## Data needed: CMBR Dipole Anisotropy: 6.706 mK

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no, scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>From:\nhttp://map.gsfc.nasa.gov/m_mm/ob_techcal.html\n\n"It is a very fortunate coincidence that sky itself provides us with an\nideal stable calibration source that is always visible. The dipole\neffect is the result of the movement of our earth, solar system, and\ngalaxy through the universe; similar to the change in pitch of a sound\nas you ride by the source in a car or train. Specifically, the CMB\ntemperature is 6.706 mK brighter in one direction of the sky than it is\nin the opposite direction as shown in the false color temperature map\nbelow as measured by the COBE mission."\n\nAccording to the article this is a stable calibration source.\n\nHowever, according to many theorists, Relative to the sun one merely\nneeds to travel about 370\nkm/sec in the proper direction to make the dipole anisotropy become\nzero. That is ~0.001 c and gamma is just slightly greater than 1.\n\nThe earth goes around the sun at about 30 km/second, so our speed wrt\nthe background should go\n\n{370-30cos (\\theta), 370 + 30 cos (\\theta)}\n\nwhere\n\n\\theta= angle between earth orbital axis and dipole axis.\n\nI believe if the above statements are correct, then the apparent\nmagnitude of the CMB temperature dipole should oscillate measurably\nover the course of a year.\n\n&gt;From what I\'ve been able to tell from online research, however, the\ndirection of the dipole (relative to the stars) shifts, but the\nmagnitude of the dipole moment does not change. As stated above, it is\nan ideal stable calibration source.\n\nThis all relates to comments I\'ve made at\nhttp://groups-beta.google.com/group/sci.physics.relativity/browse_frm/thread/d92bd5950d6ca0be/311510fd2bb73aec?hl=en#311510fd2bb73aec\n(Topic: Postulates of Relativity and The Cosmic Background - Question\n)\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">&nbsp;&nbsp;View this Usenet post in original ASCII form </a></div><P></jabberwocky>From:
http://map.gsfc.nasa.gov/m_{mm}/ob_techcal.html

"It is a very fortunate coincidence that sky itself provides us with an
ideal stable calibration source that is always visible. The dipole
effect is the result of the movement of our earth, solar system, and
galaxy through the universe; similar to the change in pitch of a sound
as you ride by the source in a car or train. Specifically, the CMB
temperature is 6.706 mK brighter in one direction of the sky than it is
in the opposite direction as shown in the false color temperature map
below as measured by the COBE mission."

According to the article this is a stable calibration source.

However, according to many theorists, Relative to the sun one merely
$km/sec$ in the proper direction to make the dipole anisotropy become
zero. That is ~0.001 c and $\gamma$ is just slightly greater than 1.

The earth goes around the sun at about 30 km/second, so our speed wrt
the background should go

$${370-30cos (\theta),[/itex] 370 $+ 30 cos (\theta)}$$ where [itex]\theta=$ angle between earth orbital axis and dipole axis.

I believe if the above statements are correct, then the apparent
magnitude of the CMB temperature dipole should oscillate measurably
over the course of a year.

>From what I've been able to tell from online research, however, the

direction of the dipole (relative to the stars) shifts, but the
magnitude of the dipole moment does not change. As stated above, it is
an ideal stable calibration source.

(Topic: Postulates of Relativity and The Cosmic Background - Question
)



In article <1114992320.845679.235010@z14g2000cwz.googlegroups.com>, Spoonfed wrote: >I believe if the above statements are correct, then the apparent >magnitude of the CMB temperature dipole should oscillate measurably >over the course of a year. Indeed it does. Not surprisingly, the people who use the CMB dipole as a calibration source know all about its annual modulation. Since the Earth's orbital parameters are quite well known, it's trivial to account for it. Both WMAP and COBE before it measure not only the average CMB dipole but the amplitude of its annual modulation. As I understand it, the annual modulation, not the DC offset, is what's used in calibrating the instrument. For details about how the WMAP calibration is done, see Hinshaw e tal., First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing Methods and Systematic Error Limits, Astrophysical Journal Supplement, 148, 63 (2003), available at http://\lambda.gsfc.nasa.gov/product...map_syserr.pdf (URL all on one line) $$-Ted$$ -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]



Spoonfed wrote: > The earth goes around the sun at about 30 km/second, so our speed wrt > the background should go > > ${370-30cos (\theta),$ 370 $+ 30 cos (\theta)}$ > > where > > $\theta=$ angle between earth orbital axis and dipole axis. > > I believe if the above statements are correct, then the apparent > magnitude of the CMB temperature dipole should oscillate measurably > over the course of a year. I'm quite sure that it does, and that it has been measured. In fact I remember George Smoot himself showing me a graph of it when I was at Berkeley. But for some reason I can't find a reference on the web. -- Ben