Category Archives: Astronomy

Transit of Mercury

Transit of Mercury 09 May 2016 from Martin Junius on Vimeo.

Somewhat cloudy, especially towards the end, but most of the transit of Mercury was clearly visible from Brück, Cologne, Germany.

Einige Wolken, besonders zum Ende hin, aber der Großteil der Merkurtransits konnte in Brück, Köln beobachtet werden.

The time-lapse video is available on / das Zeitraffervideo gibt’s auf: Facebook, Vimeo, Youtube.

Equipment:

  • Canon 5D Mark II, Televue Powermate 2x, William Optics FT 81 FD f/5.9 478mm, Baader filter, Skywatcher AZ EQ6 GT
  • Canon 5D Mark III, EF 8-15 f/4 L Fisheye @ 14mm
  • GoPro Hero4 Silver
  • 2x ISR Twin1 timer

Location: near Friedhof Brück, Cologne, Germany
50°55’45” N 7°4’43” E

Blurb PDF Upload

Namibia 2015 - IAS Edition

Namibia 2015 – IAS Edition

FINALLY! ;-) It seems that I’ve solved my problems with Scribus PDF/X-3 photobooks failing the preflight check when uploading them to Blurb. The photobook above used to be rejected during excessive tests a couple weeks ago.

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Himmelshintergrund mit der Kamera messen

Screenshot Lightroom

Screenshot Lightroom

Manchmal lässt sich das “engineer by trade” nicht ganz leugnen und etwas Analytik ist gerade in der Astrofotografie nicht verkehrt.

Fragestellung: wie kann man anhand eines Fotos des Nachthimmels die Hintergrundhelligkeit ermitteln? Analog zu den Messwerten des Sky Quality Meters?

Samir Kharusi hat unter “Measuring Skyfog from Camera JPEG” die Methodik beschrieben, ich hab mir die Mühe gemacht, das mit Raw-Dateien, Lightroom und Excel zu operationalisieren.

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Astrophotography IAS, Hakos 2015

Trifid Nebula - M20 or NGC 6514

Trifid Nebula – M20 or NGC 6514, 32 x 300s

Southern Pinwheel Galaxy - M83 or NGC 5236

Southern Pinwheel Galaxy – M83 or NGC 5236, 30 x 300s

Omega Centauri - NGC 5139

Omega Centauri – NGC 5139, 24 x 90s

NGC 6726, 6727, 6729, IC 4812 in Corona Australis

NGC 6726, 6727, 6729, IC 4812 in Corona Australis

NGC 6188

NGC 6188, 24 x 300s

IC 4603 and Rho Ophiuchi

IC 4603 and Rho Ophiuchi, 16 x 300s

Centaurus A - NGC 5128

Centaurus A – NGC 5128, 25 x 300s

Cat's Paw Nebula - NGC 6334

Cat’s Paw Nebula – NGC 6334, 16 x 300s

IAS Observatory, Hakos, Namibia
20″ Philipp Keller Cassegrain primary focus @ 1500mm f/3
Liebscher Mount with FS2
Off axis guiding with Lodestar X2, dithering with BackyardEOS and PHD2
Canon 5D Mark II (a) or 5D Mark III (unmod), varying crop
Varying # of subs and exposure, see above, ISO 800 + sky flats/bias, no darks
Image processing DeepSkyStacker, Lightroom, Photoshop

Flight into Darkness

Total Solar Eclipse 20 Mar 2015 #5 - 3rd Contact

Total Solar Eclipse 20 Mar 2015 #5 – 3rd Contact

More than two years after our last one, we took the plunge and off into the darkness. Literally.

What I’m writing about is the total solar eclipse of 20 March 2015 over the Northern Atlantic Ocean, of course. A place and time where weather prospect weren’t exactly stellar or solar, thus quite early, already in 2013, we booked Eclipse Reisen’s e-flight (operated by Air Berlin, AB 1000) from Düsseldorf.

Into the car, onto the plane, into the darkness, back into the light and the Düsseldorfian fog, and home-bound again. 12 hours round-trip, certainly a very “efficient” eclipse trip. ;-)

The experience in the air was quite different from our previous ground-based eclipse excursions. A lot of the anxiety and anticipation – will we really see totality? – is missing, as success is almost guaranteed. And when the plane finally navigates into the “eclipse run”, the partial phase is mostly completed, we didn’t get to see C1 or C4.

But absolutely priceless is the view of the moon’s umbra moving across the clouds below, seemingly slowly catching up with the air plane, then plunging us into darkness, and finally off it goes, moving away from of us. Thus I’m very happy that I was able to catch this on video.

35,000 ft above the Northern Atlantic / Norwegian Sea with mid totality at 63°31’21.3″N 7°53’05.6″W / UTC 09:43:30. From the telephoto shots I did, the contact times and positions were as follows:

  • C2 at UTC 09:41:35 / 63°20’18” N 8°13’23” W
  • C3 at UTC 09:45:15 / 63°40’53” N 7°35’37” W

for a totality duration of 3min 40s.

