Spirit retrospective, - a few details from my current project Options

[Phil Stooke]

I'm working on Spirit at the moment. I will post a few examples of things as I go.

Right now the important job is updating the contemporary route map by locating the stops on HiRISE images. The existing maps at JPL, for the early part of the mission, were plotted on MOC images with inferior resolution and lighting, so I find many locations were about 15 or 20 m out. So at every site I am making circular panoramas (examples later) for comparison with HiRISE. Here's a first example, a map of the route during the Primary Mission. I have added a few extra placenames from the MER Analyst's Notebook at PDS.

Phil

[fredk]

We also got Andromeda--it was barely detectable in the largest practical exposures.

I believe it was A/1941, night time opacity field A (aka the "diffuse sensitivity test").

(I hope Phil doesn't mind me using his thread to do some Spirit retrospection - this definitely doesn't belong in the Oppy thread where those quotes come from.)

Thanks for digging that up, Deimos. "Barely detectable" is a good description! With some effort I was able to squeeze the Andromeda Galaxy/M31 out of the 1941 pics. If anyone wants to try this at home, here are the details: I used these two frames:
2P298641880EFFB1E5P2731L1M1.JPG (frame 1)
2P298642075EFFB1E5P2731L1M1.JPG (frame 2)
I added 256 to the frame 2 values, then subtracted frame 1. The result was stretched and smoothed. (Strangely, the PDS RAD images show less detail than the jpl jpegs.)

The result is that most of the frame averages to neutral grey. Any real object (eg a star) will appear as a lighter-than-neutral-grey streak adjacent to a darker streak, which stands out very well. I've identified M31 in this crop:

It's clearly fuzzier than the stars, and it is exactly where it should be, as you can see from this flicker gif comparing the difference image with a star chart:

Extragalactic imaging from Mars!