HST and Mars

Considering the image received from the HST, I hazard to guess its some
1000-2000 X's magnification.
Is that the limit?..why can't they put the peddle to the metal and get some
moon-like closeups of the polar caps or something??

http://cherokee.stsci.edu/newscenter/2003/22/

Considering the image received from the HST, I hazard to guess its some
1000-2000 X's magnification.
Is that the limit?..why can't they put the peddle to the metal and get
some
moon-like closeups of the polar caps or something??

Because the HST has no magnification in the usual sense. It has a camera
(well,
several really) at the focus of its optical system, and its resolution is
determined by the focal length of the telescope and the pixel size of the
sensor. That's it. The planetary camera is a bit undersampled, meaning
that it
would be capable somewhat more resolution, although they can get most of
that
back by drizzle processing. The situation is similar for Earth based
imagers-
there is no magnification defined for images. We can change our pixel
scale by
modifying the focal length of the telescope (adding a barlow, or eyepiece
projection.) But there is no point in doing that beyond the theoretical
resolution of the telescope, and the same is true of the HST.

Also, I don't think they are real serious about using the HST for imaging
Mars.
Why should they be with a probe orbiting Mars taking much higher
resolution
images of the surface than the HST is remotely capable of from orbit
around the
Earth?

Thanks for the insight...essentially what your describing is prime focus
imaging for the HST..the fact
remains however that there is a magnification and that image to me is like
being in orbit maybe 57,000 kms from Mars (1000 X's mag)..just guessing

Considering the image received from the HST, I hazard to guess its some
1000-2000 X's magnification.
Is that the limit?..why can't they put the peddle to the metal and get
some
moon-like closeups of the polar caps or something??

Because the HST has no magnification in the usual sense. It has a camera
(well,
several really) at the focus of its optical system, and its resolution is
determined by the focal length of the telescope and the pixel size of the
sensor. That's it. The planetary camera is a bit undersampled, meaning
that it
would be capable somewhat more resolution, although they can get most of
that
back by drizzle processing. The situation is similar for Earth based
imagers-
there is no magnification defined for images. We can change our pixel
scale by
modifying the focal length of the telescope (adding a barlow, or eyepiece
projection.) But there is no point in doing that beyond the theoretical
resolution of the telescope, and the same is true of the HST.

Also, I don't think they are real serious about using the HST for imaging
Mars.
Why should they be with a probe orbiting Mars taking much higher
resolution
images of the surface than the HST is remotely capable of from orbit
around the
Earth?

Thanks for the insight...essentially what your describing is prime focus
imaging for the HST..the fact
remains however that there is a magnification and that image to me is like
being in orbit maybe 57,000 kms from Mars (1000 X's mag)..just guessing

On Thu, 28 Aug 2003 11:46:23 GMT, "Mick" wrote:

Thanks for the insight...essentially what your describing is prime focus
imaging for the HST..the fact
remains however that there is a magnification and that image to me is like
being in orbit maybe 57,000 kms from Mars (1000 X's mag)..just guessing

The reason "magnification" isn't generally used for imaging is because you know
nothing about the final viewing conditions. If you look at the image in a little
window on a small monitor and I blow it up to full screen on a big one, we are
seeing it at completely different "magnifications". So images are normally
defined in terms of resolution, with a statement of the smallest visible detail
size (e.g. the smallest features visible in this image are approximately 2 km
across.)

Put your nose up against the screen and it will look like you are re-entering
Mars in your spacesuit! g

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On Thu, 28 Aug 2003 11:46:23 GMT, "Mick" wrote:

Thanks for the insight...essentially what your describing is prime focus
imaging for the HST..the fact
remains however that there is a magnification and that image to me is like
being in orbit maybe 57,000 kms from Mars (1000 X's mag)..just guessing

The reason "magnification" isn't generally used for imaging is because you know
nothing about the final viewing conditions. If you look at the image in a little
window on a small monitor and I blow it up to full screen on a big one, we are
seeing it at completely different "magnifications". So images are normally
defined in terms of resolution, with a statement of the smallest visible detail
size (e.g. the smallest features visible in this image are approximately 2 km
across.)

Put your nose up against the screen and it will look like you are re-entering
Mars in your spacesuit! g

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

HST can take a image of Mars as a whole, no small thing...
Orion

"Chris L Peterson" wrote in message
...
On Thu, 28 Aug 2003 04:12:26 GMT, "Mick" wrote:

Considering the image received from the HST, I hazard to guess its some
1000-2000 X's magnification.
Is that the limit?..why can't they put the peddle to the metal and get
some
moon-like closeups of the polar caps or something??

Because the HST has no magnification in the usual sense. It has a camera
(well,
several really) at the focus of its optical system, and its resolution is
determined by the focal length of the telescope and the pixel size of the
sensor. That's it. The planetary camera is a bit undersampled, meaning
that it
would be capable somewhat more resolution, although they can get most of
that
back by drizzle processing. The situation is similar for Earth based
imagers-
there is no magnification defined for images. We can change our pixel
scale by
modifying the focal length of the telescope (adding a barlow, or eyepiece
projection.) But there is no point in doing that beyond the theoretical
resolution of the telescope, and the same is true of the HST.

