PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "M. GORDON 2008-09-26" RECORD_TYPE = STREAM OBJECT = DATA_SET DATA_SET_ID = "IRTF-S-NSFCAM-1/3-RPX-V1.0" OBJECT = DATA_SET_INFORMATION DATA_SET_NAME = " IRTF S NSFCAM RAW AND CALIBRATED RING PLANE CROSSING V1.0" ARCHIVE_STATUS = "IN PEER REVIEW" DATA_SET_COLLECTION_MEMBER_FLG = N DATA_OBJECT_TYPE = IMAGE START_TIME = 1995-08-06T06:00:00 STOP_TIME = 1995-08-08T15:00:00 DATA_SET_RELEASE_DATE = 2008-09-26 PRODUCER_FULL_NAME = "MITCHELL K. GORDON" DETAILED_CATALOG_FLAG = N DATA_SET_TERSE_DESC = " This data set contains images of the Saturn system obtained using the NSFCam on the NASA IRTF in early August 1995. The observations were obtained a few days prior to the ring plane crossing." CITATION_DESC = " Bauer, J., J.J. Lissauer, and M. Simon, IRTF Observations of the August 1995 Saturn Ring Plane Crossing, IRTF-S-NSFCAM-1/3-RPX- V1.0, USA_NASA_PDS_RPX_0201, NASA Planetary Data System, 2008." ABSTRACT_DESC = " This dataset contains IRTF images of the Saturn system obtained with the NSFCam in early August 1995. The observations were made four days prior to the ring plane crossing when the sun and Earth were on opposite sides of the ring plane. The observations include sequences of rapid exposures of several satellite mutual events and spectroscopic data of the main rings and the E and G rings." DATA_SET_DESC = " Data Set Overview ================= This dataset contains images of the Saturn system taken at the NASA Infrared Telescope Facility (IRTF) using the NSFCam in early August 1995. This period preceeds the actual August plane crossing by 4 days. The Viewing geometry was such that the Earth and the Sun were on opposite sides of the ring plane, and the ring opening angle was less than 0.2 degrees. Every image showing Saturn, its rings or the region of the inner satellites has been included in this data set, regardless of the original intended purpose. The IRTF observing program whose results are included in this dataset is: Details on thse observations and the subsequent processing and analysis can be found in: Bauer, J., J.J. Lissauer, and M. Simon, Edge-on observations of Saturn's E and G Rings in the Near-IR, Icarus 125, 440-445, 1997. Proposal: NAGW-4659 Title: Unknown PI: Bauer, James (State University of New York, Stony Brook) Objectives ========== The primary objective for this set of observations was to obtain detailed spectral information about the faint E Ring. The secondary objective was to obtain some photometric and astrometric data for the following satellites of saturn: Janus, Pandora, Prometheus, Epimetheus, and Enceladus. Observation summary and conditions ================================== The Instrument used to study the Saturn Ring Plane Crossing event was the NSFCam, the facility 256x256 InSb array camera, with a pixel size of 0.31 arcsec. The Saturn system was viewed through six filters. These filters are used to reduce the planet's disk brightness. They are described briefly below: (1) the standard J band filter centered at 1.26 microns (2) A narrow filter within the H band centered at 1.62 microns (3) A narrow band filter in the K band centered at 2.21 microns (4) A standard L' filter centered at 3.78 microns (5) Two narrow band filters, Spencer 1.7 and Spencer 2.3 centered at 1.73 and 2.28 microns respectively. Several thousand exposures were taken on the nights of August 6th, 7th, and 8th of 1995. There was also a series of calibation runs using standard stars on the nights of May 21st, 22nd, and 25th. The calibration observations were made at airmass similar to the faint ring and satilite exposures. The night on which the best faint ring data were obtained was photometric at about the 10% level. The seeing was roughly the same for all three nights. The image preparation and data reduction were done in IDL. Non-Linearity ============== The total counts are the sum of the CO-ADDs and non-destructive reads(NDR) stacked on top of eachother. The number of CO-ADDs (CO_ADDS), NDRs (NDR) and the number, or divisor that the image counts should be divided by (DIVISOR) are keywords in the header, but the DIVISOR keyword is the accurate one. The CAL files have the DIVISOR value divided out of the count values, the RAW files do not. Linearity, or the point of non-linearity depends on the detector voltage gain (keyword VDET). Far beyond the linearity level, and the counts become negative in the image. Prior to this, but still in the nonlinear regime, the image pixels can take on a cross-hatched or canvas appearance. A few hundred counts above nonlinearity results in a few percent nonlinearity in the counts. At 1000 counts above and the non-linearity is severe. VDET Start of Nonlinearity (approx & conservative) -3.4 2000-2500 -3.2 4000 -2.9 8000 -2.7 10000 Hence the number of counts in the frame will be increased by a factor equal to the number of NDR. If more than [1] coadd has been requested then this entire process is repeated for the number of coadds, and the frame that is stored is the sum of the frames. Hence when reducing your data the counts in each frame need to be divided by the number of NDR and the number of coadds. This value is given in the FITS header as 'Divisor'. At the time of writing a non-linear correction has not been determined for NSFCAM - however a correction will be determined in the near future. The array behaves in a similar manner to the CSHELL SBRC InSb array. The plots shown in the back of the CSHELL manual of counts versus integration time, as a function of bias voltage, can be used as a guide for the camera. These relationships imply the following conservative upper limits to retain linearity in your data: TABLE 9.1: Maximum Counts for Data Linearity VDET -3.4 -3.2 -2.9 -2.7 bias mV 300 500 800 1000 Counts should not exceed (excluding bad pixels) 2000 4000 8000 10000 Observations of photometric standards with a 300mV bias show that counts around the 2500 level result in a 5% non-linear effect. ( Some of the information above is taken from the NSFCam users guide located in the DOCUMENT directory in this archive. ) Parameters ========== The PDS label for each file contains a broad variety of additional parameters enabling the user to determine image geometry and to convert pixel values to physically meaningful quantities. Processing ========== The calibrated images have been processed using IRAF. This includes: analog bias correction, dark current correction, flat field correction, and sky correction. Spectra wavelengths were registered with a copper-argon reference source and compared to known absorption lines in the spectra. Data ==== The data provided here are images in FITS format. For each data file, a detached PDS label is provided containing additional parameters. Most users will probably prefer to focus on the calibrated images or the processed data. Most of the calibration data may be found in subdirectories under the /CALIB/ directory. However, ring observations were made in a mode whre the images alternated by target and sky. These associated sky images are in the separate subdirectories under the /DATA/ directroy. Below the /CALIB/ and /DATA/ directories, the data are furthur subdivided by date_target directories, and finally processing level. Ancillary Data ============== Additional calibration files are provided to assist in the analysis and interpretation of the data. The appropriate subdirectories under the CALIBRATION subdirectory contain bias, flat field, sky, and spectral standard files as well as filter profiles for most of the filters used in this data set. Coordinate System ================= All geometric quantities appearing in the labels are in J2000 coordinates. In this coordinate frame, the z-axis points northward along the Earth's J2000 rotation axis and the x-axis points toward the First Point of Aries. Media/Format ============ This data set is archived on electronic media. Organization and formats are according to PDS and ISO 9660 level 2 standards." CONFIDENCE_LEVEL_NOTE = " Confidence Level Overview ========================= The NSFCam was calibrated using standard stas HD1160 and HD161903 as well as the UKIRT faint standard stars fs27, fs28, and fs32. These calibration runs were made at airmass similar to faint ring and satelite exposures during the ring plane crossing. The night on which the best faint ring data was obtained was photometric at about the 10% level. The seing was roughly the same for all three nights. Review ====== This data set passed peer review on August 29, 2007. The peer reviewers were James Bauer, Steve Larson, and Cathy Olkin. Ron Joyner represented the PDS Engineering Node at JPL. Data Coverage and Quality ========================= The deepest exposures targeted the region beyond the East and West ring ansae of the main rings. To reduce scattered light, Saturn's limb was placed just off the array's edge for these exposures. The best exposures were obtained on August 8th, when East ansae was clear of the saturnian satelites. Citing this dataset =================== The following is the recommended information to include in a journal citation of this dataset: Bauer, J., J.J. Lissauer, and M. Simon, IRTF Observations of the August 1995 Saturn Ring Plane Crossing, IRTF-S-NSFCAM-1/3-RPX-V1.0, USA_NASA_PDS_RPX_0201, NASA Planetary Data System, 2008." END_OBJECT = DATA_SET_INFORMATION OBJECT = DATA_SET_TARGET TARGET_NAME = "S RINGS" END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = SATURN END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = JANUS END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = PANDORA END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = PROMETHEUS END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = EPIMETHEUS END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = ENCELADUS END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_HOST INSTRUMENT_HOST_ID = IRTF INSTRUMENT_ID = NSFCAM END_OBJECT = DATA_SET_HOST OBJECT = DATA_SET_MISSION MISSION_NAME = "SATURN RING PLANE CROSSING 1995" END_OBJECT = DATA_SET_MISSION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BAUERETAL1997" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BAUER1996" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "LEGGETT&DENAULT1996" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BAUMETAL1980" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "NICHOLSONETAL1996" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "LARSON1984" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "FEIBELMAN1967" END_OBJECT = DATA_SET_REFERENCE_INFORMATION END_OBJECT = DATA_SET END