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Availability: At NSSDC, Ready for Offline Distribution (or Staging if Digital)


This description was generated automatically using input from the Planetary Data System.

Data Set Overview

This data set contains global mosaics of the Dawn VIR band centers and depths of phyllosilicate absorption bands, located at 2.7 (OH band) and 3.1 microns (NH4 band), from the Ceres encounter. The data set was acquired during the Survey and Ceres Science RC3 (CSR) phases between 2015-04-25 and 2015-06-27.

VIR Ceres Observations

The following table contains a listing of VIR mosaics at Ceres. ---------------------------------------------------------------------VIR mosaics ---------------------------------------------------------------------Target Spectral Product Coverage Parameter Name ====================================================================== GLOBAL OH Absorption Band Center CMT_MOSAIC-BI_CENTER ---------------------------------------------------------------------GLOBAL OH Absorption Band Depth CMT_MOSAIC-BI_DEPTH ---------------------------------------------------------------------GLOBAL NH4 Absorption Band Center CMT_MOSAIC-BII_CENTER ---------------------------------------------------------------------GLOBAL NH4 Absorption Band Depth CMT_MOSAIC-BII_DEPTH ---------------------------------------------------------------------


The archived maps contain four spectral parameters relative to the strong phyllosilicate bands observed on VIR data of Ceres's surface [DESANCTISETAL2015]. The mapped spectral parameters are following: 1. Band center at 2.7 micron; 2. Band center at 3.1 micron; 3. Band depth at 2.7 micron; 4. Band depth at 3.1 micron; The dataset used to retrieve the spectral parameters is Ceres Science Survey (CSS) phases of the mission. VIR data provided in radiance units were converted into reflectance in order to calculate the spectral parameters (for more details see VIR Calibration Document in the /DOCUMENT directory). The photometric correction applied to these data is described in detail in [AMMANNITOETAL2016] but can be briefly described as radiance (R) is the product of the Lommel Seeliger disk function (LS) and the phase function (F), R = LS*F. The dataset has corrected with a 30 deg function D(i=30,e=0,p=30). Below the steps to derive the spectral parameters, as described by supplementary online material of[AMMANNITOETAL2016]. The artifact removing procedure (described in the VIR Calibration Document) was not applied to these data. Band centers: The band centers were computed with the following steps: 1. Smoothing of the spectra. The spectra have been smoothed with a boxcar average of 3 spectral channels. 2. Evaluation of the continuum and continuum removal. The band continuum of each band has been computed as the straight line between the two local maxima in the range 2.58 -3.00 microns for OH band and 2.85 -3.30 for the NH4 band. 3. Band centers: after the continuum removal, the band center is the wavelength which corresponds to the minimum of the spectra. Band depth: Band depths have been calculated by using the definition of [CLARKETAL1984]: 1-Rc/Rb, where Rb is the reflectance at the band minimum and Rc is the reflectance of the continuum at the same wavelength as Rb. Projection and Coordinate System: All of the products use the same projection, a simple cylindrical projection in Ceres IAU coordinates (SPICE refers to this as Ceres BODY-FIXED ROTATING coordinates). The geometric information were derived by using the SPICE kernels available at []. The map projection was done onto a sphere with the mean radius of 470 km, and refer to east longitude positive direction and planetocentric latitude. See the Ceres Coordinate System document in the document directory for details of the Ceres coordinate system. The spatial resolution is constant throughout the image and is 11.4 pixels/degree, with a map scale of 0.72 km/pixel. Spatially overlapping data are averaged (simple) after projection.


The data are in PDS format image format and are described by detached PDS labels.

Ancillary Data

No ancillary data are included in this data set.


De Sanctis, M.C., J.P. Combe, E. Ammannito, E. Palomba, A. Longobardo, T.B. McCord, S. Marchi, F. Capaccioni, M.T. Capria, D.W. Mittlefehldt, C.M. Pieters, J. Sunshine, F. Tosi, F. Zambon, F. Carraro, S. Fonte, A. Frigeri, G. Magni, C.A. Raymond, C.T. Russell, and D. Turrini, Detection of Widespread Hydrated Materials on Vesta by the VIR Imaging Spectrometer on board the Dawn Mission, Astrophys. J. Lett. 758 L36, 2012, doi:10.1088/2041-8205/758/2/L36. Clark, R.N., R.H. Brown, P.D. Owensby, and A. Steele, Saturn's Satellites: Near-Infrared Spectrophotometry (0.65-2.5/~m) of the Leading and Trailing Sides and Compositional Implications, Icarus, 58, p265-281, 1984, doi:10.1016/0019-1035(84)90043-5. Ammannito, E., DeSanctis, M. C., Ciarniello, M., Frigeri, A., Carrozzo, F. G., Combe, J.-P., Ehlmann, B. L., Marchi, S., McSween, H. Y., Raponi, A., Toplis, M. J., Tosi, F., Castillo-Rogez, J. C., Capaccioni, F., Capria, M. T., Fonte, S., Giardino, M., Jaumann, R., Longobardo, A., Joy, S. P., Magni, G., McCord, T. B., McFadden, L. A., Palomba, E., Pieters, C. M., Polanskey, C. A., Rayman, M. D., Raymond, C. A., Schenk, P. M., Zambon, F. and Russell, C. T., Distribution of phyllosilicates on the surface of Ceres, Science, 353, pp. aaf4279, 2016, doi:10.1126/science.aaf4279.

These data are available on-line from the Planetary Data System (PDS) at:

Alternate Names



  • Planetary Science: Small Bodies

Additional Information



Questions and comments about this data collection can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. Maria Christina de SanctisData ProviderIstituto Nazionale di
Ms. Mariano De La RivaGeneral Contact
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