Galaxies and Stuff

I’ve been experimenting with a relatively cheap dedicated astrophotography camera, the Svbony SC311. It’s a self contained camera with wifi and a dedicated phone app, making it very easy to take pictures through a telescope and store them on a removable flash drive. For reasons I won’t go into, I probably won’t be keeping it. However, before sending it back, I did manage to snap a couple of images of the sun and the moon. These are among the most detailed pictures that I’ve taken to date. Here are a couple of samples.

https://mega.nz/file/M1AlTZqR#4ew3LQNWOBuV38Qpnag2o8WDCB7R3YWxlFWqweeEhsU

https://mega.nz/file/xwxEmAAI#ME0g9G-HPXL5yCiY7a0sUkpiMXGlihazm9GIM4Kw3Aw

The trouble with this camera is that, while it takes great photos of the sun and the moon, it takes absolutely terrible photos of everything else. Don’t ask me why. I haven’t got a clue.

For deep sky images I’m now almost totally reliant on my new “smart” telescope, the Seestar S50. It’s just so easy to set it up and them come back inside and do something else, or even just go to bed. This is M51, the “Whirlpool” galaxy. It’s the result of about two hours of stacked images.

https://en.wikipedia.org/wiki/Whirlpool_Galaxy

You can find this near the handle of the Plough,

For comparison, my previous efforts, that involved a lot of manual picture taking and shivering in the cold, resulted in some much poorer images.

The Whirlpool galaxy is a very popular target for amateur astrophotographers. A much less popular target is the nearby M106. Despite being closer to us than the Whirlpool galaxy, it’s a good bit dimmer and appears to show a lot less structure. I’ve made several attempts to image this over the last month. The picture below is a combination of three nights worth of pictures, totalling about four hours’ exposure.

https://en.wikipedia.org/wiki/Messier_106

M106 is principally of interest to astronomers because of it’s contribution to setting the distance scale to nearby galaxies. The wikipedia article has some details. If I’ve understood this correctly, it goes something like this. Water MASERs emit radiation at a specific frequency. MASER clouds in M106 are bright enough that their doppler shift can be monitored. This allows their acceleration to be determined. This in turn determines their exact distance from the central galactic black hole. This absolute distance can be compared to their angular separation. From there it’s simple geometry to determine distance. Once this is known, other “standard candles”, such as Cepheid Variable stars, can be more accurately calibrated.

If you look just above M106 in the picture you’ll see a short, elongated, fuzzy blob. This is another galaxy, NGC 4248. The following Hubble image is quite beautiful.

And near the top of my picture, are yet another pair of galaxies, NGC 4231 and 4232. Here are some close up pictures.

https://commons.wikimedia.org/wiki/Category:NGC_4231

One of the things I’ve mentioned before is that the Seestar isn’t very good at long exposures because it can’t fully compensate for the apparent rotation of the sky (it uses an alt-azimuth mount rather than an equatorial mount, for anyone who’s interested). As M106 is just such a long exposure I thought I’d do a short movie that shows the camera as it struggles to keep the galaxy in view. (You might need to enable insecure links in your browser to see this.) This is about 100x normal speed.

http://www.platitudes.org.uk/m106_edit.mkv

As you can see. I’ve been quite busy over the last few weeks.

Oh, and T Cor Bor still hasn’t exploded.

A Multiplicity of Moon Images

It’s been a splendid couple of weeks for moon pics. And unusually for my part of the world, there’s even be a few clear skies.

I’ll start off with the phases of the moon, beginning with first quarter on 6 Jan, all the way through to the full moon on 13 Jan. There were still a couple of cloudy nights, so it isn’t a complete record. I also haven’t got the scale and illumination quite right, so don’t pay too much attention to that. The first two photos on the top left are from consecutive nights and give a good, clear indication of how much the phase changes in a single day. These were all taken with my main 6″ telescope and the Panasonic Lumix GF7 camera.

The moon’s been doing a regular tour of the night sky, starting on 4th Jan by visiting Venus. Sadly, I didn’t get a picture of this one, so you’ll have to rely on the BBC for that.

https://www.bbc.co.uk/news/articles/c3rqe2ndl0lo

On the 9 Jan it was the turn of the Pleiades star cluster, better known as the Seven Sisters, to receive a visit from the moon.

The photo above is really a composite of two photos taken a few seconds apart with very different exposures. The moon is much, much brighter than the brightest stars. A single image tends to either grossly over expose the moon, or make the stars invisible. Here’s what a single exposure from a few minutes later looked like.

Both the above images taken with the GF7 and a Carl Zeiss 135mm lens.

Next up on the grand tour was Jupiter. Once again, I needed to combine two separate images. Even Jupiter is no match for the brightness of the moon.

The inset on this image is a crop of Jupiter from the same photo, showing a close up of some of the Galilean moons. GF7 + Carl Zeiss again.

Finally, on the morning of 14 Jan, there was a lunar occultation of Mars, where the planet passed behind the moon. This wasn’t fully visible in the UK. Here, the moon just edged closer and closer to Mars, but never actually obscured it. For an excellent description of why occultations are important, especially when it’s a full moon, see this post by Matt Strassler.

