No.1 - Welcome to the EAA Universe

Welcome to my new blog, covering that little corner of the amateur astronomy world know as Electronically Assisted Astronomy - or just EAA for short. Let's start with the obvious question in most people's minds.....

What is EAA?

Fortunately for me, I can't be blamed for picking that name and acronym, which really gives no clue as to its meaning. Well, what do EAAers do?  Quick answer: 

Take a digital camera, place it at the focus of a telescope (or sometimes a telephoto lens), point it at a target in the sky, and use specialized EAA software  to create a continuously updated image of the target in real time, usually with the telescope on a tracking mount. When I talk about "targets",  I am primarily referring to deep sky objects (DSOs), like star clusters, nebulae and galaxies, although EAA can be used to view planets, comets, the moon and the sun.   

How does that differ from astrophotography (AP),  you may ask? Well, like EAA,  astrophotography uses a camera to take one or more pictures through a tracking telescope, but with the goal of eventually producing a single final image of the target with as much detail as possible... and for AP that final image could involve multiple hours collecting images. The key difference between EAA and AP in my mind is that, unlike AP,  EAA is about producing a view of the target in near real time while the EAAer is actually observing the object, albeit on a screen. That observation takes place with the EAA-observer either in front of a computer at the telescope, or perhaps (on a cold winter night) in front of a computer and screen inside the house, which is remotely connected to the computer at the scope. In either case the EAAer is looking at the target on a screen, while the telescope is pointed at the target. Good EAA software will allow the observer to tweak that view in real time,  on-the-fly, to bring out details while still  watching the image on a screen. Nearly all EAA software will also use a tool, called live stacking, to continuously align short sub-exposures, and display the growing live stacked image of accumulated aligned sub-exposures on that same screen. So, for example, the view of a target after a single 15 sec exposure will evolve after, say 5 minutes, into a more detailed live stack, consisting of 20 x 15 sec exposures. During those 5 minutes, someone doing EAA will see more details  in the target emerge, as each sub-exposure is layered onto the previous ones in a stack - those details could be the spiral arms gradually becoming visible in a galaxy image, or wisps of nebulosity becoming clearer over time when viewing an emission nebula.

Doing EAA, unlike AP, is not a "data collection" exercise where images are collected as part of a data set (along with calibration frames) to be processed into a (hopefully) stunning image at some future point in time (next week, next month?) using the magic tools of modern post-processing AP software, such as PixInsight. Instead, EAA is  the experience of seeing  (on your phone/tablet/computer's screen) and perhaps recording, a continuously updated view of the target of interest while at the telescope in near real time - not later. In contrast to AP, any processing in EAA is done in real time, on-the-fly, by the EAA software controlling the camera, as that image builds on the screen since EAA is primarily an observing experience. Some people straddle both EAA and AP, by saving their EAA images as a record of what they have observed at the scope (i.e. EAA),  and later on post-processing these EAA captures to produce a "nicer image" (i.e. AP).  Post processing an EAA capture to either produce a better/nicer image than the original, or perhaps to extract additional details in the image,  is what I would consider casual AP, as the goal  has shifted from the original intent of documenting what is seen in real time. There is nothing wrong with casually enhancing one's EAA image, but if we're being honest,  it's AP not EAA.... in my humble opinion.😉

 What can you see doing EAA ?

Now that I've tried to describe what EAA is, the natural question to ask is what can an amateur expect to see using EAA? That of course depends, like so much in amateur astronomy, on what equipment you have (how big or fast a scope, what camera, etc.), as well as how much light pollution is present,  what total exposure you use for your EAA capture, and what type of target you want to look at.  

Omega Centauri; 1 x 15s

  Perhaps a couple of  images will help to show what can be seen via EAA. For example, I recently wanted to try and  get a quick look at Omega Centauri, the brightest and largest globular in the sky; unfortunately it only reaches about 9 degrees above my horizon.  I took a brief single 15sec EAA snapshot with my 130mm f/7 triplet refractor, using SharpCap EAA software to control a Player One Apollo-M Mini camera and capture this view, which is what I saw on the screen.  I did continue to view it over the course of a longer live stack, but the single 15sec snapshot showed enough detail, down to the globular's core, for me to get a sense of how this target compares with other globulars - it's huge: larger in apparent size than the moon!

Horsehead Nebula; 12 x 15s

You may have noticed that the above black and white image of Omega Centauri was taken with a monochrome camera, rather than the one-shot-colour  (OSC) cameras that are widely used in EAA. For a target with a lot of colour, such as bright emission nebulae, many EAAers prefer the extra dimension that colour provides - a good example being this 3 minute exposure of the celebrated Horsehead Nebula. It was taken with the same AT130EDT as Omega Centauri, but in an  f/1.6 afocal configuration for this fainter target, and with a Player One Neptune- C II camera, and dual narrowband filter to accentuate the nebulosity. As a general rule in both EAA and AP,  different targets benefit from specific combinations of cameras, filters and scope configurations:  one-size- fits-all is usually not the best way to go. There is also a trade-off with the ultrafast f/1.6 configuration - you get to see the target details in less time, but at the cost of aberrations away from the centre of the field of view. Sure, there are alternate very fast optical configurations that don't have those pesky off-axis aberrations, but those optics usually are not inexpensive....

 

Part of the fun of EAA, at least for me, is trying out different set-ups to see what combinations work best at teasing out detail for a particular object. I will be adding monthly lists of possible EAA targets that are within reach using EAA equipment and typical EAA exposures. For me, that can mean anything from say 15secs (such as Omega Centauri) or less, up to perhaps half an hour - That is about as long as my attention can hold while I watch a live stack, but some people might want to go longer. 

I have added a variety of objects for May and June on this blog website under the category EAA Monthly Target Lists, and will cover other months down the road. Happy hunting!