Impressive, as it always has been and will be. Where’s the next one? …

Hakos Time-lapse

Hakos, Namibia 2014 Time-lapse from Martin Junius on Vimeo.

Time-lapse video from a short trip to the IAS Observatory (Internationale Amateur Sternwarte) at Hakos, Namibia in June 2014.

Natürlich darf auch ein Zeitraffervideo von der  Internationalen Amateursternwarte IAS auf Hakos, Namibia nicht fehlen. Und so pittoresk die Wolken hier auch sind, in drei von acht Beobachtungsnächten waren sie dann doch störend. Insbesondere für Michael und Lutz, die eine Sternbedeckung durch den Asteroiden Chariklo bzw. dessen Ringen vermessen wollten.

Video erstellt mit Lightroom, Starstax, Avisynth, VIrtualdub, Handbrake. Schön, dass einige freie “Old School” Werkzeuge für die Videoverarbeitung da noch mal richtig nützlich sind.

Musik erstellt mit Ableton Live, Native Instruments Komplete und meinem Kawai ES-6 als Master-Keyboard. Das iPad musste beim Musikmachen mal außen vor bleiben. ;-)

Astrofotografie

Antares, M4, rho Ophiuchi

Antares, M4, rho Ophiuchi

Hier im Blog ist es noch nicht so in Erscheinung getreten, aber wer meine Aktivitäten auf Facebook, Twitter, Google+ und ipernity verfolgt, wird es schon gemerkt haben: seit Herbst letzten Jahres hat mich das Thema Astrofotografie gepackt.

Sogar so sehr, dass ich doch glatt im Juni mit Michael nach Namibia geflogen bin, um einen wirklich dunklen Sternen(süd)himmel zu erleben. Was wiederum so begeisternd war, dass ich jetzt auch Mitglied bei der Internationalen Amateursternwarte (IAS) geworden bin, die auf der Hakos-Farm und dem Gamsberg eine fantastische astronomische Infrastruktur bietet.

Wie will man es beschreiben? In weiten Teilen Europas haben wir den dunklen Sternenhimmel zu einem hell zubetonierten Garten gemacht. Nur hier und da schauen ein größerer Baum oder Strauch raus. In Namibia sieht man den kompletten Garten mit noch den kleinsten Blumen.

Allerdings haben wir dort auch Lichtverschmutzung feststellen müssen. Morgens vor Beginn der astronomischen Dämmerung war das Zodiakallicht doch ganz schön hell und störend. ;-)

Lightroom and Star Trails

Rügen Star Trail

Rügen Star Trail

The relatively dark skies and several clear nights on Rügen’s “Muttland” during our recent Berlin-Rügen-Wismar trip had to be portrayed as a star trail, of course. With the new fisheye toy, the camera was just lying on its back on a small table in the hotel garden while we were stargazing. ;-) Result ist the image above, compiled from 264 single exposures at f/4, ISO 400, 30 s (in reality approx. 32 s) for a total time of 8630 s.

Combining the images can be done with a variety of tools. Photoshop or other image manipulation tools, and the “lighten” layer mode being somewhat obvious, but 264 layers with 21 Mpxl would certainly stress resources heavily. So there are some specialists out there: StarStaX and Startrails, both Windows programs offering a “lighten” and a “gap filling” mode among others.

For the circular fisheye here “gap filling” is not really required. Nevertheless the result shown above is from StarStaX in “gap filling” mode, as I like StarStaX’s slight increase in local contrast compared to “lighten”. When stacking images in “lighten” mode, both programs will output absolutely identical results. In “gap filling”, I found that Startrails yielded a too bright background for the image series. All in all I tend to prefer StarStaX, even if “comet mode” in StarStaX wasn’t that much of a success.

Neither StarStaX nor Startrails handle embedded meta data, so some postprocessing with exiftool is required:

exiftool -tagsfromfile FIRSTIMAGE.jpg -Keywords= -Subject= -ThumbnailImage= -ExposureTime=NNNN OUTPUT.jpg

An alternative is to use ImageMagick, the command line tool convert can do the “lighten” stacking as follows:

convert INPUT*.jpg -evaluate-sequence max OUTPUT.jpg

For the stacking, the image series needs to be exported from Lightroom first, JPEGs at max quality are sufficient. StarStaX supports 16 bit TIFFs on input, but not for output. Make sure to check the “Write Keywords as Lightroom Hierarchy” setting, the exiftool command above ensures that the “flat” keywords don’t mess up the keyword hierarchy during import.

One big caveat, and I found this out the hard way: in preparing the image series for export from Lightroom, don’t apply any development settings which change the geometry of the image, e.g. crop with rotation or lens distortion correction! Doing so will result in banding-like artefacts in the stacked result! An example of these early trial and errors can be seen here at this image on ipernity (Gröde star trail, artefacts visible in the lower part just above the horizon).