Angle of crab pulsar to the ecliptic

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    Angle Ecliptic Pulsar
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Discussion Overview

The discussion revolves around the angle of the Crab Pulsar relative to the ecliptic, as well as inquiries about its period and frequency. Participants explore the implications of these measurements for calculating radial velocity and the timing of observations from Earth.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant asks for the angle the Crab Pulsar makes to the ecliptic, indicating a need for this information for calculations involving radial velocity.
  • Another participant suggests that celestial coordinates can be found online and mentions the need to convert these coordinates from equatorial to ecliptic.
  • A separate inquiry is made regarding the precise value of the Crab Pulsar's period, with concerns about the reliability of the Wikipedia entry and a request for a more accurate source.
  • One participant provides a suggestion to use the SIMBAD Astronomical Database to find the pulsar's coordinates, though it does not contain the period.
  • Another participant discusses calculating the radial velocity of the Crab Pulsar based on observed frequency data from the Canary Islands, noting the difference between observed and intrinsic frequency due to the radial velocity.
  • There is an exploration of how to determine the time of year when the radial velocity of the Crab Pulsar would equal a specific value, linking this to the right ascension coordinate.
  • A follow-up question is raised about identifying the right ascension of objects that would yield zero radial velocity at specific solstices and equinoxes.

Areas of Agreement / Disagreement

Participants express various inquiries and hypotheses, but there is no consensus on the angle of the Crab Pulsar to the ecliptic or the precise period of the pulsar. Multiple competing views and methods for calculation are presented without resolution.

Contextual Notes

Participants mention approximations in their calculations, such as neglecting Earth's rotational motion and assuming the Crab Pulsar lies on the ecliptic. There are also references to the need for reliable sources for specific values, indicating potential limitations in available data.

Who May Find This Useful

This discussion may be of interest to those studying pulsars, celestial mechanics, or anyone involved in observational astronomy, particularly in relation to the Crab Pulsar and its properties.

SUDOnym
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Hi there

Can any1 tell me, what is the angle that the crab pulsar makes to the ecliptic? - (I am trying to make calculations that require knowledge of the radial velocity between the Earth and Crab)

Thanks
 
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It should be easy to discover online:
The celestial coordinates of the Crab Nebula (right ascension, declination)
How to change celestial coordinates from equatorial to ecliptic

I don't feel like posting Celestial Coordinates 101 at this time -- it should be easy to discover in places like Wikipedia.
 
just a related question... can any1 tell me where I might find a very precise value for the period/frequency of the Crab pulsar? I have looked at the Wikipedia page which is clearly not kosher and his given a period of 33.08471603 miliseconds... the source that is referenced with this value is linked below :

http://www.atnf.csiro.au/research/p...x=51&table_bottom.y=36&expert=expert&db_file=

only problem is this source only gives a value of 0.033085 seconds ... so it is not clear to me how the wikipedia page is justified in giving the value to so many more significant figures...

To clarify, my query is - where might I find a reliable and accurate value for the period of the crab?
 
Sorry if I seemed snotty earlier about posting Celestial Coordinates 101.

But I found what you were asking about. Start at the SIMBAD Astronomical Database and go to "basic search". Searching for "crab pulsar" reveals one entry: SIMBAD's Crab-pulsar page

It has that pulsar's coordinates, though not its period. I had to search through the "External archives" links, and the one that gave its period was PSR B0531+21, in the third row and fourth column.
 
another follow up question if I may... !

I have been given data recorded from the Canary islands and from this data a certain frequency for the crab can be calculated - call this the observed frequency.. this will be different from the intrinsic frequency of the crab because of the radial velocity between the observer (at the Canary islands) and the crab...

so from the difference of the observed frequency and intrinsic frequency, I was then able to calculate this radial velocity by using the electromagnetic doppler equation and I found this equal to about 20.4km/s...

now, making the approximation that the crab pulsar lies on the ecliptic (in fact it lies about 1.5 degrees off the ecliptic) and also making the approximation that the only radial velocity contribution is from the orbital motion of the Earth about the sun (ie neglect the Earth's rotational motion), we can say that the maximum radial velocity will be approximately 30km/s - that is the Earth's tangential velocity will be equal to its angular velocity omega multiplies by the radius of the circle of its orbit - so omega=(2*pi)/(365*24*60*60)rads/second and radius=1AU=1.5*10^11meters and so omega*radius is approximately 30km/s...

What I am having trouble doing (and using the approximations I calculated) is figuring out what time of year it must have been such that the radial velocity was equal to about 20.4km/s..
I think that it must be down to the right ascension coordinate.. for the crab RA=05h 34min...
how can I figure out from this RA value and the radial velocity value, what time of year it must have been... ?
 
to add to my last post...

What I don't know is how to figure what time of year will create a given radial velocity to the crab,
I think what would help figure this out is if I knew what would be the RA of an object such that the radial velocity (only due to Earth's orbit) would be zero at both the summer and winter solstice..

And in a similar vain, what be the RA of an object such that the radial velocity would be zero at the spring and autumn equinox...?
 

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