it with filament dissolved in acetone.
5a02141d610ac_Bottom03.thumb.png.c708a7ce0dd280d245e40d9b00efb966.png

Middle parts glued together.
5a0214188e531_MiddleTop06.thumb.png.ee7b486ea5c040c1d571738371fbf313.png

 

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Some images from tonight.  Moon is up too much now for any more.  It could do with dark subtraction to get rid of hot pixels.  And a touch more cooling to reduce noise.  I'm currently getting about 15°C of cooling.  It would probably help to provide better cooling of the hot side of the Peltier TEC.  Maybe some fins on the aluminium pipe just below the ASC casing.  Final image is with 30s exposure, gain at 250 and gamma of 10. Oh and the picture has gone green again!  Though the sky looks alright.  It will be nice when I can get some clear night sky with no moon later in the evening and night when people have gone to bed, house lights are off and fewer vehicles with their headlights shining on the trees.

5a021781610e9_Screenshotfrom2017-11-0719-21-31.thumb.png.c9c6fee6223ecd381d84d5bc58d984c5.png5a02177c95700_Screenshotfrom2017-11-0719-53-19.thumb.png.eeebd1df9e892c520978812e54d4f763.png5a02177759a26_Screenshotfrom2017-11-0720-04-44.thumb.png.5f3ee935f08fba3ad957b32f302421d0.png

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Tried the casing on the ASC this morning and...  it didn't fit!! :(  So I engaged brain and had a good think about possible answers.  And now it does! :)  The aluminium block was stopping the bottom engaging with the middle.  Possible solutions were :-

  1. Saw a bit off the ali block (Oh no!! That's hard work!!)
  2. Redesign and print the bottom part (when will all this redesign end??)
  3. Soften the side of the middle part with hot air gun and push it out a bit from inside.

I went for option 3. using the handle of a screwdriver to push the ABS outwards.  Job done :)

Edited by Gina
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Its great when You can make minor adjustments on these prints by just heating it up and pushing it in/out a bit :icon_biggrin:

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Yes and I've also used heat to adjust the shape of levers and suchlike.  Plastic does have its advantages :D

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ASC complete with casing now outdoors with pole hooked on guttering.  Clearish ATM but cloud forecast.  Lens moved when I attached casing - so have to sort that out.

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Apart from that I shall have to arrange a screen to block out next door's floodlight.  I can see it's cloudy but only just.  At least it isn't as bad as it was with the dome.  Then, of course, there's the cover and it's control to sort out.

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Thin high cloud tonight.  Orion rising, Cassiopeia well up

5a04d915de09d_Screenshotfrom2017-11-0922-17-47.thumb.png.fd37bb991db9a0b3a32e815d36ff92e9.png

Edited by Gina
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And now it's raining - brought the rig indoors a few minutes ago :)  Next door turned their billion candle power floodlight on.

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First attempt with Ubuntu Mate wouldn't boot so trying again with a new image write to card.

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Back to the working system (my experiments are with a separate RPi and card).  It looks like I am going to have to arrange remote control of the focussing and lens angle.  The image attached was after manually focussing and then putting the casing on.  It's not bad to the SE but well out to the NW.  I think maybe putting the casing on disturbed it and if that's the problem I might be able to improve the manual adjustments and make them stronger.

5a088a95042ef_Screenshotfrom2017-11-1217-45-48.thumb.png.259dc230a54c42b0777a5a6bd0a4392d.png

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