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Posted by: djellison Feb 28 2006, 10:12 AM

The joy of data

edited:

Right - done all the ACS one's I can find.....

Jan '03 : 297 Million km
http://www.unmannedspaceflight.com/doug_images/mars_hst/j8fv01gcq_drz.jpg

March '03 : 218 Million km
http://www.unmannedspaceflight.com/doug_images/mars_hst/j8fv03ahq_drz.jpg

May '03 : 128 Million km
http://www.unmannedspaceflight.com/doug_images/mars_hst/j8fv05l8q_drz.jpg

June '03 : 86 Million km
http://www.unmannedspaceflight.com/doug_images/mars_hst/j8fv07unq_drz.jpg

Aug '03: 60 Million km
http://www.unmannedspaceflight.com/doug_images/mars_hst/j8n410lmq_drz.jpg

Sept '03 : 57 Million km
http://www.unmannedspaceflight.com/doug_images/mars_hst/j8p722jfq_drz.jpg

Sept '03 : 58 Million km
http://www.unmannedspaceflight.com/doug_images/mars_hst/j8p723tdq_drz.jpg

Feb '04 : 228 Million km
http://www.unmannedspaceflight.com/doug_images/mars_hst/j8n470otq_drz.jpg

The little 'tick' mark is still there, even though I'm using geometric and flat/noise/dark field correction - I think this is why the outside of Hubble press images of mars appear pixelated, they're re-projected to take out the 'tick' on the CCD. Still looking into exactly what it is.

Doug

Posted by: Bob Shaw Feb 28 2006, 01:16 PM

Doug:

Possibly the nicest view of the remnant polar cap I've seen!

More! More! More!

(please)

Bob Shaw

Posted by: dilo Feb 28 2006, 10:01 PM

Posted by: djellison Feb 28 2006, 10:25 PM

All done - see top post. I'm going to have a hack at WFPC2 ones as well at some point.

Doug

Posted by: Bob Shaw Feb 28 2006, 10:34 PM

Doug:

Lovely images! The 'tick' looks like a physical object somewhere in the optics - it protrudes the same amount into all the images. I bet it's there in the images with a largely black sky and just a small planet.

Bob Shaw

Posted by: djellison Feb 28 2006, 10:36 PM

Oh yes - it's in every image from the high res channel - enough stretching shows them in the data for every image thru every filter, it's something to do with the camera, I just don't know what/why. Nothing I can do to 'combat' it though - just morbid curiosty as to what it is

Doug

(PS - ahh - it appears the HRC is giving me the finger...
http://www.stsci.edu/hst/acs/faqs/finger.html )

Posted by: djellison Mar 1 2006, 10:40 AM

I've searched for WFPC2 observations using similar filter (410, 502, 673 if memory serves me right - blueish, greenish, near IR ish)

I've requested some 208 images from the server - almost 70 individual rgb sets of observations.

That'll be nice.

(should never have got started on this )

Doug

Posted by: djellison Mar 2 2006, 12:02 PM

This is the first WFPC2 image I've done, they're 800^2 not 1024^2 - so a little smaller, but in terms of image quality, they're just as good - and there's a LOT of them - as you can see this one is from 1994

Doug

Posted by: Bob Shaw Mar 2 2006, 06:59 PM

Doug:

Found any Moon images?

Bob Shaw

Posted by: djellison Mar 2 2006, 07:21 PM

I've looked - but searching under 'moon' doesnt work. Searching for 'mars' does (for mars images) - ditto 'luna' or 'lunar' - nothing.. Not sure what other values to try using to be honest.

Have a look for yourself if you like - http://archive.eso.org


Doug

Posted by: Bob Shaw Mar 2 2006, 08:32 PM

I think the PI for the Moon shots was J Garvin, if that helps - I'll have a look on Friday.

Bob shaw

Posted by: helvick Mar 2 2006, 08:46 PM

Yep
http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/29/ from last year
And there is a also http://hubblesite.org/newscenter/newsdesk/archive/releases/1999/14/ in 1999

Posted by: Bob Shaw Mar 2 2006, 08:51 PM

Doug:

And these comments at http://www.spacetelescope.org/images/html/opo0534m.html

Doug:

'Hubble's High Resolution Camera - "Mind the Gap"

The Advanced Camera for Surveys on Hubble Space Telescope includes two cameras, the Wide Field Channel (WFC) and the High Resolution Channel (HRC). Images from the WFC are roughly 4,000 pixels square with a scale of roughly 0.05 arcseconds per pixel. Images from the HRC are smaller in pixel size, 1,000 pixels square, but have a finer resolution, 0.025 arcseconds per pixel. The HRC is preferred for images of planets, or objects appearing smaller on the sky, where higher resolution outweighs larger field of view. The HRC also has two occulting masks that can block starlight from bright sources, and allow fainter objects nearby that are otherwise lost in the glare of the brighter object to be visible. One of the masks can be removed, but the other mask, seen in this Mars image at the lower left corner, can not be moved out of the light path. This "occulting finger" blocked a small portion of the light from Mars. The small amount of missing data in the final color composite of Mars was corrected by filling with nearby sections of the image of similar color and texture. This is a method commonly used in digital photography to remove blemishes, but is not used with data published in scientific papers.'

