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View Poll Results: Radiation from Bigbang was from about 13.7 billion years old. It is not from any star
yes 10 66.67%
I didn't get your point 3 20.00%
no 2 13.33%
Voters: 15. You may not vote on this poll

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  #91 (permalink)  
Old 25-September-2008, 01:34 AM
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Originally Posted by Tim Thompson View Post
Look at the plots again. The first peak is not 6000 micro Kelvins in the WMAP plot, it is 6000 micro Kelvins squared. The plots are not normalized to the same units, so naturally the Y-axes are different.
I am sorry I missed writing 6000 micro Kelvin squared. If that is the only difference between your url and WMAP url, then how will you represent in your graph the negative temperature differences expressed in micro Kelvin squared values.

For your information, the peak negative value (-3756.2) at multipole ell=944. Mathematically (61.29i) is it? It is (+61.29i) or (-61.29i)? I am poor in math. Can you please help me?

By the way what is the meaning of negative temperature differences expressed in micro Kelvin squared values in WMAP data? Why such things occur in Physics?

Please refer: WMAP results At

http://lambda.gsfc.nasa.gov/data/map...m_5yr_v3p1.txt

Quote:

Do you mean they don't have the same relative heights? That's because the scales are different. Otherwise, I don't know what you are asking.
In your graph the MAP values are represented by black-dots. The dots in the region of angular scale 0.5 to 0.2 degrees ( multipole vales ell= 400 to 950 approx), have peaks higher than first peak. In the other words see WMAP results at

http://lambda.gsfc.nasa.gov/data/map...m_5yr_v3p1.txt

The first peak at ell = 215 is 6673.733 which is lower than the other peaks at ell= 937,897,& 903; which are 7135,7977 & 8074 micro Kelvin squared

Question is why these values are higher than first peak?
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Old 25-September-2008, 01:54 AM
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Originally Posted by snp.gupta View Post
How to interpret/ understand these temperature fluctuates on different anglular sizes in the map?
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Originally Posted by Tim Thompson View Post
That depends on the cosmological model. ...
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Originally Posted by snp.gupta View Post
Which Cosmological Model?
First of all, we should remove the thinking that they are model based. This name model is causing BIAS in our minds. They don’t dependent on any model. Simple physical properties of astronomical bodies and the errors caused by measuring instruments are causing this anisotropy in what we call measured CMB…


That's the whole point. You have to choose or invent one before you can make any attempt to interpret the CMB.
See my post # 85, which cosmological model refers to your question only.
HERE I REPRODUCED IT IN FULL. READ IT AGAIN
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Old 25-September-2008, 02:33 AM
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Dead wrong. Once you do that you are doomed to eternal ignorance.
No sir, Not wrong, you are biased by Bigbang requirements…

Quote:
You only know what you actually measure.
WMAP measured, Other instruments measured. I only read what you write…

Quote:
In the case of the CMB we can measure the total energy,
Which CMB? Measured or Bigbang predicted?, what is that total energy? It is of all stars and Galaxies?
Quote:
and we can measure its dependence on wavelength (or frequency), that's the spectral energy density or spectral energy distribution, synonymous terms both abbreviated simply as SED. In the standard model of Big Bang cosmology, the CMB is a fossil remnant of the "bang" and therefore can carry clues to the nature of the origin of the universe.
Did any body measure Planck SED Bigbang predicted CMB till today?
Quote:
In the "SNP.GUPTA" model the CMB is nothing more than an artifact of astronomers who forgot to correct for the gain of the side lobes of their antenna. How does one choose between them?
No, here it is the combined radiation from stars and galaxies including Sun and planets etc. Not by Removing this patch here and removing that patch there and finally make a hatch-patch.
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Old 25-September-2008, 02:38 AM
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First, a hint: It would be a lot easier if the pages were actually numbered, rather then requiring people to take time to count pages to find out where they are.
Yes sir., I will do...
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Old 25-September-2008, 05:25 AM
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Default Thank you for your excellent post



Sir,

Thank you for your excellent post. I can understand how much valuable time you have spent on that despite of your busy schedules.

I am also requesting you not to get offended by my erratic behavior and the way I post. I am sorry. My vocabulary is less and my English language understanding and usage are also may not be proper.

I am also requesting you to please note that the help given by you is very high and boosted my inner strength. Your understanding about the present CMB science is really commendable and praiseworthy.

Thanking you sir
Warm regards
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Old 25-September-2008, 05:27 AM
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Sir,

Thank you for your excellent post. I can understand how much valuable time you have spent on that despite of your busy schedules.

I am also requesting you not to get offended by my erratic behavior and the way I post. I am sorry. My vocabulary is less and my English language understanding and usage are also may not be proper.

I am also requesting you to please note that the help given by you is very high and boosted my inner strength. Your understanding about the present CMB science is really commendable and praiseworthy.

Thanking you sir
Warm regards
This post is for TIM THOMPSON sir,
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Old 25-September-2008, 05:57 AM
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Default The Big Bang or Blackhole?

From my own personal studies with the universe I theorize that the cosmic microwave background or CMB was created by a star in some gargantuan galaxy that still spins in the outer reaches of space beyond the CMB. Though this star would have been entirely beyond our scale of concept it would have adhered to scaled scientific laws according to octave theory and at its death it would've collapsed into a blackhole. What we see as the CMB would be the visible inner shell of this blackhole and the contents inside - the products of physics and relativity.

The light being compacted into this blackhole would've been hyper-accelerated in all directions, compacting and shrinking based on universal laws, octave & infinite matter theory until the threshold of gravity (the limited space within the octave of compaction) inacted a hyper-pressure system (the collision and rebound of all matter within the blackhole) pushing a wave of matter back outward in all directions. These two systems of outer blackhole gravity and inner threshold pressure would eventually create the vacuum of space that we currently reside in today.

The inner-threshold-pressure system would eventually help push the bits and pieces contained in the CMB outward creating both a pocket of what appears to be empty space inside the CMB and jets of dark matter out of the polar ends of the blackhole, while the outer-blackhole-gravity would continue to force large dust clouds of protons, nuetrons and electrons through the empty void of space created by the inner-threshold-pressure system causing the protons, neutrons and electrons to interact as the outer-gravity and inner-pressure systems vibrate against each other. Eventually atoms of hydrogen are formed and the rest is pretty well known stuff until the miniture stars (which are massive in scale to us) inside the blackhole collapse and form other blackholes taking in matter and light creating new pockets of space while generating dark matter to fill and help expand existing space.

