A DMK 37AUX273 (USB3.0, 12 bit ADC) camera, fitted with an 850nm IR pass filter was placed at the prime focus of a Bresser Messier-AR-102-AS ED refractor, mounted on a Skywatcher Star Discovery AZ, GOTO mount, and AstroDMx Capture for Linux was used to capture 2 overlapping, 5,000 frame SER files of the 58% waxing, gibbous Moon at full resolution 1440 x 1080, in a twilight sky. The best 25% of the frames in the SER files were stacked in Autostakkert! 3.10 and wavelet processed in Registax 5.1 running in Wine. The two resulting images were combined in Microsoft ICE running in Wine and post processed in the Gimp 2.10.
58% waxing, gibbous Moon
Screenshot of AstroDMx Capture for Linux capturing data from the DMK 37AUX273
The DMK 37AUX273 again proving that it is a very capable Lunar imager.
Comet 21P/Giacobini-Zinner was imaged using AstroDMx Capture for Linux with a ZWO ASI178MC camera at the prime focus of a Bresser Messier-AR-102-AS ED refractor, mounted on an iOptron Cube Pro AZ, GOTO mount. 10s, 16 bit TIFFs were collected with matching dark frames. The images were stacked and dark frame corrected in Deep Sky Stacker running in Wine. The image was post processed in the Gimp 2.10.
Alignment was difficult from the site chosen, and tracking was not perfect. However, about a third of the images captured were good enough to stack. The exposures were of limited duration due to tracking issues. Nevertheless, the comet tail and star colours showed up quite well. Focus was a little soft and is not as easy to achieve as with a dual speed focuser.
The ZWO ASI178MC camera
This camera has a 14 bit ADC so it is much less likely to saturate. AstroDMx Capture for Linux auto detects the ADC bit depth and so correctly places the data into either the bottom or the top bits (User defined) of a 16 bit container.
The 11.6% waxing, crescent Moon was imaged in broad daylight with a DMK 37AUX273 camera fitted with a 850nm IR pass filter attached to a Skywatcher Explorer 130 PDS 130mm, f/5 Newtonian, mounted on a Celestron AVX EQ, GOTO mount. A 5,000 frame SER file was captured using AstroDMx Capture for Linux running on a Fedora machine. The SER file was stacked and wavelet processed in Registax 5.1 running in Wine and the final image was post processed in the Gimp 2.10.
At full resolution, the camera maintained a frame rate of 52 fps, which allows the acquisition of large numbers of frames in a short period of time.
A Solarmax ll, 60, BF15 H-alpha scope was mounted on a Celestron AVX mount. A DMK 37AUX273 camera was fitted with the lens from a 2x Barlow and was placed at the focus of the scope. AstroDMx Capture for Linux was used to capture a 10,000 frame SER file exposed for a prominence at 160 fps with a ROI of 640 x 480. A 3000 frame SER file was captured, exposed for the disk. Autostakkert! 3.1 running in Wine was used to stack the best 15% of the prominence frames and 50% of the disk frames. Registax 5.1, running in Wine was used to wavelet process the resulting images. The two images were combined and post processed in the Gimp 2.10.
Again, the DMK 37AUX273 proved its worth as a high speed capture device for H-alpha solar imaging with a ROI.
The telescope featured here is a Skywatcher Explorer 130 PDS 130mm, f/5 imaging Newtonian. The back end of the primary mirror is protected by a black, rubberised sheet.
The bottom of the Newtonian reflector
A problem with Newtonian reflectors is that in very cold weather, the back of the primary mirror can cooled by being exposed almost directly to the cold, ambient air. This can result in the front of the primary mirror dewing up even though it is at the bottom of a long telescope tube.
One way to ameliorate this problem is to use foam packing material, cut to size and attached to the sheet at the back of the primary mirror. Two layers of this material can be used (depending on thickness) and they can be attached using double sided sticky tape.
The foam insulation in place
This insulating foam protects the back of the primary mirror from the cold, ambient air. However, if any stray light should happen to fall on the bottom of the scope, the white, semi-translucent foam will direct some of it outwards towards the edge of the telescope tube. This presents the danger that some unwanted light might make its way from the back of the scope onto the edge of the primary mirror. Sources of such light could be street lights, light from windows, street light reflected off building walls etc.
What is required is to cut a disk of matt black, 1mm styrene Plasicard and attach at least one sheet to the foam insulation and with a slightly greater diameter than the foam insulation. This serves to prevent extraneous light from falling onto the foam insulation, as well as adding another thin layer between the ambient air and the back of the primary mirror.
The black styrene Plasticard on top of the insulation foam
A finishing touch could be to attach a black shower cap to the bottom of the scope. In addition to extra darkening, this would trap another layer of air at the bottom of the scope to act as extra insulation. 1mm black Plasticard, A4 styrene sheets can be obtained from Amazon.
Explorer 130 PDS 130mm, f/5 Newtonian was mounted on a Celestron AVX
EQ, GOTO mount. A ZWO ASI178MC (USB3.0, 14 bit ADC) camera was placed
at the Newtonian focus.
AstroDMx Capture for Linux was used to
capture 45 x 55s Tiff files in RAW, undebayered format of M27. The best 40
images were stacked and debayered in Autostakkert! 3.10 running in
Wine. The final image was post processed and scaled in the Gimp 2.10 and Neat
Having a 14 bit ADC means that this camera can yield 16,384 levels of brightness, compared with 4,096 levels with a 12 bit ADC camera. The data can either be saved to the lower bits of a 16 bit container, or to the upper bits, when captured by AstroDMx Capture for Linux.
