iantaylor2uk

I think there has been a lot of published work on the experimental measurement of the proton radius, because two different ways of doing the measurements came up with two slightly different values. So I think it makes sense that a proton has a volume, and surface area, but can't see how knowing this helps determine the size of the universe.

Physics tends to try to find the simplest possible theories to explain nature. You would need to explain why you think the speed of light should be anisotropic. If we assume it is isotropic and the theories agree with experimental data, then that tends to confirm the assumption that it is isotropic. Incidentally, my reading of Feynman's book "QED: The strange theory of light and matter" is that there are paths a photon can take in which the speed of light is different, but when you do the path integral over all possibilities, the photon travels through a vacuum at the speed of light we measure (i.e. these other paths make a negligible contribution to the path integral).

Hydrogen bonding is key to the behaviour of water and I think each water molecule has hydrogen bonds to about 4 or 5 other water molecules.

Not sure I understand this. The ZWO EAF couplers are tightened onto the shafts using grub screws, so do you mean the grub screws were tightened on too much that you couldn't get them off?

You can certainly see the right shape there. You might be better with an easier target like M13 to start with which usually need shorter subs. Also the images definitely improve if you take dark and flat frames.

Sorry, wasn't thinking when I wrote this. They are both APS-C sensors so will have the same FOV but the larger pixel size means you get more arc-seconds per pixel with the 071 camera.

There are various ways in which photons can interact with the mirror that results in a reflection. However it is meaningless to say whether the reflected photon is the same as the incoming photo since photons are indistinguishable from each other.

I think it is fair to say the 071 is older tech compared to the 2600. There is likely to be old stock out there still for sale. If you can pick one up cheaply it's probably worth going for. I haven't had a lot of dew/frost problems with mine as I only usually cool it down to -5C. One thing worth mentioning is that the pixel size, at 4.78 microns, is quite a bit bigger than that of the 2600, which can be an advantage in terms of wider field of view and easier guiding.

I have two of the coowoo USB dew straps (from Amazon) and they have worked well with my guide scope and 102mm refractor. I couldn't get these to work with the ASI Air Pro but just used a separate plug with 2 USB ports in.

Not sure why you want such a long exposure time for flats. I use the auto exposure function in the ASI Air Pro and use a flat panel with no paper. With just an IR/UV filter the exposure time is around 30 milliseconds or so, whereas with the L-enhance filter the exposure time is around 300 milliseconds. The flats used from these short exposures seem to work fine for my ASI 071 MC Pro camera.

My new light weight set-up: WO 81 GT IV with 0.8x reducer/flattener on RST-135 mount on Innorel RT90C tripod controlled by ASI Air Pro, with a celestron powertank battery. Everything was working great, with autoguiding in the 0.4-0.6" RMS range, and I got about 10 two minute images of the Crescent nebula with an L-Enhance filter ... and then it clouded over ☹️

I had one of these a couple of years ago (I was 58 at the time). The advice from the 111 hotline was to go to A&E to get checked out (as they want to make sure the retina doesn't become detached). When they checked me out they did find a small hole on the retina of my other eye, and I had to get it Lasered a few months later - sounds bad but it only took a couple of minutes and wasn't painful. You're more likely to get floaters if you are short sighted.

I usually use Deep Sky Stacker but don't think there is a Mac version of this. ASI Studio also does stacking but not sure of there is a Mac version.

The fits files should have been stored by the ASI Air Pro - look on the thumb stick under the Light folder (if you used Autorun) or they could be on the memory card (depends what option you ticked when you were imaging). The fits files should in the same folder as the jpg files. I've dug out an old image I took of M81 from February. The first image is the stretched jpg, and the second image is the final result after stacking approx 70 frames. I also used an ASI Air Pro and ASI 071 MC Pro camera (I used a gain of 200, exposure length of 30 seconds, and cooled the sensor to -5C). I also took dark, flat and bias calibration frames. It is also important on this camera to use a UV/IR filter, as the camera does not have one built in. This was taken using a Tak TSA 102 refractor, with a 1x flattener, so the focal length was approx 820mm. The files were stacked in DSS, then further processed using Nebulosity 4. Hope this helps.