Some of these processes discussed are happening so fast they are virtually simultaneous and are naturally influencing each other. This theory is based on my theories of octaves & infinite matter, which deal with the questions of the scaling (shrinking and expansion) of space. Feel free to ask any questions and point out any flaws. I'm in the business of finding and refining truth and I need everybody and everythings opinion and testimony to do so. So criticism is welcome.
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  #98 (permalink)  
Old 25-September-2008, 07:45 AM
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From my own personal studies with the universe I theorize that the cosmic microwave background or CMB was created by a star in some gargantuan galaxy that still spins in the outer reaches of space beyond the CMB. Though this star would have been entirely beyond our scale of concept it would have adhered to scaled scientific laws according to octave theory and at its death it would've collapsed into a blackhole. What we see as the CMB would be the visible inner shell of this blackhole and the contents inside - the products of physics and relativity.

The light being compacted into this blackhole would've been hyper-accelerated in all directions, compacting and shrinking based on universal laws, octave & infinite matter theory until the threshold of gravity (the limited space within the octave of compaction) inacted a hyper-pressure system (the collision and rebound of all matter within the blackhole) pushing a wave of matter back outward in all directions. These two systems of outer blackhole gravity and inner threshold pressure would eventually create the vacuum of space that we currently reside in today.

The inner-threshold-pressure system would eventually help push the bits and pieces contained in the CMB outward creating both a pocket of what appears to be empty space inside the CMB and jets of dark matter out of the polar ends of the blackhole, while the outer-blackhole-gravity would continue to force large dust clouds of protons, nuetrons and electrons through the empty void of space created by the inner-threshold-pressure system causing the protons, neutrons and electrons to interact as the outer-gravity and inner-pressure systems vibrate against each other. Eventually atoms of hydrogen are formed and the rest is pretty well known stuff until the miniture stars (which are massive in scale to us) inside the blackhole collapse and form other blackholes taking in matter and light creating new pockets of space while generating dark matter to fill and help expand existing space.

Some of these processes discussed are happening so fast they are virtually simultaneous and are naturally influencing each other. This theory is based on my theories of octaves & infinite matter, which deal with the questions of the scaling (shrinking and expansion) of space. Feel free to ask any questions and point out any flaws. I'm in the business of finding and refining truth and I need everybody and everythings opinion and testimony to do so. So criticism is welcome.
To test the hypothesis, you please find out what are the properties of CMB in your proposition and please check physically
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Old 25-September-2008, 07:52 AM
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(2): The paper assumes that professional astronomers are sufficiently ignorant of their craft as to interpret side lobe emission as CMB.

Lets see what they have done to check side lobes…
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Old 25-September-2008, 08:06 AM
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First, on point number 1, a matter of clarification is in order. The paper defines the term Vakradiation as follows:

Let's define the term "Vakradiation" as radiation received per unit area from a distant source in space per unit time over all frequencies.
Page 2
Astronomers define the bolometric luminosity of a source as the emission (usually normalized per unit time) integrated over all wavelengths. So the "Vakradiation" is really nothing more than a bolometric measurement.

There were three / four similar terms used in technical literature in the field of Radiation heat transfer and allied fields. They have same physical units, but have different physical contexts and meanings. Now the question comes which one to use. People will get confused with the term’s usual meaning. That’s why a new word “Vakradiation” coined.
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Old 25-September-2008, 09:25 AM
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Originally Posted by Albohrt View Post
From my own personal studies with the universe I theorize that the cosmic microwave background or CMB was created by a star in some gargantuan galaxy that still spins in the outer reaches of space beyond the CMB. Though this star would have been entirely beyond our scale of concept it would have adhered to scaled scientific laws according to octave theory and at its death it would've collapsed into a blackhole. What we see as the CMB would be the visible inner shell of this blackhole and the contents inside - the products of physics and relativity.

The light being compacted into this blackhole would've been hyper-accelerated in all directions, compacting and shrinking based on universal laws, octave & infinite matter theory until the threshold of gravity (the limited space within the octave of compaction) inacted a hyper-pressure system (the collision and rebound of all matter within the blackhole) pushing a wave of matter back outward in all directions. These two systems of outer blackhole gravity and inner threshold pressure would eventually create the vacuum of space that we currently reside in today.

The inner-threshold-pressure system would eventually help push the bits and pieces contained in the CMB outward creating both a pocket of what appears to be empty space inside the CMB and jets of dark matter out of the polar ends of the blackhole, while the outer-blackhole-gravity would continue to force large dust clouds of protons, nuetrons and electrons through the empty void of space created by the inner-threshold-pressure system causing the protons, neutrons and electrons to interact as the outer-gravity and inner-pressure systems vibrate against each other.
I'm in the business of finding and refining truth and I need everybody and everythings opinion and testimony to do so. So criticism is welcome.
At the magnitudes you're talking about, a star that size would collapse into a black hole but expand again shortly thereafter exponentially.
Essentially, the further that massive star collapsed, passing the threshold of black hole- The greater the extreme concentration would push back against gravity, eventually overwhelming it.
It would do something like a reverse implosion and go from being a black hole to being a white hole.
There is another problem.
It would need to be a wandering star- one that essentially moves almost everywhere within the blackbody spectrum posing as a white hole.
It is very good with octaves in theory.

It is very difficult to make observations of this former black hole now turned white hole since it travels significantly. Oftentimes it remains masked by dark matter.

However, observation is possible and clicking this link here will enable you to view the star in it's current location.
  #102 (permalink)  
Old 25-September-2008, 12:34 PM
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From my own personal studies with the universe I theorize that the cosmic microwave background or CMB was created by a

snip...


Feel free to ask any questions and point out any flaws. I'm in the business of finding and refining truth and I need everybody and everythings opinion and testimony to do so. So criticism is welcome.

can this be split out into it's own thread?
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Old 26-September-2008, 12:07 AM
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....
The Vakradiation Paper

The Vakradiation paper posted earlier is fatally flawed on two major points:
(1): The paper relies on the Stefan-Boltzmann Law rather than a proper Planck Law SED.

First, on point number 1, a matter of clarification is in order. The paper defines the term Vakradiation as follows:

Let's define the term "Vakradiation" as radiation received per unit area from a distant source in space per unit time over all frequencies.
Page 2
Astronomers define the bolometric luminosity of a source as the emission (usually normalized per unit time) integrated over all wavelengths. So the "Vakradiation" is really nothing more than a bolometric measurement.