So they just cloned in some colour and detail for the press images!

Bob Shaw

Posted by: djellison Mar 2 2006, 09:48 PM

That stuff from Garvin wont be release for raw-pleasure until later this year ( it's usually 12 months )

However - I think I've found the Storrs stuff - it's listed as 'copernicus' with the PI Caldwell (as I believe these obs were a ride-along type observation)

Having a look at them now

Doug

Posted by: djellison Mar 2 2006, 10:18 PM

7 frames in all -

(Some were duplicate frames, multiple filters on the same spot)

Interesting little mosaic - nice bit of fun - here's the official job ( notice the properly calibrated imagery doesnt have the between-ccd-'cracks' http://hubblesite.org/newscenter/newsdesk/archive/releases/1999/14/image/b+warn

Doug

Posted by: djellison Mar 3 2006, 01:24 PM

68 Colour observations of Mars that I've been able to make into reasonable images - the job of putting these into order, adding the ACS images into the chronological sequence and annotating them is 1) long and 2) saved for later...however

http://www.unmannedspaceflight.com/doug_images/mars_hst/mars_wfpc2_contact/

12 contact sheets ( 6 to a page ) outlining all of them at a browser-worthy res.

Doug

Posted by: tedstryk Mar 3 2006, 09:14 PM

Doug, I was wondering your thoughts about that pervasive green. In my earlier WPFC1 work, I did everything I could to get rid of it, which nearly wiped out the color varations in the images. It seems like it shouldn't be there, but keeps poping up.

Posted by: djellison Mar 3 2006, 09:48 PM

I figure it's because of using filter sets that are not particularly faithful to 'rgb' - it's more like the MER equiv of using L257 (and infact, that can come out a little green as well). Also - I'm not 100% confident when using the FITS Liberator - which high and low end value to use. I tried to use identical values for all of them but it varied a lot - and arguably the exposure is in the mix there somewhere.

Doug

Posted by: tedstryk Mar 4 2006, 12:15 AM

So far, this is the best luck I have had. It is from Jan 2, 1991 with WFPC 1.



And the improved version...

Posted by: dvandorn Mar 5 2006, 04:10 AM

Hmmm... I've seen Mars directly, with my own eye, through a 3-inch reflector and a 10-inch reflector. In both cases, the dark markings I could make out really looked distinctly greenish. No filters involved, and I don't think the mirrors in question failed to reflect any given wavelengths, or emphasized any others.

Is it possible that there *is* a certain greenish tinge to the dark-colored regions of Mars?

-the other Doug

Posted by: David Mar 5 2006, 04:49 AM

I think that the greenish tint has been reported since the 19th century. I've often seen it put down to a trick of the eye, looking for a contrast with the reddish tint of the rest of Mars; but it certainly looks real enough on those Hubble images.

The greenishness was one of the things that convinced some early astronomers that there must be life on Mars -- they were interpreting the patches as vegetation! Seasonal changes (due to wind transport and deposition) were interpreted as seasonal growth and retreat of whatever it was (lichens?) that was thought to form the green bits.

And of course earlier they were thought to be seas, and still have Mare... names in albedo maps. The idea that they were seas was dropped when Lowell thought he saw canals running through them -- an example of the right conclusion being drawn for the wrong reasons. This was then transformed into the concept that Mars had had seas, but then lost them -- a concept that we are still struggling with today, though hopefully on a sounder basis. Once an idea takes hold and captures the imagination, it can be very difficult to eradicate!

Posted by: djellison Mar 5 2006, 08:15 AM

You're assuming that the Hubble images are right, given my processing so far, I'd wager they're more wrong that right.

Doug

Posted by: David Mar 5 2006, 02:35 PM

I've got all kinds of assumptions, but with regard to the large-scale dark patches on Mars my assumption is that the "real" color is something like what we saw at El Dorado. I simply meant that in the Hubble images you processed the color looks to be really greenish, and not just an optical effect; but I assume that's an artifact of how the images are put together. So I can't take your wager, as I'd be betting against myself.

Posted by: djellison Mar 5 2006, 05:05 PM

But think of the odd's you could give yourself

Doug