PHT03 (Multi-filter Photometry with PHT-P Detectors)
(July 4, 1995)
PHT03 (Multi-filter Photometry with PHT-P Detectors)
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Prior to your visit at IPAC, for each target, please prepare the following parameters for
entry into the PGA:
==> Common Data for All AOTs (explained on a separate sheet).
==> Parameters for All Filters:
o PEAK-UP: (Y or N) Pick-Up flag for High Precision Pointing (HPP). If the nominal
spacecraft pointing accuracy (~ 12") is not enough, this flag should be
set to Y and the default option of picking up on a nearby bright source
should be selected.
o RASTER: (Y or N) Y indicates a raster map and N indicates a single pointing observation.
For the raster mode, neither PICK-UP nor CHOPPING is allowed and only filters
available to one detector (P1, P2 or P3) should be used. The following
parameters are needed for a raster:
o M = number of pointings along each raster leg (the orientation axis) (<=32).
o N = number of raster legs (<=32).
o STEP = Step sizes in arcsec in each of the two directions.
o REFERENCE FRAME (Y or N) = Reference frame for the raster map defined
with respect to either the spacecraft Y-axis (Y) or the celestial North (N).
In the latter case, the raster orientation axis may not be aligned with the
spacecraft Y-axis, and one has to specify the following ORIENTATION ANGLE.
o ORIENTATION ANGLE = The angle of the raster orientation axis with respect
to the REFERENCE FRAME (N to E, 0-180 deg).
o CHOPPER: (Y or N) Chopping (Y) or staring mode (N) for a single pointing observation.
Note: due to detector drift effect, chopping is not recommended for sources
that are brighter than the background, say, by more than a factor of 2 or 3.
The following parameters are needed for chopping:
o CHOPPER MODE: Rectangular/Triangular/Sawtooth.
o CHOPPER THROW: Select one from the on-screen list (cf. ISOPHOT manual).
o CHOPPER AVOIDANCE ANGLE (Y or N): If yes, specify the starting and ending
position angles (N to E). Note: since the chopping has to be along the
spacecraft Y-axis, a large angle here may tighten constraints on scheduling
this AOT.
o SOURCE TYPE: P (point source) or E (extended source)
==> Parameters for Each Individual Filter:
o FILTER: Select one from the on-screen list (cf. ISOPHOT manual).
o APERTURE: Select one from the on-screen list (cf. ISOPHOT manual).
o SOURCE FLUX DENSITY: Jy for a point source or MJy/sr for an extended source.
* UNCERTAINTY IN SOURCE FLUX DENSITY: Jy (point source) or MJy/sr (extended source).
Notes: this quantity determines the maximum expected source flux in the quantity
[(SOURCE_FLUX_DENSITY + UNCERTAINTY_IN_SOURCE_FLUX_DENSITY) + (MAX_BACKGROUND_
FLUX_DENSITY)], to be used in setting the detector dynamic range. Values up to 10
times the SOURCE FLUX DENSITY are allowed.
o MAXIMUM BACKGROUND FLUX DENSITY: In units of MJy/sr.
* S/N: Leave 0.0 if you want to enter the INTEGRATION TIME below or enter the requested
minimum signal-to-noise ratio.
* INTEGRATION TIME: Leave 0.0 if you have requested a minimum S/N ratio or enter the
requested minimum integration time. Notes: (1) For a single pointing observation
with or without chopping, this is the on-source integration time expressed in
a power of 2 seconds (if you input a non-power of 2, the software will round up your
value, e.g., 129 -> 256). (2) For a raster, this is the integration time per raster
point. (3) Because of the detector drift effect, a minimum (on-source) integration
of 32 sec is recommended to achieve a 5% accuracy in the relative flux calibration.
For a raster mapping over more or less uniform surface brightness, an exposure time
per raster point shorter than 32 sec may be used.