Date: Thu, 25 Mar 2004 16:42:08 -0800 (PST) From: Dick Simpson 650-723-3525 To: mgordon@mail.arc.nasa.gov, mshowalter@mail.arc.nasa.gov, rsimpson@magellan.Stanford.EDU Subject: VG_2803 Early Data File Comments X-Junkmail-Status: score=29/60, host=arc-relay2.arc.nasa.gov S_RINGS/CALIB/RSnCmS.{LBL,TAB} 1. Perhaps I'm being unnecessarily dense here, but I don't understand what this noise power represents. What are the questions being asked that motivate you to generate these files? Noise power seems to increase from about 0.03 to nearly 0.06 in RS1C1S.TAB. This COULD mean "noise power" is following the system temperature with decreasing elevation angle at the DSN station; but I don't recall that Stanford paid much attention to system temperature in the 1980's. It was sufficient that the carrier level remain essentially constant during the course of the observations. If related to system temperature, I would expect numbers to be on the order of 1e-20 watts, not 0.05. I also expect noise power to have units of watts; in RS1C1S.LBL UNIT = "N/A". 2. Much of the DESCRIPTION in the label files seems to be about files that are in the DOCUMENT directory. The antecedents for many uses of "this" are not clear - are we talking about the files in S_RINGS/CALIB or the files in DOCUMENT/CALIB? 3. There seems to be an implicit criticism that "the noise power had been held fixed in 10-km intervals." But the tabulated values here are at 100 km intervals; I don't follow the logic in criticizing 10 km averages, then following up with 100 km spline fit results. - S-RINGS/SORCDATA/DATAINFO.TXT: There are a number of content and editorials problems. Line 37 lists RSnS2B3.DAT as being one of the files; I think this should be RSnS1B3.DAT. Files #1 and #2 are described as X-band impulse and step responses; I believe these files are not wavelength related. One of the section headings is titled "Overview of Saturn Raw Data" when, in fact, these are being called "source" data to distinguish them from "raw" data, which are located elsewhere on the volume. I have rewritten DATAINFO.TXT. - S_RINGS/SORCDATA/RS1S1B{1,2,3}.LBL: The first two labels show WAVELENGTH = 3.5E04, the third shows WAVELENGTH = {3.5E04, 13E04}; all DESCRIPTION entries refer to X-band. In fact, these files should be exclusively S-band. - U_RINGS/CALIB/RSnCmS.{LBL,TAB} 1. The same kinds of questions. But the calibration files are now even more puzzling since there is not even any variation in the noise power with radial distance. Even if the system temperature were stable to 4 significant figures, it's hard to believe the ring profiles would match up that well. 2. there were both ingress and egress at Uranus and they weren't identical (at least, not all of them). - S_RINGS/RAWDATA/RS1R1BDI.LBL: This label includes the keyword=value pair PLANETARY_OCCULTATION_FLAG = N But the definition of PLANETARY_OCCULTATION_FLAG in DOCUMENT/PDSDD.TXT is not clear. It says DESCRIPTION = " The planetary_occultation_flag element is a yes-or-no flag that indicates whether a ring occultation track also intersects the planet." But what is a 'track'? Is it the experimental geometry? If so, then this track definitely did include a planetary occultation. That planetary occultation is included in the experimental data (but not this data set), and maybe the value should be 'Y'? - S-RINGS/RAWDATA/RS1R1BDP.LBL: 1. Confirm that units of phase are CYCLE. I think maybe it should be DEGREE. Uncertainties on the order of 0.5 and larger would make many of these phase numbers unusable. 2. Isn't PC_REAL the same as either IEEE_REAL or VAX_REAL? - S_RINGS/SORCDATA/RS1S1B1.LBL: The keyword=value pair WAVELENGTH = 3.5625981e4 /* microns, X-band */ implies this file is not to be used with S-band. I don't believe that is true. The inversion procedure is INDEPENDENT of the original wavelength. If this so, then this keyword needs to be checked in ALL of the labels. It probably should be set to both values everywhere; or not used except for labels describing data derived from file 3 on any Stanford tape. - S_RINGS/RAWDATA/RS1S1BT.LBL: 1. The pointer in this label is ^TABLE; but there is no table. 