Catching up on Images

It’s been something of a hectic week, so it was nice to have a chance this weekend to download some pictures from last week, when Andy and James were round, and do a bit of processing.

Firstly- the best of the moon photos. These were mostly captured with my Meade ETX105 Mak, which I’ve mounted on my HEQ5 mount, because the original mount is not reliable. The pictures were taken with an ASI224 camera through a 2x Barlow- which gives a focal length of 2.8m and a hard time focusing! Each image is a 30second avi that I  stacked using Autostakkert, and then the multiscale process in Pixinsight for the sharpening. This seems to work in the same way as wavelets in Registax.

This is one of Sam’s of the Mare on the Eastern Side:

This is one that James took centred on the Cuvier crater:

This is one of mine – I loved this view, because you can just see the summit of the central mountain in what I think is the Walther Crater, upper left. This view was stunning in the eyepiece. If I’ve identified it correctly then this little spec is 4.1k high- i.e. it’s a similar size to Mont Blanc sat on a crater floor that’s about the same size as the entire English Midlands.

Finally, on the moon, from a bit later in the week is Montes Jura, which is the prominent range towards the top of the picture. This feature is 3800m high and 422km long- it’d be a pretty substantial mountain range here on earth.

Next up were some globs, which are a great target when the sky’s not properly dark. I took these with the 130pd-s, and again used the ASI224, but taking 20 second .pngs rather than .avi’s. The mount was unguided (the ASI224 is usually my guide camera) and even over 20 seconds there were some wobbles so when I stacked it I set DSS to only take the best 50%. Each imaging run was 30 minutes, so these are effectively a 15 minute exposure and all use darks and bias frames. I took flats as well, but between M92 and M3 a big lump of something landed somewhere on the image train which meant they could only be used on the last 2 images.

First up was M13:

Next was M92. I’d normally crop and re-size this to present it better, but I wanted to make it comparable to the M13 pic above, so all the settings are exactly the same, although my processing has yielded a slightly different background colour. You can clearly see M92 is a bit smaller, but I think it’s also neater and more compact.

Next up was M3- again with the same parameters:

Finally, I had meant to go over to M5 and get another glob, but went for M64, the Black Eye galaxy. I took this with exactly the same parameters as the globs above (mainly because I was having fun doing visual and didn’t want to faf around with settings). I’m quite pleased with this; at the Practical Astronomy Show earlier in the year Dr Robin Glover (author of Sharpcap) gave a talk about how, for CMOS cameras, long exposures are not necessarily needed, or, indeed, optimal. This has enormous potential, because, by stacking loads of shorter sub exposures instead of a small number of long ones, it greatly reduces the precision (and therefore cost) needed for an AP setup. Well, that’s all well in theory, but I’ve had a go at M81 and NGC2903 using this method and the results were pretty pants! In this case, the exposures, at 20s were a bit longer, and the gain a bit lower and I’m really pleased with the outcome. I mean you can see what it is, which is more than can be said for the other 2 I’ve had a go with.


1 Response

  1. How many 20 sec exposures did you do for M64, Rob? The short exposure method is what I do with the PD of course! Looking back at what I did for M64 (4 years ago) I did 7X 20 sec exposures. That was before I discovered Sharpcap, and I did it manually!

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