PHT25 (Single-Filter Absolute Photometry with a PHT-C Array Detector)
(July 4, 1995)
PHT25 (Single-Filter Absolute Photometry with a PHT-C Array Detector)
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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 This AOT:
o RASTER: (Y or N) Y indicates a raster map and N indicates a single pointing
observation. For a raster map, neither PICK-UP nor CHOPPING is allowed and
only filters available to one detector (C100 or C200) 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) = Frame of reference 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 the following ORIENTATION ANGLE has to be specified.
o ORIENTATION ANGLE = The angle of the raster orientation axis with respect
to the REFERENCE FRAME (N to E, 0-180 deg).
o FILTER: Select only one from the on-screen list (cf. ISOPHOT manual).
o SOURCE TYPE: P (point source) or E (extended source)
o FINE CALIBRATION SOURCE ON (Y or N): Y = using a FSC that is heated to a flux level to
be entered as REFERENCE FLUX LEVEL by the user (see the next parameter),
or N = unheated FSC at about 4K. To avoid a large detector drift, the
latter case is only recommended if rather low total sky flux levels are
measured (~10e-16 W).
o REFERENCE FLUX LEVEL: The value should be in the range of 0.1 to 10 (times the sum of
source and sky flux densities) for a heated FSC.
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
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.