The PREP Package

Working Draft! (Currently under edit)

Overview

The prep package is a set of IRAF tasks for designing LRIS slitmasks and creating the files necessary for mask fabrication. This process has been evolving for some time, but now appears fairly stable. This software assumes you have precessed all coordinates to a common equinox, and have applied any proper motion for the epoch of observation. This software is designed around the box/star alignment strategy, and enables use of the "pickoff mirror" attached to the bar if you want to guide directly off the mask.

Here's the famous pick-off mirror as seen by the LRIS slit-viewing camera:

Tasks 

pr> fabmask     gen_igi     mapmask     qmask_plot  simulator

Notes for Use (Temporary)

SIMULATOR is the graphical task for sample selection. This task changed recently: after the RA and DEC of the objects, it needs the individual PA and length of the desired slits (use INDEF or leave blank if you don't care, that is, if you want vertical slits of minimum length).
MAPMASK converts the output from simulator into slitmask coordinates and places slits over the objects. Unlike AUTOSLIT, this task _will_ place a slit over each input object even if it violates minimum slit lengths requested. The output file is similar (but not identical) to the "setup" file of AUTOSLIT.

Currently, you must hand-edit the priorities of the guide star (-1) and the alignment stars (-2).

FABMASK actually produces the files sent to Keck. There are two format options: "punch" and "mill" -- the mill is currently in use, so you should select this option. Input is the output file produced by MAPMASK, and you may modify slit lengths, etc., in the input file before running this task.

SIMULATOR:

This is the layout of the graphical display, with no objects or slits shown. Note that slits outside the white area (or under the pickoff mirror) will be occulted.

Here the objects in the input file are displayed; no objects have been selected yet.

These are the symbols used in SIMULATOR:

[This following is very old:] 


Here are MY parameter files; some of the parameters are not too obvious,
unless you're familiar with the procedure:

# simulator:
      objfile = "2a.test"       file of primary objects (NORRIS w/: )
         (ra0 = 14.2953)        Initial RA of field (can be in hh:mm:ss.ss)
        (dec0 = 52.48)          Initial Dec of field
   (other_obj = "")             file of other objects (NORRIS w/: )
      (output = "")             output list (AUTOSLIT input)
          (ha = )               Initial Hour Angle
    (exposure = 1.)             Total Exposure (hours)
    (min_slit = 12.)            Minimum slit length (arcsec)
        (slit = 1.1)            Width of slit (arcsec)
        (blue = 7500.)          Shortest wavelength of interest
         (red = 9000.)          Longest wavelength of interest
  (dispersion = 1.28)           Dispersion in A/pix
          (x1 = 1.)             Min. X (mm) for mask punch
          (x2 = 185.)           Max. X (mm) for mask punch
          (y1 = 1.)             Min. Y (mm) for mask punch
          (y2 = 335.)           Max. Y (mm) for mask punch
(long_slit_mo = no)             Long slit (vs. slit mask) mode
       (coord = "")             graphics cursor input
           PA =                 [PA of mask]
        width =                 [width of field in arcsec]

where input files (objfile,other_obj) look like this
(ID            priority mag     RA           DEC        PA   min_bot min_top):

CENTER          9999 1950.  14:17:41.10   52:27:45.00  
06:3:36:58:23.5  500 23.53  14:17:53.91   52:30:23.03  INDEF 10.0   10.0
08:4:31:11:22.4  500 22.43  14:17:38.85   52:27:20.80  
10:4:40:24:23.L  500 23.07  14:17:27.00   52:24:50.93  25.   14.    18.
REFER_OBJ         -2 10.00  14:17:41.10   52:27:45.00  

(Note that the "CENTER" line is optional here.)

-----------------------------------------------------------
# mapmask:
      objfile = "try1"          file of objects
       output = "mask.out"      output file
          ha0 = 0.              Hour Angle
  (lambda_cen = 7500.)          wavelength for refraction
        (temp = 0.)             Air temp (C)
    (pressure = 615.)           Air pressure (mm Hg)
   (lower_min = 5.5)            Minimum length below object (arcsec)
   (upper_min = 5.5)            Minimum length above object (arcsec)
      (box_sz = 4.)             Alignment box size (arcsec)
     (prescan = 42.)            Columns of CCD prescan
     (verbose = )               slit review option (y/n)
        (mode = "ql")           

where input looks like this:

CENTER   9999 1950.0  0:14:42.32   15:29:06.8   53.0
4170     1500  23.00  0:14:29.20   15:28:01.77    40.0     7.5  7.5 
4649     1500  23.70  0:14:38.04   15:28:54.59    45.0     7.5  7.5 
4939     1500  21.80  0:14:42.80   15:29:23.61    57.9     7.5  7.5 
	...
B1781    1000  22.40  0:14:49.906  15:32:20.98
B0651    1000  21.60  0:14:41.701  15:29:07.13
4337     1000  23.43  0:14:26.345  15:28:21.10
GS         -1  20.    0:14:38.34   15:29:42.69
4910-AS    -2  19.13  0:14:33.311  15:29:21.35
6794-AS    -2  19.55  0:14:49.304  15:32:16.14
6208-AS    -2  20.14  0:14:52.585  15:31:21.29

(Note the mirror and mask-alignment stars have specific priorities.)

