800Whrs+ Staying Up Late ideas Options

[djellison]

MER CCD response is in this paper
http://pancam.astro.cornell.edu/pancam_ins..._Pancam_JGR.pdf - Pg 13.

[Stu]

Playing about with STARRY NIGHT again just now I found that the magnitude of Earth on March 8th, 2004, when the famous "Pale Dot in the sky" image was taken ( http://solarsystem.nasa.gov/multimedia/gal...rs_to_Earth.jpg ) was -2.37. Earth's magnitude at the moment is -2.2, so hopefully Earth should be bright enough to be recorded on an image now, too..? I know it won't be a priority, but I'd love to see it!

[fredk]

Stu, can you find out what our elongation from the Sun was then? Looking at the current solar system layout, we're not too far from greatest elongation right now, which is a nice coincidence.

The other factor is dust. I don't know if we can find out what the tau was at that time, but I'm sure dust would have a big impact on visibility.

[Stu]

Then...



... and now...

[fredk]

Thanks Stu. I get around 29 or 30 degrees elongation now versus 35 or so then.

But it's getting steadily better. Fiddling around with the solar system simulator, I very roughly estimate that greatest elongation will be in September, at something like 38 degrees.

[Deimos]

Dust opacity was actually higher then, but Earth was 8.5 deg higher in the sky for the same solar depression angle. Roughly, I get a 35% fainter Earth and actually an even fainter sky. So, more than "iffy", even thought the filters won't be as sensitive as for that image. In any case, some images are on the agenda. They are not optimized specifically for planet hunting, but they are aimed so that's a bonus (and you'll see little Earth trails...). Aside: an RGB set could be quite fun in a couple weeks when E & V are at their closest, but it will still be close to Earth's current altitude.

[Stu]

Oh, just click away, you'll get something. It's not as if you're wasting film!

Seriously tho, Deimos, I really appreciate the comments on this. I know that if you manage to capture it, Earth will just be a spot of light but... well... come on, EARTH, shining in the sky on Mars... it doesn't get a lot cooler than that.

And the Outreach value of such images, even less than perfect ones, simply cannot be over-stated. I gave a talk to a Womens' Institute last week, deep in the South Cumbrian outback, and part of my "Tour of the Universe" is a zoom-out from Earth to see how it shrinks and changes in apearance, using views from orbit, the Moon and of course Mars. The images of Earth taken by Kaguya always go down well, but they're familiar in that they look like better quality versions of well-known Apollo images. The Cassini image of Earth shining through a gap in the rings goes down well too, but takes quite a lot of explaining. Ah, but that image of Earth shining in Mars's sky... everyone at the talk had seen Venus shining after sunset as an Evening Star, so they found it easy to grasp the concept that Mars' evening star is often Earth... During the Mars section of my talk I always show an artist's impression of what Earth would look like in the sky from Mars, as a teaser, so when the real pic comes up on the screen later the response is always, always, "Wow... look at that... that's beautiful..."

So go for it. Anything you get will be great!

[marswiggle]

I don't have any parameters at hand, but I suppose also a rising (tiny) crescent Phobos could be caught in the west some time after sunset?

[Pertinax]

So much of the low and even middle hanging fruit has been picked, and my tired brain has not conspired with me to conceive of any higher fruit -- yet -- that I will plug my favorite out of the ideas Astro0 borrowed from my brain....

- Long shadow view back towards Husband Hill in multi-filters.
Just to make up for the version UMSF worked on in what seems like years ago (hey it was!)

Would a 5x1 or even a 5x2 pancam 3,5,7 or 4,5,6 or such panorama be feasible between Tsiolkovsky and Husband Hill at a low sun angle (~~15 Deg or less)? My concern would be that too much time would elapse between filter sets making near shadows fringed with little rainbows. If feasible, my deeper dream would be a series at say 5 degree solar elevation angles (say 20, 15, 10, and 5) -- only 120 pancam frames!


-- Pertinax

[akuo]

No, the mast precision is large compared to the typical star-trails.

That's interesting. I would have thought the motors are "ultra-precise", but I guess pointing accuracy was also a problem with Phoenix. What sort of accuracy do you have with pancam pointing after a slew, arc-minutes, degrees? How much marginal do you leave in Pancam images to count for pointing errors? Thanks.

[Deimos]

The MER PMA points much more precisely and accurately than the Phoenix SSI. Accuracy is a good thing, but precision is not really needed--for navigation, you are just trying to get the right 14-45 deg field of view. I forget the exact numbers for the PMA (*) but I think it's in the few arc-minute range (driven by MTES 8 mrad stares, as far as I know).

(*) for PHX/SSI, pointing was generally in motor steps, leading to intimate knowledge of the step-angle relation. For MER, pointing is typically in radians with conversions done on board.

[climber]

From Scott Twitter: Amazingly, we're planning *overnight* observations on Spirit. We've got *that* kind of energy. Stay tuned for PANCAMs of the night sky

[Stu]

Yep, time for another Gusev AS star party...!

[Deimos]

Yes, we've gotten some nice twilight imaging (not spectacular, but model-constraining). We have planned an observation that I dug out of email (original subject: "Spirit sol 706A or 707A night-time opacity") from when our previous glory nights came to an end, as well as some other star imaging for night opacity. And of course there are a few goodies in the pipeline... The twilight images are only down in thumbnail form, and unfortunately had to be downsampled; but you still might recognize a couple of the pixels.

[Stu]

Yes, we've gotten some nice twilight imaging... you still might recognize a couple of the pixels.

You big tease! If those pixels aren't Earth and Venus after you've said that I'm going to be seriously frakked off!

Looking forward to the big pix!