There are several tables in the paper where the Vakradiation from various sources is calculated. In all cases what is calculated is the total power, in Watts/meter2, using the Stefan-Boltzmann Law. I simply point out that this is a useless & irrelevant exercise when it comes to the CMB, because we do not simply measure the total power, we measure the SED (example and see Fixsen, et al., 1996; Mather, et al., 2004; Wright, et al., 1994).

The Stefan-Boltzmann law (SBL) is an integration of the Planck Law (PL). This means the SBL only gives you the area under the curve, whereas the PL gives you the shape of the curve. Of course there are an infinite number of curves of various shapes, all of which will enclose the same area as does a PL curve at a given temperature. The shape of the curve for the CMB is crucial and ignoring it in your paper makes it impossible to relate what you have done to the actual measured CMB. This is a fatal flaw.

It seems clear to me that you are trying to explain the the CMB anisotropy maps, and why the CMB is not the same in all directions. But the CMB that is mapped in these images is known to have a Planck Law SED, whereas the radiation calculations you make are known not to have a Planck Law SED (i.e., scattered starlight). You have to show that the SED for the radiation you calculate is that of a Planck Law.

Furthermore, you do say that ... "These radiations and their directions are well known, and they are avoided by computer calculations." Given the discussion of side lobes in the power pattern, the implication is obvious that the CMB is really nothing more than uncompensated side lobes. Do you really think such an obvious mistake is going to be overlooked systematically by every professional astronomer in an entire generation of professional astronomers? That would be an incredibly embarrassing mistake for any professional astronomer to make. And they don't in fact make it. All emission detected in the side lobes of any telescope is always either removed or compensated before any analysis like this is ever done, by any astronomer at any wavelength. In the specific case of the CMB, see for instance Fixsen, et al., 1994, which describes the calibration of the FIRAS instrument on COBE which measured the Planck Law peak of the CMB SED. Also see Fixsen, et al., 1997 which compares the calibration of the COBE FIRAS & DIRBE instruments. WMAP calibration is discussed in Hinshaw, et al., 2008 and references therein, especially Jarosik, et al., 2003; Jaroski, et al., 2007; Hinshaw, et al, 2003.

My conclusions are ...
1. Your paper does not properly concern the CMB because it ignores the SED.
I want we should observe and measure radiation in the universe. See the radiation pattern how it comes. By putting the Planck’s law SED as the precondition, we will go nowhere. People did these searches resulted in vain, already. That’s why I did not bother about SED.

In other words Planck’s law SED is a bias, while we try to search different radiations for our understanding the universe. We are searching the universe with the particular search parameters only. That often leads to partiality and favoritism towards a particular theory.

I will elaborate this point with an example. It is like searching a Lincoln Penny minted in 1830, in everybody’s pocket. Some may not have change; some might have kept it in the house or at some other place. Others may have different currencies like pounds, rupees, euros or yen with them. But seeing different types of pennies some other places does not mean such penny exists. Please think in the unbiased way such penny may not exist at all and such penny may not have been minted at all.

What I am requesting you is to remove your preconceived notion about Planck’s law SED. Think in a unbiased manner.
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Old 26-September-2008, 05:29 AM
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Default Final portion of your excellent post,,,

Quote:
Originally Posted by Tim Thompson View Post
....
2. Your assumption that side lobes are ignored is factually incorrect.
Sir,
There are two ways of explaining physical phenomena. Say falling of an apple on Newton’s head...
1. Try to find a reason for that incidence.
2. We already have theory and try to fit there.

I am trying the first one. We saw a physical phenomenon called Radiation in the space. Lets call it measured CMB. Now what are all the physical reasons for that happening?
a) Radiation from astronomical bodies. b) Averaging done by lobes of Dish antenna. etc.
.
What are the other physical properties of that physical phenomenon? Frequency spectrum it covers, almost uniform temperature of that radiation etc. Observed frequency spectrum is not bound by Planck’s law SED. Lobes, Interstellar Dust scattering, Distribution of stars and Galaxies etc., are reasons for uniformity and fog like anisotropy.

You are trying the second one. You trying to measure CMB predicted by Bigbang theory. You are measuring the radiation from stars and Galaxies ( 85% of sky) after eliminating the bright ones and Milkyway disk. Compensating for synchrotron radiations, free-free radiations, dust scattering, sidelobes gains etc., and say we achieved 98% to99% of Planck’s Law SED of a Blackbody at that temperature. But your basic measurement it self is wrong.

so...

I did not say you did not compensate for sidelobe gains. What I said was this physical phenomena with its observed properties, can be explained without using Bigbang theory. There I used those physical properties of dish
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Old 26-September-2008, 05:49 AM
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Originally Posted by snp.gupta View Post
Sir,
There are two ways of explaining physical phenomena. Say falling of an apple on Newton’s head...
1. Try to find a reason for that incidence.
2. We already have theory and try to fit there.

I am trying the first one. We saw a physical phenomenon called Radiation in the space. Lets call it measured CMB. Now what are all the physical reasons for that happening?
a) Radiation from astronomical bodies. b) Averaging done by lobes of Dish antenna. etc.
.
What are the other physical properties of that physical phenomenon? Frequency spectrum it covers, almost uniform temperature of that radiation etc. Observed frequency spectrum is not bound by Planck’s law SED. Lobes, Interstellar Dust scattering, Distribution of stars and Galaxies etc., are reasons for uniformity and fog like anisotropy.

You are trying the second one. You trying to measure CMB predicted by Bigbang theory. You are measuring the radiation from stars and Galaxies ( 85% of sky) after eliminating the bright ones and Milkyway disk. Compensating for synchrotron radiations, free-free radiations, dust scattering, sidelobes gains etc., and say we achieved 98% to99% of Planck’s Law SED of a Blackbody at that temperature. But your basic measurement it self is wrong.

so...

I did not say you did not compensate for sidelobe gains. What I said was this physical phenomena with its observed properties, can be explained without using Bigbang theory. There I used those physical properties of dish
This is inaccurate at just about every turn.

We specifically were LOOKING for what theory predicted- The CMB.
We didn't look up at the sky one day and see it and wonder what it was...
Next, you seem to have ignored Tim Thompson's explanations about the Thermal background.

