scholarly journals New Northern hemisphere common proper-motion pairs

2004 ◽  
Vol 355 (2) ◽  
pp. 585-590 ◽  
Author(s):  
John Greaves
Keyword(s):  
Northern Hemisphere ◽  
Proper Motion

Status of “AGK4” Project

1978 ◽  
Vol 48 ◽  
pp. 527-533
Author(s):  
Chr. de Vegt
Keyword(s):  
Northern Hemisphere ◽  
Proper Motion ◽  
The Mean ◽  
Spectral Bandpass

The present accuracy limit for the majority of fainter stars on the northern hemisphere is set by the AGK2/3-catalogue, recently completely finished, but it should be noted that its epoch is much earlier (1960). Furtheron the AGK3-catalogue is a direct repetition of the AGK2, the plates have been taken with the same astrograph in a broad blue spectral bandpass and measured visually with the same equipment, therefore virtually an instrumental standard of 1930 is realized again. Figure 1 shows the mean errors of the AGK2/3 catalogue positions as a function of magnitude. The best accuracy for the AGK2/3 data is obtained for the stars of about ninth magnitude: 017 (AGK2) and 020 (AGK3) but decreases for the faint stars with mpg11 to 019 (AGK2) and Pg 027 (AGK3). Here the AGK3 data are even less accurate. With increasing distance to the catalogue epochs, the accuracy of positions decreases due to the proper motion errors. In the upper part of figure 2 the dependence of the AGK2/3 catalogue accuracy on time is shown for the faint stars separately and an averaged value.

scholarly journals The Absolute Proper Motion of the Pleiades Cluster

1970 ◽  
Vol 7 ◽  
pp. 103-104
Author(s):  
W. F. van Altena ◽  
B. F. Jones
Keyword(s):  
Northern Hemisphere ◽  
Proper Motion ◽  
Reference System ◽  
The Absolute

The establishment of a truly inertial reference system is a problem that has defied solution for many years. However, with the completion of the Lick proper motion survey (Wright 1950) and the USSR program (Deutsch 1954) the situation for the northern hemisphere should be satisfactory.

scholarly journals Status of the Lowell Proper Motion Survey

1970 ◽  
Vol 7 ◽  
pp. 64-66 ◽  
Author(s):  
H. L. Giclas
Keyword(s):  
Northern Hemisphere ◽  
Proper Motion ◽  
Proper Motions

A proper motion survey of the northern hemisphere, utilizing first epoch plates made some thirty years ago with the 13 – inch Pluto search telescope of the Lowell Observatory, was begun in 1957. The relative proper motions of stars fainter than the eighth magnitude and with motions greater than 0.″26 per year are measured directly on the calibrated grid of the projection blink comparator.

scholarly journals Kinematics of Faint Stars, and the Reduction from Relative to Absolute Proper Motion

1970 ◽  
Vol 7 ◽  
pp. 131-145
Author(s):  
C. A. Murray ◽  
S. V. M. Clube
Keyword(s):  
Reference Frame ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Proper Motion ◽  
Proper Motions ◽  
Fundamental Reference

With the imminent completion of AGK3 in the northern hemisphere, and the prospect of results from the SRS programme in the southern hemisphere becoming available within the next few years, we may regard the problem of the establishment of a fundamental reference frame for proper motions down to about mpg = 11 as, in principle, solved. This reference frame, through the large number of stars involved, will be readily accessible to photographic observers, with carte-du-ciel type, and even longer focus telescopes, for the reduction of relative proper motions to an absolute system.

scholarly journals 5. The Identification of White Dwarf Suspects in the Lowell Proper Motion Program

1971 ◽  
Vol 42 ◽  
pp. 24-31 ◽  
Author(s):  
H. L. Giclas
Keyword(s):  
Northern Hemisphere ◽  
White Dwarf ◽  
Proper Motion ◽  
Proper Motions ◽  
Individual Stars ◽  
Color Class ◽  
Class 1

During the course of the Lowell proper motion survey that has been in progress since 1957, an effort has been made to identify the very blue stars and more recently the extremely red ones. The proper motions are detected and measured directly by projection on the calibrated grid of the blink microscope. The regular program catalogs all motions found >0″.26/year and fainter than the eighth magnitude. From this portion of the program, we have identified 179 white dwarf suspects, 48 of color class– 1 and 131 of color class 0, which have been published in the Lowell Bulletins under the title of ‘Lowell Proper Motions II through XV’. These lists cover the entire northern hemisphere, and a few regions down as far as −;10° South, and contain 10382 different individual stars. Finding charts are provided for each object.

Alpha-Effect, Current and Kinetic Helicities for Magnetically Driven Turbulence, and Solar Dynamo

2000 ◽  
Vol 179 ◽  
pp. 387-388
Author(s):  
Gaetano Belvedere ◽  
V. V. Pipin ◽  
G. Rüdiger
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Convection Zone ◽  
Solar Surface ◽  
Momentum Transport ◽  
Angular Momentum Transport ◽  
Magnetic Buoyancy ◽  
Alpha Effect ◽  
Current Helicity

Extended AbstractRecent numerical simulations lead to the result that turbulence is much more magnetically driven than believed. In particular the role ofmagnetic buoyancyappears quite important for the generation ofα-effect and angular momentum transport (Brandenburg & Schmitt 1998). We present results obtained for a turbulence field driven by a (given) Lorentz force in a non-stratified but rotating convection zone. The main result confirms the numerical findings of Brandenburg & Schmitt that in the northern hemisphere theα-effect and the kinetic helicityℋkin= 〈u′ · rotu′〉 are positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicityℋcurr= 〈j′ ·B′〉, which is negative in the northern hemisphere (and positive in the southern hemisphere). There has been an increasing number of papers presenting observations of current helicity at the solar surface, all showing that it isnegativein the northern hemisphere and positive in the southern hemisphere (see Rüdigeret al. 2000, also for a review).

The Hemispheric Sign Rule of Current Helicity during the Rising Phase of Cycle 23

2000 ◽  
Vol 179 ◽  
pp. 303-306
Author(s):  
S. D. Bao ◽  
G. X. Ai ◽  
H. Q. Zhang
Keyword(s):  
Solar Cycle ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Active Regions ◽  
Hemispheric Preference ◽  
Current Helicity

AbstractWe compute the signs of two different current helicity parameters (i.e., αbestandHc) for 87 active regions during the rise of cycle 23. The results indicate that 59% of the active regions in the northern hemisphere have negative αbestand 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameterHcshows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed.

Large-scale Motion of Solar Filaments

2000 ◽  
Vol 179 ◽  
pp. 205-208
Author(s):  
Pavel Ambrož ◽  
Alfred Schroll
Keyword(s):  
Magnetic Flux ◽  
Proper Motion ◽  
Time Scale ◽  
Large Scale ◽  
Accuracy Of Measurements ◽  
Solar Filaments ◽  
General Movement ◽  
Scale Motion ◽  
Velocity Scatter

AbstractPrecise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.

Status of the Lick Proper Motion Program

1978 ◽  
Vol 48 ◽  
pp. 387-388
Author(s):  
A. R. Klemola
Keyword(s):  
Proper Motion ◽  
The Future

Second-epoch photographs have now been obtained for nearly 850 of the 1246 fields of the proper motion program with centers at declination -20° and northwards. For the sky at 0° and northward only 130 fields remain to be taken in the next year or two. The 270 southern fields with centers at -5° to -20° remain for the future.

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