astroavani

A Saturn that had not yet had time to process, I had to travel. Posting late but still worth it because the good nights here are diminishing with the approach of winter and the polar fleet starting to make itself present.
https://www.astrobin.com/full/407458/0/?nc=user

That is one of the few things I like to observe visually, LOL, I am exclusively a lunar and planetarium photographer.
Here in the southern hemisphere we have some beautiful stars of carbon, among which I think is very beautiful is one that is next to Mimosa (beta crux) the contrast between white and blue Mimosa red star is an exceptional sight. https://www.flickr.com/photos/lrargerich/8465766540/
Here is a quick description: Beta Cru (b), Mimosa mag 1.2 is a brilliant blue white giant marking the end of the eastern limb of Crux. A crimson-red carbon star, EsB 365 mag 8.6 lies 2'.4 in pa 260 ° in the same field. Center beta in your field of view and the carbon star is easily located at approximately 9 0'clock as a bright red pinpoint star. If you have difficulty seeing this, look slightly away so your vision is averted as your peripheral vision is more sensitive to faint objects. In your telescope, 86 x magnification should distinguish it clearly.
Nice photo, Reggie, I'll try to look at it at the first opportunity.

A doubt!
Before April 1st, images are not accepted in the challenge?
Only those that are made after that date?
Best regards
Avani Soares

On 02/03/2018 at 09:18, vlaiv said:

Honestly, I don't quite understand what you said

But I would like to point something out.

2.4 pixels per Airy disk radius is theoretical optimum sampling value based on ideal seeing and ability to do frequency restoration for those frequencies that are attenuated to 0.01 of their original value. This means good SNR (like 50-100 SNR) to be able to do that, as well as good processing tools that enable one to do it.

In real life scenario, seeing will cause additional attenuation of frequencies (but not cut off like Airy pattern), that is combined with Airy pattern attenuation and cut off. So while ideal sampling will allow one to capture all potential information - it is not guaranteed that all information will be captured. On the other hand, I just had a discussion with Avani in this thread:

where I performed simple experiment on his wonderful image of Jupiter taken at F/22 with ASI290 to show that same amount of detail could be captured with F/11 with this camera. He confirmed that by taking another image at F/11, but said that for his workflow and processing he prefers using F/22 as it gives him material that is easier to work with. So while theoretical value is correct, sometimes people will benefit from lower sampling - if seeing is poor, and sometimes people will benefit from higher sampling simply because post processing and tools better handle such data.

So bottom line to this is that one should not try to achieve theoretical sampling value at all costs. It is still good guideline but everyone should do a bit experimenting (if gear allows for it) to find what they see as best sampling resolution for their conditions - seeing and also tools and processing workflow.

Yes, we've been talking about this in another post!
I do not know if they can understand me, I do not speak English and I depend on the translator,
 One very interesting thing is this Signal / Noise issue. According to Vlaiv, considering the Niquist theorem, he used the Fourier transform to determine the best point of image capture, in which case he arrived at F / 11. No problem at all! Very straightforward, since the Fourier transform is used in the manipulation of analogue / digital signals.
I found the approach quite pertinent. On the other hand, he exemplified with an image of mine, in which he transposed to another image that would be the image in F / 11 so as to compare the capture of details. I do not know how he does it with JPEG image, everything he approached has his application share and he knows the limitations (even because he does not mention them). In theory, all that applies and would be the ideal of worlds. But the world is not ideal and one of the biggest variables that I see is precisely that of the lack of idealism.
Translating, under controlled conditions, all mathematics will apply to Niquist's theorem and all. In practice, variation occurs. Because? Because the system is not ideal, it is stochastic, that is, it varies at every moment. This is the domain of stochastic calculation, much more complex and difficult in order to generate a mathematical model that comes closer to reality. That's what stochastic calculation tries to do. We can? Yes, but not in full. For example, use the Monte Carlo Method to get a template that applies to the conditions in which you capture your data. For this we would have to have a large mass of data and determine what data (variables) we would consider. The more variables, the more computation time is applied, which can take hours, days or months. So nobody does it amateurishly.
You have to have access to supercomputers or computer clusters. Some variables: humidity, temperature, pressure, number of particles in the atmosphere, optical distortion of your equipment, electric flow in the CCD, data capture and drainage speed, data archiving form, processor TDP, processing capacity, etc. That's why math helps you not to waste time, but reality is far from it, it comes close, but it's not reality. All this is a simulation to represent reality and not reality. So what's this for? So you do not waste time on empiricism. In other words, the best catch of subtle details is, in your case, around F / 11. It may be F / 18, F / 22, but it will not be F / 60 or F / 80. How to know? As Dr. Strange's movie says: Study and Practice? The study tells you where you can be, but practice, where it really is. Its atmosphere does not leave, it is not mathematical, it approaches, but it is not ....

20 hours ago, Pete Presland said:

Fantastic construction Avani, nice to put a face to your very familiar name. The internet gets a lot of bad press at times, but I love the fact we can interact with fellow astronomers all around the world with such ease.

Thank you, friend Pete! It really is good to meet people who hide behind Nick sometimes. Of course this is not always advisable, but we can not deny that it creates greater intimacy.

15 hours ago, andyboy1970 said:

Very nice.

How do you rate the 12" GSO as a scope?

It's a great telescope! I had two exactly alike and all two had very good optics, this makes us think that good optics is the rule, not the exception. I also really like the mechanics of GSO being the first to offer crayford focal point as standard on relatively inexpensive cost. Collimation is easy and will last for a long time if you consider other Newtonians I've had such as Sky Watcher and Orion UK.
Anyway I have a certain passion for them and I can say that they are worth every cent invested, only, in my case you can not compete with a C14 still above the Edge line.

A cool video my friend Rafael Compassi made about the Parsec Observatory: https://youtu.be/TzUTI4_c-O4