Can you focus on that particular bit for now- until everyone is satisfied they are understood?
Then work your way over to the next facet...
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Old 26-September-2008, 03:01 PM
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First the definition. Thermal is not an approximation but rather a precisely defined spectral energy density (SED). The SED of the emitted radiation must correspond to a single temperature Planck Law SED. If it does then it is thermal. If it does not, then it is not thermal. Stars are not thermal emitters for three reasons, which I will try to give in the order of their importance as I understand it.
ok
Quote:

1) Planck Law thermal emission can come only from a source that is in thermodynamic equilibrium. The photosphere of a star is not in thermodynamic equilibrium so it cannot be a truly thermal emitter. This is the least important of the reasons. Stellar photospheres are commonly modeled under the assumption of local thermodynamic equilibrium (LTE), partly because it is a good approximation for most purposes, and partly because it is a lot easier than the alternative. The determination of solar photospheric abundances from observed spectra has long been done assuming LTE. But modern high resolution spectroscopy has reached the point where analysis of the spectra can no longer rely on that approximation.
ok
Quote:


2) The photosphere is not a single temperature surface, but rather an extended layer that is hot on the bottom and cool at the top. In the case of the sun, the bottom of the photosphere has a temperature of about 9400 Kelvins, cools to about 4400 Kelvins, and then warms again to about 6150 Kelvins at the top. So we see an effective temperature of about 5700 Kelvins, derived by finding the best fit Planck Law SED to the true SED, which is a superimposition of multiple Planck Law SEDs. This is more important than the difference between LTE and non-LTE because it is responsible for the major deformation of the continuum from a thermal SED. But you can still use an approximate thermal SED using the effective temperature and as long as you aren't picky about the results,

you will be close enough.
ok, The approximation will get Close enogh results, you said above
Quote:


3) Spectral absorption lines seriously distort the emission of a star from a thermal SED. This is the most important and effective reason for insisting that stars are not thermal emitters. It is less important for high temperature stars, say the O & B classes, which have fewer absorption lines, but it is critical for low temperature red giant and red dwarf stars (the latter being by far the most numerous), where molecular absorption lines are numerous.
ok
Quote:


Now consider the starlight in space, the combined light from all the stars shining together.
I gave my comment for this
Quote:


Even if each star were a perfect thermal emitter, their combined light would not be thermal. The SED of the combined light would be a superposition of the SED from each star, each at a different temperature, all the way from about 2000 Kelvins for a wimpy red dwarf to 40,000 Kelvins for a high end blue giant (i.e., Theta 1C Orionis). There is such a wide range of temperatures superimposed that it makes no sense to speak of an approximate effective temperature
In my paper I took each star having seperate temperature depending on its type, see it again...
Quote:
..., a point already realized by Eddington 80 years ago. But in fact they are not thermal emitters, and most importantly, the far more numerous red stars are the ones most seriously non thermal.
Ok
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Old 26-September-2008, 04:15 PM
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....
There are several tables in the paper where the Vakradiation from various sources is calculated. In all cases what is calculated is the total power, in Watts/meter2, using the Stefan-Boltzmann Law. I simply point out that this is a useless & irrelevant exercise when it comes to the CMB, because we do not simply measure the total power, we measure the SED
I am not calculating total pwer. I am calculating the power in that half degree cone in that direction. You are not measured SED for all stars. Did you have any catalog for that...
Quote:
(example and see Fixsen, et al., 1996; Mather, et al., 2004; Wright, et al., 1994).

The Stefan-Boltzmann law (SBL) is an integration of the Planck Law (PL). This means the SBL only gives you the area under the curve, whereas the PL gives you the shape of the curve. Of course there are an infinite number of curves of various shapes, all of which will enclose the same area as does a PL curve at a given temperature. The shape of the curve for the CMB is crucial and ignoring it in your paper makes it impossible to relate what you have done to the actual measured CMB. This is a fatal flaw.
I am not bothered for Planck's law SED. That Blackbody spectrum you will get only after lots of manipulations. I am seeing for the spectrum powers in that WMAP spectrum only. That is our measuring instrument.

I am not working for Bigbang, some how to prove its predicted balckbody CBM radiation. I am seeing theoritically what WMAP measures.
Quote:
Now, on the point number 2. Your paper has a discussion of the power pattern for a radio antenna (optical astronomers call it the point spread function) and the relative gain of the side lobes. In the "Results and Conclusion" section near the end of your paper you say:

Theoretical VAKRADIATION from stars and Galaxies after dust attenuation, scattered light received from this direction due to interstellar and inter Galaxy dust, averaging done dish antenna due to main lobe, minor lobe radiation received from all the directions other than main lobe. All these factors contribute to CMB, actual values depend on place to place, direction to direction, and from time to time. TIME variations depend mainly on radiation scattering, and Major powerful / prominent sources of microwave radiation like Sun, Planets, Moon and asteroids etc. These radiations and their directions are well known, and they are avoided by computer calculations. We can now see clearly with all these physical contributing factors to CMB, no pure mathematical entity like Bigbang singularity is necessary to create CMB.
It seems clear to me that you are trying to explain the the CMB anisotropy maps, and why the CMB is not the same in all directions. But the CMB that is mapped in these images is known to have a Planck Law SED, whereas the radiation calculations you make are known not to have a Planck Law SED (i.e., scattered starlight). You have to show that the SED for the radiation you calculate is that of a Planck Law.
See the post no 106. You have already accepted that the error introduced by such approximation is very less. There is no catalog that gives SED's for millions of stars. We have to approximate a little.

Quote:
Furthermore, you do say that ... "These radiations and their directions are well known, and they are avoided by computer calculations."
You avoided SUN, Moon, Planets, Earth, bright stars etc thro' computer calculations
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Old 26-September-2008, 04:25 PM
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Originally Posted by Neverfly View Post
This is inaccurate at just about every turn.
Correct, that what I am saying, you can see it clearly...
Quote:
We specifically were LOOKING for what theory predicted- The CMB.
Where, in the spectrums of Stars and Galaxies and eleminating un-necessary portions!
Quote:
We didn't look up at the sky one day and see it and wonder what it was...
Every day sky change dynamically.
Quote:
Next, you seem to have ignored Tim Thompson's explanations about the Thermal background.
See posts 106 and 107. Hope that will satisfy you. If not please ask me.
Quote:
Can you focus on that particular bit for now- until everyone is satisfied they are understood?
Then work your way over to the next facet...
Thank you for the Good wish. If you have any further questions please let me know.
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Old 26-September-2008, 05:12 PM
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You haven't answered Anything snp.gupta.
You said, "Ok, ok ok"
And then expressed further doubts as to whether or not the measured CMB is from stars, planets, moons, etc.
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Old 26-September-2008, 10:14 PM
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I am not bothered for Planck's law SED. That Blackbody spectrum you will get only after lots of manipulations.
That misconception appears to be at the root of your misunderstanding. No, the Planck Law spectrum is directly measured on the sky with no manipulations. It is the directly measured SED of the cosmic background. See Mather, et al., 1990 for a description of the observations; you can follow the links to gif images or a PDF copy of the paper. The data and best fit Planck Law SED are illustrated in figure 1. The observations are made at high galactic latitude, 65 to 76 degrees, and at galactic longitudes well removed from the center direction of the Milky Way, 112 to 231 degrees. There the Galactic foreground is negligible and we can see the CMB directly. Only the all sky maps require foreground removal.

