Showing posts from June, 2021

Problems with the Hubble Space Telescope

The Hubble Space Telescope has been in orbit since 1990. That's incredible for the high-radiation environment it has to work in. After a shaky start, it's been sending mind-boggling photos back to Earth for more than 30 years. Image: NASA But a few weeks ago the payload computer stopped. The computer equipment on board the HST has many levels of redundancies: there are backups for their backups. So the first problem is identifying the component that has failed. But even after they've found the problem, NASA can't just go up there and start soldering. Since the retirement of the Space Shuttle, they have to do it all remotely. What's currently up there is going to have to do. What's more, while many astronomers on Earth communicate with their equipment at a distance, remote maintenance is difficult when it might be the remote computer that's gone on the fritz! There are a few suspect parts. Initially, NASA though it may have been a bank

John Iramiyan's M16, the Eagle Nebula in narrowband

Just take a look at this photo of M16 - the Eagle nebula. The Pillars of Creation are right in the centre of the image, and to the left there's the Stellar Spire. Note the horseshoe shaped structure at the top of the nebula - I'll get back to that. John uses a saxon 127mm FCD100 triplet refractor. This is one of the big ones. For an imaging array, John uses the popular ZWO ASI1600MM-Pro monochrome camera and shoots through narrowband filters. All his exposures are four minutes long. John has presented his image in the so-called "Hubble Palette", where images taken though the Sulphur filter are shown as red, those taken though the Hydrogen alpha filter are shown as green and those taken through the Oxygen filter are shows as blue. As a contrast, here's one of my own photos of M16. It's taken with similar equipment, an ASI1600MM-Pro, a slightly smaller 107mm triplet refractor and narrowband filters, which are presented using the Hu

Viewing targets for the Winter (June) solstice 2020

With the winter solstice coming up, it's time to send around my regular viewing list. Those of you who have small telescopes or (like me) are stuck in the city, start by searching for clusters, either open clusters (which are pretty groups of stars) or globular clusters (which are tight spectacular swarms). Once you've done that, start looking for double stars, which are pretty in a different way. One day I'll get around to photographing some... For planets, Saturn and Jupiter are currently your best bet. Here's a photo I took of Saturn. I used budget equipment (about $1000), which I was testing for work. Open cluster: Mel 111 - Coma Berenices Star Cluster (06:55 PM) Galaxy: M 87 - Virgo A (01:55 AM) Galaxy: M 104 - Sombrero Galaxy (02:09 AM) Dark nebula: C 99 - Coalsack Nebula (02:24 AM) Open cluster: NGC 4755 - Jewel Box Cluster (02:24 AM) Galaxy: NGC 5128 - Centaurus A (02:52 AM) Globular cluster: NGC 5139 - Omega Centauri (02:52 AM) Galaxy:

Illuminated reticule eyepiece

During the latest lockdown in Melbourne, I was at home, but had taken with me a small Newtonian telescope and a guide camera. I was wondering what sort of photo of Jupiter I could get with simple and inexpensive equipment. I put the scope up onto my NEQ6 mount, but it didn't have a finderscope. Complicating matters, the guide camera was set into the focuser of the telescope and it was nicely focused. I didn't want to move it. How was I going to see where the scope was pointed? How was I going to align the scope to the sky? Reusing old equipment I have an old guide scope at home - an Orion. It's not as good as the saxon one, but it does the job. I've also got an ancient illuminated reticule eyepiece which I rescued out a junk bin at an astro meet once. I planned to use this in the guide scope. The eyepiece was filthy. When I looked through it, all I could see was nicely-focused grit and dust across the whole field. I had to pull the eyepiece apart to c

Getting to Mars

There have been a lot of spacecraft arriving at Mars in the last few months. Since February, the US, China and the United Arab Emirates have all arrived there. The US and China have now landed, and the UAE will remain in orbit. The soviets did it ages ago, of course. Here's a model of their probe. This is all very cool, but more interesting is how they reached Mars, and why all three arrived at about the same time. How do you get there? I probably don't have to say this, but getting to Mars isn't as simple as hopping in your car and driving to Mildura. One of the complexities of rocket science is that to have fuel available for manoeuvre s such as landing, you have to lift that fuel off Earth's surface, and that takes ... well, fuel! How do you get to Mars using the absolute minimum amount? You figure out the shortest way. Mars is one planet out from the Sun. Because of this, it orbits slower than Earth. A Mars "year" is about 23 Earth

What type of telescope is best for me? A really rough guide based on what you want to see.

Classifying telescopes When clients come in and ask about a new telescope, the first thing we normally ask is what they want to see with it. People often look at us weirdly when I ask this. "The sky?" they tend to venture. We're after an idea whether they want to look at planets or deep sky targets like nebulas and galaxies. What we're getting towards is what type of telescope is best for them. Telescopes aren't the same. They're highly specific tools, each with their own area of specialisation. Get the wrong one and it's not going to give you what you want. Ferraris and Land Cruisers We explain by asking people what is the best type of car: a Land Cruiser or a Ferrari? They're both great for what they're intended for, but used for a different purpose... not so much. So how do we decide what type? Aperture and focal length Telescopes are fairly comprehensively described in two measurements, aperture and focal length. Aperture - how much ligh