Sky & Telescope - May 2023 - 59

STACKING: JOHNNY HORNE
stacks short exposures, building up the
photograph while you simply sit back and
watch. This type of imaging is known as
live stacking. It opens up a lot of possibilities
for deep-sky photographers at
any level of expertise and makes capturing
impressive images much easier. Live
stacking is long-exposure astrophotography
approached a different way.
Several current programs
TABLET STACKING Several manufacturers
offer live-stacking programs that work with
their cameras and other devices. Seen at left
is the ASIAir Plus performing live stacking of
hundreds of short exposures of NGC 2244,
the Rosette Nebula in Monoceros.
puter or tablet to run the software.
Your choice of camera is important
include live-stacking capabilities:
AstroToaster (astrotoaster.com),
Jocular (https://is.gd/jocular), SharpCap
(sharpcap.co.uk), and TheSkyX
(bisque.com) as well as some programs
tailored for specific cameras. (The ASIAir
Plus reviewed in the May 2022 issue
includes ASI Studios with a live-stacking feature.)
Originally intended for electronically assisted astronomy
(EAA), in which the image slowly builds up on the computer
or tablet screen as you keep exposing, live stacking allows
you to share the image with the public right at the telescope.
This type of " observational imaging " has been around for
quite some time. Manufacturers like Mallincam have long
included it with their own cameras.
Live stacking isn't limited to outreach. It can simplify your
astrophotography rig by eliminating the need for autoguiding
- the tracking corrections typically required when taking
exposures of several minutes or more. That means you can put
away the guidescope, extra tube rings, and autoguiding camera
as well as all the cables and additional power needs. At the
most basic level, you only need four things to live-stack: your
telescope, a tracking mount, a low-noise camera, and a comfor
live stacking. As noted, those with
the latest low-noise CMOS sensors will
yield the best results. Rather than seeking
a specific detector, look for models
that have low readout noise levels as
well as high quantum efficiency.
You can live-stack with planetary
cameras as well as cameras with active
cooling designed specifically for deepsky
astrophotography. I've had great results with planetary
cameras by ZWO, Player One Astronomy, and QHY while
imaging during cool-weather months in the fall and winter.
But bear in mind that uncooled cameras such as these will
produce more thermal noise in warm conditions, so a cooled
camera will give you better results year-round.
Another important factor to consider is the size of the
camera's field of view. Models featuring small detectors may
make it difficult to place your target within the frame. In
addition, a good Go To mount will take the difficulty out
of finding objects and help you image multiple targets in a
single evening.
Tracking and Exposure
As with other forms of imaging, your telescope mount's
ability to track the sky remains the most important factor to
SLOW BUILD Left: A single, 30-second exposure of NGC 891 in Andromeda reveals the galaxy amidst a field of noise. Right: After one hour of livestacking
120 individual 30-second exposures, NGC 891 achieves a smooth appearance, and several background galaxies become visible.
sk yand tele scope .o r g * MAY 2023 59

http://www.astrotoaster.com https://www.is.gd/jocular http://sharpcap.co.uk http://www.bisque.com https://skyandtelescope.org/

Sky & Telescope - May 2023

Table of Contents for the Digital Edition of Sky & Telescope - May 2023