Contents of: VI/111/./abstract/RSTENCEL_VEGADISX.abs

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SCIENTIFIC ABSTRACT
The IRAS discovery of far-infrared excesses among seemingly 
normal main-sequence star motivates this proposal.  These
have been interpreted in terms of disks of cold material. 
The aim of this proposal is to establish the true frequency for 
far-infrared excesses in a volume-limited sample of main 
sequence and related stars using PHT-P, PHT-C, CAM and SWS 
measurements, in order to address the success or failure of 
single stars in processes related to the forming of planetary 
systems.  For brighter sources, more extensive wavelength 
coverage and spatial resolution will be attempted, with PHT-P, 
PHT-C, PHT-S and SWS.  Finally, observations of Kuiper Belt 
objects will be attempted.

OBSERVATION SUMMARY
This proposal is split into three parts: this is PART 1
It is planned to obtain more accurate coordinates for sources
in this proposal, beyond the SIMBAD information used so far.  
Annual proper motions, where available, are listed.
For a volume-limited sample of main sequence and related 
stars, PHT03 measurements at 3.6, 11.5, 20 and 60 microns will
be obtained, using a 120 arcsec aperture in all cases to 
eliminate possible companion confusion with differing apertures. 
For the M dwarfs, 100 micron observations will 
also be obtained.  Rectangular chopping will be used for sources 
above and below 10 degrees galactic or ecliptic latitude; triangular
chopping otherwise, with a throw of 120 arcsec.  For selected 
bright stars, CAM01 observations using microscans with 5 second 
exposures and 6 arcsec pfov and 6 arcsec steps, for 10 linear 
steps using the LW3 filter are planned.

The signal to noise ratios are predicted, from the PHOT Cookbook
to be in excess of 1000 for 32 second observations of sources 
brighter than 0.7 Jy at 3.6 microns, decreasing to 300 at 11.5  
and 20 microns and declining to 2.5 at 60 microns, even at 
the ecliptic equator.  Therefore the minimum 32 sec for each 
PHT-P filter will be sufficient for the continuum measurements 
at 3.6, 11.5  and 20 microns, and 64 seconds for the 60 micron 
observations.  The 100 micron observations for the M stars 
will require chopping and a minimum of 128 sec to obtain S/N 
of >2.  Total time per star is therefore (3 * 32 s + 64 s (+128 s)) 
* 2 for chopping, + 180 s acquisition + 155s other overheads = 
655s (921s).  PHT-S, CAM and SWS observations are more 
exploratory, with S/N in excess of 3 are based on comparisons 
with Central Programme estimates.

PART 2: Concerns spatial mapping and spectra of selected brighter  
far IR sources.

PART 3: Concerns local Kuiper Belt observations.

LINKED OBSERVATIONS: No
FIXED TIME OBSERVATIONS: No
CONCATENATION: Yes - several AOTs on some sources.
 


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