Knight of Clear Skies

I you have a clear horizon, you could try aiming at a light in the distance and take a long exposure with the tracking on. It should produce a clean arc, if it wriggles back and forth it's likely to be periodic error. I had my SA replaced and the new one seems to be fine, but I've had very little opportunity to use it.

Here's the same article on Medium, for better readability. As currently planned, Starlink is going to kill survey telescopes such as the LSST and Pan-STARRS.

Nice work. Hadley Rille pops out with the zoom, here's the view from the surface.

What camera did you use please?

Agree it's a good low-cost lens, but it's not necessarily the best budget choice. There are some decent 400mm m42 lenses out there which will give better results on the Moon if you can nail the focus, as I said in my post above mine cost £10 from a charity shop. That said, I was lucky to find one for that little and the ef-s 50-250mm is a better all-round lens, with its auto-focus, image stabilisation and larger aperture.

135mm lenses tend to work well, possibly because the old ones have a simple optical design. 50mm lenses are usually good at about f4-f4.5.

I can only guess those filaments are the result of one or more supernovae, probably the latter.

Interesting thanks. Many online sources still quote Deneb as a possible ionizing source but reading the linked article that seems unlikely.

Just to add, I believe H beta filters are more useful for visual astronomy as the human eye is more sensitive to blue light than red.

That's a surprisingly deep image, those outer arms are pretty faint and people spend a lot of time chasing them. It would be handy if you could put your equipment in your signature please, as I'm not sure camera and lens you used.

Your post is correct and well explained, but just to be clear increasing the sub length is likely to be counterproductive if it leads to a high proportion of lost subs. It's difficult to know what the optimal sub length is, I believe it can only be calculated from the read noise of the camera, the local sky brightness and speed of the optics. But longer subs run into diminishing returns fairly quickly. If I'm remembering correctly from a dark site and a camera with moderate read noise such as a 600D the improvement in SNR becomes quite small beyond about the 2-4 minute mark. (Treat what I'm saying with a little caution here, I'm a bit sketchy on the subject). Long subs are most important when using a high read-noise CCD to image the faintest objects. From my own experience, it's possible to pick up a fair bit of IFN using a DSLR and unguided 1 minute subs at f2.8. (This would be equivalent to a 4-minute sub at f5.6.)

Shame about the wind, but hope you got some decent data from the dark site. Probably, yes, in this particular case. Longer subs reduce read noise in the stack, but I'd be surprised if that could make up for losing 2/3rd of your data.

From a relatively low-cost imaging rig too.

Nice small stars, did you use a front aperture mask to stop down to f2.8?

It's a tricky one, while the ASI 294MC Pro is certainly good ~£1,000 is a lot to pay for a colour camera, where only 1/4 of the pixels are sensitive to Ha. Just a thought but would getting the 1100D modded and investing in a clip-in Ha filter be more cost effective? I've been getting good results with mine, even when shooting from a very dark site it allows much fainter nebulosity to be isolated from the background. Blending Ha into the red channel of an RGB image is easy if you can get the images aligned. Below I've shown the difference that blending 46m of Ha data into a 2h20m RGB image makes. But please bear in mind I'm shooting at f2.