MSL - Astronomical Observations, Phobos/Deimos, planetary/celestial observations and more Options

[Gerald]

Four combined and enhanced Sol 441 ChemCam RMI nightshots, derived from the enhanced PNGs:

Still contain vertically displaced ghost image.

Edit: By Joe's site, and Uranometria 2000.0 Deep Sky Atlas I could identify the bright object as Vega.

[Phil Stooke]

I'm waiting for RMI images of Phobos and Deimos. I was wondering if this was Deimos until you posted that.

Phil

[Gerald]

You made me curious, how Deimos would look like with RMI.

According to this paper the fov of MR is 6.3° x 5.1°. MR images are usually 1344 pixels wide.
ChemCam has a fov of about 1.1° for 1024 pixels.
This translates to a factor of 6.3° * 1024 pixels / (1.1° * 1344 pixels) = 4.36 for the size of a pixel between RMI and MR.

Taking a crop of this Sol 606 MR image of Deimos, and magnifying it by the factor of 4.36 returns an estimated image of Deimos for RMI of about this size (somewhere between 50 and 60 pixels diameter) :


Maybe we've luck, and they'll make some pointing and timing tests with Phobos and Deimos to prepare the comet imaging; the comet should move faster than even Phobos.


Edit: With 1600 pixels width for the MR, the factor for the pixel sizes is about 3.67, making the image of Deimos 84% the size of the above simulated one (about 45 pixels diameter), to give an idea of the uncertainty of the above estimate.

[Deimos]

The comet should not move across the sky faster than Phobos at a time it can be observed. Anytime that the comet is up and the sky is dark (for either rover) is hours from closest approach.

I'm not expecting lunar images with RMI anytime soon--it is risky at this season. There are many precautions taken to keep the RMI from being damaged by the Sun, including damage that could occur after (for instance) RSM motion becomes precluded mid-sequence for some reason. There are times of year that this is not a risk, but I think the risk may be peaking right around now.

[fredk]

(about 45 pixels diameter)

Remember that chemcam's psf is quite a bit wider than a pixel due to structural constraints - see eg this site. The actual resolution is something like 100 microrad, versus the pixel scale of around 19 microrad/pixel. So Deimos (the moon, not the poster) would look big, but not as sharp as with MR.

[nprev]

MOD NOTE: Just a reminder that there's a thread for observations of the Siding Spring encounter happening next month. Please try to put related posts over there in the interest of having a single-point repository of comments & work related to the event; thanks!

[Gerald]

Sol 741 MR, Vega images cleaned, combined, enhanced, annotated:

Epsilon 1/2 Lyrae "Double Double" is well separated in two stars; the two components are 3.47 arc minutes (0.05783°) separated; this should correspond to a separation of 13.6 pixels for MR (with 1200 pixels for 5.1°).

[Gerald]

Sol 741 ML Lyra images, cleaned, combined, enhanced, annotated:

Enhancement has been a little different from the MR enhancement, since the streaks are shorter in the ML images used here.
Epsilon Lyrae is separated in the ML images, as well.

The Sol 741 MastCam shots have been a bit tricky to combine, since they are taken about 13 minutes apart; therefore one of each pair needed to be rotated about 3.4 degrees to register.

To roughly locate the MR and ML images, I've used Joe's site. For identification of the stars I relied mainly on Redshift 7 planetarium software.

[jmknapp]

Given the right conditions, would a long mastcam R exposure show trails from sunlight reflecting off orbiting satellites like MRO, ODY, Maven, Mangalyaan, MGS, even Viking?

[djellison]

Spirit successfully imaged Mars Odyssey with Pancam, so one would infer that yes, MastCam should be able to do the same.

[Phil Stooke]

The Spirit observations were overnight on sols 653-654 and 660-661.

I had a note that they were unsuccessful on sol 660, but now I can't back that up either way. Do you know which sol was successful?

EDIT - never mind, I found your earlier post with the sol 661 animation. Very cool!

Phil

[fredk]

(Sorry, this is off topic for MSL, but I'm not sure where else to post.)

The Spirit 661 observations in the gif by Doug I believe show a star. If you look elsewhere in the frames, you can see other point sources moving parallel to and at the same rate as the source in Doug's gif, which suggests they are all setting stars. Here I've pointed to a couple other point sources in addition to Doug's, which is the brightest:

Also, given the time interval between frames, the rate of motion agrees with stellar motion. I'd expect a satellite to have a considerably higher angular speed.

I haven't looked at the PDS - it might very well be that ODY is in there, but may take work to pull out. Has anyone heard official confirmation that ODY was spotted?

[Deimos]

I haven't heard any official conformation.

According to my notes, the bright object setting in the west is Rigel. ODY, in polar orbit, would go S-N (l-r) across the bottom-middle of the frame. I have a note about a horizontal streak (likely cosmic ray), but I do not see it in a quick look. In any case, it was in the wrong position and the wrong length for ODY, and not seen in a second image. But I encourage people to have a look at PDS data, if interested, because I am fairly sure ODY is geometrically in one or more of those frames.

For the original question--yes, under the right conditions, an orbiter could be seen. But those conditions would include a specular reflection off a shiny surface, which is difficult to predict with sufficient accuracy with available data. I looked at recent MOI geometries, but those were definitely not the right conditions.

[jmknapp]

Would there be a scientific interest in spotting one of the decommissioned orbiters like MGS or Viking to, say, determine the long term evolution of the last known orbits? Or maybe those kind of effects are already known to a high degree?

[mcaplinger]

Would there be a scientific interest in spotting one of the decommissioned orbiters like MGS or Viking to, say, determine the long term evolution of the last known orbits?

We have almost no idea where MGS or Viking are by now, so the chance of spotting them in a random search is nearly zero. We can't even see orbiters with certainty when we know exactly where they are. We couldn't find MGS with HiRISE right after it was lost.