eVscope - How to Confirm Finds?

Introduction | Nova Astrometry.net | Preliminary Conclusions | References

On this page, I will go again, for the eVscope, into the question of how to confirm that you have actually photographed or seen the intended sky object. I already wrote the essentials in the section about the Atik Infiniy camera and this can be read there. Here I only add first experiences with so-called "plate solving" programs, more precisely, only one, namely Astronomy.net.

Note: See page Overview of the eVscope Pages for just that!

 

Introduction

So the basic question is when doing quick astro photography with the eVscope: Is what you see in the eyepiece or on the smartphone screen indeed the sky object you are or were looking for?

Successful Finds

First, I would like to address the successful finds! Unlike visual observations, photography provides a result that can be easily compared with photos or sketches from books or the Internet. My preferred sources are described on page Atik Infinity Colour Camera - How to Confirm Finds? further below. In addition, the eVscope delivers a result that is more similar to that of cameras than to the visual impression. Therefore, comparing photos with photos is usually preferable to comparing them with drawings, which usually correspond to the visual impression. But I often use both to see how the individual representations differ and complement each other.

Not so Successful Finds

Now let me turn to the "not so successful finds"! When I compare my photos with photos or drawings from books or the Internet, I can unfortunately not find a match in some of them. Obviously I had photographed something completely different than intended - but what? Initially, I had the obvious idea to use astronomy programs to search the surroundings of the "unknown objects" for matching patterns. But so far my experiences with these programs have been such that I was hardly able to establish a relationship between what the camera photographed and what the programs show. In other words, the programs do not help me in my search.

The Solution: Plate Solving

So I looked for other solutions. And that is when I came up with the term "plate solving," which stands for algorithms that can recognize which part of the sky a camera or a photo shows. I had already stumbled across this term in connection with the eVscope, because it uses this technique itself to find objects in the sky. But I had not pursued this topic any further, particularly since I did not see any practical use in it for me at first. But after so many failures in photographing open star clusters with the Atik Infinity camera, plate solving appeared to me as a viable approach way to find out what the camera actually photographed. This impression was also confirmed when I came across the Website of Dietrich Kracht, who describes this method and programs in detail (in German). More about this on page Atik Infinity Colour Camera - How to Confirm Finds? > Plate Solving!

At the beginning of 2020, I had a similar problem with the eVscope: On some of the photos that I took with the eVscope, it was not clear to me whether the object on the photo (or as it was labelled on the photo) was really the object I was looking for. Visual comparisons with my books did not always lead to success, and so I resorted to the plate solving method!

 

Nova Astrometry.net

Dietrich Kracht describes two plate solving applications, All Sky Plate Solver and Nova Astrometry.net. The latter is a Website that allows you to find out which part of the sky is shown on photos (instructions for Nova Astrometry.net by Dietrich Kracht, in German) and thus, an "easy" alternative to All Sky Plate Solver. In contrast to the latter, you have to be connected to the Internet (there also seems to be available a way to work offline using Windows). As with All Sky Plate Solver you start from photos, but upload them to the Website and have them be processed there.

One advantage of Nova Astrometry.net is that you get sky maps right away and do not have to enter coordinates into an astronomy program to see the corresponding part of the sky.

I tried Nova Astrometry.net with several photos taken with the eVscope. These were photos where I was not sure what they showed or whether they were labelled correct. Here are some examples!

NGC 884/869

NGC 884/869 - eVscope, processed (below NGC 884)

NGC 884/869 - eVscope (far left of NGC 884)

NGC 884/869 - eVscope (NGC 884)

M 35, M 36, M 38

M 35 - eVscope

M 36 - eVscope - wrong label

M 38 - eVscope

 

Preliminary Conclusions

With Nova Astrometry.net, thanks to the Website of Dietrich Kracht, I found a solution that make it quite easy to determine which part of the sky my eVscope photographed.

 

References

 

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27.09.2020