I don’t claim to be an expert in EAA but here is my attempt at an explanation based on my experience of using EAA since 2012. Comments are always welcome! :o)

EAA stands for Electronically Assisted Astronomy. Some other names (which might give you a clue to what it is) include:

• Video Astronomy or VA (the original name for this area of astronomy)
• Electronically Assisted Observing
• Camera Assisted Observing
• Near real time imaging
• Live imaging........you get the idea!

Basically EAA/VA is a way of enhancing the observing of astronomical objects by using a telescope with a camera or image intensifier instead of an eyepiece. It is different to astronomical imaging in that the results are seen during the course of an observing session rather than spending hours or days taking exposures and processing the images. There are some very clever dedicated cameras and software available which allow the astronomer to ‘do’ EAA but equally it can be done with a simple webcam and laptop.

Why?

There are many reasons why astronomers use EAA/VA. These include:

• Overcoming problems such as light polluted skies or poor eyesight which make visual observing (with an eyepiece) difficult or unsatisfying
• Performing outreach activities, where many people at once can see spectacular results on a screen rather than peering through an eyepiece
• Wanting to go 'deeper' than visual can go, so for example a 30 second exposure with my setup can pick up galaxies as faint as magnitude 20!
• Wanting to share captures of the night's observations with others (like me on this website)
• Wanting to provide live video streams to share with others via Youtube, etc
• Wanting to do more scientific observing such as variables, supernovae, spectra, etc.

But whatever the motivation, EAA/VA is growing in popularity as the technology improves and amateurs see the possibilities.

How?

In general EAA requires the use of a sensitive camera connected to a ‘fast’ telescope, typically F5 or faster. The whole thing must be mounted on a mount which can track accurately without star trailing for 30 to 60 seconds. The images captured are typically viewed on a laptop or sometimes a monitor in the case of analogue ‘video’ cameras. Software on the laptop allows the images to be adjusted in real time as they are viewed. Some software also stacks multiple images over the course of several minutes to gradually improve the quality of the image. Let’s leave image intensifiers to another time as they employ different technology!

A very quick history

The term Video Astronomy came about because very sensitive low light analogue video security cameras were commonly used to capture real time images or video. This technology is still in common use but bespoke CCD and CMOS imaging cameras are commonly being used and the technology is evolving rapidly. There has traditionally been a clear distinction between imaging (which traditionally uses long exposures and lots of post processing) and EAA/VAA (which uses very short exposures and no post processing). Today the boundary between imaging and EAA/VA is becoming more blurred. Some people are producing very fine 'traditional' post processed images using 30 second exposures on alt-az mounts. Conversely others are doing EAA/VA using the sames exposure, mounts and sometimes the same cameras. Often the only difference between the two is the software used to capture and process the images.

Examples

Lots of good examples of what can be achieved and useful resources can be found at the dedicated EAA forums on www.stargazerslounge.com and www.cloudynights.com. Two good examples of what can be achieved are as follows:

• HiloDon does outreach sessions with an ultra-fast 14” telescope and camera on top of a mountain in Hawaii. Possibly the ultimate EAA setup! His gallery shows the kinds of results that can be had from a wide range of setups. Click here to view his gallery.

• Maurice Gavin (aka Nytecam on the astronomy forums) has pioneered the use of sensitive guide cameras with very short exposures to reveal faint objects from his home in a very light polluted London. Click here to view his website.