Lucky shot this morning... The skies cleared just before sunrise to allow for a portrait of Venus chasing the moon out of the morning sky. I have seen them closer together, even Venus disappearing behind the moon, but it always makes a nice sight.
On national television weather forecast, it looked like this:
A little clockwork
Last monday I put to service the iOptron Sky Tracker. This little device will be used on trips to dark skies to make guided pictures of the sky. It comes with an excellent iOptron polar scope (an iOs/Android app to calculate the exact spot of Polaris for a given time and location can be downloaded for a low fee - but other apps do the same for free).
The iOptron app on iPhone
The most recent version of the Skytracker features an altitude adjusment wedge to help aligning the mount to the pole. It works, but is a little wiggly. Locking it requires some force, with enough risk to lose the just achieved alignment. Maybe the better idea remains to use a heavy duty geared tripod head with fine motion (Manfrotto has one), surely if you want to use lenses like the Canon 200mm 2.8 in my picture. Swapping lenses or camera accessories must be done with some care, not moving tripod or Sky Tracker. Double check polar alignment after any change in the configuration.
The iOptron provides two tracking rates: half sidereal to combine star motion with not yet too blurred landscape backgrounds, or full sidereal. The half speed is very handy, but with a 50mm lens on full frame DSLR stars looked trailed after one minute - which is quite as expected. For the image of Gemini below, I captured about 45 minutes of data (in 2 minute single frame exposure) with a Canon 6D and 50mm 1.4 lens from my backyard. None of the single frames had stars trailing. From what I saw during the stacking process single exposures of 10 minutes must be possible.
OK, I did it. I just got me one of those new, advanced Skywatcher Flextube GOTO dobsonian telescopes. I mean, 12 inch full aperture, tracking and finding faint fuzzies in the sky without having to fall back to Olympic gymnastics was just too tempting to resist.
I picked it up at Astromarket.be in Nieuwpoort, near the Belgian coast (if you ever visit the town, I can recommend Boothuis, excellent food we got in that resto). Astromarket is led by Jim Oostvogels, a nice guy. Much nicer than the blokes from UPS who dropped one of the boxes with a bit of cosmetical damage to one side of the scopes' rockerbox. Oh well, Oostvogels ordered a replacement part for the non-critical component.
Jim is holding a 6 inch APM ED refractor here. Which is rather small and light. Left in the picture, you can see the boxes for the Skywatcher dobsonian. I mean, these are *huge*. We succeeded in putting the boxes in our car. Just.
Last night was partially clear, so I started the construction of the rocker box. People who buy their furniture at Ikea: mounting a dobsonian rocker box is more or less the same story. Skywatcher included the necessary tools, very Swedish for a Chinese company. No surprises here, everything worked out very well, and after an hour, I had a complete rockerbox, ready for use.
Make no mistake: a 12 inch Skywatcher Flextube Goto is heavy, and big. It allows for a one man operation, but not by a big margin. It might be a good idea to put it on wheels and roll it outside, especially in my case, after years of back problems. Luckily, Martine is willing to help till the wheels are ready.
Martine in the dunes, making a selfie video, wearing a kinda Mick Jagger coat.
I first tried working the telescope manually. But I did not like it, too much friction for a dobsonian, making push and overshoot happening too frequently. The telescope really is designed for automated operation and tracking. Which luckily is not too difficult to do: connect a cable between the two motors, add the keypad and a power cable and you are all set. The alignment procedure seemed to work fine. After entering local coordinates, time, time zone and daylight saving time, the scope was ready to align on two bright stars. This was enough to bring objects in the finder after a goto operation. Not in the center of the field of the main telescope as it should be expected, but I am not yet worried: the scope was not level at all, a prerequisite for more or less accurate goto's.
Did I mention collimating the optics was straightforward? It is, with the big knobs on the primary mirror cell. Optics kept collimation very well, even after sliding the secondary mirror cage to the primary one for storage.
Optically, the scope seems to perform well. Unfortunately, before I could really do an accurate startest (easy, because the dobsonian was tracking the star very well), clouds ended the show the first night.
