... At the summer date, at the chosen time, the Sun is high in the sky. at point S, while at the winter date, it is low in the sky, at point W. The shadow of the gnomon is always in the plane containing the Sun and the points A and B. If AB is a thin line, the shadow will also be a thin line, the intersection of this plane with the base of the sundial. ... Summer or winter, the shadow is therefore along the same line, the intersection of the above plane and the base of the sundial. ...

... At the summer date, at the chosen time, the Sun is high in the sky. at point S, while at the winter date, it is low in the sky, at point W. The shadow of the gnomon is always in the plane containing the Sun and the points A and B. If AB is a thin line, the shadow will also be a thin line, the intersection of this plane with the base of the sundial. ... Summer or winter, the shadow is therefore along the same line, the intersection of the above plane and the base of the sundial. ...

... Current APO Weather . ... Search Site . ... Information for New Users . ... Technical Staff pages . Night Logs and Mailing Lists (maintained by APO) . ... Technical Documents and Database Search . ... Observer's Documentation and Procedures . ... Problem Reporting and APO Technical Documents Database Search . ... APO Drawing/Document Management Procedures . ... APO Technical Documents Database Search . Home Astrophysical Research Consortium . ... Mail Lists (maintained by APO) . ...

... connection points . ... The point P3 is the connection between the horizontal and vertical actuators and is the axis of rotation for the tail gunner motion. processing: survey/020204/reduc We can compute P3,P5 (the moveable points) in dome centerline coordinates if we have the actuator distances and we know the positions of the above connection points in dome centerline coordinates for a given position of the tertiary (say the nominal focus position).(see actuator distances to dome centerline ). ...

Next: Star Formation Rate and Up: No Title Previous: Calculation of Evolutionary Tracks . To start calculations, we choose the distributions of the initial binary parameters: the mass of the primary ZAMS component, , binary mass ratio, , orbital separation a . ... whereas the mass ratio distribution is not. ... The zero assumption often made is that the mass ratio distribution has a flat shape, that is binaries with a high mass ratio occur as frequently as those with equal masses. ...

... We now describe the input parameters to the self-calibration tasks. ... For selfcal , you need not perform source , dra , or ddec selection if you use the selradec option (see below). minants : The minimum number of antenna that must be present before the tasks will attempt to find a solution. ... and phase : This determines whether the self-calibration tasks solve for just phase ( options=phase , which is the default) or amplitude and phase solution ( options=amplitude ). mfs : . ...

... While the three NICMOS cameras are no longer at a common focus, under many circumstances it is desirable to obtain data simultaneously in multiple cameras. ... From the ground, the infrared background is affected by telluric absorption and emission which limits the depth of astronomical imaging. ... Now, the dominant sources of background radiation will be the zodiacal light at short wavelengths and the thermal background emission from the telescope at long wavelengths. ...

Astronomy Discussion Forums . Forums: . ... How Do You Feel About Numbers? ... Post Message | ... Posted by Richard D. Stafford, Ph.D. on September 15, 2002 16:22:25 UTC . ... Wait - harvey1 - September 15, 2002 - 22:20 UTC . I don't follow you! - doctordick - September 16, 2002 - 14:59 UTC . ... www.astronomy.net . About Astronomy Net | ... Forum posts are Copyright their authors as specified in the heading above the post. "dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET" . ...

OptInt PmWiki : MROI Fast Tip Tilt / Tech Meet 9 . Nasmyth Optical Table . ... XS analysis: Attach:FTT_mount_analysis_05.pdf . DFB analysis: see below . ... How to locate and support optics . ... Assume that the table is supported by a vertical support (representing the side of the telescope) and a diagonal support running from the telescope to the end of the table furthest from the table. ... Printable View of http://www.mrao.cam.ac.uk/projects/OAS/pmwiki/pmwiki.php/MROIFastTipTilt/TechMeet9) ...

IBIS Data Analysis . ... IBIS . ... Flat Fielding - Introduction . The images obtained by IBIS will have intensity variations across the field of view that are not due to the solar image, but rather caused by instrumental effects that alter the observed intensity in each point of the field of view. ... IBIS Flat Fielding Techniques . ... Therefore, it is desirable to obtain the flat field measurements center on a point along the equator near the heliographic center of the solar disk. ...

