iantaylor2uk

Another vote for the ASKAR FRA 300 Pro - I am using this with an APS-C sized sensor (ZWO 071 MC Pro) and get a field of view of 4.5 x 3 degrees (at 3.3" per pixel) A recent (large) photo I took with this combination, which is best viewed on a computer screen rather than on a phone, is available at: https://drive.google.com/file/d/1ekx3ibz3QnfTha3xX3PBIaGB36Vh1LLn/view?usp=sharing If you have a 183mc camera, the field of view would be 2.5 x 1.7 degrees with 1.65" per pixel The only downside of this scope is that it is mainly aimed at astrophotographers, and I think you need a special diagonal from ASKAR if you want to use it for visual.

Akihabara is an amazing part of Tokyo. Will have to visit this store next time I'm in Japan. Hope you're enjoying the amazing food over there

There is a great book on this topic, "The wisdom of crowds" by James Surowiecki. If you assume there are enough people, and assume their guesses are random, and plot the results on a graph, I'm pretty sure you would get a gaussian distribution due to the central limit theorem in maths. It is a good question though as to how close you would expect the guess is to the real value. I would think you would get closer as the number of people guessing goes up.

There's lots of good stuff at: https://math.ucr.edu/home/baez/ - although not sure he gets into debates with random interneters

I think the key is to price your unwanted goods correctly. There are loads of traders on ebay who pick up second hand goods if they are priced too low. Similarly, I use MPB for buying and selling old camera equipment, and it is fairly obvious they are in the business of making a profit on anything they buy from you. I know people say price at around 2/3 of new, but now inflation is high, retail prices are going up, so you could argue why is my second hand telescope now worth more than a year before. Ultimately, if you set a price and someone pays it, and you were happy with the deal, the goods are no longer yours, and if they then try and sell it on for a profit later on, the lesson is you probably priced it too low. It's hard enough to sell astro gear at the best of times, so if you restrict who you sell to, you're only going to shoot yourself in the foot.

If space is quantized it will be at the Plank scale, which is many orders of magnitude lower than anything we can measure at the moment. I think it is quite likely that space-time is quantized as I don't think infinity has any place in physics (infinity is a mathematical concept not a physical one). The fact that continuity breaks down at the lowest length scales also means we will end up with difference equations rather than differential equations.

If you think about what is needed for hydrocarbon intelligent life: 1. You need to have plenty of early supernovae to generate elements like carbon and nitrogen and oxygen (probably a few billion years) 2. The universe needs to last long enough to develop intelligent life (probably a few billion years) 3. The various fundamental physical constants need to be such that carbon and water have the properties they have - some of which are quite unusual (such as the density behavior of water) 4. Gravity needs to have the right value so stars are not too close or two far apart as life develops. All of the above put some constraints on what the fundamental constants are.

You could argue that if the parameters didn't have the values they have, then intelligent life (i.e. us) would not have happened. So to be in a universe where intelligent beings can observe what's going on, the various cosmological parameters have to be constrained somewhat.

People will expect you to sell good quality unused equipment for a fraction of the original price, unless you have a rare piece of equipment, and then people will accuse you of profiteering!

I recently got an ASKAR FRA 300 Pro telescope, and had the chance to try it out last week on the Orion Nebula. I took 60 thirty second exposures (with gain on ZWO 071 MC Pro camera set to 200, and sensor cooled to 0 deg C) and stacked the best 54 of these frames, along with dark, bias and flat calibration frames, and then processed the stacked image with GraXpert and Nebulosity 4. I was pretty pleased with the final image which can be seen at: https://drive.google.com/file/d/1ekx3ibz3QnfTha3xX3PBIaGB36Vh1LLn/view?usp=sharing Anyhow, I took one of the FITS frames and analysed it with ASTAP - with results as shown below: It looks pretty good to me: median HFD = 3.4 pixels, tilt is 5%, described by ASTAP as almost none, and off-axis aberration = 0.16 pixels. Althought the HFD looks low, since the scale is about 3.3" per pixel, it is actually equal to 11.1", which doesn't sound quite as good. However, the final image looks good and the stars look round right out to the edges. It is a nice change not to worry about flatteners and spacings etc. I would think if someone is looking at a WO81GT or a WO71GT, with a 0.8x flattener/reducer, the ASKAR FRA 300 Pro may make a good, and possibly cheaper alternative.