I was in my back garden until about 3.30 am. The closest approach wasn’t until about 4.30, but I was just getting too cold and too tired to wait up longer. So this was one of the final pictures that I took.

Taken with my 6″ scope and the GF7. It’s been cropped and I’ve slightly increased the brightness and colour saturation of Mars, but otherwise it’s a single image from the camera. I was reasonably chuffed with this. Then I saw this totally amazing image on Astronomy Picture of the Day.

https://apod.nasa.gov/apod/ap250115.html

Oh well, keep practising!

First Light With my New Scope

Over the last couple of years I’ve been struggling to do a little astrophotography on the cheap. I’ve used an entry level Newtonian with a second hand mirrorless camera, neither of which were designed for the purpose. However, the limitations of the equipment were beginning to show. Attempts to photograph the Virgo galaxy cluster and the Horsehead nebula proved fruitless. The scope and camera had to be controlled independently, so I had to sit beside them outside and monitor everything they do, manually taking individual pictures with no real idea how they would turn out.

So I bought myself one of these, a Seestar S50, one of the new generation of “smart” telescopes.

https://www.365astronomy.com/zwo-seestar-s50-all-in-one-smart-apo-refractor-telescope

It’s a bit more money than I’m used to spending on this hobby, but if my first night out with it is anything to judge by then I think it’ll be worth it. And in comparison to some, it’s relatively cheap.

https://www.365astronomy.com/celestron-origin-intelligent-home-observatory-6-rasa-smart-telescope

It’s about two feet tall, including the tripod, and weighs roughly the same as a bag of sugar. So you can pick it up with one hand and take it anywhere. It contains a highly quality lens system, a low noise camera sensor, a dew heater to prevent it misting up, a dual narrow-band light pollution filter, a solar filter, an auto-focuser, tracking software and image stacking software. Everything is controlled from a single phone app that, fortunately for me, is almost idiot proof.

I used to spend a considerable part of each night just trying to get things in focus. Sometimes I’d have to repeat each session multiple times just to be sure of getting the focus spot on. The Seestar app has an auto-focus button. I just press that and, as if by magic, within a few seconds everything is in perfect focus.

It seems to have quickly become a tradition that the first thing everybody does with the Seestar S50 is photograph either Andromeda or the Orion Nebula, and I’m no exception. so let’s get them out of the way.

andrOrion2

These are pretty much how they came out of the box. I’ve brightened them a bit, probably too much in the case of Andromeda, but otherwise haven’t done any post processing on them. The Seestar also let’s you save the individual image files so that you can do your own selection and stacking rather than rely on its algorithms. I haven’t got around to that yet. The one night I’ve spent with it gave me more data than I previously got in a month. It’ll take me weeks to work my way through it all.

Just to prove that it really could take the pictures that I couldn’t take before. Here’s part of the Virgo cluster of galaxies and the famous horsehead nebula. Again, I’ve cropped and brightened the images very quickly, with no real attention to detail.

The big white blob at the top of the horsehead picture is the star Alnitak, the left hand star in Orion’s belt.

One of the downsides of the Seestar is also illustrated in the horsehead picture. If you look carefully at the right hand side of that image, you’ll see vertical streaks running at an increasing angle down the right hand side. This is because of the type of mount that it uses. It can go up and down and left to right. This allows it to track the positions of objects in the sky. However, if you think about it, objects don’t just appear to move across the sky, they also appear to rotate. The Seestar can’t fully compensate for this, with the result that longer exposures cause the effect you see. There’s a well known way around this, but as this was my first night out I wasn’t going to try anything elaborate.

A couple of more galaxies, Bode’s galaxies and the Triangulum galaxy.

There are a couple of lines across the bottom of the left hand image of Bode’s galaxies. This isn’t a telescope artefact this time, but a plane flying across one of the frames. When I do my own stacking I’ll get rid of this frame.

And now a couple of old favourites, the Double Cluster in Perseus and T Corona Borealis – our unexploded star. The Double Cluster picture is way better than anything I’ve previously taken with my old setup. Despite being one of the largest and brightest objects in the sky, my old telescope often had difficulty finding the Double Cluster. The Seestar uses a technique called “plate solving”. Essentially it compares what it sees with its internal database of stars, figures out where it’s pointing, and moves to the desired location. All with no user intervention whatever.

T Cor Bor has disappeared from the evening sky in the west, but if you wait until about 4 am it rises above the eastern horizon again.

And finally, that sun-with-a-bird picture. This time I’ve included another sun-with-a-bird picture from the next day. When you’re imaging the sun, especially when you take movies over a couple of minutes, it’s actually surprisingly common to see a plane or a flock of birds transit the sun’s disk. Notice how the sunspots move with the sun’s rotation from one day to the next.

My other scope has about ten times the light gathering power of the Seestar, so it isn’t redundant. And it’s got one thing that the Seestar doesn’t have, an eyepiece, so you can actually look at the sky with your eyes rather than a phone. But for sheer convenience and it’s ability to record images, the new box is quite unbelievable. I might even try driving a few miles out of town to escape some of the light pollution in my back yard.

