Astrophoto thread (your own photos please)

Messierhunter

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All your works are truly great! During my sleep last night, a voice told me the following:

With your new AO-7 adaptive optics system, you are certainly the one in this forum to be able to attempt the Man and Planets challenge: with Venus, Mars, Jupiter and Saturn!:thumbup:
Thank you! Unfortunately the AO-7 system is not well suited for that kind of challenge. You need a bright guide star to use the system, which isn't usually practical at the horizon. The window to capture a planet next to a person at the horizon at that kind of magnification is incredibly short; by the time a guide star is acquired (assuming you can find one) and the system is running the opportunity has probably passed. You're also limited to still images; you have to use an SBIG ST- camera with the system. Even my USB ST-2000XCM has a full frame download time of several seconds.

A more practical method would be to use good old fashioned "lucky imaging" techniques, but this will require compositing the stacked image onto a frame of the horizon since the planet is not stationary relative to the horizon. Atmospheric turbulence at the horizon will be quite severe though as you see in that video, so the gains from lucky imaging are unlikely to reach diffraction limits.
 

Soheil_Esy

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You need a bright guide star to use the system, which isn't usually practical at the horizon.
Can you then consider the use of a laser as a guide star ?

Edit: Maybe it's not even legal where you live, to point powerful lasers toward the sky...
 
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Messierhunter

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Can you then consider the use of a laser as a guide star ?

Edit: Maybe it's not even legal where you live, to point powerful lasers toward the sky...
The AO-7 system cannot be used with a laser guide star; the type of correction it applies requires the use of a natural guide star. From the AO-7 manual:
AO-7 Manual said:
The simplest technique, which we have implemented, uses a high speed steering
device to suppress the wander and hold the star image fixed on the sensing device. A second
level of sophistication is to try to correct the lower level aberrations produced by the atmosphere,
in addition to stabilizing the image, while viewing a star. The ultimate technique, developed by
the military, uses a laser guide star to provide a point-like source high in the atmosphere that
provides enough light to enable accurate sensing of the wavefront, and therefore correction. The
laser guide star approach, however, can only correct the higher order aberrations; the image must
still be stabilized by a tip-tilt mirror viewing the object, not the laser guide star.
https://diffractionlimited.com/wp-content/uploads/2016/03/ao7manual.pdf
 

Soheil_Esy

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The AO-7 system cannot be used with a laser guide star; the type of correction it applies requires the use of a natural guide star.
It seems that imaging Jupiter and Saturn might be possible though:

AO-7 Manual said:
It cannot improve planet imaging unless a guide star is close by, such as might be provided by a moon of Jupiter.
 

Soheil_Esy

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The AO-7 system cannot be used with a laser guide star; the type of correction it applies requires the use of a natural guide star.


Observing Venus (and Mars) with Adaptive Optics

2004?

Current AO Systems

Require a guide “star” close to the science object.
With a planet like Mars or Venus …
Too big to be used as a guide star itself.
Too bright to allow a nearby star to be used as a guide star (scattered light).
e.g. Attempts to use Phobos (mag 10.4) as a guide star for Mars (mag -2.8) have not been successful.
Laser guide stars don’t help.


Solution

We need an AO wavefront sensor that can work on the extended structure of the image of Mars or Venus (rather than a point source).
For Venus use the 2.3 mm cloud structure or 1.27 mm airglow (or perhaps the sunlit crescent in the visible).
For Mars use the surface albedo features.
We know this is possible because solar AO systems work on extended structure (e.g. solar granulation).


http://www.lesia.obspm.fr/venus-atm/bailey.ppt
One possible solution:

Orbiting Laser Beacons for Adaptive Optics Observations of Mars and Other Planets

2004

ABSTRACT.

The use of adaptive optics to correct the effects of seeing is rapidly becoming a standard technique
in astronomical observing and is fundamental to current plans for extremely large telescopes. Adaptive optics
has proved effective for studies of small solar system objects that can be used as their own reference sources.
However, it is much harder to apply adaptive optics techniques to bright planets such as Mars and Venus, because
of the difficulty of finding a suitable reference star that is not drowned out by the intense scattered light from
the planet itself. A possible solution to the problem might be provided by current plans for laser communications
systems. For example, the Mars Telecommunications Orbiter, planned for launch in 2009, will carry a 5 W laser
to beam data back to Earth. This laser system in orbit around Mars will provide a very bright guide star, with
a magnitude ranging from 1.8 to 5.8. Such a guide star is more than bright enough for existing adaptive optics
systems and is in the range needed to support “extreme AO” systems, producing very high Strehl ratios. Used
in conjunction with large ground-based telescopes, this could allow studies of Mars with spatial resolutions down
to a few kilometers and allow the ground-based study of Mars to extend around much of its orbit, rather than
be limited to the time around opposition.

iopscience.iop.org/article/10.1086/423904/pdf
No need to go this far, and too extravagant. Thus, a solution nearer to the surface:


Sodium-layer Synthetic Beacons for Adaptive Optics

1992

Using adaptive optics to compensate for atmospherically induced wavefront distortions requires a remote beacon.
In astronomical imaging the beacon can be the object of interest or a nearby bright star.
For a satellite the beacon can be a retroreflector illuminated by a ground-based laser.
Unfortunately, dim stars don't always have bright neighbors.

