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Saturday, December 07, 2013

Jupiter and moons

Image 1: Jupiter's bands (20.12.2013)

Check a better image at: http://bit.ly/1cn4mcV
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Data: DBK21@4000mm FL, f/31, 10% of 600 photos used with 1/30s each, processed with Giotto and Aperture.
Image 2: Left to right: The icy moon Europa, the big moon Ganymede, the volcano moon Io and the gas planet Jupiter.

A high resolution image is available at: http://bit.ly/1gMZOLU
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Data: DBK21@2500mm FL, f/19, 10% of 600 photos used with 1/30s each, processed with Giotto and Aperture.

Thursday, November 07, 2013

NGC4038 NGC4039 Interacting Galaxies in Corvus

Image 1: The "Antennae Galaxies" in the Corvus constellation

The low altitude of these galaxies in the horizon and the light pollution of my location made the photo processing of the raw photos a real challenge. I could find the objects only by Goto-telescope-control. Due to the light pollution both the galaxies and even the nearby stars were invisible(!) through the eyepiece on the 5 inches telescope. A high resolution photo is available here.
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Do you use an OSC color astrocamera for astrophotography? Learn how to remove the light pollution gradients from your photos at http://dark.astrodigital.net/removelightpollution

Sunday, September 15, 2013

Impressions from the "AME 2013" astronomy expo

Astronomy expo AME 2013, Germany
Image 1: A Knaeble RC telescope

Image 2: ASA astrograph and mount 

Image 3: ATIK CCD cameras

Image 4: Takahashi Epsilon telescope 


Image 5: ICS Newton

Image 6: Avalon mount 

Image 6: Hasenstein mount with Astroholgi weights 

Image 7: The BkSternguckers, Germany 

Image 8: Celestron EHD telescope

Image 9: Hofheim Instruments Dobson telescope 

Image 10: ASA astrograph and mount 

Image 11: ASA astrograph on ASA DDM mount 

All photos from the expo are available at: http://dark.astrodigital.net/ame2013

Saturday, September 14, 2013

The star field around NGC891

Image 1: The galaxy NGC891

NGC 891 (also known as Caldwell 23) is an edge-on unbarred spiral galaxy (actually barred) about 30 million light-years away in the constellation Andromeda. [1]

Image 2: Galaxy groups near to NGC891

No kidding. This shot is a really deep one! Watch the many galaxies out there! NGC 898, NGC914, NGC906, NGC909, NGC911, NGC910, NGC912, NGC913 and numerous other faint PGC galaxies are visible!

Image 3: The star field around NGC891

This is the region (2° 2' x 1° 21' ) around the edge-on galaxy NGC891. Numerous other faint galaxies down to 17,5 mag are visible in this photo.
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Photo stuff: NP127is, QHY8L OSC, FS-60C, Lodestar, NJP/JPZ, 6x1200s RGB, EZCAP (image acquisition), MaximDL (calibration/ alignment/ stacking), IRIS (gradient removal), Aperture (post processing).

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[1]  http://en.wikipedia.org/wiki/NGC_891

Sunday, August 18, 2013

The Tadpoles IC410 - a nebula in Auriga

Image: The Tadpoles IC410

IC 410 is an emission nebula approx. 1200 light years away from the Earth. It spans 100 light years. A young star cluster called NGC 1893 is embedded in IC410. Its stellar winds distort the denser gas clouds that form the "Tadpoles" visible in the middle of the image.
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Exposure data: RGB series 5x1200s with an OSC CCD camera, median stack, taken at low attitude 5°-36° degrees, and good atmospheric conditions.

Monday, July 29, 2013

A ten days old moon

This photo is taken at 5° altitude (!) just a few minutes before the storm yesterday.

Saturday, July 20, 2013

100 minutes Andromeda (M31)

Image 1: The Great Andromeda Galaxy (M31)

Those friends want to download or view this photo in a higher resolution, should follow this link:
http://bit.ly/18jDXrD

Saturday, July 06, 2013

Shading plate for visual observations

Image 1: The plate on the telescope

This shading plate is an optional tool for improving your viewing experience through a telescope. It significantly increases the contrast of details in the FOV, since it blocks scattered light coming from the front side. This thing really works! Unlike similar plates found in the market, this plate is NOT simply held by friction between both 2" ends. It is screwed on a special tailor-made 2"<->2" inches adapter, which is part of the system! The plate is slightly bent at the side of the observator to provide enough space for him. 

Hence, it is not just a simple "plate", but a complete mechanical shading system. It is robustly built and tailor-made by AstroHolgiShop (http://www.astroholgi.de).

A Baader diagonal mirror is used, since if offers a SC (Schmidt-Cassegrain) thread at the telescope side, making it suitable for screwing a shorter tailor-made adapter to 2" since the used Dall Kirkham telescope had a very limited backfocus.

Image 2: The contrast improvement is noticable

More photos:
http://dark.astrodigital.net/shadingdevice

/px

Monday, June 10, 2013

Thursday, May 09, 2013

NGC7023 - The Iris nebula

Image: The Iris nebula in the Cepheus constellation

The Iris reflection nebula is surrounded by a dark nebula. The dark nebula is a huge amount of interstellar dust hiding the stars behind it. The few stars being visible to our human eyes "in" the dark nebula region are obviously between us and the nebula. The blue-greenish reflection nebula is caused by the light of a hot star called SAO 19158, that illuminates the dust clouds around it. Only IR (infrared) light can penetrate the thick dust clouds, that means an infrared photo should show more stars in the dark nebula region.

