Monday, 16 July 2018

Slight delay in the release of the next version of AstroDMx Capture for Linux

Nicola is making great progress with the implementation of the Atik 314L in AstroDMx Capture for Linux as previous posts have shown. However, she has also been trying to resolve a problem over the QHY cameras giving unreliable exposures at certain long exposures. This is a problem with the QHY SDK.

The problems have been reported and new SDKs have been released. However, with each new SDK release, a number of other serious, deal-breaker problems have been introduced. These in turn are being reported, and the hope is that the QHY SDK developers will soon resolve all of the problems. In the meantime, it may be necessary to produce a release of AstroDMx Capture for Linux that implements the Atik 314L (and possibly others) before the QHY issues are resolved.

This is unfortunate and disappointing, but it is important to realise that the problem is not with the AstroDMx Capture code, but rather, with the SDK that has to be used to call the camera functions.

I will make sure that when a new release is made, the information will be posted here. Nicola will implement a hack that should improve the exposure situation for the QHY, but that is no substitute for a reliable SDK.

Sunday, 15 July 2018

Testing a new display function in AstroDMx Capture for Linux with an Atik 314L camera

An Atik 314L camera was placed at the Newtonian focus of a Skywatcher 130 PDS 130mm, f/5 Newtonian, mounted on a Celestron AVX GOTO mount. 16 x 48s exposures were captured of M8, the Lagoon nebula and 5 matching dark-frames using AstroDMx Capture for Linux. The images were dark-frame corrected and stacked in Deep Sky Stacker running in Wine. The final image was processed in Fits Liberator, running in Wine and the Gimp 2.10.

The problem with 16 bit imaging is that the image being captured has to be rendered in 8 bits so that it can be viewed on the computer screen. Moreover, the interesting parts of the data are very dim and with a simple scaling of the results to 8 bits, much of the object being image will probably be invisible. What is needed are transfer functions that will brighten, in a non-linear fashion, the image data, so that the fainter parts of the object are revealed. These transformations are only made to the displayed image, leaving the saved data untouched. AstroDMx Capture for Linux has been given a number of controls to optimise the visualisation of the data being captured. Here we were testing a gammalog display function to help reveal the object whilst being captured.

Final image of M8, the Lagoon Nebula

The images were captured while testing the new gammalog image display function in AstroDMx Capture for Linux.

The preview image can be brightened or dimmed using the other non-destructive controls of gamma, brightness and contrast.
Additional display transformation functions are being implemented now and will be tested as soon as possible.

Tuesday, 10 July 2018

Occultation disks and streetlights

To the astronomical imager, streetlights can be such a problem as to make imaging all but impossible. I don't mean the general problem of light pollution in the sky caused by streetlights, I mean the glare from nearby streetlights that can shine directly into the telescope and ruin any results.
We have a streetlight right outside the front of the house. The council fitted internal baffles to the lamp on request, which reduced it in brightness a little, but it is still able to cast its bean of light onto our scopes that we have to use at the front of the house in order to image objects lower in the sky. This problem is solved by mounting a blackened occultation board on a sturdy tripod and placing it so that it casts its shadow onto the scope. This solution works very well and occultation disks or boards can help problems with more distant street lights that are in the general direction of where the scope is to be pointed.

The streetlight can be seen very close beyond the occultation board.

From the point of view of the scope, the street light is completely obscured and does not cause a problem.
Smaller occultation boards, strategicall placed, can deal with problems caused by more distant lights.

Saturday, 7 July 2018

First Light for the Atik 314L implementation in AstroDMx Capture for Linux

An Atik 314L camera was placed at the Newtonian focus of a Skywatcher 130PDS, 130mm, f/5 Newtonian, mounted on a Celestron AVX, EQ, GOTO mount. 16 bit Fits images were captured of  M16 (40s), M17 (40s) and M13 (35s) using AstroDMx Capture for Linux. For each object, the best 26 frames were stacked in Deep Sky Stacker, running in Wine. The images were post-processed in Fitswork (running in Wine), The Gimp 2.10, RawTherapee and Neat Image.