-----------------------------------------------------------
# fabmask:
        input = "mask.out"      input file
       output = "fab.out"       output file
      (format = )               output format (lick|keck)
   (tool_diam = 0.8)            tool diameter (mm)
 (punch_width = 0.5)            punch width (mm)
      (double = no)             double punch?
       (x_zpt = 0.)             X zeropoint offset (normally 0)
       (y_zpt = 0.)             Y zeropoint offset (normally 0)
        (mode = "ql")           

where input file looks like this:

###########
##
##     MAPMASK:   INPUT = try1
	...
##
## Xobj   Yobj     Ymin    Ymax   Rel_PA  CCDx   CCDy  Code  Mag  ID
##
124.724   9.544   15.291   3.500   2.50  1172.9 2105.9 1500 23.20 6376
172.458  19.506   21.657  15.291   0.00  1475.6 2041.6 1000 22.40 B1781
120.661  23.108   24.558  21.657   0.00  1147.1 2018.4   -2 20.14 6208-AS
173.516  26.661   28.111  25.210   0.00  1482.3 1995.4   -2 19.55 6794-AS
124.826  39.581   47.660  31.344   8.00  1173.5 1912.0 1500 21.60 6107
 86.788  53.584   56.116  47.660   0.00   932.3 1821.7 1000 22.40 B1043
	...
122.994 314.309  317.946 310.932   0.00  1161.9  139.1 1000 23.06 B0099
182.155 321.582  332.000 317.946   0.00  1537.1   92.2 1000 23.43 4337
154.149 185.479  185.579 185.379   0.00  1359.5  970.5   -1 20.00 GS


==============================================================================
Yet more info -- the cookbook approach (based in part on the Aug 95 run):


I.  Edit and Run	cl < sim1.cl

where sim1.cl looks like this

# Mask 1  0:14:42.32  15:29:06.8
simulator.ra0=0:14:42.32
simulator.dec=15:29:06.8
simulator.red=8000.
simulator.blue=7000.
simulator.PA=53.
simulator.ha=0.
del tmp1,tmp2,tmp3,try1
sim mask1.sim oth=""				# Demonstration; verify center
sim mask1.sim oth=cat/bnoz.sam out=tmp1 	# Select primary, next priority
sim tmp1      oth=cat/i.sam    out=tmp2 	# Select primary, next priority
sim tmp2      oth=cat/f.sam    out=tmp3 	# Select primary, next priority
sim tmp3      oth=cat/b.sam    out=try1 	# Select primary, lowest prior

# Note that the input file, mask1.sim, has slit lengths and PAs added as needed.
# This script is used to select targets from different priority catalogs -- the
highest priority objects belong to "mask1.sim", the next are in "cat/bnoz.sam",
etc, until the lowest priority, "cat/b.sam". Each time simulator is run,
the first thing you do is select all of the primary targets -- that's
to say, you want to KEEP all the primary targets, and fill in additional
targets from the secondary list.  In this way you can build up the mask
from highest--to-lowest priority objects.  For simpler cases (all objects
are from the same general catalog) you can just run simulator once, rather than
creating a cl-script for multiple passes. Note that each catalog can have its
own set of internal priorities.  The automated select function in simulator
will use these priorities while selecting objects, attempting to maximize the
sum of priorities appearing on the mask.

(Note added 07 may: There's now a "remain" parameter in simulator,
which, when given a file name, will produce a list of target objects
which were _not_ used. This is useful for designing several masks
which cover the same area of the sky.)


Ia.  Edit the output ("try1") to update priority levels -- alignment stars (-2),
pickoff mirror guide star (-1)


II.  Run	mapmask try1 map.out verb+ > map.review
				or
		mapmask try1 map.out verb+ | page


IIa. (opt)  Edit output (map.out) to adjust any slit ends as desired.
IIb. (opt)  Run qmask_plot to get plots of the mask as designed.


III.  Run	fabmask map.out mask.ascii form=lick tool_diam=0.43

# The value of "tool_diam" depends on the slit-width desired.


IV. Write the file(s) to diskette:

!fdformat -db LRISMASK
!/home/taiyang/wirth/bin/mwrite -t mask1.asc a:
!/home/taiyang/wirth/bin/mdir
!eject


V.  Relax, you're done.

=============================================================================

SOME MISCELLANEOUS NOTES:
Your guide star should be something suitable for guiding on (see the LRIS
documentation; we've been quite successful with objects around 19-20 mag in
R).

Alignment stars should be in the range of 19-21 R magnitude, for alignment
exposures of 30--60 sec.  Remember, for the alignment box method you want
both good _stellar_and_sky_ signal. Outside of the stated magnitude range,
there's a poor balance between sky and star. Fainter stars require longer
exposures, brighter can saturate. It's better if the alignment stars are all
of similar magnitude as well.

SIMULATOR shows the outline of the pickoff mirror, but in addition there
is a frame to the mirror which is _not_ shown.  This frame projects 12 mm
from the edge of the mirror toward the center of the mask -- thus, you should
avoid selecting objects that are within about 15" of the left edge of the
mirror.  Simlarly, the mirror frame extends a fair distance along the
bar on either side of the mirror:
	                  **                         **
		  BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
		  BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
			|||||||||||||||||||||||||||||||||
			|||||||||||||||||||||||||||||||||
			     |||||||mmmmmmmmmmmmmm
			     |||||||mmmmmmmmmmmmmm    
			     |||||||mmmmmmmmmmmmmm    
			     |||||||mmmmmmmmmmmmmm    
			     |||||||mmmmmmmmmmmmmm    
			     |||||||mmmmmmmmmmmmmm    
			     |||||||mmmmmmmmmmmmmm    

where B=bar, m=mirror, |=frame;  the extension is where the mirror is
bolted to the bar (**=screw head).

Standard Disclaimer

This software was written by Drew Phillips at Lick observatory for the private use of the DEEP team at UCSC. It is available for other users on a "use-at-your-own-risk" basis. It is not official Keck software nor is it supported by them, so don't bother them with questions/complaints. Send comments to phillips@ucolick.org.
Andrew C. Phillips / Lick Observatory
Last modified: 17 feb 99
phillips@ucolick.org