18 Dec 2002: Instructions for relinking the deimos package are now available. Also, in porting the package to a MacOSX system, I have found several small bugs which may cause problems on Linux systems (but I haven't heard of any such problems); these will all be fixed in the next release.

24 Sept 2002: Anyone who picked up Rev 0b between Sep 20 and Sep 23 should re-install it; there were two map files which were not updated, so the guider astrometry was old, not updated as advertised!

20 Sept 2002: The next mini-release is now available (Rev 0b); it contains several small extensions. The only modification to results is that the guider astrometry offsets are now included. Also note that the Linux version was compiled under RedHat 7.x (7.2?). Main changes:

• Guider astrometry updated, and is printed out reversed to orient it correctly to the guider image display.
• an additional limit check has been put in place to handle a recently-discovered limit on the cut corner.
• Graphics key 't' will toggle the PCODE of a star between alignment and guide star.
• Graphics output prints the full data line to the text screen and a shorter (but better annotated) information line to the graphics screen.
• The Guider Field center is printed out in case anyone wants to use, eg, the DSS to make images of the guider field.

Update (26Aug2002): NB! The TV astrometry in the mask-design code is NO LONGER CORRECT as the DEIMOS PXL camera was moved during repairs. Alison Coil reports that offsets of +2 X and +19 Y are needed.

Update (21Aug2002): First modified release (Redhat Linux 6.1 included) is now available. Follow instructions below.

How to Retrieve/Install

ftp ftp.ucolick.org		# login anonymous
cd pub/users/phillips
binary
get deimos_rev0b.tar
quit

tar -xvf <tarfile> 

setenv deimos /<path...>/deimos/

set deimos = "/<path...>/deimos/"
task deimos = deimos$deimos.cl

cl>   deimos

DEIMOS slit masks will be milled at UCO/Lick for the duration of the shared-risk period, and possibly for a short time beyond. We are still experimenting with the optimal way to fabricate these masks. In addition, the mask-design and alignment tools are not yet finished at the level we would like them to be.

Planning: The Lick shops ask that they be given no more than 6 masks per day for milling. Thus, please plan on 1 weeks + N/6 working days (M-F), where N=number of masks, at a minimum. The Shops have also requested a minimum of 2 weeks (if this is more than the previous equation) unless special arrangements have been made in advance. This allows the Shops time to schedule the mill, fabricate the masks, and Fedex the masks to Hawaii in time for the run.

Overview

Fabrication Considerations

Second, there is a minimum slit width that can be milled with a given endmill. Due to various limitations, the shops strongly prefer to use 0.015-inch-diam ("15 thou") endmills. As the plate scale is 0.728 mm/arcsec, this places an absolute minimum of 0.524 arcsec on the available slitwidth; however, if tilted slits are used, the minimum in the dispersion direction is inreased by 1./cos(theta), where theta is the PA difference of the slit wrt the mask PA.

In addition, it is good to bear in mind that the slitlets are actually milled in a multi-pass manner at present, producing a relieved pocket around each slitlet, and allowing a clean-up cut to be made along the edge of each slitlet. The width of that clean-up cut must be factored into the effective endmill diameter if the user wishes it to be made (strongly advised); this width is currently set to 0.038 mm (each side), so the effective diameter of the endmill is 20% larger.

Requests for endmills other than the preferred (15 thou) size requires code development and debugging and such requests will only be accepted by special arrangement.

Magnified view of DEIMOS slitlet, showing actual slitlet and relieved pocket. The pocket is cut without an additional cleanup cut, and thus is significantly rougher than the actual slitlet cut. The slitlet in this case was cut (experimentally) with a 12-thou endmill, and is 0.6 arcsec wide.

Steve Allen watches a DEIMOS slitmask being milled at the UCO/Lick shops.

Closeup of the high-speed mill cutting slitlets.

Mask Design Tools: DSIMULATOR

    objfile = "t1103.sim"     input file of targets
     output = "draco1.list"   output list selected/non-selected
        mdf = "draco1.fits    Mask Design File (FITS)
  (plotfile = "draco.mng")    (opt) plotfile [Mongo commands]
       (ra0 = 0.005)          Initial RA of field (hr)
      (dec0 = 0.)             Initial Dec of field (deg)
       (PA0 = 180.)           Initial PA of field (deg)
   (equinox = 2000.)          Equinox of coordinates
       (ha0 = -1.5)           Initial Hour Angle (hr)
  (min_slit = 8.)             Minimum slit length (arcsec)
  (sep_slit = 0.5)            Separation between slits (arcsec)
(slit_width = 0.75)           Width of slit (arcsec)
    (box_sz = 4.)             Alignment box size (arcsec)
      (blue = 5000.)          Shortest wavelength of interest [NOT USED]
       (red = 9000.)          Longest wavelength of interest [NOT USED]
  (proj_len = no)             Project slit length to preserve in spatial directi
(no_overlap = yes)            Adjust slit lengths to avoid overlap? (YES)
(std_format = yes)            Is input standard text format?
(lambda_cen = 7500.)          wavelength for refraction
      (temp = 0.)             Air temp (C)
  (pressure = 620.)           Air pressure (millibars==hPa)
    (author = "Drew Phillips <acp@ucolick.org>") Designer of Mask (name <email>)
  (observer = "Sandy Faber <smf@ucolick.org>")   Observer (name <email>)
   (project = "Astrometry--Commissioning")       Project name
    (maskid = "Draco_Astrometry_1")              Full Name of Mask
   (guiname = "DRACO1")       Name of Mask for GUI (6 char or less, no whitespace)
   (dateobs = "2002-07-03")   Date of intended use (YYYY-MM-DD)

ra0, dec0, equinox and PA0 may be entered via the input file (see below).