M16 the Eagle nebula and cluster

The Pillars of Creation

M17, the Swan or Omega nebula


 Nicola hasn't quite finished the Atik 314L implementation. When it is finished, it will be present in the next release; which has been delayed by problems with the latest QHY SDK. QHY have been made aware of the problem and are currently working on it. In the meantime, the Atik 314L implementation goes ahead.

Tuesday, 19 June 2018

Adjusting the azimuth clutch on a Skywatcher Star Discovery mount.

Unlike the Synscan AZ, GOTO mounts, the Star Discovery Mount has FreedomFind™ dual encoder technology. This allows the mount to be pushed manually in either axis during use, and the controller keeps track of where the mount is pointing. The altitude axis has a sturdy clutch release and adjuster. However, the azimuth axis does not. With use, it is commonly found that the azimuth clutch becomes slack and the mount can be turned manually too easily. Even a gust of wind might be able to turn the scope on the azimuth axis.

Four screws hold the plastic top on the mount. When this is removed the double clutch assembly is exposed. The bottom clutch controls how difficult it is to manually turn the azimuth axis.

A spanner was made by hammering and filing a tool that came with a self assembly item, until it was wide enough to slide onto the flats on the bottom clutch. There are two Allen-key grub-screws between the flats opposite each other and these are slackened off with an Allen key. The clutch is then turned a very tiny amount clockwise and the grub screws tightened.
It is clearly a matter of trial and error to get the adjustment right, but this procedure works. It is best to turn the clutch by an almost imperceptible amount at one go. If it is overtightened, then the mount will stall while slewing in certain directions due to some asymmetry within the system.

Manufactured spanner and Allen-Key

The spanner engaging the flats

One of the retaining grub-screws is visible
I don’t know whether this procedure will invalidate the warranty, but I found that without doing it, the mount was virtually unusable. Nowhere in the manual is it explained how to correct this problem.

I use this mount as a substantial, quick setup, AZ GOTO mount for Solar system and deep sky observing and imaging. Previous postings on this blog show the mount in action. Of course there is image rotation, but as long as there is no perceptible rotation within images, then Deep Sky Stacker and lxnstack for example, are able to de-rotate the images during stacking. Keeping the azimuth clutch adjusted correctly is going to be critical for the continued use of this mount.

Monday, 11 June 2018

M17 with AstroDMx Capture for Linux and a QHY 5L-II-M

An f/5, Skywatcher Explorer 130 P-DS Newtonian Was mounted on a Celestron AVX, EQ, GOTO mount. A QHY 5L-II-M camera was placed at the Newtonian focus and AstroDMx Capture for Linux was used to capture 40 x 25s exposures of M17, the Omega or Swan Nebula as Tiff files. Matching dark-frames were captured. The frames were stacked in Deep Sky Stacker running in wine and the resulting Fits file was processed in the ESO, ESA, NASA FITS Liberator 3 software running in Wine. The resulting Tiff file was processed in Neat Image V8 and RawTherapee.

FITS Liberator
FITS Liberator is a very good program for non-linear stretching of Fits Images


Full Size

Wednesday, 30 May 2018

Nature study with AstroDMx Capture for Linux

A Zoom TV lens was fitted to a DFK mounted on a small tripod and the camera was aimed at an active bird nesting box.

DFK with a zoom TV lens

AstroDMx Capture was used to capture a SER file of the nesting box.

Te Debian laptop capturing data

Screenshot of AstroDMx Capture for Linux capturing data

SER player was used to cut out the frames containing action. A SER file and AVI were made as high quality recordings and an animated GIF was made to show the results here on the blog.

Animated GIF

Full size

The software has the capacity for time-lapse imaging down to 0.1s intervals, but for the fast flight of the blue-tits, a 30fps SER file was the best way to capture the data

Saturday, 26 May 2018

ChromeOS, Android and the SVBONY SV105 camera

There are two operating systems based on the Linux kernel that are not usually thought of as Linux. This is because, whilst they are both based on the Linux kernel, they are both, by design, unable to run Linux desktop applications. With ChromeOS, most of the applications run in the Chrome browser environment. In Android, a whole ecosystem of applications run in the Android environment, and cannot be run on a normal Linux desktop.

The low cost SVBONY SV105 camera and a Chromebook.

