Polish your metal mirror - Sir William Herschel

This is an example of a polishing machine devissed by William Herschel for small speculum metal mirrors. Image: Herschel Museum of Astronomy, Bath 

For your book shelve

From: The Complete Guide to the Herschel Objects: Sir William Herschel's Star Clusters, Nebulae and Galaxies - by Mark Bratton

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•  Herschel Museum of Astronomy  

• Herschel Museum of Astronomy (Wikipedia)

Near-Earth Asteroid 2012 DA14 to Miss Earth on February 15, 2013

In this oblique view, the path of near-Earth asteroid 2012 DA14 is seen passing close to Earth on Feb. 15, 2013. 

Discovered by the LaSagra observatory in southern Spain, the small asteroid 2012 DA14 will pass within about 3.5 Earth radii of the Earth's surface on February 15, 2013. Although its size is not well determined, this near-Earth asteroid is thought to be about 45 meters in diameter. Asteroid 2012 DA14 will pass inside the geosynchronous satellite ring, located about 35,800 km above the equator. Its orbit about the sun can bring it no closer to the Earth's surface than 3.2 Earth radii on February 15, 2013. On this date, the asteroid will travel rapidly from the southern evening sky into the northern morning sky with its closest Earth approach occurring about 19:26 UTC when it will achieve a magnitude of less than seven, which is somewhat fainter than naked eye visibility. About 4 minutes after its Earth close approach, there is a good chance it will pass into the Earth's shadow for about 18 minutes or so before reappearing from the eclipse. When traveling rapidly into the northern morning sky, 2012 DA14 will quickly fade in brightness.

Source: NASA

Sunspot AR1654 (12 January 2013)

 Photo: Dennis Simmons, Brisbane, Australia

Since it first appeared four days ago, sunspot AR1654 has been facing away from Earth. But now it is turning toward us, increasing the "geo-effectiveness" of its explosions. This could be the sunspot that breaks the recent lengthy spell of calm space weather around our planet.

Amateur astronomers with backyard solar telescopes are encouraged to monitor in the days ahead. It is not only crackling, but also growing. As of Jan 12th, the behemoth stretches more than 180,000 km (14 Earth diameters) from end to end. Dennis Simmons sends this picture of the behemoth from Brisbane, Australia: "Although the air was milky from nearby bush fires burning north of Brisbane, the seeing turned out to be good enough for a high-resolution shot," says Simmons. "I dedicate this image to the brave Australian fire fighters, working in horrendous, hot and windy conditions whilst fighting fires burning out of control across the south-east states of our country. I salute your selfless courage."

Visit: Spaceweather.com

AR1654 is a Monster Sunspot. (And It’s Aiming Our Way.)

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 Active Region 1654 on the Sun’s western limb, seen by SDO on Jan. 11 (NASA/SDO/HMI team. Diagram by J. Major.)

Sir Patrick Moore death: Tributes to the astronomer

Sir Patrick Moore's contribution to the world of astronomy

• Visit this page for a tribute to this remarkable man

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)
 

The Washington Double Star Catalog

• Visit the The Washington Double Star Catalog and learn more...

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....

• NASA Eclipse Web Site

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.

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Smile! The Curiosity Rover’s Ultimate Self-Portrait

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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…

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