Venus parallax demonstration project

Beat the transit!

Just a thought but with the Venus/Pleiades conjunction that peaks on
the 3rd April, it should be possible to display a small, but
measurable parallax effect using UK or European observers. Unlike the
lunar parallax demonstration project, the zone of visibility for
simutaneous imaging is much narrower (i.e. it's not possible to image
Venus + stars from the UK and the US at the same time).

A very rough and ready calculation (I'd be pleased if someone could
double check this for me) gives a parallax shift of 1 arcmin per
500km.

Anyone want to give this a go? I'm happy to act as a clearing house
for the images.

All that would be needed would be an image that shows Venus and at
least two (preferably more) stars in the field. Exposure should aim
to show Venus as a planetary disk + the stars. This may not be easy
to do but there's time to practice. A bright over exposed Venus + two
or more stars is better than nothing. Don't try for loads of stars
and a grossly overexposed Venus - this will generate the most
uncertainty in the final results.

What time to take the images? Let's say 20:00UT and every 10 minutes
thereafter until 20:30UT. Exposure dates considered will be the 1st,
2nd, 3rd and 4th April 2004.

The key time will 20h30mUT, the others are just backups.

As big an image scale as possible would help - i.e. it's not necessary
to try and get all of the Pleiades into the frame - just the area
around Venus will do. We're not after a beauty shot here - just a
measurement.

Nothing too serious at this stage but it could be another nice project
if there are enough contributors.

If you intend to have a go - please let me know.

Best results will be if we can get images from the maximum length of
the country.
--
Pete Lawrence
http://www.pbl33.co.uk
Astronomy & digital astroimaging

Hi Pete

I was impressed by the lunar parallax project that you carried out and I'm
keen to get involved in this project.

No doubt the weather will play it's part in thwarting my efforts. Do you
think a digital camera hand held at the eyepiece will give good enough
results?

Regards

Alistair Thomson


"Pete Lawrence" wrote in message
...
Beat the transit!

Just a thought but with the Venus/Pleiades conjunction that peaks on
the 3rd April, it should be possible to display a small, but
measurable parallax effect using UK or European observers. Unlike the
lunar parallax demonstration project, the zone of visibility for
simutaneous imaging is much narrower (i.e. it's not possible to image
Venus + stars from the UK and the US at the same time).

A very rough and ready calculation (I'd be pleased if someone could
double check this for me) gives a parallax shift of 1 arcmin per
500km.

Anyone want to give this a go? I'm happy to act as a clearing house
for the images.

All that would be needed would be an image that shows Venus and at
least two (preferably more) stars in the field. Exposure should aim
to show Venus as a planetary disk + the stars. This may not be easy
to do but there's time to practice. A bright over exposed Venus + two
or more stars is better than nothing. Don't try for loads of stars
and a grossly overexposed Venus - this will generate the most
uncertainty in the final results.

What time to take the images? Let's say 20:00UT and every 10 minutes
thereafter until 20:30UT. Exposure dates considered will be the 1st,
2nd, 3rd and 4th April 2004.

The key time will 20h30mUT, the others are just backups.

As big an image scale as possible would help - i.e. it's not necessary
to try and get all of the Pleiades into the frame - just the area
around Venus will do. We're not after a beauty shot here - just a
measurement.

Nothing too serious at this stage but it could be another nice project
if there are enough contributors.

If you intend to have a go - please let me know.

Best results will be if we can get images from the maximum length of
the country.
--
Pete Lawrence
http://www.pbl33.co.uk
Astronomy & digital astroimaging

On Thu, 1 Apr 2004 16:22:34 +0100, "Alistair Thomson"
wrote:

Hi Pete

I was impressed by the lunar parallax project that you carried out and I'm
keen to get involved in this project.

No doubt the weather will play it's part in thwarting my efforts. Do you
think a digital camera hand held at the eyepiece will give good enough
results?

Hi Alistair of the 150mm reflector. You know you'll never be able to
upgrade the size of your scope ;-). Your site is a greatly underated
resource IMHO.

Weather isn't actually going to be that much of a problem Alistair.
This project could be done at any time that Venus is visible in a dark
sky with stars in the field. The Pleiades offer a convenient 'focus'
point to get people to have a go though.

As I said in my last post, the picture doesn't need to be a beauty
shot. A shortish exposure would be ideal so long as it can capture
Venus and at least two identifiable stars.

I suggested the 1st to the 4th as project dates. Saturday is the best
day to get this done as Venus is going to have a lot of reasonable
stars in the field. If it's clear tonight or tomorrow night and you
want to have a go then let's use these dates as a test run. I will
post a link to an example photo (if I can get one!) with my camera's
settings for guidance.

I would not think that handholding a camera at the eyepiece would be a
problem so long as you can get it to register point stars. May be a
good time to bodge up a temporary coupling.

Timing is critical here though so it's best to get your
watches/PCs/whatever synchronised to a very accurate source just
before your imaging session. That goes for setting your camera time
too. Very convenient to have the accurate time recorded in the EXIF
header of any images you take.

