Astrophotography can be a complex process, and anything that simplifies the task is welcomed with open arms. An easily overlooked aspect of astrophotography is the software that helps to not only allow your equipment to function, but to help plan shoots, and to process the perfect image. These handy tools are a must have in any astrophotographer’s arsenal. This guide will breakdown the different types of software available, as well as some of the leading programs for each category and what they do. Before we begin, an unfortunate truth about astrophotography software is that there is an unbalanced favor toward Windows over Mac operating systems, and while we do our best to get around this, and provide alternatives for Mac users, this guide will primarily be of benefit for Windows users. Links to all of the software downloads are provided in the descriptions, and it is highly recommended that after downloading, you view associated YouTube video tutorials so that you can master these programs.
Equipment Interface: ASOM, INDI
There are a number of different pieces of equipment that you will operate during any given astrophotography session, from your mount, to your guide scope, cameras, focusers, and filter wheels. As each piece of equipment is developed by different companies, and in many ways they are often communicated in their own languages, making it difficult for this array of equipment to work together as needed. This is where an Equipment Interface comes in—working as a sort of middleman between all of your equipment, an Equipment Interface is a collection of drivers and scripts that allows different programs to work together on a single piece of equipment. This means that you can have one program meant to find a celestial object and another meant to guide your scope both interfacing with your mount at the same time, allowing you to build a fully automatic environment from a single computer station.
The leading Equipment Interface, by far, is ASCOM—or, the AStronomy Common Object Model. ASCOM was developed in 1997 by Bob Denny, and began to be implemented in observatories as early as 1998. Since then, ASCOM has become a staple in almost every astrophotographer’s software kit, amateur or otherwise. ASCOM is a free to use, open source software, so many of the software on this list were specifically designed with ASCOM compatibility in mind. And this is where Windows users have the advantage, as ASCOM was designed under COM standards, and other astrophotography software followed in order to take advantage of ASCOM’s capabilities, leaving Mac behind. Although it has been in development for many years, ASCOM Alpaca is a Mac alternative that has yet to be released.
An alternative to ASCOM is the INDI Library—or, the Instrument Neutral Distributed Interface. Created by Elwood Downey in 2003, INDI functions as a single server that performs input/output for all users, not only on Macs but on Windows as well, although it does not run natively on Windows and is not as decently maintained. While not as popular as ASCOM due to the lack of equipment support in comparison, INDI has made some great strides in recent years, and is the number one choice in Equipment Interfaces for Mac users.
Camera Drivers
Of course, you will need the individual drivers for your camera. These can be found at the manufacturer website, but the reason it is included in this list is because you will need to make sure that these drivers are compatible with either ASCOM or INDI. Sometimes, this only requires the download of one driver, other times this requires the download of specific drivers that are compatible with your chosen Equipment Interface.
Planetarium Software and Mount Control
Knowing when and what celestial objects are available to shoot in the night sky is a large part of the battle for astrophotographers. Thankfully there are a number of different planetarium software available that can help you to plan your shoot, and even help you to frame your shot based on the equipment that you are using, all ahead of time. There are two main leaders in planetarium software, Stellarium and Cartes du Ciel, and what’s even more impressive is that both software are available for free and for both Windows and Mac.
From these programs, you can easily set the viewing location, date, and time to see what is available at the location and planned time of your shoot. Stellarium takes this a step further by enabling a user to create a simulation of your shoot by experimenting with different telescope, lens, and eyepiece combinations to create an accurate approximation of what you can expect out of your shoot. Save, of course, for any weather interruptions. Where Cartes du Ciel excels is the clean interface, ability to schedule in a calendar, and the fact that it is slightly more technical. Typically, amateur astronomers and astrophotographers alike will download both Steallarium and Cartes du Ciel for their individual benefits and use them in conjunction with one another.
Both software also allow for GoTo mount control with your telescope, although many astrophotographers will also utilize EQmod, which is explicit mount control software designed for use with Synta EQ mounts, meaning both Sky Watcher and Orion. Stellarium and Cartes du Ciel will work, but EQmod is the preferred form of mount control should it be compatible with your EQ mount.
Autoguiding
A requirement of all deep sky astrophotography is Autoguiding software, which utilizes a second guide telescope and camera, to track the movement of stars as the earth rotates. While this used to be adjusted for manually, Autoguiding software removes the labor and huge risk of mistake in trying to track your celestial target during and between long exposures. Autoguiding software detects any movements and then provides real-time correction commands that are sent directly to the mount, taking almost all of the guiding work off of your shoulders.
Although there are numerous programs out there, the most popular Autoguiding software is easily PHD—or, Push Here Dummy. PHD is a free software that, just as impressively, is also available for both Windows and Mac. Designed with an incredibly simple to use interface, hence the name, PHD is an automatic calibration and Autoguiding program that takes into account camera orientation, pixel size, scope focal length, etc. Most of this is even done automatically, so that you can just click on the PHD Guide button and the program does the rest. It’s as simple as Autoguiding comes.
