andrew s

There are two main constraints, money and practicality (size and weight). In reality it depends on what you want to do and how you intend to do it. Visual v imaging , permanent obs v travel to dark sight etc. We all suffer. Find the type of observing you want to do and see what most use succesfully in that field. Regards Andrew PS then take the tablets

About 5 petabytes (5*2^50) according to the internet. Regards Andrew

It might be revealed by the lensing of background galaxies etc. Regards Andrew

I think a lot depends on if you are talking about the imaged black hole or black holes in general. Some black holes seem to be without a accreation disks and my have a quiet environment. Regards Andrew

How about elastic scattering. On a lab scale light reflects of a mirror without losing energy. Passes through a glass block an emerges with the same frequently. Regards Andrew

I think the close in photon orbits are unstable to small perturbations (interaction with charged particles) and it is this that sends them into the black hole with or without an energy change. Regards Andrew

In effect yes. I am not exactly sure if the black edge is the projected event horizon as the light is bent and distorted round it. I would have to look at the paper they have published to be sure. Regards Andrew

A black hole is defined by mass, charge and spin. You need to study the subject to understand it impact on the event horizon. Regards Andrew

But the event horizon can and does. Regards Andrew

See BBC 4 at 9 tonight. Regards Andrew

Thanks a major step forward in seeing the acretion disc of a black hole. Regards Andrew

Not sure. I just leave them on as I don't image local seeing is not a big issue for me. Sorry I can't help more. Regards Andrew

I got mine fitted by OO on my ODK 16 at the time of order. Regards Andrew

If you have multiple paths to earth this can cause trouble with current flowing in them v to ground. Try and collect all earth points together and connect them all to ground once. You also want to avoid earth loops where two bits of kit have an earth connection and both are grounded. This often causes hum in audio equipment. Regards Andrew

Yes I study star spectra with a home built echelle spectrograph. I have a guide head on a telescope which feeds the starlight into a fibre optic which guides the light to the spectrograph. This allows the spectrograph to be stable as it does not move as the telescope tracks the star. Regards Andrew

The reflective version should be ok with any camera. A prism adds aberrations when off axis. I use mine as the input to a spectrograph. Regards Andrew

Looking at yours it must have a reflective coating on the 45 deg face. This is mine https://www.teleskop-express.de/shop/product_info.php/info/p641_TS-Optics-Off-Axis-Guider-TSOAG9---Baulaenge-nur-9-mm.html it uses the prism with total internal reflection. You can see they are quite different. It is probably that yours uses reflection as yours is for an EOS camera with a large field. Regards Andrew

Then the 45 deg face is reflecting about 5% of the light to the guide port? It looks nothing like my teleskop services OAG prism. You live and learn. Regards Andrew

That prism looks slivered and is acting as a mirror. Is that correct? Regards Andrew

The second coloured diagram is not correct. The blue prism is the wrong way round. No known material could deviate the light at a right angle in this configuration. Regards Andrew

I think the first was correct. The light undergoes total internal reflection at the 45 deg face. The light path in the coloured diagram is impossible. Regards Andrew

Offset is to stop the AD converter from trying to convert -ve analogue values. It needs to be high enough to prevent this. It is a bit like saturation but at the low end. Regards Andrew

I thought there was an app called timber or something similar for that kind of thing? Regards Andrew

I think I have one of the smallest. A 50 micron guided fibre for solar spectroscopy. Regards Andrew

I quite agree. It was the "first thoughts" that amused me. Regards Andrew