Thursday, April 25, 2013

Partial Moon Eclipse 2013 - Partielle Mondfinsternis 2013

Image 1: Partial Moon Eclipse - 25.4.2013


Image 2: Partial Moon eclipse and the planet Saturn in the same evening


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See also: [Wikipedia]

Saturday, April 20, 2013

QHY8L camera: Dark, Flat, and Bias images

The QHY8L is a low cost, entry level, scientific camera equipped with an APS-C size color chip. It has a good sensitivity also in Ha emission line. It is cooled and it has been primarily designed for astronomical use. The resulted photos go deep, e.g. 21th magnitude celestial objects can be captured in only 3 hours exposures at f/5.3 and 130mm aperture.

Image 1: QHY8L one shot color astrocamera

For those people making scientific work on CCD sensors without any commercial interesst, I am making available the dark, flat and bias images of a QHY8L camera: => click here to download them now <=
 Image 2: Against any specification, both QHY8L cameras I have used so far
were able to cool down to -45°C under ambient

As usual, every image coming down from the camera must be calibrated. I do that in MaximDL by using flat field images made with Gerd Neumann's "Aurora flatfield panel", since it is also suitable for OSC CCD sensors. Flat fields remove artifacts caused by inhomogeneities of the CCD sensor, dust particles on both the sensor and the optics, and vignetting. A master flat field should be calibrated by subtracting a master Bias frame.
Image 3: Some tips how to calibrate QHY8L images in MaximDL

The dark frames (download link) will completely remove the so called "amplifier glow" artifact in your QHY8L light frames. The "amplifier glow" is a small bright area at top-left edge of your light/dark images. The bias frames will remove the noise of the electronics.

Image 4: How to convert the QHY8L raw images in color in MaximDL.

Process your QHY8L images strictly in the following way in MaximDL:
  1. image acquisition with this OSC camera => RGBRAW
  2. image calibration RGBRAW => RGBCAL (using dark, bias, flat frames) 
  3. color conversion (RGBCAL => RGB)
  4. color split (RGB => R,G,B)
  5. remove gradient (i.e. the light pollution) in R channel => Rclean
  6. remove gradient in G channel  => Gclean
  7. remove gradient in B channel  => Bclean
  8. color combine (Rclean,Gclean,Bclean => RGBclean)
  9. repeat from step (2) for all your images 
  10. align all images   
  11. stack all images   
  12. ...   
  13. further steps  
Download an example here. Do NOT align your images before the color conversion, since this will move the RGGB map and you will loose the color information. The according procedure is also explained here.

The 2D Fast Fourier Transformation (FFT) of the master BIAS averaged of 30 Bias gives information about the electronics. Periodical patterns indicate badly shielded electronics. A point in the middle of the image with perfect noise around it without any pattern is a very good sign. See also here.
Image 5: Fast fourier transformation (FFT) of the master BIAS frame

There some slight differences between the BIAS of both QHY8L cameras I have used so far.
Image 6: Comparison of the BIAS frames of two different QHY8L cameras

I calculated the read noise of my QHY8L according to the instructions in users.libero.it/mnico and I found it to be 10.96e-, assuming a system gain of 0.5e- /ADU  as shown in oleg.milantiev.com and tienda.lunatico.es 

Image 7: Processed image of a QHY8L (5x1200s, 660mm, f/5.2)

These are the gain and offset settings I use for the QHY8L.
Image 8: Gain and Offset settings for the QHY8L camera

Finally, I would like to present you a collection of my QHY8L photos at: http://dark.astrodigital.net/qhy8l

Thanks for reading.

Panagiotis Xipteras

Monday, March 25, 2013

The field around NGC5317 in Virgo

 Image 1: The region around NGC5317 (negative)


 Image 2: NGC5317 is located in the Virgo constellation (photo dimensions 2°x1,3°) 

  Image 3: Several faint galaxies are in the same field of view

The image #2 shows a small part of the sky in the constellation of Virgo. This region is rarely photographed since the galaxies there are very dim and due to the fact that there are much more attractive targets "next to" it.

Description in greek language:
Η φωτογραφια δειχνει ενα κομματι του ουρανου στον αστερισμο της Παρθενου που σπανια φωτογραφιζετε λογο του οτι οι γαλαξιες εκει ειναι πολυ αμυδροι και λογο του γεγονος οτι εκει "κοντα" στο ιδιο αστερισμο εχει πολυ πιο ελκυστικους στοχους για τον αστροφωτογραφο.  Να πω την αληθεια το διπλοσκεφτηκα να κατσω να φωτογραφισω αυτο το κομματι του ουρανου αλλα τελικα η περιεργια νικησε.

Wednesday, March 20, 2013

Comet C/2011 L4 PANSTARRS

This is the comet C/2011L4 PANSTARRS. Get more info at: http://en.wikipedia.org/wiki/C/2011_L4

 Image 1: The tail is clearly visible at 280mm focal length, 30s, ISO200

Image 2: Wide view at 55mm focal length, 10s, ISO200

Date: 20.03.2013 at 19:30 MET
Equipment: Nikon d3100, Nikkor 55-300mm lenses, Vixen GP mount.