pete_l

I have a smarteq. It is good enough for camera + lens. But it is far too "light" for an ED80 and astrophotograhy. EQMOD only works with Skywatcher mounts. A GPDX is a good mount if it has been looked after. But you will need a Skysensor 2000 handset to control it from a PC. Depending on the firmware level, people have mixed experiences of "computerising" them.. There are aftermarket controllers you can buy for a few £ hundred that will attach instead of the SS2K and that emulate a Skywatcher mount (so work with EQMOD). But I have not tried one of those.

That's very interesting Han. Thank you for doing this work. Looking at the time lost between exposures, do you think the speed difference between USB2 and USB3 is a factor here? On a Pi4 with a lot of memory there is the option to create a RAMDISK and save the image there. That will remove any time spent saving the image to the SD card.

I'd say there are only 4 mounts that are easily available that are within your price limit: Celestron CGX-L CEM120 (basic version) Losmandy G11GT Skywatcher EQ8 Your OTA is around 20kg and say another 8-10kg of toys. And from that list any one of them would do the job.

Yes. I think this is a more relevant issue. It amuses me when we see (for example) 6MP images displayed on a standard HD monitor of only 2MPix. We are fortunate that 4K monitors allow us to display 10 MPix images natively. But when you sit at a normal distance for computer work (much closer than one would watch a TV programme) it is not easy to take in the entire view. My "work" screen is 107cm wide. At 3840 pixels that is 36px/cm or 90 DPI. I get perfectly good images displayed on that, despite only sitting 60-80 cm away. Yet mobile phone screens make a big deal of "retina" displays with much higher resolutions. I assume the users hold their phones very close to their eyes. I recall having a conversation with a "professional" photographer many years ago. They insisted that all photos had to be printed at 300 DPI. No matter their size. No matter how far away they would be viewed from. I feel that if they revisited the subject now, with a more accepting mind, they would see (!) the error of their ways.

So in practical terms. your final resolution would be a little worse than your seeing. Although using the RMS figure for guiding does, itself, hide a multitude of other problems and assumptions. Ones that make any real accuracy in modelling performance rather suspect. While the CEM60 does look better on paper, can anybody actually point a finger at the images from that mount and say they are consistently any better than the same images (scope, camera, target) taken from an EQ6? Or that the imaging process s significantly easier? Those are the factors I would investigate if comparing the mounts: the results, not the specs.

Very interesting Tony. At first glance the charts showing the improvement in RA and Dec backlash don't look that impressive. Then I saw the difference in scale! 5000 vs 1000. 🤯 I also found your web page of the Synta EQ8 Re-imagined. I will follow the project with interest.

The FLO page says wonderfluid is not suitable for cleaning mirrors. I wonder why? Though we are always told to "dab" not rub, when cleaning optical surfaces. Due to the risk of picking up grit and scratching the surface.

I'd have a word with local builders. See how deep they feel it is necessary to go for footings on buildings such as sheds or raised decks.

https://stackoverflow.com/questions/9699930/cmake-complains-the-cxx-compiler-identification-is-unknown

Like this? That's a B 3+ The O/S from an older RPi model 3 won't run on it.

Is that not what you get when you try to run a RPi 3B+ with an incompatible earlier version of software?

How about using antifreeze?

Fortunately with the 4GB version if the RPi 4, there is sufficient RAM to buffer quite a bit of data without a disk/SD-card bottleneck. Once captured you can put it to n/v storage at a more leisurely pace. Just as long as your average rate of data production doesn't overrun the speed of writing.

Here's an update. I received a second IMX291 camera today. This time with a 4mm F/0.95 lens. First results were ...... interesting I still have lots to try with this thing, but as a taster, here's a screenshot of a single live streamed image from VLC running inthe VM I spun up to play with these cameras. The camera is this one from Aliexpress It runs rather hot, so I have bolted a little 12V fan to the back. For those unfamiliar with the stars from southern Spain, that is Lupus and Centaurus underneath and to the right of Scorpius

I agree. There are far more small and interesting targets than large and interesting ones. We tend to pay a lot of attention to the "crowd pleasers" M42, Andromeda, N. America neb etc. I can understand why: they are quick to image and produce nice, bright, colourful results. But imaging small stuff takes time. It also takes money as the kit needed is larger, higher quality and more complex. There is obviously room for all-comer in the hobby. But ultimately it IS a hobby, not a competition. Once it stops pleasing people, that's the time to stop.

Perl Astro::Coords https://metacpan.org/pod/Astro::Coords

When I did this, the library I used had next_rising and next_setting functions. It was just a case of stepping through those. Although how you handle the case of two in one day is down to your design. Personally I worked on the basis of "nights" rather than 24 hour days.

So fairly near to me. I'm just outside Benamaurel towards Jabalcon.

There must be a reason why none of the world's largest telescopes are situated on the Cape Verde islands. I couldn't guess why, but a great deal of "on the ground" work goes into selecting suitable sites. It is telling that the paper you cited shows only 16 observable nights in 1.6 months from Cape Verde (see page 10). One benefit that Cape Verde has over the Canaries is being closer to the equator. That means the difference between day / night (and hence the number of dark hours each night) lessens the closer you get to 0° As does the seasonal variation. And, of course, it makes more southern hemisphere targets easier (or possible) to view.

It might be worth considering the effects of 100% humidity inside the observatory. Condensation can be as harmful as water ingress. In England I found that this (inside my water-tight garage) caused things to rust and connectors to corrode.

That's interesting The image I posted has some 4.5 Mag stars just about visible near U Maj's "tail" (the handle) - if you give it an extreme stretch. I guess the lens is a big part of that sort of sensitivity. As would be reducing the thermal noise in the sensor. This link: https://www.meteornews.net/2018/12/16/the-2018-geminids-from-croatia-with-raspberry-pi-meteor-systems/

Yes, it's an IP camera. This one. I have no idea what the FR of the lens is, but the image circle is about 6mm, which is a shame since the sensor is too narrow to fit it all in. Like you, I can't find a way to get more than the programmed maximum exposure time which is purportedly 80mS, hence the stacking. The camera does get quite warm in use, which is where the noise comes from. It looks like it might be possible to separate the imaging part from the SOC which handles the connectivity. As for the LP, it varies with atmospheric moisture. Usually around an SQM of 21.5 and occasionally down to an SQM of 21.8

If it's any consolation, here's a sample from my IMX291 + 1.7mm lens The image is a stack of 10 shots taken at about 23:00 a few nights ago. North is to the top. You can see Polaris, U.Maj and Bootes - Arturus is the bright star in the lower half The red light on the right is my Wimax internet connection

Was that the $10,000 Astrophysics cardboard box or the one from the local supermarket, for free?

None of the options you are looking at are cooled cameras. So on that basis I'd suggest another uncooled camera, an OSC one ...... a modded DSLR.