The AstroHutech Hinode SG solar autoguider has but one task in life, namely to keep a telescope pointing directly at the Sun.
Autoguiding is most commonly used in long-exposure night-time imaging, when a dedicated guide camera feeds your computer with an image, which is monitored using software.
If a designated star on the image drifts out of position, the program issues the necessary commands to the telescope mount to correct the situation.
Of course, you don’t need to take long exposures of the Sun because it’s so bright.
However, with daylight hiding every other star, it’s not possible to accurately polar align.
For short solar imaging sessions a rough polar alignment is normally sufficient.
For longer ones – public demonstrations or timelapse imaging, for example – the lack of alignment and having to constantly correct the telescope’s aim can be a real pain.
This is where the Hinode solar autoguider comes to the rescue.
The main part is a detector unit, which fits into a standard Vixen/Orion/Sky-Watcher finder shoe and replaces the regular finderscope, which isn’t required for solar sessions.
The detector connects to a hand controller, which can be hung on the mount by a small cord loop.
Separate cables connect the detector unit to the hand controller and the mount autoguider port. Both ST-4 and Losmandy-type autoguiding mounts are supported.
Simple set up
Power is supplied via a USB cable connected to either a computer’s USB 2.0 port or a 12V supply with a suitable adaptor – so it is not necessary to have a laptop present to operate the autoguider, although if you’re planning on photographing the Sun it’s certainly convenient to power it through one of the imaging computer’s USB ports.
The device is easy to operate.
A coarse solar finder is used to get you pointing in the right direction first.
A simple LED display then shows where the autoguider is pointing and the device can emit audio tones to assist centring the Sun too.
Once aligned, you need to calibrate the guider.
This is really simple, requiring nothing more than the press of a button.
The hand controller’s LEDs flash away while calibration occurs, which can take a couple of minutes, but once done can be stored and recalled for future sessions without having to recalibrate again.
As mount characteristics may change with the scope pointing either side of the meridian, a separate morning and afternoon calibration profile can be stored and recalled.
We used the guider many times and it performed perfectly on most occasions.
Capturing images for timelapse sequences was simple: a number of ours extended to several hours in length, but the autoguider did a great job of keeping the correct part of the Sun in view.
This was especially impressive when we came to recording the movement and changes of prominences over several hours.
Even at high magnification, the autoguider managed to keep the features of interest on the camera’s chip the majority of the time.
We tested this using a software-generated crosshair to mark a target feature.
We even deliberately misaligned our equatorial mount far more than you would achieve by poor guessing.
The autoguider didn’t seem phased by this at all and still managed to keep the scope pointing accurately.
Amazingly, it dealt with clouds quite well too, only giving up the ghost when the Sun’s disc virtually disappeared from view.
When this happens, a descending tone sounds to indicate guiding has been interrupted.
If the clouds do clear again, the guider sounds an ascending tone and moves back to the original guide position.
There’s no doubt that this is a niche piece of kit and it isn’t particularly cheap.
However, for serious timelapse work, or for all-day solar monitoring with a non-permanent setup, the Hinode solar autoguider is invaluable.
For public solar demonstrations and outreach work, you’ll wonder how you ever managed without it.
Is this an accurate autoguider?
The Hinode solar autoguider works superbly. Guiding is achieved by monitoring the Sun’s edge and so is not reliant on variable visibility features such as sunspots.
The accuracy of the guiding can be adjusted by changing the ‘correction aggressiveness’ via the hand controller.
In addition, a more accurate measurement of the Sun’s disc can be achieved by exposure averaging.
This can be adjusted between one shot (no averaging), four shots or nine shots; the greater number of averaged shots, the greater the accuracy, although this will also slow the guider’s responsiveness slightly.
Guide accuracy is stated to be typically 1.5 arcseconds or better, but this will depend on your setup and local seeing conditions.
During our testing, the unit was certainly accurate enough to keep a highly magnified portion of the Sun’s disc aligned to our imaging camera frame for several hours at a time.
The autoguider is tenacious.
Forget to turn it off while moving to another part of the Sun’s disc and you’ll find the telescope obediently moving you back to where you had it pointing before.
AstroHutech Hinode SG’s 5 best features
The low-tech coarse finder is effective. When the detector is mounted into a telescope’s finder shoe, a raised, perforated plate on the front of the body creates a bright dot of sunlight. Everything is aligned to the Sun when the dot is made to sit on a target on a second raised plate at the rear of the detector.
Two apertures are visible at the front of the detector unit: these let the Sun’s image pass through to the electronics inside. They require no adjustment and simply need to be positioned so that they have an unobstructed view pointing directly towards the Sun.
USB 2.0 Connection
The detector unit gets its power from a USB connection. As only power is required, this doesn’t necessarily have to be plugged into a computer. However, if the cable is connected to a computer, additional software, available from the AstroHutech website, can be used to monitor the output of the guider on a PC.
The hand controller is operated through a set of buttons and also has LED indicators. The interface is simple but extremely effective. Two main modes of operation are provided: ‘Guide’ activates the autoguider, while ‘Finder’ turns it off so you can centre up another part of the Sun’s disc.
Audible tones are used to indicate that certain operations are ongoing or completed – they provide feedback when you’re trying to centre the Sun in the detector, for example. A descending tone sounds if autoguiding is interrupted by clouds, followed by an ascending tone if the clouds clear, allowing autoguiding to recommence.