A very convenient tecnique in c++ programming is the one known with many names: "d-pointer" (found in Qt/KDE contexts), shadow pointer, "pimpl", opaque pointer. Basically the idea is to hide all the private details of a class in a forward declared private pointer, which will be the only real private member of the class. Since this member will never change, this will guarantee binary compatibility among different versions of a library.
But there are other advantages in using d-pointers: one is compilation speedup during development (usually if you change a private member of a class, the header changes, and you have to recomplile all units using that header, while with d-pointer you change only the .cpp file), and another is code cleanup: you will have very compact header files, describing your class public interface without private stuff pollution. Also, sometimes you may want to add your d-pointer definition in a separate header file, ending up with three well defined files:
- myclass.h: class declaration, only public stuff, without private stuff
- myclass_p.hpp: private class declaration: only private stuff, no implementations
- myclass.cpp: only implementations
The classical approach is to create a plain raw pointer to a forward declared class, initialize it in the constructor, and delete it on the destructor. A nice addition is to have the private class be a nested type, so that you can avoid polluting your IDE class list.
It has happened in a few occasions, to launch a command in a shell only after a command in another shell has successfully finished (for instance, after a long task like source code compilation, i want to launch tests on another shell).
This sunspot was particularly big, so I waited for the best moment to try and catch it.
Seeing wasn’t great, and my solar filter was a bit damaged, but the final image doesn’t look too bad anyway.
Unfortunately, this will be the last image for a while.
Just a few hours later, someone opened my car, and took away my HEQ5 mount, together with all my eyepieces and the camera I used for all my planetary shots.
I’ll also be relocating in a while, so I’ll wait a few months before buying a new setup.
If someone is interested, I’m selling my current main optical tube here: http://www.astrosell.it/annuncio.php?Id=70007
This was meant to be an improvement to the previous ISS shooting, since I tried to do it with a bigger telescope, but the low altitude and the very bad seeing did actually worsen the quality.
The shape of the Space Station is anyway clearly visible, as it passes in front of the Moon. It is dark, this time, because it already entered in Earth shadow. We could actually see it rising, bright as usual, and then slowly fade until it completely disappeared just a few seconds before crossing the Moon.
Technical details of the shot can be found on the pagina Youtube.
Mars is getting really close to 2016 opposition, the best in the last 10 years, since it’s very close to earth.
Weather in Milan wasn’t great these days, so me and Alessia tried to catch the first night offering a clear sky and a possibly good seeing.
We were pretty much lucky: seeing wasn’t the top, with mars being very low on the horizon, but it was good enough to get a proper look: we were able to distinguish a few major features, particularly when it began to rise a little bit over 20°.
I also took a few pictures, this is the best result, shown here with a Stellarium simulation for that day and hour.
We observed also Saturn, getting close to its own opposition too, although even lower in the horizon than Mars, and Jupiter, still quite high and bright in the sky.
At the eyepiece, it was impressive: the great read spot was particularly evident, and a satellite (we later identified it being Europa) was getting closer and closer to the planet disk.
When I started shooting with my camera it was already over Jupiter, and it’s visible as the bright spot in the left part of the planet.
Although the images are not as good as I was hoping, it was a very nice evening, we could finally have a good couple of hours doing astronomy, and it was a relief after a long time being unable to observe due to bad weather.
Last august I had the chance to see the International Space Station passing in front of the moon right from my home.
The ISS is clearly visible many nights, and depending on the user position on Earth, it might align with some object in the sky.
These days I was reorganizing my gallery, and I found the original video.
So, after reprocessing it a while, I decided to republish it.
The ISS is really fast: the video is slightly slowed down. I remember that during the transit I couldn’t see the station, and I waited a few minutes because I couldn’t know if the transit already happened or not: it was still daylight, and in the original frames is barely visible.
Only after watching the video I could finally notice that tiny dot passing right in front of the moon.
For this shot, I used my old Celestron Astromaster 130, in an alt-azimuth mount, and my QHY5L-IIm as shooting camera. I had to try following manually the moon, since I obviously had no motorized tracking.
I had to use the 130mm scope instead of my main 8″ scope because of the shorter focal length: this way I could shoot almost the whole moon, so I could be sure that I didn’t miss the ISS.
Spring is back, and here in Milan we finally had a few days (and nights) of very nice weather.
I also bought a new lightweight battery for my HEQ5 mount, instead of the usual heavy car battery I’ve been using until now, so I took a minimal setup and placed myself in a local park.
Seeing wasn’t perfect, but it was fine enough to shoot a few nice details of an almost full moon.
More importantly, Jupiter was at opposition a few weeks ago, so it’s still in a very favourable position.
After rediscovering Siril, a nice astronomical images preprocessing tool for GNU/Linux, I wanted to give another try at processing a few test images taken this summer.
It’s surely not a masterpieces, but I’m not too disappointed either by what I could make of them, given that it was just a basic attempt, with no more than half hour total shoot time.
Postrocessing was done using DarkTable.
Another couple of high resolution images, taken on the Appennines, with quite a lucky seeing.
Jupiter is now rising earlier, and it was a welcome preview to the observing night.
Firstly I tried shooting on prime focus, using small magnification, and then I used a 2.5 barlow lens. The prime focus shooting should have been just a test, but it proved to be the better one, as I had troubles focusing with the barlow lens (we were already in “night” mode, and I had to darken a lot my monitor, so focusing was really difficult).
This is the prime focus shooting elaboration.
Saturn is starting to rise earlier, and around 4am is starting to be fairly hight for a few shots.
Since we already finished observing I could remove my notebook darkening panel, and focus quite better with the 2.5x barlow.
It was also a very satisfying deep sky stargazing night (which was actually the main purpouse of our trip to the Appennines).
Spring constellations enable us to go really “deep”, with very far and suggestive galaxy clusters.
Another shooting, much improved in quality compared to the previous ones: Jupiter bands are very well defined, rich of details, much more compared to the images of fifteen days ago: probably both because of the better seeing, and of the removal of the IR-pass filter, replaced with a more classical IR-Block, gathering much more light.
The “guest” of the title is the dark dot almost at the center of the planet: it’s not an image artifact, but it’s the shadow of the Io satellite projected on the planet. Basically, a solar eclipse on Jupiter.
The satellite itself is not visible on the picture, submerged in the planet disk. The other two satellites are, from closest to farthest, Europa e Ganimede.