PDS_VERSION_ID     = PDS3

RECORD_TYPE        = STREAM
OBJECT             = TEXT
  NOTE             = "Known errors and/or anomalies in the volumes"
  PUBLICATION_DATE = 2018-03-15
END_OBJECT         = TEXT
END

ERRORS AND/OR ANOMALIES IN THE CURRENT VOLUME

Volume CORADR_0294, Version 02
------------------------------

1.  The Cassini Radar Transition file (EXTRAS/CRT_294_V02.TAB) contains
no information about ScanStart and ScanEnd transitions.

2.  The uncompressed LBDR product has an attached labels.
Normally, a file that has been compressed with ZIP would have been
generated without an attached label.

3.  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.

4.  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,
"&#945;" 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.

5.  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.
The best current algorithm for correcting the archived antenna temperatures is
Ta_corrected = Ta_archive * ( 0.920 - 0.0041*( t - 1.90 ) )
where t = time in years and fractional years since 2004.0
(0 UTC on 1 Jan 2004)
This algorithm is based on the radioastronomical flux scale at 2-cm wavelength
by direct comparison of distant (unresolved) Titan measurements by the Cassini
radiometer with VLA measurements of Titan reported by Butler and Gurwell,
2004.  This algorithm will improve with time as more distant Titan
measurements are obtained and as more radioastronomical comparison sources are
included.
Butler, B. J., Gurwell, M. A. 2004. Radio Wavelength Observations of Titan
with the  VLA. Bull. Am. Astron. Soc. 36, 6.04.
This algorithm applies also to all preceeding volumes.

6. 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 defined for this application
as just the average brightness temperature in the measured beam out to 2
degrees from the beam axis, and does not allow for possible contributions from
the far sidelobes (sidelobes outside of 2 degreees).  The archived value will
include an additional contribution if the  far sidelobes happen to fall on 
other than cold sky.   In particular, there is an offset to be expected and 
accounted for when an extended source like Titan or Saturn is observed from a 
close distance.  A more detailed explanation will be found in Janssen et al.,
2009. 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).


7. 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.

8.The submitted volume CORADR_0143 has an erroneous INDEX and CUMINDEX entry
for BIFQE10N073_D143_I049S01_V02. 

9.Every volume from CORADR_0144 to CORADR_0229 has missing CUMINDEX entries 
for Iapetus_049_3.  

10. There are some invalid resistive load counts at the very beginning which
result in incorrect antenna temperatures. 

11. Volumes CORADR_0265 and CORADR_0266 have missing CUMINDEX entries for 
COARDR_0035_V03.

12. The AAREADME file that is included as part of each PDS volume
has a section addressing the version number of all the data products.
The AAREADME file for flybys TA-T30 had erroneously reported
that the volumes with PRODUCT_VERSION_ID 02 for flybys T36-T77
represent products processed with the non-synchronous pole, instead
of reporting as being processed by the synchronous pole. This
comment is corrected in the AAREADME files in later flybys.

13. The SBDR and LBDR files contain only raw data. No backscattering
cross-section nor altimeter results are included because this observation
was non-standard and requires specialized processing.  Refer to the
sequence design memo for more information.

14. SPECTRA files are not included with this Titan observation becuase it
is not distant enough for disk integrated results to make sense.

ERRORS AND/OR ANOMALIES IN PREVIOUS VOLUMES

1. The last field of a few records in the ABDR SUMMARY file 
corresponding to Flyby T8 have unusually large numbers. These erroneous
values will not be fixed. Instead, the user can exclude these data points
while using results from the ABDR SUMMARY file.