Update: today the weather gods allowed me for one full hour of observing with the Skywatcher. I perfected the collimation and leveled the scope. Optics seem to be of excellent quality indeed. Visually I could see quite some detail around the Red Spot region on Jupiter, together with the pitch black dot from the shadow of one of the moons. The goto operations got a lot better too. Going from Betelgeuse to M35 in Gemini put the object in the field of view of a 20mm widefield eyepiece. Tracking was excellent and having a keypad to center objects is a blessing.
One thing I did not like so far. Both Celestron and Skywatcher use a Synta handcontroller with nearly identical keypad layout, from the same factory, but the functions of the controller are behind different buttons on the keypad. Why can't they keep this standard? Using a Celestron mount too, I often ended up pushing the wrong button, interrupting an alignment procedure, selecting a different menu than I expected. Too much confusion here. Hope they correct this, one day.
Finishing my blog for today, here are a few Jupiter images of last week. Seeing was good, and I got some nice detail with the 6 inch refractor. Not as much as I would have liked tho. I found the images to render less detail in the red channel, rather odd. Red is normally very good. Giving it some thought, I realized I had mounted the filter wheel backwards after the move to our new home. A quick test yesterday proved that just flipping the wheel solved the little issue. It seems reflections and glare from the filter killed the contrast of the red channel more than it did green and blue. There is a reason manufacturers of RGB filters recommend which side to mount towards the CCD chip...
For the record, the two leftmost images were made with a monochrome ASI 120MM camera, the rightmost one with an ASI 120MC color camera.
The other night my SBIG STT8300 saw first photographic light. It sat idle in its Pelican case for a few months since the day I acquired it - the duration of our move to a new house. Finally the skies briefly cleared, there was a supernova in M82. I rushed the Celestron VX mount and Takahashi FSQ106ED into the observatory (having not yet received the big equatorial). I aligned the mount using the controller and its excellent built-in polar alignment routine. Which turned out fine, till
I incidentally hit the mount tripod in the darkness of the night. Oh well, life's too short to bother about a tad of misalignment. Exact polar alignment only happens to nerds. I hope to graduate a junior nerd in the near future.
The SBIG STT8300 is a deeply cooled monochrome CCD camera, and mine is equipped with a self-guiding filterwheel with LRGB and S2, O3 and Ha filters in front of the sensor. Self-guiding in the sense it features a small pick-up prism in front of the filter wheel to redirect some light onto a second, small CCD chip. The camera is intelligent enough to work in concert with a software program to hold the stars perfectly still, by sending control signals to the mount in near real-time correcting for bad polar alignment (if you don't exaggerate that is) or less than perfect mechanics (as is the case with any cheapish mount and some of the more expensive too).
I had installed the camera software months ago and updated the SBIG drivers for the device, I thought. I couldn't get to start Software Bisque's CCDsoft to control the camera without errors, but with the time constraints of renovating a house in mind, I just postponed further investigation of the issue. And it bit me - hard.
The sky would only be clear for a few hours on February 3, so I connected the SBIG to the FSQ106ED and using the GoTo controller steered the scope towards M81 and M82. Camera settled at a nice -20 degrees of temperature in the meantime. Didn't want to push it deeper for this short session in 2x2 binning mode of the chip. As I remembered the trouble I had with CCDsoft, I installed a test version of Maxim/DL, a very complete image capturing and processing program. Amongst other features, it allows one to program sequences, automating exposure duration, which filters to use and number of exposures for each filter. When taking test exposures I received the dreaded 'Filterwheel Error' message. I had heard about it before, and seen it myself months ago, while installing the camera.
A retry after the error worked out ok. So I launched a long sequence, lasting nearly 60 minutes hoping all would be fine. Not so. When I came back into the observatory after 30 minutes, the camera was found jammed on a filter change. Unattended photography was out of the question for the night. In the end, before the clouds rolled in, I managed to grab just enough images to produce the following picture of galaxies M81 and M82. By far not enough (color) data to make it a pretty picture, but at least the supernova is visible.
