Parallax

I'm sure that most regulars here could give a short explanation of the basic
method whereby stellar parallaxes were determined in the past century or so
suing ground based (or other) telescopes.

However, at University of London Observatory we are in the midst of sending
our old plate archive to secure storage. These are plates from the
Radcliffe Observatory parallax programme starting shortly after they got the
24-inch telescope [now at London] up and running in the first decade of the
20th century.

http://www.ulo.ucl.ac.uk/telescopes/radcliffe/

What is remarkable is the technique actually used. The plates were exposed
as follows, as shown by our inspection and the log books:

Observation 1: three images, displaced by 30 arcsec in dec, over a few
minutes, with selected parallax candidate near the centre.

Put the undeveloped plate away for six months, stored VERY carefully.

Observation 2 and 3: On the same night six months later, take two sets of
three images as above on the same plate, but displaced by a few seconds of
time in RA.

Put the undeveloped plate away again.

Observation 4: Six months on, take another three exposures, displaced in RA
again. Then move a bit more, take a couple of shorter exposures so we can
tell which set was the fourth.

Then develop the plate, and measure the relative displacements vs other
stars in the field and compare to expected parallax displacements. You get,
in effect, two independent pairs of data point sets for the parallax.

Think of the effort and patience required, and the care required to preserve
plates safely for a year...

We are scanning some examples for our archives. Maybe remeasurement of
digital scans could be an interesting student project...

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

On Mar 30, 8:19 pm, "Mike Dworetsky"
wrote:
I'm sure that most regulars here could give a short explanation of the basic
method whereby stellar parallaxes were determined in the past century or so
suing ground based (or other) telescopes.

However, at University of London Observatory we are in the midst of sending
our old plate archive to secure storage. These are plates from the
Radcliffe Observatory parallax programme starting shortly after they got the
24-inch telescope [now at London] up and running in the first decade of the
20th century.

http://www.ulo.ucl.ac.uk/telescopes/radcliffe/

What is remarkable is the technique actually used. The plates were exposed
as follows, as shown by our inspection and the log books:

Observation 1: three images, displaced by 30 arcsec in dec, over a few
minutes, with selected parallax candidate near the centre.

Put the undeveloped plate away for six months, stored VERY carefully.

Observation 2 and 3: On the same night six months later, take two sets of
three images as above on the same plate, but displaced by a few seconds of
time in RA.

Put the undeveloped plate away again.

Observation 4: Six months on, take another three exposures, displaced in RA
again. Then move a bit more, take a couple of shorter exposures so we can
tell which set was the fourth.

Then develop the plate, and measure the relative displacements vs other
stars in the field and compare to expected parallax displacements. You get,
in effect, two independent pairs of data point sets for the parallax.

Think of the effort and patience required, and the care required to preserve
plates safely for a year...

We are scanning some examples for our archives. Maybe remeasurement of
digital scans could be an interesting student project...

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

Do you realise how counter-productive this stellar parallax is.

Here is your Ra/Dec geometry with a star returning to a location in 23
hours 56 minutes 04 seconds based ona system of 3 years of 365 days
and 1 year of 366 days -

http://www.opencourse.info/astronomy...phere_anim.gif

As every star will return to a meridian in 23 hours 56 minutes,you are
creating a constellational geometry built of stars,a prospect so
intutively frightening that not even the astrologers would touch
it.The basis of the Roemerian insight on lightspeed is make from
orbital comparisons between Earth and Jupiter with the motion of Io as
the bridge between the apparent motion and the actual motion,the
difference being finite light speed.In short,it is an astronomical
correction which has profound implications for the position of
external galaxies to the riotation of the foreground Milky Way stars.

You are not going to open up a very exciting and very intricate avenue
by sticking with celestial sphere/constellational geometry born of
very poor late 17th century maneuvering

On Mar 30, 8:46 pm, "oriel36" wrote:
On Mar 30, 8:19 pm, "Mike Dworetsky"



wrote:
I'm sure that most regulars here could give a short explanation of the basic
method whereby stellar parallaxes were determined in the past century or so
suing ground based (or other) telescopes.

However, at University of London Observatory we are in the midst of sending
our old plate archive to secure storage. These are plates from the
Radcliffe Observatory parallax programme starting shortly after they got the
24-inch telescope [now at London] up and running in the first decade of the
20th century.

http://www.ulo.ucl.ac.uk/telescopes/radcliffe/

What is remarkable is the technique actually used. The plates were exposed
as follows, as shown by our inspection and the log books:

Observation 1: three images, displaced by 30 arcsec in dec, over a few
minutes, with selected parallax candidate near the centre.

Put the undeveloped plate away for six months, stored VERY carefully.

Observation 2 and 3: On the same night six months later, take two sets of
three images as above on the same plate, but displaced by a few seconds of
time in RA.

