Hi BrianMy reply 73 image was indeed u...

Hi Brian

My reply 73 image was indeed using a strong magnet substrate with rotation 13411. That rotation is noted in the table which only goes up to images taken up to sol 30. The rotation for my reply 74 image is given in the image header and elsewhere but is not found on either the rotation wheel nor the table. It appears that that table would have to be updated to include many of the recent sol 57 and 58 OM releases. It appears to be just happenstance that the substrate of my reply 73 image was indeed referenced.

There are a number of statements in the document and elsewhere about the use of "before" and "after" images. However, I have not been able to find the "before" images for any of the releases that I and others have coloured. It is therefore possible that some of the discrete objects seen on those colourations might be artifacts in the substrates since no "before" images were available for comparison.

For example. A number of OM images were taken before sol 30 but none of those have been released as raw images so far. e.g. on sol 15 some "before" images without samples were taken and on sol 17 some "after" images with samples were taken. Similarly on Sol 25 some "before" images without samples were taken and on sol 26 some "after" images with samples were taken. None of those images appear to have been released so far. Indeed, only one "before" image seems to have been released so far. That is one that has been processed and is included in the NASA document that you referenced in your reply #78.

I will hold my judgement until some "before" and "after" images are released, but I have a few concerns re. the OM being able to truly resolve images that may be of the typical sizes of largish spores (c. 10-30 uM) in the presence of mineral grain particles of similar sizes.

Thanks again for your assistance and interest.

Winston