... Moon Phase below . ... ARTICLE: Why the moon always shows us the same face . ... Before you continue reading, you should know that this was not always the case, i.e. the Moon once was rotating with respect to the Earth, so that on every night a terrestrial observer (if there was one, because this was long, long before mankind appeared on our planet, and even before any major animals had appeared) saw another face of the Moon. ... Figure 1 (not to scale) shows how we can imagine the system Earth-Moon...

Next: Related Table Commands Up: Multivariate Analysis Methods Previous: Discriminant Analysis . Correspondence Analysis may be described as a PCA in a different metric (the metric replaces the usual Euclidean metric). ... While PCA is particularly suitable for quantitative data, CA is recommendable for the following types of input data, which will subsequently be looked at more closely: frequencies, contingency tables, probabilities, categorical data, and mixed qualitative/categorical data. ...

... If the Earth is round, the Sun must be north of the equator in northern summer, and south of the equator in northern winter. ... From the Earth's perspective, the Sun is spiraling from north to south and back again along the ecliptic (see figure 7 ). ... The round Earth, at the summer solstice. ... If the rotation axis of the Earth is tilted with respect to its orbit, the equator bobs back and forth, causing the Sun to be north for half the year, and south for the other half (see figure 9 ). ...

... This thread contains a step-by-step recipe to extract MOS spectra of a point-like source observed in Imaging mode and to create associated response matrices, starting from a calibrated, concatenated event list (either produced with emproc or available as PPS product; here it has the assumed file name MOS.fits ). ... The users should note that the SAS metatask xmmselect allows them to interactively define source and background regions (via ds9) and to run backscale on the fly. ...

Geometric region markers can be placed on the screen interactively or via the XPA "regions" public access point. ... To define a data region (by default, an "Include in Source" region): . ... Move to the desired image location and click the left mouse button. ... Type "Ctrl-e" to change from "include data with region" to "exclude data within region". ... Closed markers (circles, ellipses, etc.) may be resized by clicking and dragging the left mouse button on the region perimeter. ...

... Bad Astronomy . ... Bad Astronomy: The North Star, Polaris, is a very bright star. Good Astronomy: Polaris is a middling-bright star, easily missed. ... He said it was close to Polaris, the North Star, but he also said it was in the East. ... It's natural, I suppose, to think that such an important star should be bright, but really, that's a conceit, like thinking that the Earth is at the center of the Universe. If more people knew just why Polaris is the North Star, this Bad Idea would stop. ...

Next: When the clock is Up: Keeping Time Previous: The hardware and software . In the Debian system, the system time zone is determined by the symbolic link /etc/localtime љ . ... If it is unset, the system time zone is assumed. ... The date љ command shows the current date and time. ... date љ is also used to set the kernel's software clock: # date 07142157 . ... While each user can have his own time zone, the clock is the same for everyone. date љ only shows or sets the software clock. ...

Atmospheric influence on the different radio-engineering system functioning . ESTIMATION OF ATMOSPHERIC OPTICAL CHARACTERISTICS AND REMOTELY SANSED IMAGE CORRECTION . ... Direct transmittance estimation results for 12 channels of the spectrometer CHRIS. ... We have managed to develop a direct method of estimating the discrete Normalized Atmospheric Point Spread Function (NAPSF) from available images alone, not using any external sources of information about the atmosphere. ... IRE RAS 1996-20 11 ...

... In astronomical parlance, an interior planet is at superior conjunction when it is located on the opposite side of the Sun from Earth. ... Water Found in Space Rock . ... HCG 87: A Small Group of Galaxies . ... The Universe Evolves . ... It's only Planet Earth, of course ... as seen on the Water Vapor Channel. ... Eclipse Over The Mountain . ... Crossing the edge of Earth's shadow the moon was only partially eclipsed - but the spectacle could be seen by observers located across the Earth's night...

... 2003 March 12 . Lunar Farside from Apollo 11 . Credit: Apollo 11 Crew , NASA . Explanation: The far side of the Moon is rough and filled with craters . By comparison, the near side of the Moon , the side we always see, is relatively smooth. Since the Moon is rotation locked to always point the same side toward Earth , humanity has only glimpsed the lunar farside recently -- last century. ... About APOD | ... NASA Technical Rep.: ... A service of: LHEA at NASA / GSFC . ...