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! | PED OUTPUT PRODUCT |
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! /data/charon4/smov/1033.prop
! Generated by PREPROCESSOR, version 7.0
! Date: Wed Dec 18 10:44:36 EST 1996
Proposal_Information
Title: NICMOS Imaging of Circumstellar Material
Proposal_Category: GO
Scientific_Category: STELLAR EJECTA
Cycle: 7
Investigators
PI_Name: Joan Smith
PI_Institution: University 1
CoI_Name: John Brown
CoI_Institution: University 2
Contact:
Abstract:
Strategy for Point Spread Function (PSF) subtraction. Circumstellar objects
without using the coronograph.
Questions
Observing_Description:
In this proposal, circumstellar material is being observed in NIC2 and
the F160W filter. The central star is so bright that its core will be
saturated in 0.1 seconds, much less than the minimum exposure time
allowed by NICMOS in the MULTIACCUM readout mode (0.204 seconds). The
use of the coronograph is NOT suitable for this observation, because
the material is located at a distance of less than 0".4 (the effective
radius of the NICMOS coronographic spot). In order to get enough
signal-to-noise on the circumstellar material, long exposures are
required. The NICMOS detectors do not suffer from bleeding, and the
central object can be allowed to saturate without compromising the
observations. The MULTIACCUM readout mode with the sequence STEP256 and
NSAMP=12 (corresponding to 512 seconds of integration) is used to
obtain enough dynamical range and signal-to-noise ratio on the
circumstellar material. For the PSF subtraction two steps are needed:
1) exposures of the central star with the BRIGHTOBJ mode to obtain
unsaturated images and determine its centroid; these exposures must be
obtained back-to-back with each primary MULTIACCUM exposure, since
they must be obtained in the same detector's position; 2) observations
with the same instrument configuration of a nearby isolated star, to
determine the PSF. The "PSF" star is selected to be a couple of
magnitudes fainter than the primary target so unsaturated images will
be obtained with the MULTIACCUM sequence 1CAMRR and NSAMP=2. Each
exposure series will be repeated to reach fainter brightness limits for the
circumstellar material (as an example, we will repeat the observation
twice); to avoid potential problems related to image persistence on
the detector, a POS TARG maneuver of 5" will be implemented between
exposure series to place the target on another detector position.
Real_Time_Justification:
Calibration_Justification:
Additional_Comments:
Fixed_Targets
Target_Number: 1
Target_Name: BRIGHTSTAR
Alternate_Names: Nice Star 1
Description: STAR
Position: RA=13H 50M 49.40S +/- 0.02S,DEC=42D 20' 58.0" +/- 0.7"
Equinox: J2000
RV_or_Z:
RA_PM: 0.0
Dec_PM: 0.0
Epoch:
Annual_Parallax: 0.0
Flux:
F(1.60)=0.00
Comments: The value of the flux is in units of Jy, at 1.6 microns. The star is very bright
Target_Number: 2
Target_Name: PSFSTAR
Alternate_Names: Nice Star 2
Description: STAR
Position: RA=13H 50M 49.40S +/- 0.02S,DEC=42D 48' 58.0" +/- 0.7"
Equinox: J2000
RV_or_Z:
RA_PM: 0.0
Dec_PM: 0.0
Epoch:
Annual_Parallax: 0.0
Flux:
F(1.60)=0.00
Comments: The value of the flux is in units of Jy, at 1.6 microns. This is the PSF star.
Solar_System_Targets
Generic_Targets
Scan_Data
Visits
Visit_Number: 01
Visit_Requirements:
On_Hold_Comments:
Visit_Comments: Two targets will be visited.
Exposure_Number: 1
Target_Name: BRIGHTSTAR
Config: NIC2
Opmode: MULTIACCUM
Aperture: NIC2
Sp_Element: F160W
Wavelength:
Optional_Parameters: SAMP-SEQ=STEP256,NSAMP=12
Number_of_Iterations: 1
Time_Per_Exposure: DEF
Special_Requirements:
Comments:
Exposure_Number: 2
Target_Name: BRIGHTSTAR
Config: NIC2
Opmode: BRIGHTOBJ
Aperture: NIC2
Sp_Element: F160W
Wavelength:
Optional_Parameters:
Number_of_Iterations: 1
Time_Per_Exposure: 0.050176 S
Special_Requirements:
Comments:
Exposure_Number: 3
Target_Name: BRIGHTSTAR
Config: NIC2
Opmode: MULTIACCUM
Aperture: NIC2
Sp_Element: F160W
Wavelength:
Optional_Parameters: SAMP-SEQ=STEP256,NSAMP=12
Number_of_Iterations: 1
Time_Per_Exposure: DEF
Special_Requirements: POS TARG 5, 5
Comments:
Exposure_Number: 4
Target_Name: BRIGHTSTAR
Config: NIC2
Opmode: BRIGHTOBJ
Aperture: NIC2
Sp_Element: F160W
Wavelength:
Optional_Parameters:
Number_of_Iterations: 1
Time_Per_Exposure: 0.050176 S
Special_Requirements: POS TARG 5, 5
Comments:
Exposure_Number: 5
Target_Name: PSFSTAR
Config: NIC2
Opmode: MULTIACCUM
Aperture: NIC2
Sp_Element: F160W
Wavelength:
Optional_Parameters: SAMP-SEQ=SCAMRR,NSAMP=2
Number_of_Iterations: 1
Time_Per_Exposure: DEF
Special_Requirements:
Comments:
Exposure_Number: 6
Target_Name: PSFSTAR
Config: NIC2
Opmode: MULTIACCUM
Aperture: NIC2
Sp_Element: F160W
Wavelength:
Optional_Parameters: SAMP-SEQ=SCAMRR,NSAMP=2
Number_of_Iterations: 1
Time_Per_Exposure: DEF
Special_Requirements: POS TARG 5, 5
Comments:
Data_Distribution ! Defaults indicated; change if desired
Medium: 8MM
Ship_To: PI_Address
Recipient_Email:
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