Program: HIFLUX
Purpose: derive fluxes and standard deviations from HIRAS images
File: hiflux.src
Category: IRAS
Author: Do Kester
Keywords:
*** MAPS= Max number of maps to be processed simultaneously [4]
All maps should be of the same size, and presumably of
the same field.
*** FILE= Name of output file [none]
The results are also written to the file.
INSET= Name of a set for which fluxes need to be determined [quit]
The program is written with sets in mind which were made
with HIRAS. There is no reason however that it would not
work with other datasets.
CLIP= As in VIEW (Actually VIEW is deputied.) [calculated]
BACKGROUND= Number to be subtracted from the flux [from INSET]
All sets made with HIRAS v5.0 and up, have the background
written as keyword ZEROLEVL in the header.
When LOCAL=y the value of the global background is overruled
by the locally calculated one.
*** COLIND= Color index for plot colours [standard]
*** LOCAL= Calculate local background [No]
The background is determined as the median of the points
within the form selected with SELECT=.
It is the users responsibility that the form is taken
large enough that more than half of the points fall in
the background. (But see also RADIUS=).
*** COOR= Transform positions to this coordinate system [from inset]
The coordinate system can be
EQUatorial
ECLiptic
GALactic
SUPergalactic
The first 3 letters are significant (case insensitive)
SELECT= The form of the area over which a flux is requested. [F]
P Point source, a form of fixed size of which only
the center is asked.
C Circle, a center and a radius is needed
E Ellipse, a center, two axes and a twist angle is
needed.
F Free form, defined by points entered by the user.
The keyword is case insensitive.
*** RADIUS= Radius of the point source in pixels [5.0]
When two numbers are given, the point source form will
be an ellipse with the given numbers as semi-axes.
When LOCAL=y the default for RADIUS is 10.0
*** ANGLE= Twist angle of the pointsource ellipse [0.0]
This keyword has effect only when radius is supplied with
two numbers.
It is measured counterclockwise from the horizontal axis
to the first item from RADIUS.
Description:
The program is written to calculate fluxes from maps made by
HIRAS, accompanied by the standard deviation of that flux.
Due to internal (anti)correlation between pixels on all
kind of scales, it is not possible to just add the pixels
from the standard deviation map quadratically. The standard
deviation map gives standard deviations for single pixels only.
To derive standard deviations for the areas where a flux is
requested, it is necessary that there is also a set containing
the 25 movie-sample-maps needed to make the standard deviation map.
The name of this set is _m
It is made by HIRAS when to the keyword MAPS= is added the
combination `mk' (= Keep Movie sample maps )
So the HIRAS keyword should be answered with e.g. MAPS= rsil; mk ;
Note that previously I thought one needed the the standard deviation
in the hidden space pyramids. THIS WAS JUST PLAINLY WRONG.
This present version of HIFLUX does not work any more on maps with
names like _s_h. I apologize for any inconveniences...
When started the program will ask for (a number of) set(s) which
will be displayed with VIEW. The last one will stay there to work on.
For each of the maps a background will be asked (BACKGROUND=).
And it is checked whether moviesample maps are present.
As all processing is done exactly the same way on all supplied
maps, it is possible to measure fluxes in all (IRAS) bands
simultaneously, using the same pixel locations throughout.
A cursor in the form of a cross (+) will appear on the display.
With the mouse the cursor can be moved to a position and one of
the following actions can be taken.
left button: add the position to the list
mid button: undo the previous button (if possible)
right button: add the position to the list and close the list.
'q' or 'Q' add nothing and close the list.
'x' or 'X' discard the list and close
'n' or 'N' discard the list and start anew (with another form)
What the points in the list mean, depend on the form which is
chosen with SELECT. For a point source (SELECT=P) only one
point in the list (the first) is relevant: it defines the center.
For a circle (SELECT=C) two points are needed: the first is
the center and the distance between the two defines the radius.
For an ellipse (SELECT=E) three points are needed: the center
and two distances which define the semi-axes. The direction
of the first semi-axis also defines the twist angle of the ellips.
In case of a free form (SELECT=F, default) the points are
connected into a loop, the last one connecting to the first,
and the inside of the loop is used. Crossing loops make funny insides.
With the keywords RADIUS and ANGLE the shape of a point source
can be changed. ANGLE only has effect when RADIUS is supplied
with 2 different numbers.
When there are no points in the list the program ends. Otherwise
it loops, asking new positions etc. The selected form can be
changed at any moment by typing an 'n'.
The form is transformed into a mask, with the size of the map,
containing ones inside and zeroes outside the form.
The flux is calculated by convolving the mask and the maps and
adding the pixels together, for each map separately.
The size of the pixels is taken in account and the result is
presented in Jansky, provided that the original map is in MJy/sr.
The positions which are reported are the position of the pixel
with the highest flux within the form, deprojected and transformed
to the coordinate system of choice.
When LOCAL=y the median over all points within the form is taken
as the (local) background. Multiplied by the number of points in
the form it is subtracted from the flux.
For the standard deviation of the flux contained in the form
the mask is used on each of the movie sample maps. The variation
in the resulting fluxes defines the standard deviation in the
usual way. This standard deviation might seem to be low but
remember that it only reflects the internal inconsistency in the
data. Nothing can be calculated about systematic errors in the
calibration. For this I refer to the IRAS Explanatory Supplement.
When no moviesample maps are present and LOCAL=y then the
standard deviation is equal to 1.5 times the distance of the
median to the lower quartile, multiplied by the sqrt of the number
of points in the form. This latter standard deviation should be
interpreted with the utmost care as it only reflects variations
in the background. It has no information at all about the source
itself. For that movie sample maps are necessary.
Updates: 1.0 06 Oct 1993 Do Kester.
2.0 31 Jan 1995 Do Kester, now working more properly on
movie sample maps.
3.0 07 Oct 1996 DK, added multiple maps, local background,
better mouse handling, file output.
3.1 22 Oct 1996 DK, option for coordinate system of choice
flux conversion corrected (was wrong in v3.0)