We actually see and directly measure a Planck Law SED. None of the sources you have mentioned, either alone or in combination, will produce a single temperature Planck Law SED, which is why your entire argument to this point is irrelevant. In the absence of an ability to explain a directly observed Planck Law SED no theory is acceptable. So far only the family of theories we call Big Bang Cosmology (BBC) actually requires that there be a CMB and that it have the Planck Law SED that is actually measured. Other cosmologies (i.e., the QSSC of Hoyle & Narlikar) can produce Planck Law SED's, but in those cases it is the exception, whereas in BBC it is the rule. So the direct observation of a Planck Law SED on the sky is an important indication that BBC is correct, and you are wrong.

Mather, et al., 1990 describes the preliminary measurement, based on only 9 hours of data. It sets the Planck Law temperature of the CMB to 2.735 +/- 0.06 Kelvins. A more complete report from COBE FIRAS, based on a larger data set, and improved instrument calibration is found in Mather, et al., 1994. Here the Planck Law temperature is found to be 2.726 +/- 0.01 Kelvins. Finally, in a detailed study of the FIRAS instrument calibration, Mather, et al., 1999, produce the final CMB temperature from COBE: 2.725 +/- 0.001 Kelvins. You see that in these three papers the temperature does not change significantly, but the uncertainties do, from 0.06 to 0.01 to 0.001 Kelvins.

Quote:
Originally Posted by snp.gupta View Post
You are not measured SED for all stars. Did you have any catalog for that ...
Yes. The Sloan Digital Sky Survey (SDSS) Data Release 6 catalogs 287,071 detailed stellar spectra, as well as 790,860 galaxies. But the full data base includes 5-band photometry from 3551 to 8931 Angstroms for 287,000,000 objects, the large majority of those being stars no doubt. That range of wavelengths extends from the ultraviolet to the near infrared, and includes the entire range where stars would be expected to be brightest. There are other observational databases. But stellar atmospheres are well enough understood for the purposes of this discussion to rely on model databases, such as The 1993 Kurucz Stellar Atmospheres Atlas at the Space Telescope Science Institute. Believe it or not, we astronomers actually know what stars look like.
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Old 26-September-2008, 10:40 PM
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But your basic measurement it self is wrong.
Is it really? Since you know that it is wrong, then I presume that you are in a good position to answer a few simple questions.
1) Can you describe the instruments that make the measurements?
2) Can you describe the methodology & process by which the measurements are made?
3) Referring to your answers from the two previous questions, will you explain, in as much detail as you can, why the basic measurements are wrong?
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Old 27-September-2008, 11:07 AM
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....
Mather, et al., 1990 describes the preliminary measurement, based on only 9 hours of data. It sets the Planck Law temperature of the CMB to 2.735 +/- 0.06 Kelvins. A more complete report from COBE FIRAS, based on a larger data set, and improved instrument calibration is found in Mather, et al., 1994. Here the Planck Law temperature is found to be 2.726 +/- 0.01 Kelvins. Finally, in a detailed study of the FIRAS instrument calibration, Mather, et al., 1999, produce the final CMB temperature from COBE: 2.725 +/- 0.001 Kelvins. You see that in these three papers the temperature does not change significantly, but the uncertainties do, from 0.06 to 0.01 to 0.001 Kelvins.
Sir,

Please see my post #12, why deglitching done?
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Old 27-September-2008, 11:14 AM
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That misconception appears to be at the root of your misunderstanding. No, the Planck Law spectrum is directly measured on the sky with no manipulations.
Sir,

Please see my post #91 and explain it first please...
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Old 27-September-2008, 11:46 AM
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Yes. The Sloan Digital Sky Survey (SDSS) Data Release 6 catalogs 287,071 detailed stellar spectra, as well as 790,860 galaxies. But the full data base includes 5-band photometry from 3551 to 8931 Angstroms for 287,000,000 objects, the large majority of those being stars no doubt. That range of wavelengths extends from the ultraviolet to the near infrared, and includes the entire range where stars would be expected to be brightest. There are other observational databases.
Sloan SDSS is not an all sky survey, if they are planning for all sky, they may take next 10 to 15 years, and we have to wait….

Quote:
But stellar atmospheres are well enough understood for the purposes of this discussion to rely on model databases, such as The 1993 Kurucz Stellar Atmospheres Atlas at the Space Telescope Science Institute. Believe it or not, we astronomers actually know what stars look like.
It is a good work sir, for detailed work on my paper such work is needed...
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Old 27-September-2008, 12:25 PM
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You haven't answered Anything snp.gupta.
You said, "Ok, ok ok"
These are facts sir, my work is also based on facts, and error will be much less.

Quote:
And then expressed further doubts as to whether or not the measured CMB is from stars, planets, moons, etc.
Oh! You mean to say stars, planets, moons, etc., does not produce any radiation in the WMAP frequency bands….
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Old 27-September-2008, 05:50 PM
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Originally Posted by snp.gupta View Post
Please see my post #12, why deglitching done?
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Originally Posted by snp.gupta View Post
Please see my post #91 and explain it first please...
No. I will not answer either question yet for the simple reason that you are now avoiding the main issue and I don't want to be distracted by irrelevancies. Both of your questions refer to the sky maps, but I am referring to the measurement of the Planck Law SED, which is not the same thing. Stick to one issue at a time to avoid confusion. I will deal with the maps after we have dealt with the Planck Law SED.

