Tolis' Astrophotography page

How these images were acquired: (unless otherwise noted)
• As a detector I use a Nikon Coolpix 950 Digital camera. The images are (almost) instantly available as electronic files amenable to digital image processing. The disadvantage is that (at present) digital camera technology has not yet attained the resolution of ordinary photographic film (but we're getting there).
• I use the camera in two modes: Either by itself on a tripod or afocally mounted on a Meade ETX125EC Maksutov-Cassegrain telescope using a parfocal mount. When in telescope mode I use either a 32mm or an 18mm Plossl eyepieces. At each image I note which one of these modes were used.
• I disable the flash, set the camera on SHUTTER PRIORITY Mode, disable colour (ie choose B&W on the options menu) and engage the 10-second delay option. The latter is important as pushing the shutter button introduces vibrations which take a few seconds to damp out.
• Exposure times vary, but typically I would use 1/125 or 1/250 sec for Venus (in daytime), 1/125 to 1/30 sec for the Moon (depending on phase), 1/4 sec for Jupiter, 1 sec for Saturn, and 4-8 sec (the maximum allowed by the hardware) for fainter objects. With an 8-sec exposure, I have been able to reach magnitude 11.
• Normally I would take 5 exposures for each target. It also pays, in terms of reducing noise and increasing sesnitivity, to allow the camera to cool down before using it and turning it off every 15 min or so.

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Image Gallery

	When the lunar phase is near New Moon, a faint glow can be observed to delineate the dark part of the Moon. This is the Earthshine, caused by sunlight reflected off the Earth and then the Moon. The reason it is so prominent when the Moon is at a crescent phase is that, at that time the Earth as seen from the Moon is near 100% phase (a Full Earth) and therefore at its most bright. This image was taken in the early morning of October 3rd, 2002. Jupiter can also be seen at the top right of the image. Tripod-mounted camera
	This image was taken just after midnight on the 23rd of September 2002. The phase is just past full; the shadows which accenuate the topography are all but washed out but the brightness differences between the mare and the highlands are readily apparent. The one feature near the terminator (the dividing line between day and night) which stands out at the top of the lunar is a feature known as Mare Humboldtanium . This is a multi ring impact basin which sits between the near and the far sides of the Moon. Two of the concentric rings which make up the basin can be readily seen. ETX 125EC w. 32mm eyepiece
	This image shows a portion of the terminator line past midnight on August 26th, 2002. The big circular feature which is half-immersed in shadow is Mare Crisium. The crater immediately next to it is 126 km Cleomedes. ETX 125EC w. 32mm eyepiece
	Showing a portion of the terminator similar to the south of that of the previous image, this picture was taken at a special time when the terminator line highlights the topography around the rim of Mare Crisium and in particular the three landing sites of the Russian third generation Luna sample return probes which flew in the 1970s. Luna 16 landed just above the crater Langrenus (the large crater with the central peak which is illuminated by the Sun right on the terminator line) and near the crater Webb. Luna 20 landed just to the North of 16, while Luna 24, the last successful soft lander to the lunar surface up to this date, landed just inside the Crisium rim, near the small "island" that can be seen near the mountains, almost in shadow, that make the southern part of the rim. Another prominent feature in the image is the twin 10-km craters Messier, notable due to the comet-like tail of rays emanating from them. These were formed when an object collided with the moon at a very shallow angle. ETX 125EC w. 18mm eyepiece
	In early May 2002, five of the planets of our solar system came together in the evening sky. This image shows four of the planets on May 5th, 2002. Mercury is the star to the lower right of the image immersed in the evening twilight. In the centre of the image the planets Mars, Saturn and Venus form a triangle which lasted only a few days before their different apparent motions in the sky broke it apart. The planet Jupiter is off the image and to the upper left. Tripod-mounted camera
	The planet Saturn never fails to amaze with its glorious rings which make it appear like a toy model suspended in space when seen through a telescope. This image was taken in Autumn 2002. ETX 125EC w. 18mm eyepiece
	Although much fainter than the Galilean satellites of Jupiter, some of the satellites of Saturn are within the capabilities of small telescopes. This 8-sec exposure shows five of these: Titan, the brighest at magnitude 8, is the only satellite in the solar system to have a thick atmosphere. Above it is 9th mag. Rhea, Saturn's second largest satellite. On the opposite side of the overexposed Saturn one can see 10th mag. Dione while just above Saturn is Tethys, also at 10th magnitude. If a line that connects Dione and Tethys is extended to the right, it will come across a faint 11th mag. object which corresponds to the position of the satellite Iapetus. This is a very intriguing object,as it has been known to very greatly in brightness as it orbits Saturn. The Voyager flybys in the 1980s showed that Iapetus has a very bright and a very dark hemisphere. Three background stars are also shown for reference. ETX 125EC w. 32mm eyepiece
	The planet Jupiter is the largest panet in the solar system, making it invariably bright in the night skies of Earth. This image shows the prominent cloud bands which encircle the planet. ETX 125EC w. 18mm eyepiece
	After the Moon, the planet Venus is the brighest object in the night sky, appearing above the western horizon after sunset or the eastern horizon before sunrise. It is sufficiently bright to cast discernible shadows and can be seen with small instruments even during the daytime. Venus orbits the sun within the orbit of the Earth and, as a result, shows a full range of phases to the observer. These three images were taken during the day at different times of the year 2002 and show the evolution of the phase and apparent size of the planet as it approached the Earth and passed through inferior conjunction in October 2002. The disk is usually bland due to the perrenial cloud layer which surrounds the planet but observers equipped with violet or ultraviolet filters can discern contrast features in the upper atmosphere. ETX 125EC w. 18mm eyepiece
	At the centre of the solar system, the Sun is an ever-variable sphere of incandescent gas. Sunspots are a common occurence on the Sun; a few can be seen at any time with a small telescope; they consists of a dark centre (the unbra) and a grey surrounding (the penumbra). WARNING: NEVER EVER LOOK AT THE SUN THROUGH ANY INSTRUMENT WITHOUT A HIGH-QUALITY SOLAR FILTER. IF YOU DO SO, YOU WILL SUFFER IRREVERSIBLE EYE DAMAGE. ETX 125EC w. 18mm eyepiece
	The Pleiades open star cluster in Taurus is one of the most prominent objects in the winter night sky. It is visible to the naked eye as a small, nebulous object while a view through a telescope reveals dozens of even hundreds of stars packed together in a small region of space. This image was taken on the 3rd of October 2002 and shows the seven brighest stars in the cluster, the so-called "seven sisters", as well as numerous fainter members down to magnitude 7. Tripod-mounted camera
	Depictions of astronomical phenomena in an earthly context are a powerful way of putting the surrounding Universe in perspective. This image shows the constellation Taurus rising over the Observatory in the early morning of August 26, 2002. The Pleiades cluster is at the upper centre of the image, while the "Taurus triangle" can be seen below the Pleiades. The bright star in the triangle is Aldebaran. Tripod-mounted camera
	Another easily recognizable constellation in the Autumn/Winter sky is Orion the Hunter. This image shows the three stars of the "best" and the fainter stars that make up the "sword" on the lower right. The "sword" also demarkates the location of the well-known Orion Nebula or M42. Tripod-mounted camera
	One of the "landmark" constellation in the Northern Hemisphere, Ursa Major or Big Bear remains above the horizon throughout the year at these latitudes. It contains one of the most famour stellar "pairs" in the sky, Mizar and Alcor (the middle star in the Bear's tail). Tripod-mounted camera