markstds - interactively mark apertures for standard star photometry
markstds image [z1] [z2] [redispl] [radstr] [append] [refstar] [verbose]
- image = ""
- Image to display and mark (standard) star apertures in
- z1 = INDEF
- Lower cut level for displaying 'image'
- z2 = INDEF
- Upper cut level for displayimg 'image'
- redispl = yes
- (Re)display image before marking apertures?
- radstr = "11,50,60"
- Comma separated list of the radius in pixels corresponding to 7 arcsec
(Landolt's standard measurement aperture), and the inner and outer radius
of the circular annulus to use for measuring the sky background. The
default values were appropriate of a particular camera with ~0.64" pixels.
- append = no
- Append to an existing position file?
- refstar = ""
- Optional name of the main (naming- or reference-) star in the field. Default
is to use the image root name, but 'refstar' will override this behavior.
- verbose = yes
- Print warnings and messages?
Task to interactively mark measurement apertures and sky annuli for
(standard) stellar aperture photometry on an image display by pointing at
the center of each star to be measured. This task does not actually
perform the aperture photometry, but interactively produces a coordinate
list that is acceptable as input when running 'digiphot.apphot.(q)phot'
non-interactively in batch mode. The explicit overlay of the apertures
and sky annuli may help in avoiding possible problems of overlap of
sources or poor sky background determination.
After displaying the image (if the image is already displayed and
'redispl = no' this step is omitted), a cursor cross or circle will
appear in the display (the cursor shape may depend on the application
used to display images, e.g. 'ximtool', 'saoimage' or 'ds9'), signaling
that the task is ready to receive input. The acceptable key-strokes
are 'c' to mark the center of a star. A small plus-sign will appear if
a key-stroke was accepted. When all stars have been marked, hitting 'q'
will exit the task.
The task will subsequently overlay and label all marked apertures and
sky annuli on the display. The name of the output coordinate file will
be constructed from the input image root name and will have the extension
If 'append=yes', one may append to an existing coordinate file (if for
example some stars were missed after a first pass), otherwise the task
will rename and save the existing files by appending a tilde '~' to their
Mark all standard stars in an image of a Landolt field:
rj> markstds a0032.MarkA_V.fits radstr="19,81,100" refstar="MarkA"
MARKSTDS: NOAO/IRAF2.12.2 raj@hasnap Mar 25 22:16:48 2005
image = a0032.MarkA_V.fits [1000 x 1000]
Wait for the cursor cross to appear in the image display area, then mark
all (standard) stars in the image using the 'c' key. Hit 'q' to quit.
Note: start with the main (i.e., naming or reference) star in the field.
(mark all stars)
This is not really a bug in 'markstds', but with either 'ds9' or the way
IRAF communicates with external display applications like 'ds9' via 'xpa':
after marking the center of a star, one needs to move the cursor (a 1 pixel
move with an arrow key suffices) in order for the mark on the overlay of
the object just entered to be drawn. I have not tested 'ds9' in combination
with imtool pipes, so do not know whether this "feature" is due to 'ds9' or
due to 'xpa' needing an event before requesting an update of the display.
This problem has sofar only surfaced when using 'ds9'.
tvmark, chkimg, sysinfo, gdate, xdisplay