Stacking the files (use software like DSS or similar) will reduce the noise. If you stack 100 frames the signal to noise ratio will be 10x better than a single frame. If you've taken any calibration frames (darks, flats etc) use these too. I have the same camera as you. Galaxies like M81 and Andromeda all look pretty underwhelming to me from a single frame but you should be able to pick up a lot more detail after stacking.

It's clearly not impossible because that is the data they are receiving. I guess a headline that says "fault not yet identified" would not attract as many readers!

I use the L-enhance filter and my images come out red too (although I tend to use Nebulosity 4 and Affinity for processing rather than PixInsight or APP) - the one below is from last year with a WO 81 GT IV

Have not posted too much recently as I've been putting together a new much lighter weight set-up. I realized that the heaviest scope I had (an Orion Optics CT8) is only around 9 or 10 kg (with rings and losmandy plate) and even with camera and guide scope should come in below 12 kg, whilst my lightest scope (a WO 81 GT IV) is only about 6 kg fully loaded, so I could go with a harmonic mount. (If I do use the 8" reflector on the RST 135 I'll probably use the counterweight even though it is below the 13.5 kg weight limit of the mount, whereas for the WO 81 GT IV and my Tak TSA 102 will probably not bother to use the counter weight). So a few weeks ago I took the plunge and went for an RST 135 mount which I'm using on a half-pier on an Innorel RT90C tripod. I realize I could have waited until the ZWO AM5 becomes available, but wasn't sure how long a wait there will be, and in addition, there are quite a few users of the RST 135 already out there using the mount and getting good results. This was all purchased through FLO who very quickly delivered all the goods which were well packed. The weight of the tripod, half pier, and RST-135 comes to only 7.5 kg. This compares to the Losmandy G11 head with heavy duty tripod which I have been using, which is 31 kg! Unfortunately I came down with COVID about 4 weeks ago so was out of action for a while, but managed to get a session with the new set-up on Friday night - however the clouds soon rolled in so couldn't get the guiding checked out. Managed a quick shot of the moon, which is below. If the guiding is good, I may well end up getting rid of the Losmandy G11 (which is a great mount, but probably better suited to someone with heavier telescopes). My initial reactions are that the mount is fairly quiet, easy to polar align (with the ASI Air Pro) and is nice to use, although the handset seemed a bit quirky (although it may just need me to get used to it - it is quite different to the Losmandy Gemini 2 handset I've been using). Also the home position of the scope is facing west, whereas for the G11 it was with the scope facing towards the pole. I've also ordered a lithium battery pack so I can have pretty low weight set-up that I could potentially use at dark sites. Once I get a good dark night I'll report back on the guiding performance of the mount.

I think most people plug the mount and the guide camera into the USB2 ports, and the USB3 ports are often used for the main camera and the memory stick. If your ZWO main camera has extra USB ports on, you can also use those (I plug the EAF into one of those, but you may also be able to plug in the guide camera too). If you save images to the memory card rather than the memory stick this would free up one of the USB3 ports.

Usually the dark current graphs use a logarithmic axis on the vertical scale. With my ASI 071 I only ever go down to -5C as I'm not convinced there is a big enough benefit to going even lower.

You do need a flattener with the WO GT81 - however with the flattener (either the 0.8x one from William Optics, or I also use a 1x Hotech flattener) it is pretty much a flat field for an APS-C sized sensor, and I've had some great images from it.

I think it depends on the camera. On my 071 MC Pro the auto flats on the ASI Air Pro typically come in at around 30 milliseconds when I use a UV/IR filter, and around 300 milliseconds if I use the L-Enhance filter. They seem to work just fine.

I got a few items from FLO this week: A quick release bracket for the finderscope on my TAK TSA-102 (https://www.firstlightoptics.com/adm-misc-mounting-accessories/adm-takahashi-quick-release-finder-bracket.html) which is really good. An RST 135 with half pier: I realized my telescopes are all fairly light (with the heaviest being 8 kg) so have decided to try using a harmonic mount on an RT90C tripod. I could have waited for the ZWO version but with all the lock downs in China I can't see this being widely available for a while. If it all works out well I may put my Losmandy G11 up for sale in the not too distant future. Just have to wait for some clear nights to try the new mount out.

And we can also measure the speed of photons even though some people believe they don't exist during their motion!

As someone else has mentioned, doing this at UK altitudes will be difficult due to water in the atmosphere. The UK used to have an infra red telescope in Hawaii, but that was at an altitude of 4.2 km to avoid this problem.