2. The NOTE in the TEXT definition refers to the "tape header file RS1R1BFV.DAT"; I think it should refer to the "HEADER RECORD of RS1R1B3.DAT". If there are other errors of this type, finding and correcting them is going to be a real chore! ============================================================================= Possible revision of /S_RINGS/SORCEDATA/DATAINFO.TXT (except that the path would be /S-RINGS/A_STNFRD/DATAINFO.TXT under my scheme): - PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM DATA_SET_ID = "VG1/VG2-SR/UR-RSS-4-OCC-V1.0" OBJECT = TEXT PUBLICATION_DATE = 2004-03-22 NOTE = "Description of the Stanford-produced Saturn data files in this directory." END_OBJECT = TEXT END DESCRIPTION OF THE STANFORD-PRODUCED SATURN DATA FILES IN THIS DIRECTORY - 1. Introduction - This summary describes the files found in the S_RINGS/A_STNFRD directory on this volume. These files are direct copies of the 9-track tapes originally provided to the Rings Node by the Stanford Radio Science group. There were four such tapes (n=1,2,3,4) with Saturn data, each with four files (m=0,1,2,3). The m=3 files contain estimates of ring opacity and phase at both S- and X-band. Values are given based on both an original analysis and on an 'inversion' in which a correction for diffraction was applied, yielding significantly higher resolution. 2. File Naming Convention - The files in this directory have names of the form RSnS1Bc.DAT where: R = Occultation instrument: R for Radio Science. S = Planet: S for Saturn. n = Saturn profile number (i.e., tape number): 1-4. S = File type: S for Stanford-produced data. 1 = Version number: 1 for all of these files. B = Wavelength: B, denoting both X and S bands. c = File contents index 0-3, indicating the corresponding file number on the tape. 3. Overview of Directory Contents - DATAINFO.TXT - This summary file. RSnS1B0.DAT - File #0 from tape n, containing documentation. RSnS1B0.LBL - A detached PDS label for the above. RSnS1B1.DAT - File #1 from tape n, containing a simulation of the impulse response. RSnS1B1.LBL - A detached PDS label for the above. RSnS1B2.DAT - File #2 from tape n, containing a simulation of the step response. RSnS1B2.LBL - A detached PDS label for the above. RSnS1B3.DAT - File #3 from tape n, containing ring profile data and geometry parameters. RSnS1B3.LBL - A detached PDS label for the above. The Stanford Radio Science group distributed its occultation profiles at several resolutions, the most widely circulated being in 5 km radial steps. The tapes used to create this data set had the following coverages and resolutions: --------------------------------------------------------------------- Tape Creation Date Version Radial Coverage (km) Resolution (m) --------------------------------------------------------------------- 1 1984-09-20 1.1 70,000-145,000 400 2 1989-02-01 1.3 70,000-115,000 400 3 UNK UNK 73,000-145,000 1000 4 UNK UNK 70,000-144,000 5000 ---------------------------------------------------------------------- The Stanford group has cautioned that the 400-m files may have 'anomalies' and are to be used with caution. But, in constructing this archive, Rings Node personnel were unable to identify any features which would qualify as anomalies. The S_RINGS/A_STNFRD directory contains direct dumps from each of the original tapes. Files were generated using the Vax/VMS COPY command and appear in VMS VARIABLE_LENGTH record format. Note that the same data may be found in more convenient formats elsewhere in this data set. Copies of the documentation (file 0) may be found in DOCUMENT/RSnS_DOC.TXT; copies of the data files may be found in the B_REFRMT directory, but reorganized and reformatted to facilitate use. The Stanford-produced files are provided for their historical value. Files in the D_EZDATA directory may be preferred by most users since they have been converted to J2000 coordinates and adjusted for an improved Saturn pole. Content-Type: application/octet-stream; name="VG_2803_datareview.doc" Content-Disposition: inline; filename="VG_2803_datareview.doc" Content-MD5: mNNmIENKmAMjq1vc80o4NQ== Attachment converted: Data:VG_2803_datareview.doc (WDBN/MSWD) (0009CE68)