A Skymax 127 Maksutov was mounted on a Celestron AVX, EQ, GOTO mount. An Imaging Source DMK 37AUX271 machine vision camera was placed at the prime focus. AstroDMx Capture for Linux was used to capture 8 overlapping, 2000 frame SER files of the 88% waning, gibbous Moon in High contrast and terminator areas, as well as the Copernicus/Kepler region.
(All running in Wine), Autostakkert! 3.10 was used to stack the best 80% of the SER file frames, Microsoft ICE was used to stitch the resulting images together and Registax 5.1 was used to wavelet process the resulting Mosaic. The resulting high resolution mosaic was post processed in the Gimp 2.10.
The scope was protected from the intrusive light from a nearby garden lamp by means of an occultation board which cast a shadow across the scope.
Copernicus and Kepler
High resolution Mosaic
Full size pane of the Aristotelese, Eudoxus, Lacus Mortis, Hercules, Atlas, Posidonius region
Full size pane of the Theophilus, Cyrillus, Catharina, Fracastorius, Mare nectaris, Piccolomini region
Full size pane of the Tycho region
The DMK 37AUX273 can be considered to be an excellent Lunar and Solar imaging device. Seeing was too poor to gather worthwhile planetary images as Mars and Saturn were far too low in the sky. However, a test showed that high frame rates could be achieved capturing monochrome planetary data through this modest 5" Maksutov. Larger, planetary imaging scopes would cope even better.
A DMK 37AUX273 camera was mounted at the prime focus of a Solarmax ll, 60, BF15 H-alpha scope, mounted on an iOptron Cube Pro, AZ GOTO mount.
AstroDMx Capture for Linux was used to capture two overlapping 1000 frame 8 bit SER files, which were Stacked in Autostakkert! 3.1, stitched in Microsoft ICE and wavelet processed in Registax 5.1, all running in Wine. The final image was post processed and colourised in the Gimp 2.10.
The Sun in H-alpha light
Active regions 2719 and 2720 are clearly visible as is a large filament.
The camera had sufficient dynamic range to be able to capture both disk and prominence details. The stitched image was duplicated and one image processed for the disk and the other processed for the prominences. The two images were then combined in the Gimp 2.1 to give the image presented here.
It is clear that this is a good camera for H-alpha solar imaging and was able to deliver over 60 fps whilst imaging at maximum resolution.
We are on the home straight towards the next release of AstroDMx Capture for Linux. These images were produced as part of the pre-release testing program.
The ZWO ASI178MC is a camera with a 14 bit ADC and a back illuminated 6.4 MP Sony IMX178 CMOS sensor with 7.4 x 5 micro metre pixels which use STARVIS and EXMOR R technologies.
These technologies produce higher sensitivity and lower noise as well as reducing rolling shutter distortion. The back illumination avoids the internal circuitry in the sensor obstructing some of the light falling on the sensor before it reaches the photodiode. This allows for the reduction in size of the pixels and higher pixel counts on the sensor without increasingly the proportion of the light that is attenuated before it reaches the photodiode. The global shutter reset reduces the rolling shutter distortions that can occur if the subject moves (In astronomical imaging, the only movement should be due to seeing. However, some people image while the object drifts across the field of view or manually nudge the scope to keep the object in the field of view).
This test was done on a night with a low, 94% waxing Moon in the sky. This produced relatively poor seeing and a sky filled with Moon glow.
The ZWO ASI178MC camera was placed at the Newtonian focus of a Skywatcher, f/5, 130PDS Newtonian mounted on a Celestron AVX EQ, GOTO mount. Two overlapping 500 frame SER files were captured at full resolution (3096 x 2080). The best 95% of the frames were stacked in Autostakkert! 3.1 running in Wine. The resulting images were wavelet processed in Registax 5.1, and stitched into a single image using Microsoft ICE, both running in Wine. The final image was post processed in the Gimp 2.10.
Deep sky on a moonlit night
The ZWO ASI178 has a 14 bit ADC unlike many of the CMOS astronomical cameras which have 12 bit ADCs. This means that it can capture images with 16384 levels of brightness, compared with a 12 bit ADC which produces 4096 levels of brightness.
AstroDMx Capture for Linux saves the 14 bit data, mapped to the lower or the upper bits of a 16 bit container. This is still not up to the 16 bit ADCs of traditional CCD based astronomical cameras, but it is a substantial improvement on 12 bit devices.
With the bright Moon illuminating the sky, the ZWO ASI178MC in the same configuration was used to capture 40 x 40s exposures of the Ring nebula.
Screenshot of AstroDMx Capture for Linux capturing images of M57.
The display was using Gammalog, but could be changed to show more contrast if required, but as all that is usually required is to correctly position the object of interest, no further adjustments were made. It should be remembered that the display controls are non destructive, so do not affect the data being captured.
The best 90% of the images were stacked in Deep Sky Stacker running in Wine, and post processed in the Gimp 2.10.
Performance and real-time display are still being improved, but a release will not be far away.
As this is not a full time enterprise and generates no funds, delays are inevitable. The aim is to keep the software as stable as possible, so, as testing reveals issues, they are systematically solved. Sometimes this takes more time than anticipated.
Nicola works on DMxCapture for Linux most days. The program is now huge and contains more than 30,000 lines of active code (many of which extend over a number of physical lines) and more than 7000 additional lines of internal documentation comments, and this excludes all dependencies.
To put this in perspective, if the source code was to be printed in a typical book, the book would run to many more than 1000 pages in length. That is a lot of code to maintain, test and extend.