I don't know what you think the physical basis is for why the speed of light would differ in direction. If you look at Maxwell's equations, there is a single speed c, predicted for electromagnetic waves, and as far as I'm aware the c that appears in those equations does not depend on direction, and electromagnetism agrees well with experiment. In addition, there have been many published papers where general relativity has been applied to pairs of spinning black holes, particularly for black hole collisions, where as I understand it the simulations agree well with the measured data. I think if the speed of light were different on the two separate paths application of GR to spinning systems would have shown up as discrepancies with experiment.

Really like the RST mount, goto is good and guiding is low with total RMS is 0.7" or lower depending on how good polar alignment is. Have used my Tak TSA 102 on the mount with no counterweights and it has been fine. Just wanted a lower focal length scope to complement it.

Photo of my new, wide field, low weight set up. Askar FRA 300 Pro on RST-135 mount. Scope only weights 2.2 kg and carbon tripod and head weight around 6 kg. First photo, taken on 24th Feb, shows a wide field view of the Orion Nebula (stack of 54 30 second images with ASI 071 MC Pro camera, gain of 200, sensor cooled to 0 C, with UV/IR filter, and dark, bias, flat frames used for calibration). DSS used for stacking and combination of GraXpert and Nebulosity used for processing. Looks like I'm going to enjoy this

There are 3 rubber bands on the flattener and you push the flattener in and screw it on and that forces the bands against the inside of the tube to self centre it. The issue with the GT81 is only two of the bands fit inside the tube. I've not found this to be an issue when imaging, to be honest.

I use a hotech sca 1x flattener on my GT81IV and it works pretty well

Just got myself an FRA300 Pro refractor from FLO - looks like a great piece of kit, 300mm f/5 refractor with fully flat field, aimed at astrophotographers. Very quick delivery from FLO, much appreciated. With my ASI 071 MC Pro APS-C camera, this will give a field of view of 4.5 x 3 degrees. For anyone thinking of getting this, if you have a OSC camera and don't have a filter wheel, you need a M48 to M42 converter, as it is only the M48 plate that comes with the 2 inch thread for filters. Hoping to try this out on the Orion and Rosette Nebulae later this week if it clears up, as it looks like a great bit of kit.

If you ask the right people you will probably get much better advice than if you ask the average person. The chatbot will most likely be in-between.

I'm surprised you can't buy a "modular" mount, in which the mechanics and the electronics are completely separate, so that the user could choose what motors and control systems to use on the mount. I guess the closest company that comes to this is Losmandy - all that sticks out from the mount are the ends of the worms, and you can attach different motors onto this (for example, I first bought a G11 with a 492 push-to system, back in 2009, but recently upgraded to the Gemini-2 system in 2020, which meant changing the motors and gearboxes and changing the controller box). However, some others use their Losmandy mounts with OnStep or EQStarPro systems (because they didn't want to go to the expense of the Gemini system). The problem as I see it is that you have either (1) good engineering companies that then put cheap (or very expensive) electronics on their mounts, or (2) companies that are good at the electronics side but may be poor on the mechanics side. I've seen lots of posts on forums where people have old mounts and have had endless problems when the electronics on those mounts have died. If there were people that made such mounts it may also stimulate innovations in the control and electronics side so we see more than just OnStep and EQStarPro, and this could lead to lower prices in the longer term. Not sure what people's thoughts are on this, but to me it seems to me some people would be interested in such mounts.

I would use it in equatorial mode rather than alt/az if you plan on taking photos. If the polar alignment is less than 5' then guiding is usually OK. 5' is one twelfth of a degree, so it is pretty close to the pole. You can try to get it closer if you want. I find it easiest to take dark, flat, and bias frames at the telescope under the same conditions as the light frames. For the dark and bias frames just cover the telescope with the lens cover. The dark frames will need to be the same exposure length, gain and temperature as the light frames. I tend to use bias frames rather than bother with dark flats.

People who are qualified scientists do believe these things, and there is a scientific process whereby theories are put forward, tested against observations, and then accepted (or not) by scientific consensus as the best (current) theory. If you are not qualified in science, what you believe or do not believe carries zero weight with the scientific community. Also just to be pedantic, if you believe the universe is infinite, how do you define where the centre is?

If I'm tracking a star with my mount, and I get the autoguding going, could I then effectively measure the periodic error of my mount by setting the RA and Dec agressiveness to zero? If I do this for say 4 periods, I would get a long enough PHD2 log to then analyze with PHD2 log viewer. I was wondering if anyone has tried this and whether or not it was successful. (The issue is that the Asiair does not support, at the moment, the PHD2 Guiding Assistant function).