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3\13 HST Daily Rpt No 3319
Part 1 of 3

 HUBBLE SPACE TELESCOPE
  DAILY REPORT # 3319

PERIOD COVERED: DOY 72

OBSERVATIONS SCHEDULED

NICMOS 8791

NICMOS Post-SAA calibration - CR Persistence Part 2

A new procedure proposed to alleviate the CR-persistence problem of 
NICMOS. Dark frames will be obtained immediately upon exiting the SAA 
contour 23, and every time a NICMOS exposure is scheduled within 50 
minutes of coming out of the SAA.  The darks will be obtained in 
parallel in all three NICMOS Cameras. The POST-SAA darks will be 
non-standard reference files available to users with a USEAFTER 
date/time mark. The keyword 'USEAFTER=date/time' will also be added to 
the header of each POST-SAA DARK frame. The keyword must be populated 
with the time, in addition to the date, because HST crosses the SAA ~8 
times per day so each POST-SAA DARK will need to have the appropriate 
time specified, for users to identify the ones they need. Both the raw 
and processed images will be archived as POST-SAA DARKSs. Generally we 
expect that all NICMOS science/calibration observations started within 
50 minutes of leaving an SAA will need such maps to remove the CR 
persistence from the science images. Each observation will need its 
own CRMAP, as different SAA passages leave different imprints on the 
NICMOS detectors.

STIS 9130

The iron abundance in the Magellanic Clouds and Bridge

The spectra of early-type main-sequence stars provide excellent probes 
of the current chemical composition of galaxies. The physics of their 
atmospheres are well understood, while their surfaces will normally be 
unaffected by the products of interior nuclear reactions. We have 
previously used optical spectra of such targets to map the abundances 
of light metals {such as C, N, O, Mg, Si} in our Galaxy, in the 
Magellanic Clouds and in a Bridge of material connecting the latter. 
However, we have been unable to obtain iron group abundances for the
Magellanic System due to the intrinsic weakness of the optical Fe 
II/III spectra and the system's low metallicity. Here we propose 
observations of strong Fe III ultraviolet lines for two Bridge stars, 
plus an LMC target. These will be supplemented by AAT and ESO optical 
spectroscopy plus HST spectra for two previously observed targets in 
the middle of the Bridge and in the SMC. Using non-LTE model 
atmosphere and careful differential methods, relative abundances
accurate to 0.1 dex should be achievable. These five stars will allow 
us to determine key element abundances and ratios {eg. O/Fe} in both 
Clouds and across the Bridge. As well as providing the first detailed 
comparison of the Bridge's metallicity with those of its parent 
Clouds, it will clarify the evolutionary history of this system.

HST 9382

A Large Targeted Survey for z < 1.6 Damped Lyman Alpha Lines in SDSS 
QSO MgII-FeII Systems.

We have searched the first public release of SDSS QSO spectra for 
low-z {z<1.65} metal absorption lines and found over 200 large rest 
equivalent width MgII-FeII systems. Previously, we empirically showed 
that such systems are good tracers of large neutral gas columns, with 
~50% being classical damped Lyman alpha {DLA} systems {N_HI>=2*10^20 
cm^-2}. Here we propose to follow up a well-defined subset of 79 of 
them to search for DLAs with 0.47 * Origin: SpaceBase[tm] Vancouver Canada [3 Lines] 604-473-9357 (1:153/719)

SEEN-BY: 633/267 270

@PATH: 153/719 715 7715 140/1 106/2000 633/267