But I’ve saved the best bit for last. As it’s controlled by a single, dedicated, phone app, and you can operate it over wi-fi, I can sit in the comfort of my living room in shorts and t-shirt, glass of wine in hand, and tell the telescope exactly what I want it to do. Then I just sit back and watch as the images appear on my screen. No more shivering for hours outside in the cold. In fact, the telescope barely needs me at all.

Jupiter

Jupiter is beautifully placed in the southern sky at midnight just now, with no moon to spoil the show. You might remember my previous effort to capture it was not a great success. Since then, I’ve picked up a new x2 magnifier for my scope. (Called a “Barlow” in telescope-speak.) I got it for £20 on Ebay, which I consider a bit of a bargain. I’ve no idea if it was responsible for any improvements. There are a myriad of factors that can affect a picture on any one night. But here are the old and the new compared, with the new picture on the right.

jup20Nov28nov

This isn’t what you actually see through the telescope. It’s heavily cropped. The original picture looks more like this. This is a 1/60s exposure at iso 1600.

I don’t normally save “raw” images on the camera. But that night I accidentally had that option switched on, and I’m glad I did. Just a reminder, most images on the web are jpeg type files, or similar. These are compressed images. But the compression algorithm is lossy, it doesn’t preserve all the original information. All the images you see above are based on jpeg originals.

This can work very well for every day pictures in bright light. However, for high magnifications, every bit of detail is important. Raw images save every bit that is captured by the camera. And what a difference it makes. Here they are compared, with the raw image on the right.

As you can see, there’s a lot more detail in the raw compared to the jpeg image. This feeds through the image processing. I took a dozen images in rapid succession and stacked them using my favourite photo processing program, called “Siril”. This is the result (raw on the right).

And here’s that final image close up.

Given the cheap equipment, and basic processing, I’m fairly chuffed with this.

Having said that, Jupiter is by far the easiest planet to photograph. More massive than all the other planets combined, and able to swallow 1,000 earths whole, it presents an easy profile to photograph in the night sky. Mars is tiny in comparison, Saturn is much further away, and Venus is just a featureless, cloudy blob. Initial attempts to photograph them haven’t been an outstanding success so far. I’ll let you know if my efforts improve.

Meanwhile, back in the Andromeda galaxy. No telescope this time, just an old Carl Zeiss lens I found in the cupboard, This was only a brief test, iso 3200 4s x28, so under2 mins total exposure. Based on the result, this might be worth playing with a bit more.

Some Photo Experiments

I’ve been trying out some different things over the last few weeks with my telescope and camera. Mostly I take photos by removing the eyepiece in the telescope and placing the camera there. This is called “Prime Focus” astrophotography. Even there I’ve been trying to push the boundaries a little bit.

Magnification is directly linked to the focal length of the telescope. This isn’t usually the main consideration in astronomy, where the size of the main lens or mirror is usually the principle characteristic. This is what controls its light gathering power and so determines the faintest objects it can see. My scope is relatively compact with quite a low magnification.

However, for planets and the moon, magnification is everything. You might have noticed that I’ve never posted any images of the planets and that’s the reason why. You need to add some extra optics to alter the focal length if you want to do planets with my scope. The result will never be as good as a dedicated instrument, but I can try. Here’s a single 1/200s iso 3200 shot of Jupiter.

jup20nov

That’s fairly typical of what you would actually see through the scope. I was hoping to get a few more over the last few nights, but weather, the moon, and me having to sleep sometime, have conspired to get in the way. To get improved results I need to take lots of images and stack them. This is most easily done by taking a movie. Here’s one of Saturn.

https://mega.nz/file/Ro4C3KTC#qwqi0L2sRXmHwE9wO8tH9om9PxEtq08ujE-g_jqB3DE

Unfortunately, my attempts to stack the frames from this haven’t worked out too well so far.

Increasing the focal length can also be used to get high magnification images of the moon.

This is the Mare Nectaris using this technique.

https://en.wikipedia.org/wiki/Mare_Nectaris

As well as increasing the focal length of the scope, I’ve also been experimenting with just using the camera directly. The problem I’ve always had with this in the past is that you need a really good tripod, with fine adjustments and preferably a motorised mount to track the sky. Expensive. Trying to take photos of the sky on an ordinary tripod has just proved too awkward.

However, I recently figured out a combination of lumps of metal, bolts and clamps that has allowed me to remove my telescope from its mount and put the camera directly in its place.

This has been great fun to use. It allows me to use the app on my phone to point the camera wherever I want and track it fairly accurately. It also lets me play with all the old lenses that are sitting in cupboards in the house. I’ve hardly begun to explore the possibilities here. At the moment I’m mainly using an old Pentax K mount f1.7 50mm lens. This has a field of view of about 15 degrees. perfect for Orion.

And Andromeda.

The way I’ve mounted the camera also allows me to balance it so that it isn’t front heavy. A big problem on a normal photographic tripod. This’ll let me play with some old telephoto lenses that are currently sitting unused. So I might be able to try out some new stuff in the months to come.