Knight of Clear Skies

Have I caught it in this wide but shallow mosaic or am I looking in the wrong place please?

https://skyandtelescope.org/astronomy-news/astronomers-discover-huge-circular-arc-near-the-big-dipper/ 30 degrees long, that's three times the apparent size of Barnard's Loop. Here's the MDW survey image.

The 250D should be good for AP although it would require modification (removal of one of the IR filters) to give the best results on nebulae by improving its sensitivity to Hydrogen-Alpha emission. There are some very large DSOs up there that don't require long focal lengths to image. For example, this is a 2-minute exposure of M31 at 135mm after a quick image process, taken from a dak site.

The Takumar 135mm f3.5 is a good budget AP lens. This is my most recent effort with it, with Ha data blended in from my Samyang 135mm f2.

Agree with the above, I'd think more about the camera than the scope. I'd just like to add, guiding isn't essential with a low-read noise CMOS camera. This was taken with 30 second unguided subs using the 1600MM cool.

I have both an unmodded 6D and an old modded 1100D, the latter offers better value for money. Here's an example image taken with a kit lens.

Very good indeed. I guess this Apollo 15 panorama was taken near 'Elbow'?

Thanks. I've had a few goes with it now, sometimes the edges come out very distorted and I've cropped out the edges, other times its much better. I think it likes slightly shorter exposures but I'm not quite sure.

Strictly, yes, although as it's a drinking song some slurring is acceptable.

I was going for metre over sense, although I doubt I've succeeded at either.

I'm not sure what to advise really, as shooting RGB with the 1600MM should work better than using an OSC camera. Could you post an example please? We may be able to diagnose the problem. Personally, I've had much less trouble with colour balance shooting through RGB filters on the 1600Mm cool than with OSC.

"What shall we do with the LX200? What shall we do with the LX200? What shall we do with LX200? Er-lee in the morn-in! Chuck it in a van and [removed word] the collimation, Chuck it in a van and [removed word] the collimation, Chuck it in a van and [removed word] the collimation, Er-lee in the morn-in! What shall we do with the LX200? What shall we do with the LX200? What shall we do with LX200? Er-lee in the morn-in! Leave the cover off and refit the tensioner knob, Leave the cover off and refit the tensioner knob, Leave the cover off and refit the tensioner knob, Er-lee in the morn-in! Shouldn't do that with the clutch knob tightened, Shouldn't do that with the clutch knob tightened, Shouldn't do that with the clutch knob tightened, Er-lee in the morn-in!"

There are other ways of expressing this but I'm not sure the (anthropomorphised) forum censor will play ball.

I've never been impressed with arguments along these lines. After all, I've never been to China but there is a great deal of indirect evidence that it exists. Similarly, we have a great deal of evidence that the wider universe contains the same elements and follows the same rules of physics. Helium is a good example, it was discovered by looking at spectral lines from the Sun before it was found on Earth. Some things we really do understand very well. Relativity has passed every test in the most extreme natural laboratories we've been able to find, and spectral lines from distant Quasars show that the fine-structure constant cannot have changed by very much (or at all) over the history of the universe. Modern physics and cosmology aren't so much wrong as incomplete, there is a classic Isaac Asimov essay on this subject. There is also a great deal we don't understand and a point we can't, and perhaps never will, go past.

Taking another look at this one, I haven't seen an image I've liked more for some time. I wonder if there is any OIII signal in the area? It might shed some light on the nature of the ring.

Great to see the detail on HH-55. I also notice there are a couple (I think) detached cometary globules on the left. Personally, I'd try reducing the saturation of the image to see how it looks.

The ancient Greeks knew the Earth was round rather than flat, for one thing they observed that the masts of ships were the first to appear over the horizon. In 240 BC Eratosthenes calculated its size. "Eratosthenes had heard from travelers about a well in Syene (now Aswan, Egypt) with an interesting property: at noon on the summer solstice, which occurs about June 21 every year, the sun illuminated the entire bottom of this well, without casting any shadows, indicating that the sun was directly overhead. Eratosthenes then measured the angle of a shadow cast by a stick at noon on the summer solstice in Alexandria, and found it made an angle of about 7.2 degrees, or about 1/50 of a complete circle. He realized that if he knew the distance from Alexandria to Syene, he could easily calculate the circumference of Earth. But in those days it was extremely difficult to determine distance with any accuracy. Some distances between cities were measured by the time it took a camel caravan to travel from one city to the other. But camels have a tendency to wander and to walk at varying speeds. So Eratosthenes hired bematists, professional surveyors trained to walk with equal length steps. They found that Syene lies about 5000 stadia from Alexandria."

Hadn't previously realised quite how high Sagittarius gets in May, here's a 40 minute timelapse from the 14th (best viewed on YouTube as the forum tries to stretch the video to the screen width). Was worth staying up for especially as I'd booked the next day off work. Taken with the 6D and Samyang 14mm and stacked in Sequator, the edges have been cropped down quite a bit to remove distortion. Used the fee edition of VSDC to create the video and add the labels. There's a quick write up and some more images from the same night here if anyone is interested.

Nice image and write-up. I can't remember seeing the outer halo on this target before.

To my eye, the starfield looks better on the left but there are details in the nebulosity in the right hand image that can't be seen on the left hand one. I wonder if a colour presentation next to a mono Ha or bicolour to show more detail is the way to go. Alternatively, put both versions on top of each other on a webpage with a slider to adjust the stars (opacity change).

Museums if they were lucky, gout remedies if not.

Very impressive. My only concern is, will I ever be able to unsee the face and look at the nebula?

Occam's razor tells us it was unlikely to be a six-year old's terrarium.

Think you mean the HEQ5? As I understand it, it depends what scope you put on it. The NEQ6 doesn't necessarily track more accurately but has a higher payload capacity, whereas the HEQ5 does track better than some cheaper mounts. Both mounts require guiding (guide-scope + camera) to achieve long exposures.

Essentially, tracking accuracy and payload capacity.