Plate Solving
The term plate solving goes back to the days when one of the first steps an astronomer would take was the referencing of glass plates on which star patterns were engraved. These plates were then matched to stars to determine accurate location in the night sky, thus solving your positioning and target with said glass plate. Today, the term is used colloquially to reference the process of capturing an image, and then comparing said image to a database of stars to determine the location of the image. This creates a multi-point star map that is then used to analyze the image for errors in polar alignment, field rotation, and whether or not you have set up your equipment at precisely the same location if you’re returning for a new, or to complete, a series. Plate Solving can be used both before and during a shoot.
The most popular Plate Solving software is SharpCap Pro, which unfortunately in only available for Windows and has a very reasonable subscription cost of $15 a year. This is especially true when considering the extra features that SharpCap Pro offers, such as focus assistance, mount control, polar alignment, and the ability to save your camera settings for individual targets, as well as many other various features, including planetary stacking.
A Mac alternative would be the Plate Solving feature contained within EKOS, a widely-used alternative to some of the Image Acquisition software covered below, particularly for people who are not fond of the Windows operating system. EKOS also works very well within the INDI suite.
Image Acquisition
Image Acquisition software is designed to streamline and automate your astrophotography sessions. These programs can help not only with remote control of your camera, but with a number of tasks associated with obtaining the perfect image, and are considered an absolute essential for most astrophotographers. They are designed to be as versatile and all-encompassing as possible, and we will cover the two main Image Acquisition programs below: APT for Windows and Nebulosity 4 for Mac.
Self-described as the Swiss Army Knife of astrophotography, APT—or, the Astro Photography Tool—is the leading Image Acquisition program for Windows. APT is compatible with nearly every camera available by Nikon and Canon, as well as SBG, Altair Astro, and ZWO. It is also compatible with both ASCOM and INDI interfaces. It can accomplish anything from planning, collimating, aligning, focusing, framing, controlling/tethering, imaging, synchronizing, scheduling, meridian flipping, analyzing and monitoring. It’s as if APT can do it all. Better yet, it’s free! However, the developers keep a reminder in the top left corner of the interface asking for a simple donation of around $21, which is a small price to pay to support such a helpful piece of software, and said donation will also unlock a small number of additional features.
For Mac users, we recommend Nebulosity 4. Although the software is available to Windows users as well, the $95 price tag is what puts it behind APT, yet it is still relatively cheap when it comes to the world of astrophotography. Nebulosity 4 is the fourth iteration of the Nebulosity software, which was developed to simplify the interface of Image Acquisition software. Where it succeeds APT as that it not only works for camera control, focus, image acquisition automation, but also for image calibration and image processing.
Image Calibration and Stacking
Image Calibration is the process of taking your desired images, called Lights, and removing what amounts to “bad data” from them known as noise, which is measured through a series of frames known as Darks and Bias. Your Dark and Bias frames are then combined and removed from the data within your Lights via a process called Stacking, which creates a layered image that highlights all the wanted contrast, color, and definition of a successful astro-photo.
The most popular of Stacking software is a free open-sourced program known as DeepSky Stacker. The program works after your register your images after a shoot, using only your best and clearest captures, and then integrates and calibrates them with your Dark and Bias frames. Taking advantage of its default setting. DeepSky Stacker can even do the integration and calibration on its own, while you step away from your computer or head to bed for the night. Unfortunately, DeepSky Stacker is only built for Windows, and, as the name implies, only functions for DeepSky objects. For stacking of planetary or lunar images, it is suggested that you take advantage of the planetary stacking feature within SharpCap Pro.
For a free alternative for Mac users there is Lynkeos, although unfortunately this software is made more so for planetary and lunar imaging than for deep sky objects, although people have made it work. If you find it lacks the tools you need for stacking deep space images, you might try Nebulosity 4, which we covered above, although unlike DeepSky Stacker and Lynkeos, the stacking process is not automated and requires more from the user in terms of labor.
Post Processing
After you have an image that has gone through the calibration and stacking process, there are a number of things you can do to refine and polish your photograph by emphasizing contrast and color, and these are done through your traditional photo editing software, such as Photoshop. There are also a number of Photoshop plug in specific to astrophotography that are available, such as the Astronomy Tools Actions Set for $21.95, the Nik Collection for $149, or GradientXTerminator for $59.95, as well as many others. However, not everyone wants to pay the Adobe subscription fee every month, and then for the plug-in licenses on top of that.
An alternative to Photoshop, that avoids the hassle of purchasing and implementing a number of extra plug-ins, is PixInsight, a post processing software that was built specifically for astrophotography, and is quickly becoming the standard software. Running at a cost of $278.91, PixInsight might be one of the more expensive software for astrophotography, but it is worth the price if you plan on seriously pursuing the hobby.
A free alternative that is used by many astrophotographers is GIMP—or, the GNU Image Manipulation Program. GIMP can do everything that Photoshop can without the cost to your pocket, and is actually preferred by many astrophotographers due to the nature of GIMP’s selection tools in regards to layering and mosaics.
