PDS_VERSION_ID     = PDS3

RECORD_TYPE        = STREAM
OBJECT             = TEXT
  NOTE             = "Known errors and/or anomalies in the volumes"
  PUBLICATION_DATE = 2006-12-22
END_OBJECT         = TEXT
END

ERRORS AND/OR ANOMALIES IN THE CURRENT VOLUME

Volume CORADR_0078, Version 1
------------------------------

1.  The Cassini Radar Transition file (EXTRAS/CRT_078_V01.TAB) contains
no information about ScanStart and ScanEnd transitions.

2.  Although this is a Titan Flyby, there are no SAR images or altimetry.
An experimental procedure was applied to produce a SAR image from 
scatterometer mode data, but the procedure failed due to pointing
and SNR issues. The experiment resulted in the development of a technique
that has produced useful imagery in other subsequent flybys.

3.  The uncompressed LBDR and BIDR products have attached labels.
Normally, a file that has been compressed with ZIP would have been
generated without an attached label.

4.  Because the LBDR product was longer than 2 GB, the product has been split
into two files.  The filenames and product ID's have an extra three characters
(_P1 or _P2) to denote part 1 and part 2.  This does not conform to the SIS.

5.  In the volume index table (INDEX/INDEX.TAB), double quotes enclose
all the date/time values.  Normally, PDS date/time values are not
quoted, but quoting makes parsing easier for some applications.

6.  The HTML documents in the DOCUMENT directory contain HTML character
codes that, while all-ASCII, are not easily interpretable by someone
who is reading the HTML documents as text documents.  For example,
"α" represents the lower-case Greek character "alpha" and is
rendered as such in a web browser.  Equivalent and more legible character
codes (e.g., "&#alpha;") are available as of the HTML 4.0 specification
but cannot be used here, as PDS requires HTML documents to comply to the
HTML 3.2 specification.

7.  Some of the scatterometer fields in the science data segment are invalid
because compressed mode scatterometry is not yet being processed.  These
records are flagged accordingly.

8. Some valid SAR anciliary fields are reported for data which was processed
in the experimental distant SAR mode. Although the imagery was deemed to be
too poor quality to archive, the anciliary parameters are available for other
researchers who wish to try alternative imaging techniques.

9. The standard deviation of the scatterometer measurement
(sigma0_uncorrected_std field in LBDR/SBDR) is incorrectly computed.

10.  The science data quality flag only specifies the validity of the active
and passive boresight geometry when the corresponding active or passive data
valid bit is zero (valid).  For example, if bit 1 is set (invalid) then all
the active boresight geometry is invalid even though bits 7 and 8 may be
zeroed.

11. Antenna temperature, brightness temperature, and receiver temperature are
defined in Janssen, M. A., "An Introduction to the Passive Microwave Remote
Sensing of Atmospheres," Chapter 1 in Atmospheric Remote Sensing by
Microwave Radiometry, (M. Janssen, ed.), pp. 1-35, Wiley & Sons,
New York (1993).  The archived value in the SBDR and LBDR files gives
uncalibrated antenna temperature in units of Kelvin.
It provides calibrated antenna temperature when multiplied by a dimensionless
factor f.  The current best value for f is 0.926.  As this improves it will
change and will likely become a function of time. This value applies also to
all preceeding volumes.

12. Ideally the calibrated antenna temperature is referenced to cold sky at
2.7 K, although no guarantee is made that this zero-level accounting has been
correctly made.  Also, the antenna temperature is not necessarily the
brightness temperature seen in the main beam; e.g., there will be an offset
if the sidelobes happen to fall on other than cold sky.  There are Cassegrain
spillover sidelobes at around 12 degrees from the main beam, and possible
primary spillover lobes in the back direction.  In particular, there is an
offset to be expected and accounted for when an extended source like Titan
or Saturn is observed from close distance.  System gain is the quantity that
multiplies the raw sky counts to convert to the uncalibrated Kelvin scale.
Receiver_temp is the receiver noise temperature Tr (comparison made at
internal reference switch).   The receiver temperature plus the antenna
temperature is equal to the total signal (raw counts times system gain).

13. ant_temp_std is a measure of the rms uncertainty of Ta, and is only an
estimation.  It is obtained as the standard deviation of Ta for three points,
Ta(I-1), Ta(I), and Ta(I+1), and is a useful measure that identifies
questionable data.  For example, it gets large when the beam is sweeping
across a brightness discontinuity.

ERRORS AND/OR ANOMALIES IN PREVIOUS VOLUMES

Not Applicable