Put the undeveloped plate away again.

Observation 4: Six months on, take another three exposures, displaced in RA
again. Then move a bit more, take a couple of shorter exposures so we can
tell which set was the fourth.

Then develop the plate, and measure the relative displacements vs other
stars in the field and compare to expected parallax displacements. You get,
in effect, two independent pairs of data point sets for the parallax.

Think of the effort and patience required, and the care required to preserve
plates safely for a year...

We are scanning some examples for our archives. Maybe remeasurement of
digital scans could be an interesting student project...

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

Do you realise how counter-productive this stellar parallax is.

Here is your Ra/Dec geometry with a star returning to a location in 23
hours 56 minutes 04 seconds based ona system of 3 years of 365 days
and 1 year of 366 days -

http://www.opencourse.info/astronomy...tion_stars_sun...

As every star will return to a meridian in 23 hours 56 minutes,you are
creating a constellational geometry built of stars,a prospect so
intutively frightening that not even the astrologers would touch
it.The basis of the Roemerian insight on lightspeed is make from
orbital comparisons between Earth and Jupiter with the motion of Io as
the bridge between the apparent motion and the actual motion,the
difference being finite light speed.In short,it is an astronomical
correction which has profound implications for the position of
external galaxies to the riotation of the foreground Milky Way stars.

You are not going to open up a very exciting and very intricate avenue
by sticking with celestial sphere/constellational geometry born of
very poor late 17th century maneuvering

I feel your pain. But tonight is bednight and I am beside myself
waiting for me to post this. "Come on" I say "time for bed."

But do I listen?

Mike,

That is really interesting. I had only a vague idea
how those early measurements were made and no
idea that the plates were replicated.
I also believed you could get a fair measurement
by photographing at 90 degree increments instead
of 180. You are opening up an exciting and intricate
study of celestial geometry pioneered by the great
Seventeenth Century innovators: Newton, Bradley,
Flamsteed, and brought to culmination by ESA's
HIPPARCOS.

Do carry on,

Ben

On Apr 3, 5:09 am, "Ben" wrote:
Mike,

That is really interesting. I had only a vague idea
how those early measurements were made and no
idea that the plates were replicated.
I also believed you could get a fair measurement
by photographing at 90 degree increments instead
of 180. You are opening up an exciting and intricate
study of celestial geometry pioneered by the great
Seventeenth Century innovators: Newton, Bradley,
Flamsteed, and brought to culmination by ESA's
HIPPARCOS.

Do carry on,

Ben

The innovators,as you call them,introduced celestial sphere geometry
into heliocentric reasoning thereby destroying the insights of
Copernicus,Kepler and Roemer and the methods they employed to present
their acvhievements to humanity.

It is therefore impossible to affirm the great Copernican insight for
the Earth's and the other planets heliocentric orbital motion when
people correlate axialrotation to celestial sphere geometry in 23
hours 56 minutes 04 seconds.The reason for this is that the original
Copernican insight used the faster orbital motion of the Earth to
explain the observed behavior of the planets leaving axial rotation
to explain the observed behavior of the Sunor rather the daily cycle.

The pre-Copernican Equation of Time correction which generates the 24
hour day average and how each of these 24 hour days elapse into the
next 24 hour day was then overlaid on the daily cycle where 4 minutes
of clock time represent 1 degree of geographical seperation thereby
clocks correlate with the daily cycle and terrestrial longitudes at
the precise value of 24 hours/360 degrees.It is probably the greatest
practical achievement of the last millenia arising from astronomy yet
men choose an alternative value.

The reason Newton could compltely obliterate the Copernican approach
and resolution of retrogrades is because of Flamsteed's false proof
for axial rotation which introduced celestial sphere geometry to
justify the motions of the Earth -

"For to the earth planetary motions appear sometimes direct,
sometimes stationary, nay, and sometimes retrograde. But from the sun
they are always seen direct.." Newton

Every participant here will use the 24 hour system devised by the
heliocentric astronomers which keep clocks in sync with axial rotation
at 4 minutes for each degree of rotation making exactly 24 hours/360
degrees.It is a result of the original Copernican insight which
resolved the apparent motion of the other planets through a faster
orbitally moving Earth -

http://antwrp.gsfc.nasa.gov/apod/ima...2000_tezel.gif

For all the people who visit this forum daily,not one single person
has ever affirmed that there is a huge difference between the actual
timelapse footage which explicitly states that we do see heliocentric
motion from a moving Earth and the false Newtonian conception which
determines that we do not nor the original error by Flamsteed -

"... our clocks kept so good a correspondence with the Heavens that I
doubt it not but they would prove the revolutions of the Earth to be
isochronical..." Flamsteed wrote in a letter in 1677

The emergence of clocks and magnification equipment in the 17th
century led to the 'innovations' which turn out to be little more than
mutations designed for observational conveniences rather than the
pursuit of astronomy contained in the cycles of the Earth and how to
use them to read the celestial arenafor structure based on physical
considerations.