There is no good imaging software for ChromeOS, however, there is a simple camera application that can be used in camera auto mode, and is suitable for outreach. It is even possible to grab images. Here is the setup with a Samsung Chromebook and SVBONY SV105 with a Skymax 127 on an iOptron AZ, GOTO mount, along with an image grabbed by the camera application.
Click on an image to get a closer view.

The Setup with scope, camera and Chromebook

An image captured by the camera software

The SVBONY SV105 camera and Android:
The SV105 comes with a 1.8m USB cable which has a short fly-out USB lead to provide extra power to the device which has a power consumption of 150mA at 5volts. This was essential for using the camera with a Samsung 10.1 inch Galaxy Note tablet. The tablet was not able to supply sufficient power to operate the camera. A 5v 2.1A mobile phone portable charging device was used as an auxiliary power supply, connected via the fly-out lead. A powered USB hub could be used alternatively to provide extra power. My Samsung tablet was temperamental so far as detecting the camera, possibly because it is quite an old device. It helped to have the device fully charged.

Auxiliary power supply

The SV105 camera was placed at the Cassegrain focus of a Skymax 127 Maksutov and was connected to the Android tablet computer.
There is, available in the Google Play store, a USB camera capture application called USB Camera. This is a particularly good application because it presents the main controls of the camera, enabling the correct exposure etc. to be set. It works with UVC cameras.

Photograph of Android tablet streaming images from the SVBONY SV105 camera

Screenshot of USB Camera streaming video

USB Camera can capture mp4 Movies or still images.

Controls for Video formats

A drop-down menu allows the selection of the camera controls which can be hidden.
Drop down menu for camera controls

Single captured image

The combination of the SV105, Android and USB Capture provides a very credible observing, eyepiece sharing and even imaging platform.

At the moment, Android seems to be the superior of the two platforms for astronomical viewing and imaging, with one caveat; that the aging tablet used for these experiments was temperamental, even with an auxiliary power supply, with respect to detecting the camera (any camera). However, once detected, everything worked fine.
There are available Android notebooks, and depending on the version of Android they are running, they could be more suitable devices than a tablet (or phone), if they can run the capture software.
The weakness of ChromeOS is the lack of suitable capture applications.
Both platforms would benefit from the development of applications that are capable of capturing movies in the SER format, a superior format for astronomical imaging. This would produce data that could be transferred to another computer for processing.

Thursday, 24 May 2018

High Definition Lunar image with SVBONY T7 W2568A camera and AstroDMx Capture for Linux

A low-cost SVBONY T7 W2568 high speed camera was placed at the Cassegrain focus of a Skymax 127 Maksutov mounted on a Celestron AVX, EQ GOTO mount. 3000 frame 8 bit SER files were captured of 4 largely overlapping regions on the terminator in the Clavius Tycho region using AstroDMx Capture for Linux. The best 50% of the frames in each of the SER files were stacked in Autostakkert!3 running in Wine and the 4 panes were stitched into a mosaic using Microsoft ICE also running in Wine. The mosaic image was wavelet processed in Registax 5.1 running in Wine. The final image was post processed in the Gimp 2.10 and RawTherapee.

Full Size

This low cost camera is definitely worth having for this kind on high definition work.

Monday, 21 May 2018

Deep Sky with the SVBONY T7 W2568A camera, AstroDMx Capture for Linux and a 10 inch, f/4.8 Newtonian

An SVBONY T7 W2568A camera was placed at the Newtonian focus of an Orion Europa, 10 inch, f/4.8 Newtonian. Exposures were captured in RAW 8, with real-time dark-frame and flat-field correction using AstroDMx Capture for Linux on a Debian laptop. The exposures were saved as Tiff files. M13 (50 x 15s exposures), M57 (30 x 45s exposures) and M82 (30 x 60s exposures). The exposures were stacked in Deep Sky Stacker running in Wine and Post processed in the Gimp 2.9 and Neat Image.


Screenshot of AstroDMx Capture for Linux capturing M82 data with real-time dark-frame and flat-field correction



Quite acceptable deep-sky images from this low cost SVBONY W2568A high-speed camera. An ideal starter camera.