Mars March 5th 2010

[Quark]

Hi All,

Had some reasonable seeing until the cloud associated with the next front moved in at 10:30 CSST. Bit of shame really as I had intended to image Saturn through to the next morning.

These images were a bit of an experiment and are IR (G) B sort of.
I have previously created a synthetic G channel from R & B but on this occasion I used IR & B. Reasonably pleased with the result especially the level of detail.
For this set of images I utilized Birds most excellent ninox program and I feel that it contributed to a better result as Registax does a better job on the cropped, centred and graded data.

Thanks for looking
Regards
Trevor

[duncan]

Lovely set of images Trevor. Plenty of detail.

Cheers,
Duncan:thumbsup:

[Clayton]

Very nice result all round Trevor

[Troy]

Good pictures with nice colour :)

[Kevnool]

Awesome mages again Trev tonight im in Bathurst and just seen the fireworks from my motel of the royal bathurst show.
one day i hope to get home to do some observing
Cheers Kev.

[h0ughy]

great work trevor

[Lester]

Wonderful images Trevor. From memory, I would say these show more contrast in the detail than your other images.

Whatever you are doing, it is good IMO.

[Quark]

Thanks Duncan, looking forward to the next favorable opposition of Mars in 2014.



Thanks Clayton, this was a bit of an experiment but then, I suppose thats the name of the game, so far as trying different approaches to imaging to see what works and what doesn't.



Thanks Clayton, the colour in these images is exactly what was produced by this particular process with no adjustment of the colour balance whatsoever after merging.



Thanks Kev, yep we must organize an observing night when you get back, Ray has made a Dob base for his scope so that he can go observing with us.



Thanks Houghy.



Thanks Lester, I think using Birds ninox program helps a lot and I did use it a lot last year with Jupiter. Only downside is the time involved in running the avi's through virtual dub, then ninox prior to Registax, Astra Image Pro and CS4.

As this capture session was cut short by cloud I only had 4 data sets of IR & B to process and that still took up most of the next day. Normally the seeing out here is pretty stable and I image over very long sessions capturing maybe 20 or 30 avi's over 4 or 5 hours, which would take me several days to process if I put them all through virtual dub and ninox.

I think, given very good seeing, I would persist with the longer processing regime that provides that extra 5 or maybe 10 % improvement, it really depends on what sort of detail I am trying to eek out of the data.

[bird]

Nice work trevor! I was away for a few days and just saw this thread... great images.

cheers, Bird

[Quark]

Thanks very much Bird,

It looks like a series of high pressure systems will be coming across from the west over the next week, so with a little cooperation from the jetstream, we all might be in for some descent seeing for a while.

Regards
Trevor

[Paul Haese]

Been a bit clouded out here, but this is nice to see your images.

[Screwdriverone]

Man, there is a lot of detail there Trevor,

Very nice indeed.

Well done.

Cheers

Chris.

[Quark]

Thanks Paul, can relate to the issues with the cloud, rain etc of late, but there seems to be some nice high pressure systems on the way, so maybe we will all get some good nights over this next week or so.



Thanks Chris, hopping for some more opportunities before Mars shrinks to much.

[malp]

These are beautifully resolved images, tremendous colour.

[coco1]

At the risk of sounding like a fool, my question is, why does mars not look round. It seems to have a flat side. I thought it was just my shots that looked not perfectly round.
Thanks Steve....

[Quark]

Thanks Malcolm for your most generous remarks.



Hi Steve, hey I am an ex mine worker that managed to do a Grad Cert Sc in Astronomy and I asked heaps of silly questions. I say to you what my unit instructors said to me, "There is no such thing as a silly question".

Steve, the further each planet is from the Sun the slower is its orbital velocity. Earth is orbiting faster than Mars. Before Christmas we were catching up to Mars and at opposition Mars was physically opposite the Earth, relative to the Sun. At that time, from our perspective the Sun fully illuminated the disk of Mars and it looked round. We are now moving away from Mars so we see one limb of Mars sharply illuminated but part of the opposite limb is now in shadow, so it now appears as more of an ellipsoid shape, this was also the case prior to opposition when we were catching up with it. Mars, tonight is exhibiting a phase of 94.88% and it is the part that is now in shadow that creates the effect that you see in current images of Mars. If you go back through this forum and look at images from late in January you will see the full disk of Mars illuminated and it will look round.

Hope this helps.

[michaellxv]

Firstly, love the images.

On the question of shape, I thought that the outer planets did not show any phase (to us) and that we would always see them fully illuminated.

Is this different for Mars due to its relatively close proximity? Or am I missing something?

How far do we see this phase go before we loose Mars to daylight?

[Quark]

Hi Michaell,

It is true that only the "inferior" planets, that is the planets inside the orbit of the Earth exhibit relatively extreme phases such as we see with the Moon.

Consider the case with the Moon, in particular, consider the geometry of the Sun , Earth, Moon at full Moon and a couple of days either side of Full Moon.

At full Moon the Moon is indeed at a greater radii from the Sun than is the Earth, it is opposite the Earth relative to the Sun and we see it to be round with the full disk illuminated. However, a couple of days either side of full, while it is still at a greater radii from the Sun than is the Earth, we no longer see the full disk illuminated, we see a phase of the full disk.

When the planets are imaged at very high magnification, even slight variations in the shape of the apparent disk are noticeable, as you have noted, Mars is relatively close to us and so the changes in the Sun, Earth, Mars angles are enough to reveal this slight change in phase.

With accurate enough equipment this effect would likely be possible to measure with the other planets, but it would be very small. If you have access to "The Sky" or "Starry Night" and bring up one of the planets and view the data on it for any specific date, it will provide the phase, if you then advance the date by a couple of months you will see from the data for that planet that the phase has changed.

Regards
Trevor

[michaellxv]

Thanks Trevor, makes sense now.