Even if you can't get the images, it'll be a good exercise to have a
go at.
--
Pete Lawrence
http://www.pbl33.co.uk
Astronomy & digital astroimaging

"Pete Lawrence" wrote in message
...
Beat the transit!

Just a thought but with the Venus/Pleiades conjunction that peaks on
the 3rd April, it should be possible to display a small, but
measurable parallax effect using UK or European observers. Unlike the
lunar parallax demonstration project, the zone of visibility for
simutaneous imaging is much narrower (i.e. it's not possible to image
Venus + stars from the UK and the US at the same time).

A very rough and ready calculation (I'd be pleased if someone could
double check this for me) gives a parallax shift of 1 arcmin per
500km.

Anyone want to give this a go? I'm happy to act as a clearing house
for the images.



Count me in skies permitting.

I am thinking of trying with a Toucam and a 270mm SLR lens. The 1deg
diagonal FOV should take in the planet and a couple of the brighter stars. I
will stop down to f8 and use an IR filter to keep the stars tight.
Resolution will be 4 arcsec/pixel or about 3 pixels per 100km. Do you think
this will do the job Pete?

Robin

Will have a go Pete, but can you fill us in a bit on the science we
are trying to achieve here.

I'mm off to synch my camera with the atomic clock

(get atomic clock sync for your PC from here
http://www.worldtimeserver.com/)

On Thu, 01 Apr 2004 20:01:50 +0100, Dr DNA wrote:

Will have a go Pete, but can you fill us in a bit on the science we
are trying to achieve here.

I'mm off to synch my camera with the atomic clock

(get atomic clock sync for your PC from here
http://www.worldtimeserver.com/)

For the basics of what it's all about, visit my website and click on
the Lunar Parallax Demonstration Project panel.

This particular observation will serve as a starter trial run to allow
us to a) see Venusian parallax and b) allow us to determine the
distance to Venus.

If it works out then we'll have the novelty of having done it and the
basis of the next stage. If we can determine what the problems are
and resolve them it would be great to try and set up a regular
parallax observation for the next 6 weeks or so. If we can determine
a distance each time we can graph these and show the distance between
the Earth and Venus running up to the transit.

Ultimately I hope it's a nice thing to do collectively.
--
Pete Lawrence
http://www.pbl33.co.uk
Astronomy and digital imaging website (last update 28-03-04)

how close to the plaieaeieiaides is venus going to be? will i be able to see
both at the same time through binoculars?

On Thu, 1 Apr 2004 19:41:28 +0100, "Robin Leadbeater"
wrote:

Count me in skies permitting.

Brilliant - thanks Robin.

I am thinking of trying with a Toucam and a 270mm SLR lens. The 1deg
diagonal FOV should take in the planet and a couple of the brighter stars. I
will stop down to f8 and use an IR filter to keep the stars tight.
Resolution will be 4 arcsec/pixel or about 3 pixels per 100km. Do you think
this will do the job Pete?

I know that a certain Gentleman in Glasgow is keen to grab some images
too. If we can get some parallax pairs of 500 - 1000km+ then I think
we're in with a shout.

The Pleaides are great as a starting point with the possible exception
that all of those stars may encourage people to image with an air to
capture as many stars as possible. This obviously isn't desired.
What we want is a couple+ of, as you say, tight stars + Venus at the
desired times. Following this, perhaps a longer exposure capturing a
number of stars may make it easier to define which tight stars were
captured would be helpful.

It's raining down here in Selsey tonight which is a nuisance as I
can't put any examples together.

From what you describe, I think you're spot on Robin.
--
Pete Lawrence
http://www.pbl33.co.uk
Astronomy and digital imaging website (last update 28-03-04)

On Thu, 1 Apr 2004 21:03:20 +0100, "jeffcapeshop"
wrote:

how close to the plaieaeieiaides is venus going to be? will i be able to see
both at the same time through binoculars?

Shouldn't be a problem, cloud permitting. Venus is more or less
within the cluster's boundary on the 2nd and 3rd. Should look nice.
--
Pete Lawrence
http://www.pbl33.co.uk
Astronomy and digital imaging website (last update 28-03-04)

JRS: In article , seen in
news:uk.sci.astronomy, Pete Lawrence
posted at Thu, 1 Apr 2004 13:07:22 :

Just a thought but with the Venus/Pleiades conjunction that peaks on
the 3rd April, it should be possible to display a small, but
measurable parallax effect using UK or European observers. Unlike the
lunar parallax demonstration project, the zone of visibility for
simutaneous imaging is much narrower (i.e. it's not possible to image
Venus + stars from the UK and the US at the same time).

A very rough and ready calculation (I'd be pleased if someone could
double check this for me) gives a parallax shift of 1 arcmin per
500km.

Well, I get 40000 km, so more checks would be useful.

Venus is near quadrature, but now coming closer; say 150E6 km away.

One arcmin = 1/60 arcdeg = 1/3600 radians, pi being near enough 3.

150E6 * 1/3600 ~= 150E3 / 3.75 = 40E3 km

That would agree with you, more or less, if you had meant to write
arcsec.

--
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