The next day I launched a support request at both SBIG and Cyanogen. They were both very helpful and asked me whether I had installed the most recent SBIG drivers. Of course I had done that, I mean the DriverCheckerUtility does that, everyone knows. What may not be known to everyone, and I certainly missed it, was the restrictions brought by the enhanced security in recent versions of Windows. I had received a message during the driver installation stating DriverCheckerUtility couldn't install a certain driver file and yada yada yada. I never paid attention to it, assuming my PC was already up to date. It wasn't. I ran the utility as Administrator to force the install. Guess what. It worked and as a side effect CCDsoft came to live. Windows, it never ever works as it should, even when it works as it should.
Did I mention the FSQ106ED does the moon too? Here's one image made a few days later, with a Canon 6D, using a Televue 4x Barlow.
Tonight I aligned a brand sparkling old Celestron CGE equatorial mount, which I use temporarily, awaiting the arrival of my own 10 Micron 2000HPS mount. I have been waiting since 4 months now, but then, it has to cross the Alps, all the way from Italy. Not an easy task for any equatorial mount. Let alone it did not even leave the factory I learned the other day. Robtics in the Netherlands was so kind to offer me an interim CGE to be able to use my telescopes.
Anyway, using the drift alignment method, two hours were needed to get the Celestron aligned with the pole (where on earth does Celestron wants me to find the azimuth adjuster on this one). I like drift aligning, keeps you staring at a little dot in a cross hair eyepiece for ages. For non-astronomers: aligning an equatorial mount is the art of putting one axis exactly parallel with the earth axis. This way, one little motor can drive the mount so it makes one rotation in 24 hours, keeping the target in the field of view of the telescope, compensating for the earth rotation.
Seeing was pretty ok during the alignment process, turbulence well below average for Belgium. So, at least it would be a good night for Jupiter - I hoped. Well not exactly. When I turned the brand sparkling new Takahashi TOA150 refractor to the imaging target, seeing definitely had gone worse. Some good detail was visible on the monitor screen, but Jupiter behaved more often than not as a neurotic/elastic little ball of light. Definitely not a great start for the Takahashi planetary adventure.
Since the circumstances were not ideal to get into high resolution imaging, I compared two ASI cameras, the 120MM (monochrome) and the 120MC (direct color), being curious if the monochrome, using red, green and blue filters would teach the color camera (with Bayer grid) a lesson in grabbing detail on a planet. No sir, it did not. The color camera offered about the same resolution in the final image. So, when seeing is only average, you might as well save yourself the trouble of using a mono camera with filters. After all, direct color is a lot easier, and allows grabbing more frames in a shorter period of time. Would the mono camera without the Bayer grid overhead fare better in decent seeing? Likely. Especially if using derotation software like Winjupos to grab enough images in RGB. Will it be spectacularly different? I expect not. At least not most of the time and not in our country where moments of excellent seeing are very rare. One disadvantage of the color camera: due to the Bayer grid, it will never be ideal to use it with an IR pass filter, the most popular wavelength to compensate for bad seeing. There's no free lunch.
This was my best result of the evening. Nothing really special, but it was the first image of Jupiter with the TOA150.
It took 3 videos of 4000 images each, a selection of 4500 of the most acceptable ones (the not too blurry ones) and some post processing. Luckily automation software like AutoStakkert! or Registax does exist. There used to be a time when going through all the frames manually was necessary.
Earlier that evening, Luc Debeck, a friend of mine, was using his 12 inch Orion Optics UK Newton for the first time. He used his 120MC camera under a tad better seeing. As you can see, the color camera works very well, just as good as the monochrome. The colors of my RGB image are more saturated, but that is a matter of taste and one click of a mouse away during processing. Let's give this comparison another try under better conditions and see what it gives.
On a technical note, when capturing video with the ASI 120MC, you may opt to record in raw format. If you are using Firecapture, switch off debayering while recording. You will be able to transfer more frames per second, as debayering does cause overhead on your recording PC. Stacking software like AS!2 can do the debayering later on in the process, and gives good color results. In AS!2 choose the 'force debayering GRBG' option for best results, under the Color menu.
Getting a nice picture not always requires these kind of titanic efforts, this one was taken with my iPhone, held against the telescopes eyepiece. Very hipstamatic.
