So much astro gear, so little time… by Steve Ringwood

Altair Solar Contrast Booster Filter 7 nm–540 nm Continuum 1.25” V3

Details at: altairastro.com/altair-solar-contrast-booster-filter-7nm---540nm-continuum-125-v3-10519-p.asp Price: £79.99

There is growing confidence that the Sun, after a broad crest of maximum activity, is now beginning its descent towards a solar minimum. But do not let that fool you into thinking the current cycle is not worth chasing down. The Sun remains very active, as the auroral activity earlier this year testifies. Afforded through the use of full aperture solar filters or Herschel wedges, white-light observation can be very rewarding, revealing as it does the photospheric structures of sunspots, bright regions on the solar surface known as faculae, limb-darkening and the huge convection cells known as granulation. You could also see the occasional white-light flare.

But even the broad delivery of white light can be further tailored to deliver better contrast, by limiting that swathe of light to a narrower window.

Altair’s (1.25” fitting) solar contrast booster has been improved again. Now in its third version, it is centred on a wavelength of 540 nm and the gate through which light passes has been closed down to 7 nm. This results in a marked improvement in definition, although excluding more light means a dimmer image. To compensate, the transmission coatings have been improved to offer up a hindrance of just 2.5%.

Changing its appearance daily, if not hourly, the Sun remains a fascinating astronomical object. Catch it whilst it’s hot.

Cyalume Technologies Military Grade Premium Red 6” SnapLight Emergency Chemical Light Stick

Details at: amazon.co.uk/Trading-Cyalume-Sticks-Military-Lightstick/dp/B0CBNRH9GD Price: (pack of 3) £8.50

Do not be one of those people using a blinding white light during your time at a dark site sky camp. To preserve our hard-won dark adaptation and that of fellow observers, it is critical to keep our nocturnal activities illuminated by only red lights.

Red torches and headlamps are available in profusion but all rely on electrical power, primarily through batteries. So, woe betide our conscientious astronomer when the battery runs dry; especially if the temptation of a forbidden white-light torch is readily available nearby.

This is where these light sticks come to the rescue. Bend the six-inch light stick to break the internal capsule and a chemical reaction takes place that produces 12 hours of glowing red light. Not a particularly new device, but one that is increasingly useful in our battery hungry pastime.

They are hard-wearing – and have a shelf-life of up to four years before use. Used handheld, or hanging via its integral hook, this vital piece of emergency lighting may just save you from an angry mob.

RVO Horizon 30 × 80 mm observation binoculars

Details at: rothervalleyoptics.co.uk/rvo-horizon-30-x-80-observational-binoculars Price: £189

As with all observational devices, the aperture of an instrument performs two jobs. Its diameter governs resolution in direct proportion (generally, twice the aperture doubles resolution). The other job of an aperture is to garner light. This is a function of its surface area and rises much faster than resolution as aperture increases. Consequently, a larger lens ‘sees’ fainter objects; which is what gives rise to the manic slavering towards ever bigger telescopes that is aperture fever. However, a more powerful tug on a galaxy’s feeble light also pulls in more of the background wash of light pollution – and this works to reduce a target’s contrast against the night sky. Infuriating, huh? But there’s a sneaky workaround. Adding a little more magnification spreads the background light pollution a bit thinner, disproportionately dimming it compared to a comparatively unaffected target. The additional magnification therefore works to improve contrast.

This is where the unusually higher magnification of these observation binoculars comes in, rather than the more commonly found 15–20 × of other instruments in this aperture range.

The 30 × does of course mean that these binoculars cannot be handheld and a stout tripod is required (a tripod post is integrated). It is also good to see that the porro prisms are made from the largely superior BAK-4 glass.

Simple maths also provides a value for the exit pupil (80 mm divided by 30×) of 2.67 mm diameter. This is the pencil-width of light that emerges from the eyepiece and enters the observer’s iris. This more easily equates to (and is therefore more comfortable for) the eyes of (ahem!) older astronomers.

Celestron Origin Mark II home observatory

Details at: celestron.com/ products/celestron-origin- intelligent-home-observatory Price: £3,999

The battle of the smartscopes continues, with each leapfrogging their competitors with increasing aperture and technologies. The results have been astonishing, with deep space objects particularly falling to their onslaught. The abilities of the Origin begin with its 6” Rowe–Ackermann Schmidt Astrograph (RASA) optics. The focal ratio of f/2.2 hoovers up the photons, lifting even invisible galaxies and nebulae from the gloom. But the aperture also works to provide resolution, the Achilles heel of many of its smaller competitors.

Like its predecessor, it operates via wireless link to an IOS or Android device. The AI assisted software looks after the location, tracking and image processing, leaving the user little to do but stand back in patient admiration.

Feedback from Mark I users has now resulted in a Mark II version. Along with some internal tweaks, it has received a major upgrade to its sensor. Previously employing Sony’s IMX178 colour CMOS chip that uses 2.4 μm pixels, the Mark II upgrades this to their IMX 678, an 8.3 MP sensor boasting 2.0 μm pixels in a 3856 × 2180 array.