Also, I don't think they are real serious about using the HST for imaging
Mars.
Why should they be with a probe orbiting Mars taking much higher
resolution
images of the surface than the HST is remotely capable of from orbit
around the
Earth?

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


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HST can take a image of Mars as a whole, no small thing...
Orion

"Chris L Peterson" wrote in message
...
On Thu, 28 Aug 2003 04:12:26 GMT, "Mick" wrote:

Considering the image received from the HST, I hazard to guess its some
1000-2000 X's magnification.
Is that the limit?..why can't they put the peddle to the metal and get
some
moon-like closeups of the polar caps or something??

Because the HST has no magnification in the usual sense. It has a camera
(well,
several really) at the focus of its optical system, and its resolution is
determined by the focal length of the telescope and the pixel size of the
sensor. That's it. The planetary camera is a bit undersampled, meaning
that it
would be capable somewhat more resolution, although they can get most of
that
back by drizzle processing. The situation is similar for Earth based
imagers-
there is no magnification defined for images. We can change our pixel
scale by
modifying the focal length of the telescope (adding a barlow, or eyepiece
projection.) But there is no point in doing that beyond the theoretical
resolution of the telescope, and the same is true of the HST.

Also, I don't think they are real serious about using the HST for imaging
Mars.
Why should they be with a probe orbiting Mars taking much higher
resolution
images of the surface than the HST is remotely capable of from orbit
around the
Earth?

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.512 / Virus Database: 309 - Release Date: 8/19/2003

"Mick" wrote in message news:jYl3b.76931$K44.30672@edtnps84...

Considering the image received from the HST, I hazard to guess its some
1000-2000 X's magnification.
Is that the limit?..why can't they put the peddle to the metal and get
some
moon-like closeups of the polar caps or something??

Because the HST has no magnification in the usual sense. It has a camera
(well,
several really) at the focus of its optical system, and its resolution is
determined by the focal length of the telescope and the pixel size of the
sensor. That's it. The planetary camera is a bit undersampled, meaning
that it
would be capable somewhat more resolution, although they can get most of
that
back by drizzle processing. The situation is similar for Earth based
imagers-
there is no magnification defined for images. We can change our pixel
scale by
modifying the focal length of the telescope (adding a barlow, or eyepiece
projection.) But there is no point in doing that beyond the theoretical
resolution of the telescope, and the same is true of the HST.

Also, I don't think they are real serious about using the HST for imaging
Mars.
Why should they be with a probe orbiting Mars taking much higher
resolution
images of the surface than the HST is remotely capable of from orbit
around the
Earth?

Thanks for the insight...essentially what your describing is prime focus
imaging for the HST..the fact
remains however that there is a magnification and that image to me is like
being in orbit maybe 57,000 kms from Mars (1000 X's mag)..just guessing

You're wrong. There is no magnification implied or otherwise in a
picture, just the scale of the picture, in this case about 7 km/px if
I'm not mistaken.

Andrea T.

My Astronomy Pages at:
http://www.geocities.com/andreatax/index.htm

"Mick" wrote in message news:jYl3b.76931$K44.30672@edtnps84...

Considering the image received from the HST, I hazard to guess its some
1000-2000 X's magnification.
Is that the limit?..why can't they put the peddle to the metal and get
some
moon-like closeups of the polar caps or something??

Because the HST has no magnification in the usual sense. It has a camera
(well,
several really) at the focus of its optical system, and its resolution is
determined by the focal length of the telescope and the pixel size of the
sensor. That's it. The planetary camera is a bit undersampled, meaning
that it
would be capable somewhat more resolution, although they can get most of
that
back by drizzle processing. The situation is similar for Earth based
imagers-
there is no magnification defined for images. We can change our pixel
scale by
modifying the focal length of the telescope (adding a barlow, or eyepiece
projection.) But there is no point in doing that beyond the theoretical
resolution of the telescope, and the same is true of the HST.

Also, I don't think they are real serious about using the HST for imaging
Mars.
Why should they be with a probe orbiting Mars taking much higher
resolution
images of the surface than the HST is remotely capable of from orbit
around the
Earth?

Thanks for the insight...essentially what your describing is prime focus
imaging for the HST..the fact
remains however that there is a magnification and that image to me is like
being in orbit maybe 57,000 kms from Mars (1000 X's mag)..just guessing

You're wrong. There is no magnification implied or otherwise in a
picture, just the scale of the picture, in this case about 7 km/px if
I'm not mistaken.

Andrea T.

My Astronomy Pages at:
http://www.geocities.com/andreatax/index.htm

You're wrong. There is no magnification implied or otherwise in a
picture, just the scale of the picture, in this case about 7 km/px if
I'm not mistaken.

Andrea T.



C. Peterson answered my question thanks..and far better too!