gorann

Actually Olly, your statement here indicate that you had issues with your cameras from ATIK, otherwise you would not need the care of the company. As I said I never had any issues with the working of my ASIs. Maybe it could be that there is less problems with CMOS than the old CCDs?

Hi Olly, I assume you realize that this is the same chip as QHY and ASI has been selling in their top-of-the-line cameras (e.g. ASI6200) for well over a year. I have the ASI version of it (mono) and have and have had a bunch of other ASIs for many years, and none have ever failed, and I had not heard of any major problems from other users. So I never even had to contact the seller (which would be mainly FLO in my case). So I am not sure that you need to worry about support from the company. But of course in general it is a bit sad that Europe (including UK😉) are not in the forefront on developing the next generation astro cameras, making most of us totally dependent on China for our supply. Out of curiosity, are you looking for a mono version or an OSC?

Thanks @ollypenrice and @vlaiv. My problem is that Bortle is mentioned a lot on SGL and many people ask me of my Bortle. Maybe Bortle is especially popular in the UK? I wish that SQM meters were not as rediculously expensive so we all could go over to that less subjective scale. How could 25 years old compare his/her impression of the sky with that of Olly and me?

After I have started posting my images of Integrated Flux Nebulosity I have got several questions about what Bortle my sky is. I do not trust my old eyes to subjectively figure this out, but I do take regular measurements with my SQM meter and it usually shows values between 21.4 and 21.6 on good nights. I had previously seen this translated to Bortle 2 - 3, see the table below and for example: https://jonrista.com/the-astrophotographers-guide/astrophotography-basics/snr/ I thought that made sence since I am in a rural area with no major light pollution near by and no city lighting up the horizon. But, when I now check on Wikipedia the translation table is completely different. Accoring to Wikipedia I am more like Bortle 4 and I expect very few people, including @ollypenrice in rural France are in Bortle 2 - 3 skies. The Wikipedia scale seems very compressed at the top. https://en.wikipedia.org/wiki/Bortle_scale Does anyone know why these scales differ so much, and which one to use? Traditional table:

I love RASAs so much that I bought a second one. Unlike the first, it turned out to need collimation and that was one of my tasks for tonight. The collimation screws cannot be reached when I have a proper imaging camera on so I need to put a mini guide camera there. While fiddeling with the screws the image screen got dark and the defocused star I was looking at was gone. I restarted the program and pulled out and reconnected the USB cable. Still no star. Only then did it struck me to look up and realize it was down to the good old clouds. Goes to show that I trust the atmosphere more than electronics.... Now both the old and new RASA are shooting away at IFN and I am off to bed.

I hope he gets back and was not scared off. Could it be that he saved his subs as jpg (8bit), some systems do that as default, and in that case it may be impossible to bring the red and blue channels up?

My problem with the subjective description of sky darkness of the Bortle sky scale is that it all depends on the observer. My soon 62 year old eyes are clearly not as light sensitive as they used to be, so I need the SQM to tell me how dark it is on a particular night.

This is an example of the Bortle scale I have seen before. Here the SQM values are much less compressed at the top than the "new" one in Wikipedia, and gives me Bortle 2-3. Source: https://www.researchgate.net/figure/Levels-of-the-Bortles-dark-skies-scale-with-the-corresponding-sky-brightness-magnitude_fig1_337547281

I also wondered about this but since I have not seen it mentioned anywhere I do not worry. It is also hard to test since the camera and its heat production and fan needs to be there. It could be that the fan in the camera mix the air so effectively that the currents are fast and nonsignificant. Maybe also currents in front of a mirror is worse than in front of a corrector lens.

Hi Carole! Yes, I also thought I had seen tables saying my SQM readings (usually between 21.3 and 21.6) was Bortle 2-3. I am on the coutryside with no major city close by so no clearly brighter horizon. But now I see a table in Wikipedia (https://en.wikipedia.org/wiki/Bortle_scale) saying it would be Bortle 4-5. I hope Wikipedia is wrong for once. How do you translate SQM readings?