Watching the destruction of heliocentric reasoning by the late 17th
century guys is an incredibly disappointing experience,why otherwise
successful men would choose to undo the major achievements which
belong to all humanity can only be seen in light of their attempt to
promote the observational convenience of the Ra/Dec system.In
short,they tried to force astronomy into the human devised principle
of the 24 hour day and the clock.

The loss has turned far more personal than I had ever imagined it
would,not the anger or contempt for the late 17th century maneuvering
but rather the loss of so much work by so many people stretching back
to remote antiquity.There is no burden attached to the ancient work
but there is a burden untangling the 17th century mutations from the
original sacred reasoning of not just the heliocentric astronomers but
the pre-Copernican men as well.

"Ben" wrote in message
ups.com...
Mike,

That is really interesting. I had only a vague idea
how those early measurements were made and no
idea that the plates were replicated.
I also believed you could get a fair measurement
by photographing at 90 degree increments instead
of 180. You are opening up an exciting and intricate
study of celestial geometry pioneered by the great
Seventeenth Century innovators: Newton, Bradley,
Flamsteed, and brought to culmination by ESA's
HIPPARCOS.

Do carry on,

Ben


Not sure exactly what you mean by 90 degrees rather than 180, but if you
mean that imaging should continue around the year, there are good reasons
why this is impractical for stars in the region of the ecliptic. You would
need to photograph the field around dusk, six months later at dawn, and in
between once at midnight and later on once at noon. The latter would not be
possible of course. Traditionally, parallax work has been done around dusk
and in the hours before dawn, to ensure that stars were observed at optimum
positions of the Earth for maximum parallaxtic displacement.

For stars near the ecliptic pole what you say is possible.

Don't forget as well, the amount of work required in measuring. This is
another reason why the astronomers of c. 100 years ago did things the way I
described.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

On Apr 4, 7:46 am, "Mike Dworetsky"
wrote:
"Ben" wrote in message

ups.com...





Mike,

That is really interesting. I had only a vague idea
how those early measurements were made and no
idea that the plates were replicated.
I also believed you could get a fair measurement
by photographing at 90 degree increments instead
of 180. You are opening up an exciting and intricate
study of celestial geometry pioneered by the great
Seventeenth Century innovators: Newton, Bradley,
Flamsteed, and brought to culmination by ESA's
HIPPARCOS.

Do carry on,

Ben

Not sure exactly what you mean by 90 degrees rather than 180, but if you
mean that imaging should continue around the year, there are good reasons
why this is impractical for stars in the region of the ecliptic. You would
need to photograph the field around dusk, six months later at dawn, and in
between once at midnight and later on once at noon. The latter would not be
possible of course. Traditionally, parallax work has been done around dusk
and in the hours before dawn, to ensure that stars were observed at optimum
positions of the Earth for maximum parallaxtic displacement.

For stars near the ecliptic pole what you say is possible.

Don't forget as well, the amount of work required in measuring. This is
another reason why the astronomers of c. 100 years ago did things the way I
described.


The guys 100 years ago were following the 17th century numbskulls who
introduced celestial sphere geometry into heliocentric reasoning and
especially the Keplerian insights.

The Newtonian 'fixed stars' statement is pure rubbish,a silly
mathematicians attempt to cobble together scraps of astronomical facts
and shove it into the observational convenience of the Ra/Dec system -


"That the fixed stars being at rest, the periodic times of the five
primary planets, and (whether of the sun about the earth, or) of the
earth about the sun, are in the sesquiplicate proportion of their
mean
distances from the sun." Newton

The actual statement of Kepler based on peiodic times between
planets ,such as between Earth and Mars looks like this -

"The proportion existing between the periodic times of any two
planets
is exactly the sesquiplicate proportion of the mean distances of the
orbits, or as generally given,the squares of the periodic times are
proportional to the cubes of the mean distances." Kepler

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)- Hide quoted text -

- Show quoted text -

Of course you have to become familiar with the periodic times argument
which Kepler used to determine orbital geometries and none of you have
shown the slightest trace of recognition of Copernican reasoning let
alone the periodic times arguments of Kepler.

The original reasoning is astronomically gorgeous whereas the
contrived Newtonian rubbish is for people who know no better and
prefer to keep it that way

Don't forget as well, the amount of work required in measuring. This
is
another reason why the astronomers of c. 100 years ago did things the way I
described.

--
Mike Dworetsky

Mike,

I once gave a talk to our club about stellar distance
measurements and although I had the principles in
order I was pretty fuzzy on the actual techniques.

Do any computational notes survive from those
studies? That would add a nice icing on this cake.

Regards,
Ben