Remember, you are the one who is making the positive assertion:
Quote:
Originally Posted by snp.gupta View Post
That Blackbody spectrum you will get only after lots of manipulations.
I have provided a direct counter example to disprove your assertion:
Quote:
Originally Posted by Tim Thompson View Post
No, the Planck Law spectrum is directly measured on the sky with no manipulations. It is the directly measured SED of the cosmic background. See Mather, et al., 1990 for a description of the observations; you can follow the links to gif images or a PDF copy of the paper.
Now you can ignore this, or you can deal with it. But I am not going to answer any other questions, or deal with any other topic, until we have dispensed with this one. Either it is or it is not a fact that the Planck Law SED is directly measured. You say it is not a fact. I say it is a fact, and I have provided the source. You can refute the source, or accept that you are in error, or you can ignore it completely. It is now up to you to respond.
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Old 28-September-2008, 01:11 PM
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Sir,

Please don’t get angry. Basically I am a poor man. I am not rich or powerful to enforce my ideas on you. Nor I am interested in forcing. You are working for science and its development. I can only suggest you to consider some points to change your thinking for betterment. What I can say is that these points are logically and analytically true.

I also beg to state again that my English is also poor like me. Some of my expressions may make you feel angry. I am sorry. When I said ‘manipulations’, I did not mean any harm to any body, any work or institution. I mean about the general thinking and basic measurement methodology. There is fever or passion to prove Bigbang among the scientific community. You have to listen what other people say also.

Now coming to your post…

Quote:
Originally Posted by Tim Thompson View Post

Quote:
Originally Posted by snp.gupta View Post
Please see my post #12, why deglitching done?
Quote:
Originally Posted by snp.gupta View Post
Please see my post #91 and explain it first please...
No. I will not answer either question yet for the simple reason that you are now avoiding the main issue and I don't want to be distracted by irrelevancies. Both of your questions refer to the sky maps,
No sir, same thing I am telling, if you cannot explain, I will explain them in my own way…
Quote:
but I am referring to the measurement of the Planck Law SED, which is not the same thing. Stick to one issue at a time to avoid confusion. I will deal with the maps after we have dealt with the Planck Law SED.
Okay, I will do, I am also doing the same…

Tim:
Remember, you are the one who is making the positive assertion:
Quote:
Originally Posted by snp.gupta View Post
That Blackbody spectrum you will get only after lots of manipulations.
Correct, You are measuring the radiation from stars and Galaxies ( 85% of sky) after eliminating the bright ones and Milkyway disk. Compensating for synchrotron radiations, free-free radiations, dust scattering, sidelobes gains etc., are some of the
manipulations…


Tim:
I have provided a direct counter example to disprove your assertion:

Quote:
Originally Posted by Tim Thompson View Post
No, the Planck Law spectrum is directly measured on the sky with no manipulations. It is the directly measured SED of the cosmic background. See Mather, et al., 1990 for a description of the observations; you can follow the links to gif images or a PDF copy of the paper.
That paper was too short, 4 pages only. A detailed paper by the same author, in 1994; I quoted the example in my post no #12 for my point of view.

Quote:
Now you can ignore this, or you can deal with it. But I am not going to answer any other questions, or deal with any other topic, until we have dispensed with this one. Either it is or it is not a fact that the Planck Law SED is directly measured.

Probably you are not getting my point. What went wrong? I will explain here. How you are measuring radiation-using COBE-FIRAS; You are taking measurements in wide frequency range unlike WMAP. But WMAP view cone radius is small. It is about 1 degree; COBE has this radius higher it is about 4 degrees. Both the cases you can check the respective data sheets for exact values. COBE has higher pixel size, ie, number of pixels are high in WMAP. These are basic data of Instruments. OK till now?

Now tell me:
1. How many individual stars, Galaxies and other point sources you have calculated and deducted from EACH pixel?

2. You mean to say that there are no stars, Galaxies and other point sources in that particular pixel in which you are taking measurement. In case of WMAP you have already taken out 15% of sky pixels for various reasons. I did not remember the data for COBE.

3. In your calculation; you made this correction based Planck’s SED of each star or any other energy distribution? What is the calculation error?

4. Now please tell me how you have identified each star, Galaxy or other point source using the beam width radius of COBE or WMAP?

5. Your calculations are based using what geometry? What curvature? Do you have
details like temperature, radius, type, distance etc for all the point sources?

6. These are some of my questions shall I ask you more? Now you please tell me how you are directly measuring the Planck’s Law based SED using COBE or WMAP as your measuring instrument and how you are eliminating radiation from stars, Galaxies and other point sources?

Quote:
You say it is not a fact. I say it is a fact, and I have provided the source. You can refute the source, or accept that you are in error, or you can ignore it completely. It is now up to you to respond.

Now you say what you want to say…what I said is a fact or not?
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Old 29-September-2008, 06:16 AM
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That paper was too short, 4 pages only. A detailed paper by the same author, in 1994; I quoted the example in my post no #12 for my point of view.
I can see and read quite well without the boldface type. How can a paper be "too short"? If it says all that it needs to say, then it is long enough, even if its just one page. Let us see what it has to say.

"The FIRAS is cooled to 1.5 K by a liquid helium cryostat similar to that used in the Infrared Astronomical Satellite (IRAS). The FIRAS is a rapid-scan polarizing Michelson interferometer similar to earlier balloon and rocket instruments (Woody, et al., 1975; Woody and Richards, 1981; Gush 1981), but with several improvements. ... The instrument is a symmetrical four-port device. The modulated power appearing at either output port is proportional to the Fourier transform of the difference spectrum between the two input ports. One input port receives power from the sky through a compound parabolic concentrator which defines a 7 degree beam on the sky. This sky horn has a smoothly flared aperture to reduce diffractive sidelobes over a wide frequency range (Mather, Toral and Hammati 1986). The second input port views a temperature controlled internal blackbody calibrator through a reference horn which is closely matched to the sky horn. Both outputs of the interferometer are used, with each output divided into a high frequency (> 20 cm-1) and a low frequency channel using dichroic beam splitters. The data for this Letter come from the more sensitive of the two low frequency channels."
Mather, et al., 1990, page L37-L38
FIRAS is an interferometer. It does not simply look at the sky and measure it. Rather, it looks at the sky and at the internal calibrator, simultaneously, and measures the difference between them. But the internal calibrator is a blackbody of known temperature. So, if the sky is also a blackbody, and if the internal calibrator is set to the same blackbody temperature as the sky, the difference between them will be zero (because both are (Planck Law) black bodies at the same temperature). Observations are made by adjusting the temperature on the calibrator blackbody to minimize the difference between the sky and the calibrator. If the difference becomes zero, then you know that the sky is in fact a blackbody. If the difference becomes almost zero, then you know that the sky is almost a blackbody, while the departure of the difference from zero tells you how far the sky is from being a blackbody. There is also a moveable external blackbody, shaped like a trumpet mute, which can be moved to fill the sky horn. This makes it possible to measure both the difference between the internal calibrator and the sky and the difference between the internal calibrator and the external calibrator. Now, the difference between those two difference measurements reveals any unwanted instrumental bias, which can then be removed from the data. It all makes for a clean observation of the sky, especially when we go to the trouble of calibrating the instruments on the ground before launch, so we know beforehand how they behave in considerable detail.

