Monday 19 November 2012

Orion vanaf Boyden-sterrewag

ASSA Bloemfontein het `n mini werkswinkel oor "Wyeveldastrofotografie met `n DSLR-kamera op `n driepoot gehou. Barbara Cunow se lesing by die Kaapse simposium het as grondslag gedien.

Daar is so bietjie afgewyk van die lesing, maar die basiese beginsel was dieselfde.

Verloop van die lesing:

Kyk eers na die YouTube-video en bespreek dit.
  •  Doing astrophotography with a DSLR on a tripod, presented by Barbara Cunow

    - YouTube
Basiese stappe.
1. DSLR-kamera (Weet hoe werk die Self Timer om die kamera eers te stabiliseer; (of `n elektroniese sluiterontspanner). Gebruik die kamera op Manual; Fokus ees op helder ster of planeet en skakel dan outofokus af.
2. Stewige driepoot
3. Hoë ISO  1600 en 3200
4. Kort beligtings 4 sekondes tot so 10 sekondes  werk goed in ligbesoedelde omgewing
5. Lens: 18 - 55mm en 100mm
6. Beligtings: 10 - 480

Sagteware.
1. Barbara eveel Regim aan om fot's op mekaar te pak (stack).   (Laai af)  Jy het die jongste Java Script-sagteware nodig en laai Regim af met 64 bit Internet Explorer). Unzip en dubbelkliek op regim.cmd.

2. Ons het Deepskystacker gebruik (DSS) (Laai af)

   - YouTube-video om Deepskystacker te gebruik
   -  Nog een wat by vorige aansluit (met aanpassings)


Die les wat ons uit die lesing geleer het is om dinge eenvoudig te hou.
Hierdie is die begin van jou eerste treetjies om astrofotografie te doen.

Bietjie afdwaal. 
Johan Smit van Pretoria het vroeër vanjaar by die Karoo-sterrefees `n eenvoudige formule gegee om met jou ISO en die fokale lengte van jou lens die regte sluiterspoed uit te werk sonder om sterstrepe (startrails) te kry.

Hierdie formule kan veral in `n donker  omgewing werk en `n goeie riglyn wees. Eksperimenteer gerus daarmee.  Hier is `n webtuiste waar dit bespreek word.  ( Tips > Stars & Star Trails ).  Barbarahet haar foto's in `n ligbesoedelde omgewing geneem.

Di. ISO ÷ Focal Length = Maximum Shutter Speed

- Onthou die goedkoper DSLR-kameras het `n X1.6  faktor.

- Vir hierdie kameras is die formule:  ISO ÷ (Focal Length X 1.6) = Maximum Shutter Speed
 Voorbeeld:  3200 ISO ÷  (24mm X 1.6) = 83 sekondes.

  Vir `n plek met baie ligbesoedeling sou jy hierdie formule kon aanpas. Stel op 400 ISO en `n 10 sekonde beligting is die gevolg.  Dit gaan jou so `n bietjie eksperimentering kos.

Groete
Hannes Pieterse
(assabfn@gmail.com)
 

Sunday 11 November 2012

The Washington Double Star Catalog


Astrometry Department, U.S. Naval Observatory
3450 Massachusetts Ave, NW, Washington, DC 20392
wds@ad.usno.navy.mil


The Washington Double Star Catalog (WDS) maintained by the United States Naval Observatory is the world's principal database of astrometric double and multiple star information. The WDS Catalog contains positions (J2000), discoverer designations, epochs, position angles, separations, magnitudes, spectral types, proper motions, and, when available, Durchmusterung numbers and notes for the components of 103,861 systems based on 750,563 means.

Global Warming Cause Felt by Satellites and Space Junk



An artist's illustration of the Canadian Space Agency's SCISAT-1 satellite in orbit, which is carrying the Atmospheric Chemistry Experiment to track carbon dioxide levels in Earth's atmosphere.
CREDIT: Canadian Space Agency

Rising carbon dioxide levels at the edge of space are apparently reducing the pull that Earth's atmosphere has on satellites and space junk, researchers say.
The findings suggest that manmade increases in carbon dioxide might be having effects on the Earth that are larger than expected, scientists added.

In the layers of atmosphere closest to Earth, carbon dioxide is a greenhouse gas, trapping heat from the sun. Rising levels of carbon dioxide due to human activity are leading to global warming of Earth's surface.

Read more...

Source: www,space.com
      




Total Solar Eclipse of 2012 November 13/14



On 2012 November 13/14, a total eclipse of the Sun is visible from within a narrow corridor that traverses Earth's southern Hemisphere. The path of the Moon's umbral shadow begins in northern Australia and crosses the South Pacific Ocean with on other no landfall. The Moon's penumbral shadow produces a partial eclipse visible from a much larger region covering Australia, New Zealand, and the South Pacific.

For those traveling to Australia for the eclipse, please note that the eclipse occurs on the morning of Nov. 14 local time.

Read more....

Source: Nasa

The Van Allen Probes: Honoring the Origins of Magnetospheric Science


A broad suite of instruments on the Van Allen Probes will help scientists understand more about the myriad types of particles and waves in the radiation belts that encircle Earth, providing a flood of new data for scientists who study the magnetosphere. Credit: NASA/Goddard Space Flight Center.

