We’re all familiar with Neil DeGrasse Tyson’s Cosmos: A Spacetime Odyssey, a reboot of Carl Sagan’s Cosmos: A Personal Journey, which was originally broadcast in the 1980s. Now thanks to Celestron there’s a telescope in association with the TV series, offering skywatchers the chance to make their own tours of the universe.
The Celestron Cosmos 90 GT comes very well equipped, ensuring that the beginner has everything they need to get started in skywatching. Two good quality 1.25-inch Plössls – a 25 mm and 10 mm – are supplied, working with the refractor’s optical system to provide magnifications of 36x and 91x respectively.
Boasting a light-gathering capability that’s 165 times better than the human eye, Celestron promises clear, sharp views thanks to fully-coated optics that ensure good light transmission.
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On unboxing the telescope, we didn’t take much time in putting the instrument together. The final set up boasts a high-quality telescope. On seeing the single fork arm alt-azimuth mount and the battery fitting, which holds eight AA batteries, we immediately saw comparisons with the Celestron NexStar 6SE.
However, despite the Cosmos 90 GT’s similarities with the NexStar 6SE, the telescope isn’t supplied with a handset to assist the beginner with finding their way around the night sky. Instead, they need to use either an internet-enabled smartphone or tablet to locate or identify targets of interest.
Some may be put off at this point but let us assure you: connecting the telescope’s built-in SkyQLink Wi-Fi network to a smartphone or tablet and downloading the free Cosmos Navigator app (available on iOS and Android) is incredibly straightforward with the provided manual and support.
Operating the telescope using our device is intuitive as we navigated the mount using the on-screen control buttons. Tapping an object and selecting the GoTo option caused the Cosmos 90 GT to slew to the target ready for us to observe – a highly impressive function of this refractor and something that beginners to observing will be grateful for. Chosen targets appeared roughly at the center of the field of view.
The connection between our smartphone and the SkyQLink WiFi network is very steady during our test of the instrument. On a couple of occasions, we manually disconnected from the WiFi to see if the telescope is capable of picking up from where it had left off during an observing run.
We weren’t disappointed in this respect – the Cosmos 90 GT connected quickly and didn’t need realignment, meaning that we could go back to viewing the last target we were observing. A useful feature should the connectivity drop.
When the power switches off, however, this is a different story and you will have to go through the realignment process again. This is nothing major, especially given the time it takes to set the telescope up ready for observations. The Cosmos 90 GT’s computerized mount doesn’t drain batteries quickly either and we were still going strong even after a continuous three hours of slewing and observing.
Celestron has ensured that this telescope is accessible for those who don’t have a tablet or smartphone – the Cosmos 90 GT can be operated using a NexStar handset (sold separately) by plugging it into the aux port on the single-arm mount. It is important to keep in mind that the telescope is pretty much useless without a handset or WiFi to control it.
Many skywatchers are all too familiar with artificial light that ruins our dark-adapted vision during observing, so we were pleased to find that the Cosmos Navigator app comes with a red light function to ensure that our night vision is preserved.
Early April saw us take advantage of Venus and Jupiter, which were both visible in a south-western sky. Venus dazzled as a bright featureless point of light, while pleasing views of Jupiter and four of its largest moons – Ganymede, Io, Europa and Callisto – were picked out by the Cosmos 90 GT with ease.
Color fringing is evident but nonetheless, the Cosmos 90 GT offered a very good performance for an entry-level telescope. As promised by Celestron the optical system offers good c…