All of your analysis of sidelobes is based on the erroneous idea that the CMB is measured with a large, single dish antenna that is not designed to reduce sidelobe gain. But FIRAS is not only specifically designed to eliminate most of the side lobe gain that you rely on, it is also an interferometer, so the difference measurements it makes eliminate all of the remaining sidelobe effects by simply nulling them out. So your sidelobe discussion does not reflect the facts of how the observations are actually made.

Note from the following quote that I erroneously said that Mather, et al., 1990, had used 9 hours of data, when it was in fact 9 minutes of data.

"The sky data reported in this Letter were taken in 9 minutes, using the short stroke length and slow scan speed, along the arc (l,b) = (112,65) to (231,79), with the center of the arc at (l,b) = (137,79). The data were taken while the spacecraft was outside known regions of high trapped particle fluxes. The interferograms were averaged together after eliminating recognizable spikes caused by cosmic ray impacts on the detectors. Residuals from the subtraction of these spike are not a major contributor to the uncertainties in the derived spectra. The details of procedure for processing interferograms are embodied in a carefully tested set of computer programs which will be documented in a future publication."
Mather, et al., 1990, page L38.
Note that (l,b) are galactic coordinates and the numbers are in degrees. The high galactic latitude guarantees that foreground emission from the Milky Way, and from stars, which are clearly more numerous close to the Galactic plane, will be minimized. Not entirely eliminated simply minimized. But any stars or galaxies or Galactic foreground will reveal themselves via a deviation of the sky from a single temperature blackbody, and that will reveal itself in the difference measurements as an offset from zero difference between the calibrator and the sky. FIRAS was designed as an interferometer specifically to make it sensitive to small offsets from zero, so it is tailor made, as they say, to detect the presence of confusing sources. What was the result?

"Since the data show a good null both when the FIRAS is looking at the external calibrator and at the sky, one can determine from the interferograms alone that the spectrum of the sky is close to a blackbody, regardless of the details of the data reduction and calibration"
Mather, et al., 1990, page L39.
The authors adopt a conservative estimate for deviation from a blackbody as 1% of the peak flux. Just looking at figure 2, where the temperature data are plotted, you can easily see that 1% is considerably larger than the internal error from the data, and is made that large in order to account for systematic effects in the instruments themselves.

So it's like I said it was. We know that the spectrum of the sky is a Planck Law blackbody within the generous limits of +/- 1%. No confusion from stars, galaxies or dust can be that close to a blackbody. But it does not matter, because the fact that the interferometer was able to make a good null tells us right off the bat that there is very little in the way of confusion sources there anyway.

The paper shows the blackbody spectrum in figure 1, and reports a preliminary temperature 2.735 +/- 0.06 Kelvins. Offsets from the zero difference are less than 0.02 Kelvins in all of the data.

In the later paper, Mather, et al., 1994, they are dealing with all sky data, where the foreground confusion in many places, especially near the plane of the Milky Way, is not negligible. They also want to decrease the size of the uncertainty from the temperature reported in 1990. So, naturally, they want to remove the foreground confusion. And how do we know if we are doing it right?

Remember, thanks to Mather, et al., 1990, we already know that there is a single temperature blackbody background. It stands to reason that if all those data are cleaned of known, non-blackbody sources, then the result should be closer to a blackbody after subtraction than it was before subtraction. If you know ahead of time that you have a distorted blackbody, and you remove non-blackbody effects, and then get something that looks even less like a blackbody, then you know you have done something wrong. That does not happen. The results look more like a blackbody, with a better determined temperature than before. We can see that process work on parts of the sky where we can see the blackbody spectrum free of foreground interference (Mather, et al., 1990), and so we have confidence that it works elsewhere on the sky.

So we are back to the two main points. First, like I said, we see a Planck Law, blackbody spectrum directly on they sky, without any of the subtractions or adjustments that you speak of. Second, the instrument used to measure the CMB on COBE and WMAP has no sidelobes, so it is not possible for the CMB to be a sidelobe effect.
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  #119 (permalink)  
Old 29-September-2008, 10:04 PM
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I can see and read quite well without the boldface type.
In my previous post , I could not put a message box as you did in your previous post. I just wrote’ Tim:’ , and to further avoid confusion, I started writing using the bold face. My know ledge is limited in using the PC and all, that is the problem
Quote:
How can a paper be "too short"? If it says all that it needs to say, then it is long enough, even if its just one page. Let us see what it has to say.
The other paper is much more elaborate and detailed. Also it was by the same author. He covers these points and more.. .
Quote:

"The FIRAS is cooled to 1.5 K by a liquid helium cryostat similar to that used in the Infrared Astronomical Satellite (IRAS). The FIRAS is a rapid-scan polarizing Michelson interferometer similar to earlier balloon and rocket instruments (Woody, et al., 1975; Woody and Richards, 1981; Gush 1981), but with several improvements. ... The instrument is a symmetrical four-port device. The modulated power appearing at either output port is proportional to the Fourier transform of the difference spectrum between the two input ports. One input port receives power from the sky through a compound parabolic concentrator which defines a 7 degree beam on the sky.