Thanks a lot! I always use gain 100, offset 30. Gain 100 is as you know the sweet spot with the sudden fall in read noise and maintained dynamic range. The offset 30 is just something that seems to work well. Temperature is set to -15°C.

I continue my hunt for Integrated Flux Nebulosity (IFN) with the RASA. The big yellow star to the left in the image is rho UMa and south is to the right in the image (which made for better framing). The big yellow and blue stars in the lower left quadrant are sig01 UMa and Sig02 UMa, respectively. My obsy is in a rural area and SQM this night showed 21.4, so quite dark. That helps a lot when hunting for IFN. The 8" F/2 scope also helps. That combination allows for detecting quite a lot of colour in the IFN. I have not seen any images of IFN this area this close up, but there are some wider field images by Nawratil and others that I use to orient myself in my hunt. I also post an annotated image (done in PI) revealing a lot of small galaxies from the PGC catalogue. Collected 4 March with a RASA8 and ASI2600MC without filter. 51 x 5 min at gain 100, so 4.25 hours.

Yes, most of my image of Mandel-Wilson 2 is 8.3 hours (https://www.astrobin.com/bftjgc/D/) but to the corner containing M81 and 82 I added 4.7 hours of RASA data from a previous night (https://www.astrobin.com/i70prl/D/). So they have totally 13 hours with is quite a lot with a RASA.

Please post a Raw sub file (tiff of fits) so we can have a look at it. Will be easy enough to find out if it can be calibrated or if your camera needs to be fixed.

Nice image Francis! Still a bit noisy but maybe you are fighting light pollution and IFN is really faint, so it is a tough task. What is your Bortle / SQM? Since the RASA only has one mirror, all images are mirror images so I first had some problem orienting myself in your image. I always flip mine when processing😉

I can't remember when I last had double figure centigrees up here Steve, unless you put a minus in front - that I can well remember. In my case the heat from the camera in combination with a dew shield means that I never need a heater on the scope, not even at -15°C.

Ed: Yes I can highly recommend a RASA 8 but you really should use it with a cooled circular CMOS camera. The new OSCs from ZWO and QHY are not far behind a mono and will make life easier. Francis: do you need to use an IR/UV filter for your OSC? My ASI OSCs (2600 and 071) have one built in

Thanks Lee! Yes, when I saw that scope for sale I knew I could not resist but I also knew I had to build her an obsy - that lady is not for carrying around😉

Looks like I get another clear night and the old EQ8 is doing admirably well in balancing 80 kg of scope and weights. Aiming at IC356 and it may catch some nice galaxy data.

Yesterday was first light with my new QHY268M. It weighs a good kilo but looked tiny on the 40 kg SCT. I aimed at collecting lum on IC356 so I skipped to put on a filterwheel. Fortunately, after I took the picture I realized that I needed at least an IR filter so I had to put a wheel on. Then I only got a few subs before clouds moved in so nothing to show yet. Just happy that my computer had no problem communicating with the camera using SharpCap. I am also just happy to finally have the camera even if the season is soon over up here where astro darknes is at most five hours now. The camera got stuck in some eternal customs loop for two weeks between the UK and Sweden, which demaded both phone calls and emails to finally be resolved.

My SQM meter shows values from 21.2 to 21.6 so Bortle 3-4.

I agree with Vlaiv on the camera. The ASI1600 is now a bit outdated and the ASI294 would be my obvious choise for a camera with that sensor size. There are now lots of ASI1600 on sale on the used market - I think that people are upgrading to the more sensitive next generation of CMOS, like the 294, or the amazing 2600 with no amp glow.

I give you all un update when Amazon delivers the ampmeter. The Mesu is such a sturdy mount that it may not make much of a difference but it may give me a good feeling to know that I have balanced it objectively.

Thanks! It is very faint so if you are going to image it be patient! I do not think you can see it visually with any ordinary scope.

Thank you Mark!