Sorry for the mess... This needs to be cleaned up!

%%%%%%%%%%%%%%%%%%%%%%%%%%%%

IMAGING AND SPECTROSCOPY OF MARS FROM 1.56 TO 4.16 Um: 1994-95 IRTF OBSERVATIONS

JIM BELL (CORNELL UNIVERSITY)

BILL GOLISCH (NASA IRTF)

DAVE GRIEP (NASA IRTF)

CHARLIE KAMINSKI (NASA IRTF)

TED ROUSH (SFSU/NASA AMES)

DAVE KLASSEN (UNIVERSITY OF WYOMING)

%%%%%%%%%%%%%%%%%%%%%%%%%%%%

GOALS:

* Characterize the Mars seasonal volatile cycle

-> Discrimination of H2O and CO2 clouds, ices

* Search for evidence of climatically-diagnostic materials

-> Carbonates, sulfates, hydrates, ices/clouds

* Spatially and temporally map variations in spectral properties

INSTRUMENTATION

* NASA IRTF near-IR array camera: NSFCAM

* 256 x 256 pixel InSb array

* Cooled 0.9% to 1.4% resolution CVFs

* Wavelength range 1.5 to 4.2 um

* Plate scale variable, to 0.06 arcsec/pixel (seeing limited)

* Automated control for rapid wavelength scanning

* Remote observing capabilities

OBSERVATIONS / DATA SET

* NSFCAM images obtained from 1994 October 1 to 1995 April 1 (Ls=356deg. to 79deg.)

* Thousands of images at up to 106 [[lambda]]'s from 1.5 to 4.2 um

* Photometric calibration possible for much of the data

* More extensive sampling of the seasonal cycle than before

Table 1: Summary of IRTF 1994-95 Mars Observations

UT Date UT Time Size Sub-Earth Ls Mars Longitudes Covered Data Mode

YYMMDD Range (") Lat. (deg.) (deg.) 0 90 180 270 360 1 2 3 4 Comments

940902 Heavy Fog: test data only

941001 1300-1500 6.0 14.4 356 ^{------ --------------------} [[radical]] [[radical]] Some cirrus; seeing 1.2"

941101 1200-1420 7.0 19.0 11 ^{------------ ----------------} [[radical]] Some cirrus; seeing 1.0"

941227 1300-1600 10.7 21.4 37 ^{----------------------------} [[radical]] [[radical]] [[radical]] Photometric; seeing <0.6"

941228 1100-1500 10.8 21.4 37 ^{------------------------------} [[radical]] [[radical]] Photometric; seeing <0.9"

950114 1200-1540 12.3 20.6 45 ^{-------------- ------------} [[radical]] Photometric; seeing <1.0"

950131 Fog, wind: test data only

950201 0715-1200 13.6 19.3 53 ^{--------------------------} [[radical]] [[radical]] [[radical]] Photometric; seeing <0.8"

950204 0700-1000 13.7 19.0 54 ^{------------------------} [[radical]] [[radical]] [[radical]] Photometric; seeing <0.6"

950219 0700-1140 13.7 17.7 61 ^{-------------- ------------------} [[radical]] [[radical]] [[radical]] Photometric; seeing <0.7"

950305 Ice storm: no data

950314 0515-1140 12.1 16.6 71 ^{------------------------------} [[radical]] [[radical]] [[radical]] Photometric; seeing <0.9"

950402 0600-1000 10.3 17.2 79 ^{------------ ------------------} [[radical]] [[radical]] [[radical]] Some cirrus; seeing 1.0"

Data Modes are: 1 = 32-wavelength image set from 1.560 to 4.100 um

2 = 58-wavelength image set from 1.918 to 2.477 um (Nyquist sampled)

3 = 48-wavelength image set from 3.000 to 4.164 um (Nyquist sampled)

4 = H, K, and L-band slit spectroscopy at R=500 (0.3 arcsec slit)

DATA REDUCTION

% Data from 4 February 1995 examined (Ls = 54deg.)

% Standard Linearity, Bias, Sky, Flatfield corrections applied

% Identified images with best spatial resolution at each [[lambda]]

% Performed relative calibration exercise (disk average)

Rrel([[lambda]]) = f(DNcor([[lambda]], x, y),DNcor([[lambda]], avg))

-> removes telluric, instrumental effects

-> provides rapid way to assess spectral variability before performing full photometric calibration

RESULTS: 3 TO 4 Um IMAGING SPECTROSCOPY

% Searched for evidence of atmospheric gas absorptions

-> provides correlation of spectral variability with topography

-> detection of features provides confidence in data quality

RESULTS: 3 TO 4 Um IMAGING SPECTROSCOPY

% Extracted representative spectra to search for evidence of other absorption features

-> H2O ice from 3.0 um band

-> CO2 ice from 3.33 um band

-> Carbonates, Sulfates, C-H, ... in 3 to 4 um region

CONCLUSIONS

% 3 to 4 um spectra consistent with previous investigations and expectations from atmospheric modeling

% Imaging aspect of these data allow spatial variability to be assessed, as well as some time variability

% Enigmatic ~ 5% spectral features at 3.32 um and 3.40 um appear to be related to surface mineralogic differences

-> Carbonate? Masked companion 3.9 um band?

-> COo(3 , ^2-), HCOo(3,^-), SOo(4 , ^2-), or HSOo(4,^-) in "mineral X"?

p.s.: The 3.32 um to 3.40 um complex is very close in wavelength to the one still-unexplained "Sinton Band" from the 1950s...