Synthetic beacons, generated by laser backscatter from the atmosphere, offer a solution to this problem.

These beacons are produced by using Rayleigh backscatter, or scattering by the air molecules, at altitudes below 20 km, or by using resonant backscatter from the mesospheric sodium layer at an altitude of approximately 90 km.

iopscience.iop.org/article/10.1086/423904/pdf
And maybe a simplier solution affordable for the amateur astro-imagers, by firing a 1kHz infrared pulse laser and using plasma emission to paint a beacon at 20 km altitude::lol:



Aerial Burton 3D display projects images into mid-air

November 12, 2014

Aerial Burton has demonstrated an aerial 3D display, which can project text and images in mid-air.

"The biggest difference between our technology and other displays is, this is a screenless display. This is the only device that can show text and pictures in mid-air, without using a screen.

"Our motivation for developing this display was that we thought it would be useful in emergencies if text could be displayed in mid-air. What makes our technology different is that, when we considered how we might display such aerial text, we thought of using a phenomenon called plasma emission."

The images are constructed by firing a 1kHz infrared pulse laser into a 3D scanner, which reflects and focuses the pulses of the laser to specific points in the air. The molecules at that point are ionized, and the energy is released as photons. Aerial Burton believes that using this technology in emergencies will aid communication after a disaster, letting people know where to evacuate, or obtain food and emergency supplies.

"When we developed this as a commercial product, as you can see today, we wanted to make it transportable by car, so users can convert any suitable vehicle into a 3D display transporter, and take the display to where it’s needed. We’d like to achieve this by early 2015."

As well as prioritizing transportability, Aerial Burton plans to market the display overseas, to increase recognition of this technology.





http://akihabaranews.com/2014/11/12...-3d-display-projects-images-mid-air-524133246

Video


:thumbup:
 
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Poscik

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Hi!

Milky way taken two days ago on the shore of Bug river in eastern Mazovian voivodeship, Poland. Just ~130km from Warsaw.



I'll be back soon with nearly 180° panorama of the same place. I need to posprocess it :)
 
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Poscik

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Hi! As I promised, here is almost 180° panorama from that place.

 

Messierhunter

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One possible solution:
And maybe a simplier solution affordable for the amateur astro-imagers, by firing a 1kHz infrared pulse laser and using plasma emission to paint a beacon at 20 km altitude::lol:
One of the largest corrections the AO-7 makes is to the scope's own residual periodic error. Even if you could project an artificial guide star, it would either need to ride with the telescope (in which case it will share the telescope's periodic error) or provide its own tracking (in which case it will super-impose any periodic or other tracking error into the image) and neither really gets you to the promised land the way a natural guide star does. For this setup, trying to guide on the extended shape of the planet doesn't help either; if the planet is in the autoguider and the guider is tracking it, then the planet is not on the imaging chip. It's just not really intended for planetary imaging, and you can use lucky imaging with the planets to get near diffraction-limited results already, so adaptive optics just isn't necessary for nearly any application involving the planets.
 

Poscik

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Hi!

My first ever attempt to shot down our friends from M31. My setup for this shot was:

22x120s ISO1600 EOS500D + Canon 70-200L @200mm f/4 + Sky Watcher Star Adventurer

 

Poscik

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Hi! The season for Milky Way center has just started ;) This year's first shot taken at Podedworskie Lake.



---------- Post added 03-25-18 at 05:41 PM ---------- Previous post was 03-24-18 at 08:34 PM ----------

Hi!

Another night spend catching milky way. This time northern east Mazovian voivodeship

FulHD :cool:
 

RisingFury

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Among bits and Bytes...
Didn't know image stacking works on mobile targets, even if it's just a few frames. I thought the image would be blurry even if you do two frames.
 

Messierhunter

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Didn't know image stacking works on mobile targets, even if it's just a few frames. I thought the image would be blurry even if you do two frames.
It depends on the way in which you stack them. For this I used maximum addition (retain the brightest pixel value for each frame stacked for each final pixel). I did have to get a bit creative with the boostback photo; I aligned the stack twice, once on the boosters (their motion relative to each other was negligible during boostback ignition) and once again on the core stage. The two stacks were then layered together to "freeze" the motion of each. It was similar to how I process my comet images when trying to show the comet and the background stars at the same time.
 

Poscik

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Hi! Orion nebula taken at 12th of October from north-eastern masovian voivodeship.

Canon EOS500D + 70-200L f/4 @200mm f/4 + Sky Watcher Star Adventurer
30x90s light frames + 35 dark frames

 

Messierhunter

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Dropcanvas stopped existing, so all my old photos are sadly gone. Oh well. Here's a new one I took last night of M87 with its black hole jet, the same black hole imaged by the Event Horizon Telescope project.
https://drive.google.com/file/d/1RkqqRk3NRB6QLpZKVn0Qv6sZM91C_ITs/view?usp=sharing
8" LX200 Classic, SBIG ST-2000XCM and AO-7 adaptive optics @ f/10.
13x5 minute exposures stacked in Deep Sky Stacker and tonemapped in IRIS.
 

kuddel

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Slight off-topic, but... dropcanvas just quit without giving you a possibility to get all your images?
 
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