** Input File Format

Required Fields:

• Values >0 act as weights in selection of program targets (ie, priority = 1000 has twice as much weight for selection as priority = 500);
• -1 indicates a guide star;
• -2 indicates an alignment star;
• 0 goes along for the ride (do not use for program targets!);
• others ignored.

Optional Fields (order is important):

There is currently no plan to calculate proper motion in the mask design tool.

Optional field center line: RA, Dec, standard_equinox and PA for the overall mask may be entered as the first non-commented line of the input file, provided it is of the form:

Name       RA    Dec    Equinox   PA=xxxx

To aid the alignment process, the slit-mask design tool outputs the expected guider coordinates of any object labeled "guide_star". These should be noted and brought to the telescope. [Currently needs updated mapping; astrometric analysis in progress.]

** Current limitations of DSIMULATOR

** Running DSIMULATOR

Also, note the information box. In addition to the standard DEIMOS axes and a compass rose, there is a section of slit (with default slit-width) shown along with a "dispersed" image, at min, central and max wavelengths. For convenience, the seeing disk plotted is the same as the slit-width. This information is useful for deciding acceptable mask PAs to avoid large slit-losses from atmospheric dispersion:

Keystrokes are used for positioning the mask; adding, deleting and auto-selecting targets; and generating slits. To see available options, type '?':

DSIMULATOR Command Summary:
 
     hjkl     translate mask (1" x speed) in the usual vi ways
     p/n      rotate mask (1 deg x speed) in a Pos/Neg sense
      .       cycle through speeds (10, 1, 0.1) for pnhjkl keys
      z       zoom (by abs factor; also 0 reset, -1,...,-5 for CCD1-4,TV fields)
      a       Add a target
      d       Delete a target
      r       Redraw
      i       Clear (initialize) the list of ALL selected objects
      s       Select workable set of objects
      g       generate slits to go over selected targets.
   <space>    print input line of nearest object
      ?       print this list
      q       quit
      I       interrupt task immediately

[09Aug: I will try to give more details on these keystroke commands shortly...]

In normal operation, the user first positions the mask on the sky using the translation commands (h j k l, in the usual vi sense, to move the mask on the sky) and rotation commands (p n, for position and negative rotations). The size of these moves is controlled by '.', which cycles through fast/medium/slow speeds (ie, large, medium, small steps).

Next, an "auto-select" ('s') is usually done, as this will try to maximize the sum of the object priorities without creating any overlap conflicts. The user may add ('a') or delete ('d') targets. "Space bar" will print information about the target nearest the cursor. Also useful here is the 'z' command, which replots the data centered on the cursor with the absolute zoom factor specified. There are also some special values defined: zoom_factor = 0 replots at normal scale; -1, -2, -3, -4 and -5 zoom in on the sections for CCDs 1, 2, 3, 4 and the TV field, respectively. The standard plot buffer commands, such as Z, P, E, etc are also useful.

Make sure that alignment stars and at least one suitable guide star are selected!

When the target selection is made, type 'g' to generate the slits, which will be overplotted in cyan:

By default, slits are lengthened to where they nearly touch each other (the slit separation is a parameter, for which 0.5 arcsec is currently recommended). In cases where overlap would occur, by default the slits are shortened to avoid overlap. In the plots, both the object (drawn to show the requested slit length) and the slit appear, so it is immediately apparent whether slits have been lengthened or truncated.

You can add and delete objects after slits have been generated; just do another 'g' after the desired modifications. Note that all selected objects will be given a slit, but slits may be badly truncated for objects very close to one another. Also, avoid allowing slits to be lengthened too much (say over 100 arcsec) -- really long slits may weaken the mask and cause a jam upon insertion. In these cases, it is best to create some new targets in empty regions and add them to the input list; these can be randomly-placed sky slits.

The final step is 'q' to quit, at which point the MDF FITS file is generated, as well as the output text file and the optional plot file. Note that the output text file has four sections:

These are all (* the TV section is commented out) in the same format required for input, so it is easy for the user to, eg, contruct new input lists with only objects that have not been selected. The first object is recognized as the field center if it has a field "PA=nnn" in place of magnitude. Note that this line is also properly formated for the Keck starlist, provided the colons are replaced with spaces.

** Known Bugs

In brief, select the MDF to be submitted and hit "Send"; then hit "Sanity" and the file will be checked for any syntax errors -- there should be none, and you will see "ALL IS WELL" printed toward the bottom. Then hit "Ingest" to place the file's information into the database. You must go through all these steps; it's currently a bit painful but we are working on streamlining it.

NB: All mask authors, observers and submitters must be recognized by the database -- you must go to the above link and "introduce" yourself (and relevant others) before attempting to submit MDFs. This is a one-time effort. Also, access to the mask submission pages is only granted to approved sites/networks. Even after you have registered as a mask user, you will not be able to access the mask submission pages from any random host -- only from hosts on approved networks. To request that your home institution be added to the list of approved networks (if it is not one already), send mail to slitmasks@ucolick.org.

Slitmask status and inventory can be monitored through the same URL.

Date: Wed, 7 Aug 2002 14:26:50 -0700
From: Steve Allen 
To: "Andrew C. Phillips" 
Subject: DSIMULATOR

Drew,    

every time I see DSIMULATOR I read  
desanguinator

Fortunately I am somehow spared a contemplation of the other three
ancient humors.