Please note it is 7 degree beam, and sky is with stars and Galaxies and other astronomical bodies
Quote:
...
This sky horn has a smoothly flared aperture to reduce diffractive sidelobes over a wide frequency range (Mather, Toral and Hammati 1986). The second input port views a temperature controlled internal blackbody calibrator through a reference horn which is closely matched to the sky horn. Both outputs of the interferometer are used, with each output divided into a high frequency (> 20 cm-1) and a low frequency channel using dichroic beam splitters. The data for this Letter come from the more sensitive of the two low frequency channels."
Mather, et al., 1990, page L37-L38
Quote:
FIRAS is an interferometer.
It works on frequency spectrum, not on temperature

Quote:
It does not simply look at the sky and measure it. Rather, it looks at the sky and at the internal calibrator, simultaneously, and measures the difference between them. But the internal calibrator is a blackbody of known temperature. So, if the sky is also a blackbody, and if the internal calibrator is set to the same blackbody temperature as the sky, the difference between them will be zero (because both are (Planck Law) black bodies at the same temperature). Observations are made by adjusting the temperature on the calibrator blackbody to minimize the difference between the sky and the calibrator. If the difference becomes zero, then you know that the sky is in fact a blackbody. If the difference becomes almost zero, then you know that the sky is almost a blackbody, while the departure of the difference from zero tells you how far the sky is from being a blackbody. There is also a moveable external blackbody, shaped like a trumpet mute, which can be moved to fill the sky horn. This makes it possible to measure both the difference between the internal calibrator and the sky and the difference between the internal calibrator and the external calibrator. Now, the difference between those two difference measurements reveals any unwanted instrumental bias, which can then be removed from the data. It all makes for a clean observation of the sky, especially when we go to the trouble of calibrating the instruments on the ground before launch, so we know beforehand how they behave in considerable detail.
They say frequency and you are saying them as temperature
Quote:
All of your analysis of sidelobes is based on the erroneous idea that the CMB is measured with a large, single dish antenna that is not designed to reduce sidelobe gain. But FIRAS is not only specifically designed to eliminate most of the side lobe gain that you rely on,
In my paper, there are many other points other than sidelobes. Mainly Radaition from astro-bodies. You say, FIRAS sidelobe gain is ZERO, is it? What about the 7 degree beam, how you have eliminated the stars and other asro-bodies?

Quote:
it is also an interferometer, so the difference measurements it makes eliminate all of the remaining sidelobe effects by simply nulling them out. So your sidelobe discussion does not reflect the facts of how the observations are actually made.

Note from the following quote that I erroneously said that Mather, et al., 1990, had used 9 hours of data, when it was in fact 9 minutes of data.
All sky scanning needs more than 1 year data, 9 min or 9 hours is too less.
Quote:

"The sky data reported in this Letter were taken in 9 minutes, using the short stroke length and slow scan speed, along the arc (l,b) = (112,65) to (231,79), with the center of the arc at (l,b) = (137,79). The data were taken while the spacecraft was outside known regions of high trapped particle fluxes. The interferograms were averaged together after eliminating recognizable spikes caused by cosmic ray impacts on the detectors. Residuals from the subtraction of these spike are not a major contributor to the uncertainties in the derived spectra. The details of procedure for processing interferograms are embodied in a carefully tested set of computer programs which will be documented in a future publication."
Mather, et al., 1990, page L38.
Note that (l,b) are galactic coordinates and the numbers are in degrees. The high galactic latitude guarantees that foreground emission from the Milky Way, and from stars, which are clearly more numerous close to the Galactic plane, will be minimized. Not entirely eliminated simply minimized.
You have not eliminated Stars...
Quote:
But any stars or galaxies or Galactic foreground will reveal themselves via a deviation of the sky from a single temperature blackbody, and that will reveal itself in the difference measurements as an offset from zero difference between the calibrator and the sky.
that is your feeling only star radiation still comes
Quote:
FIRAS was designed as an interferometer specifically to make it sensitive to small offsets from zero, so it is tailor made, as they say, to detect the presence of confusing sources. What was the result?

"Since the data show a good null both when the FIRAS is looking at the external calibrator and at the sky, one can determine from the interferograms alone that the spectrum of the sky is close to a blackbody, regardless of the details of the data reduction and calibration"
Mather, et al., 1990, page L39.
The authors adopt a conservative estimate for deviation from a blackbody as 1% of the peak flux. Just looking at figure 2, where the temperature data are plotted, you can easily see that 1% is considerably larger than the internal error from the data, and is made that large in order to account for systematic effects in the instruments themselves.

So it's like I said it was. We know that the spectrum of the sky is a Planck Law blackbody within the generous limits of +/- 1%. No confusion from stars, galaxies or dust can be that close to a blackbody.
You have not eliminated star etc., radiation, you are measuring the same in the name of sky and say it is from Bigbang ????????
Quote:

But it does not matter, because the fact that the interferometer was able to make a good null tells us right off the bat that there is very little in the way of confusion sources there anyway.

The paper shows the blackbody spectrum in figure 1, and reports a preliminary temperature 2.735 +/- 0.06 Kelvins. Offsets from the zero difference are less than 0.02 Kelvins in all of the data.

In the later paper, Mather, et al., 1994, they are dealing with all sky data, where the foreground confusion in many places, especially near the plane of the Milky Way, is not negligible. They also want to decrease the size of the uncertainty from the temperature reported in 1990. So, naturally, they want to remove the foreground confusion. And how do we know if we are doing it right?

Remember, thanks to Mather, et al., 1990, we already know that there is a single temperature blackbody background. It stands to reason that if all those data are cleaned of known, non-blackbody sources, then the result should be closer to a blackbody after subtraction than it was before subtraction. If you know ahead of time that you have a distorted blackbody, and you remove non-blackbody effects, and then get something that looks even less like a blackbody, then you know you have done something wrong. That does not happen. The results look more like a blackbody, with a better determined temperature than before. We can see that process work on parts of the sky where we can see the blackbody spectrum free of foreground interference (Mather, et al., 1990), and so we have confidence that it works elsewhere on the sky.

So we are back to the two main points. First, like I said, we see a Planck Law, blackbody spectrum directly on they sky, without any of the subtractions or adjustments that you speak of. Second, the instrument used to measure the CMB on COBE and WMAP has no sidelobes, so it is not possible for the CMB to be a sidelobe effect.
Your both points are wrong, methodology is wrong, Conclusions are wrong, please I request you to think cool...

warm regards
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Old 29-September-2008, 10:24 PM
Fortis Fortis is offline
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snp.Gupta, have you tried doing any sensitivity analysis? Take two thermal sources, one at say 6000 K, and another at 2.7 K. Create a composite radiance curve by linearly adding the two blackbody curves due to the two sources. Now find the mixing ratio which leads to the low temperature source dominating the spectral profile in the microwave region. What is that ratio, and does it look like a plausible fill factor for the fraction of sky covered by stars?
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