Gina

This is the second Fujinon lens I've had and I think the first one was better. OTOH I was using an ASI 185MC camera and the full colour spectrum in my ASC rather than Ha.

Now running a test to see if the routing of air from the camera cooler up to the lens affects the cooling. I ran the cooling for a while with the casing on with the unit indoors and then with the top of the casing removed so that the air was free to escape straight out. There is a slight difference but it's only about 0.3°C - from -14.7°C to -15.0°C. It is a warm day and the indoor temperature is around 22°C so the cooling may be struggling anyway. EDIT - the camera temperature reading has now risen to -14.5°C so that small difference noted earlier is not significant - the ambient temperature is varying a lot more than that. The cooling performance of this ASI 1600MM-Cool camera has definitely deteriorated then - I can get down to -20°C with the cooling system in my ASC with the DIY cooled ASI 178MC. Maybe I would be better using the same system as in my ASC except with the mono version of the camera (ASI 178MM).

Focus was adjusted remotely for sharpest image in daylight.

To get enough cooling from a TEC-12706 it needs an efficient heatsink - the 40mm ones aren't sufficient so I shall use the 60mm x 65mm one. For the condenser I'm not sure but the same size would seem logical (with the same air capacity) so I've ordered another of these CPU coolers. Due to arrive tomorrow. At least that gives me another option to try.

Looks like I might have caught a meteor. And clouds are coming in! This is a screenshot from KStars FITS Viewer which seems to be trying to debayer a mono image!

I'm going to try stacking. This means that I've had to change the ROI to exclude ground based lights so that the stacking routine can use stars for alignment. I have reduced exposure to 90s to avoid star trailing. Maybe if I can get a dozen or two frames it might show the hydrogen clouds better. I think the test so far shows promise.

OK 5 minutes exposure.

Exposure increased to 4m. Stars are now trailing.

If I can improve the cooling on the camera and increase the gain I think this technique may reveal the hydrogen gas clouds (nebulae). I think it possible that directing the warm air from the camera up to the lens may be restricting it and reducing the amount of cooling available. Maybe vent the air straight out and use some other way to stop dew on the lens.

3m exposure. Converted from FITS to PNG in PI. I think I may be seeing nebulae in the Milky Way in the bottom of the picture - NW.

Here's an image converted from FITS to PNG format in PixInsight and contrast increased slightly.

What I don't understand is that I'm getting coloured noise from a monochrome camera with all mono processing AFAIK.

Darker now and gain increased to 420 but it's showing noise. I used to get -30C from this camera but not now. ?

First night sky image in Ha. Exposure of 90s gain 240 temperature -21C (the best I'm getting at 100% cooling in the ASI 1800MM-Cool). North is at around 5 o'clock.

I have the rig temporarily attached to a length of wood which I've clamped to the observatory wall rather close to an apple tree but it'll do for testing.

I see. Mine isn't - unless next door have their quadrillion candlepower floodlight on. They don't usually have it on for very long and I can always ask them to turn it off.

The new version didn't work for me so I'm still on 16.04. That works fine so I'm happy.

I think I have the all sky NB Ha rig just about ready to test tonight before the moon comes up.

Of course not!

Garden lights along the path are a good idea for night access to an observatory. Just small ones that are charged up in daylight and light up at night.

Just don't cover both eyes at the same time!

I didn't seal the screws in my rails but the wood was well soaked in wood preserver. No problem so far

From tests of the ASC with the ASI 178MC camera, it doesn't seem necessary to reduce camera temperature as far as -20°C and something like -5°C would seem quite adequate. This leads to another possible arrangement for cooling and dehumidifying. The camera temperature is not much below that needed for condensing the moisture in the air so an aluminium plate between TEC and camera casing extended out to the side with a heatsink on it may work as a dehumidifier.

I've seen what might be a bit of a problem with this - nothing must go above the level of the lens otherwise it would be in the FOV and that includes the air duct to the fan. Of course, the air doesn't have to go into the top of the heatsink, it can go in one side and out the other with a "lid" to keep the air in between the fins.

Set up a test rig with the 60mm CPU cooler on the big TEC on the aluminium plate with a 40mm heatsink underneath. The cooling on the plate and small heatsink is sufficient for condensation which can be seen in the photos.