Earth's magnetism has captured human attention since the first innovator noticed that a freely moving piece of magnetized iron would always align itself with Earth's poles. Throughout most of history, the origins and physics of this magnetism remained mysterious, though by the 20th century certain things had been learned by measuring the magnetic field at Earth's surface. These measurements suggested that Earth's magnetic field was consistent with that of a giant bar magnet embedded deep inside Earth. However, the magnetic field observed at the surface of our planet is constantly fluctuating. During the 1930s scientists pioneered explanations that such fluctuations were due to streams of particles from the sun striking and becoming entrapped within Earth’s magnetic field.

Truly understanding Earth's magnetic environment, however, required traveling to space. In 1958, the first US rocket -- known as Explorer 1 and led by James Van Allen at the University of Iowa -- was launched. By providing observations of a giant swath of magnetized radiation trapped around Earth, now known as the Van Allen Belts, Explorer 1 confirmed that Earth's magnetic environment, the magnetosphere, was not a simple place. We now know that it has a complex shape – compressed on the side facing the sun, but stretched out into a long tail trailing off away from the sun -- affected as much by incoming material from the sun as Earth's own intrinsic magnetism. This magnetic field constantly fluctuates in response to both internal instabilities and events on the sun. It also provides a home for a host of electrified particles spiraling through this complex system.


Read more...

Sunday 4 November 2012

Smile! The Curiosity Rover’s Ultimate Self-Portrait

Click to Enlarge

The Curiosity rover self portrait. Credit: NASA/JPL-Caltech/Malin Space Science Systems

Source: Universe Today
OK, we thought the low-resolution self-portrait from yesterday was great… but here’s the real goods: a monster, high-resolution awesome mosaic of 55 images taken by the Mars Hand Lens Imager (MAHLI), showing the rover at its spot in Gale Crater — called Rocknest — with the base of Gale Crater’s 5-kilometer- (3-mile-) high mountain, Aeolis Mons or Mount Sharp, rising in the background. The images were taken on Sol 84 (Oct. 31, 2012), and sent to Earth today. In the foreground, four scoop scars can be seen in the regolith in front of the rover. As we mentioned about the previous MAHLI mosaic, the arm was moved for each of the 55 images, so the arm and the camera doesn’t show up, just like any photographer behind the camera (or their arms) isn’t visible in a photograph.

You can get access to the full resolution version at this link. It’s amazing.
But that’s not all…

Read more:

Scientists Monitor Comet Breakup


Comet 168P-Hergenrother was imaged by the NOAO/Gemini telescope on Nov. 2, 2011 at about 6 a.m. UTC. Image credit: NASA/JPL-Caltech/NOAO/Gemini › Full view

The Hergenrother comet is currently traversing the inner-solar system. Amateur and professional astronomers alike have been following the icy-dirt ball over the past several weeks as it has been generating a series of impressive outbursts of cometary-dust material. Now comes word that the comet's nucleus has taken the next step in its relationship with Mother Nature.
"Comet Hergenrother is splitting apart," said Rachel Stevenson, a post-doctoral fellow working at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Using the National Optical Astronomy Observatory's Gemini North Telescope on top of Mauna Kea, Hawaii, we have resolved that the nucleus of the comet has separated into at least four distinct pieces resulting in a large increase in dust material in its coma."
With more material to reflect the sun's rays, the comet's coma has brightened considerably.
"The comet fragments are considerably fainter than the nucleus," said James Bauer, the deputy principal investigator for NASA's NEOWISE mission, from the California Institute of Technology. "This is suggestive of chunks of material being ejected from the surface."
The comet's fragmentation event was initially detected on Oct. 26 by a team of astronomers from the Remanzacco Observatory, using the Faulkes Telescope North in Haleakala, Hawaii. The initial fragment was also imaged by the WIYN telescope group at Kitt Peak National Observatory in Arizona.
For those interested in viewing Hergenrother, with a larger-sized telescope and a dark sky, the comet can be seen in between the constellations of Andromeda and Lacerta.
The orbit of comet 168P/Hergenrother comet is well understood. The comet, nor any of its fragments, are a threat to Earth.
 
 Source:  Visit NASA
DC Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov

Saturday 3 November 2012

Popular on the blog: How to find the South Celestial Pole (SCP) almost accurately.



The Most Pobular Post on the Blog!

Sky Guide Africa South 2013

Prepared by the Astronomical Society of Southern Africa for use by novice, amateur and professional astronomers, Sky Guide Africa South 2013 is a practical resource, offering information for the whole year on the movement of the planets, upcoming eclipses, the dates of meteor showers, as well as star charts to aid in identifying stars and constellations in the southern African night skies.

The book also presents a wealth of information in a clear and accessible way about the Sun, Moon, planets, comets, meteors and bright stars, with many supporting diagrams, charts, illustrations and images.

An annual publication, Sky Guide Africa South is an invaluable resource for anyone with an interest in the night skies of southern Africa; ‘… an absolute must for first-time star-gazers and professional astronomers alike’.