The images I’ve at least located and successfully transferred from the external drive:

C3490901_GEOMED.IMG C3496515_GEOMED.IMG C4399054_GEOMED.IMG
C3491231_GEOMED.IMG C3496519_GEOMED.IMG C4399058_GEOMED.IMG
C3492126_GEOMED.IMG C4398423_GEOMED.IMG C4399102_GEOMED.IMG
C3494401_GEOMED.IMG C4398429_GEOMED.IMG C4399621_GEOMED.IMG
C3494405_GEOMED.IMG C4398435_GEOMED.IMG C4399624_GEOMED.IMG
C3494440_GEOMED.IMG C4399043_GEOMED.IMG C4399627_GEOMED.IMG
C3494841_GEOMED.IMG C4399046_GEOMED.IMG
C3494845_GEOMED.IMG C4399050_GEOMED.IMG

All correspond to images I already have on file, which means they’re all Titan or Saturn’s limb. No rings, no other satellites, and none without some black sky somewhere on the image.

Transfer proceeded without problems.

No surprises involving formatting or image headers; my 25-years-in-the-making suite of Fortran image handling routines likes them just fine.

34921.26 — Sometime in 1980, at JPL, somebody hit the ‘SATURN’ key on a data-entry system when they should have hit ‘TITAN’. And for a quarter-century since then, this image has been misfiled on every Voyager data set I’ve encountered (including still on the JPL PDS Imaging Node). Can it please, please, please, PLEASE end here?!?! 34921.26 is a TITAN image. And not just any Titan image, either. It’s the Voyager 1 limb shot at 160° solar phase angle with ~1 km spatial resolution that shows all kinds of structure in the limb haze and got on the cover of Science and everywhere else in garishly false-colored form. And nobody will ever be able to find it in VGR029/SATURN/C3492xxx. That’s TITAN. (The fact that the canned SEDR data for 34921.26 also uses Saturn as the target body is a whole separate can of worms. Idiots.)

We have updated the index files and the labels for this image. We have also added a note to ERRATA.TXT indicating that TARGET fields can be erroneous, and requesting that any other identified errors be reported to the Rings Node.

Files with terrible dark current subtraction: 34948.41, 34948.45, 34965.15, 34965.19. That’s four out of about eight I’ve looked at in detail. 48.4[15] were taken under absolutely unique lighting conditions (solar phase angle 170°), but there is nothing particularly unusual about 65.1[59]. So far all the abominable dark currents I’ve found have been files with the JUPITER calibration (see next paragraph). On the other hand 34912.31 has beautiful dark current subtraction despite JUPITER calibration.

We identified flaws in some of our original dark currents. These have now been corrected and all images have been re-calibrated. The new versions of these images look fairly clean to us. We have added a note to TUTORIAL.TXT warning users that dark sky regions of an image can be negative, due to uncertainties in the dark current.

Files processed by USER=’DANNY’ in early September 2005 have the incorrect (default) JUPITER calibration in FICOR77:

TASK='FICOR77' USER='DANNY' DAT_TIM='Sun Sep 4 00:17:57 2005'
 FICOR77 MINSAT=32767 NUMSAT= 0
 FOR NANOWATTS/CM**2/STER/NM MULTIPLY DN VALUE BY 0.20224
 FOR (I/F)*10000., MULTIPLY DN VALUE BY 1.00000
 FICOR77 DARK CURRENT FDS = 34938.50
 PICTURE MULTIPLIED BY 0.93 FICOR 2/02/86 VERSION
 SCALE='JUPITER'

as opposed to:

TASK='FICOR77' USER='SHOWALTER' DAT_TIM='Fri Sep 23 18:11:28 2005'
 FICOR77 MINSAT= 8341 NUMSAT= 42
 FOR NANOWATTS/CM**2/STER/NM MULTIPLY DN VALUE BY 0.20116
 FOR (I/F)*10000., MULTIPLY DN VALUE BY 1.00000
 FICOR77 DARK CURRENT FDS = 43959.53
 PICTURE MULTIPLIED BY 3.05 FICOR 2/02/86 VERSION
 SCALE='SATURN '

… or maybe it’s a Voyager 1 / Voyager 2 thing. But it’s a terrible idea to turn these images loose on a bunch of unsuspecting users who were in diapers in 1980-81 with a random factor of 3 in the radiometric calibration. (And I hope I don’t need to specify which way I want to see it resolved.)

This is an issue with all Voyager 1 Saturn images, because the FICOR77 software was never updated for the Voyager 1 Saturn flyby. All image labels contain a parameter REFLECTANCE_SCALING_FACTOR, containing the correct conversion factor from pixel DN values to I/F. However, we have not modified the VICAR labels. This is noted in ERRATA.TXT and repeatedly in TUTORIAL.TXT.

Aside from variations in dark current, radiometric calibration appears to match up with my previously-on-file images.

Geometric correction looks good. At least it looks the same as the previously-on-file images I’m comparing it with. Reseau removal is largely successful (except right on the limb sometimes … sigh).