MOIRCS Mask Design Program Manual

0. Introduction
1. Preparation
2. MDP Startup
3. Mask Design
4. Save the images
5. Submit the results
6. Acknowledgment

0. Introduction

"MDP" is an abbreviation of "Mask Design Program". This software provides a graphical interface for interactive designing of the custom slit mask of the MOIRCS Multi-Object Spectroscopy "MOS" mode observation, and will be used by open-use observers.

This document describes the usage of the MDP program.

1. Preparation

1.0 System requirement

1. Computers with Unix / Linux / Solaris or related OS is required. Performance on the Mac OS is not confirmed. MDP program does not work on the Windows 2000/XP.
2. The IDL Virtual Machine (IDL VM: ver. 6.3 or higher) is required to run the MDP program. IDL VM is a free software and runs on the various OS without IDL. Please download and install a most recent IDL VM to your Linux/Unix computer (not Windows!). IDL VM can be downloaded from the following web site.
   IDL Virtual Machine ( http://www.ittvis.com/idlvm/ )
   Note that the IDL VM sometimes fails if the version of your Linux is too old or too new. Please ask the ISS Support Desk about the failure.
3. Ask the MOIRCS Support Astronomer (SA) for current MDP program file ( wmdp_moircs.sav ) for IDL VM.

1.1 Preparing the images

Usually we take some images of your MOS fields for mask design ("preimage") on 2 to 4 months before your MOS observation. Please read the document about the detail of how to prepare for preimaging observation.

1.2 Target selection

• Choose your targets on a distortion-corrected, mosaicked MOIRCS image. The image should be the one or similar to the one that are prepared using the software which the MOIRCS SA provide when preimage data is ditributed^(Note).
• Find detector coordinates ( X, Y ) of your targets on the mosaicked images with an unit of PIXEL.
• Use your favorite FITS image viewer (e.g., SAOimage, ds9, Skycat) to find out the object coordinates.
  Note:
  The use of a mosaicked image by FOCAS may also be used under wmdp_moircs.sav (the use should be under your own risk). Please reverse the FOCAS "bigimage", which is the distortion-corrected mosaicked image properly processed using the FOCASRED software, along the X-direction, then change the pixel scale of the reversed image to that of MOIRCS image (from 0.1038 arcsec/pixel to 0.1170 arcsec/pixel). The procedure afterwards should be basically the same as the one descibed below. Any mistakes during the image processing will cause the failure of the MOS observation. Please try with caution.
  Suprime-cam image case should also be similar, under the condition that the images are properly reduced using the distributed software "NekoSoft" or "SDFRED" and has been taken in red (5000-8000 Angstrom) bands. In Suprime-cam sase, the pixel scale is 0.202(arcsec/pix) so again please resample the image to 0.1170/pixel. You do not need to reverse in x direction. We do not recommend to use the areas that are away from the Suprime-cam optical center for mask design.

  The use of your own image taken by other instruments, after registering it to the MOIRCS preimage (e.g. by IRAF geomap: use "fitgeo=general, with fitting order equal or larger than 3.), is recommended. Please be careful not to choose the stars that are so bright in K (< 14 mag.) for the Alignment Stars, because it may be saturated and unusable during the mask alignment procedure.

1.3 Creating *.mdp file

Make your input file for the MDP program (.mdp file). The .mdp file contains the information on the slit position and shape of your targets. This file is not always required to prepare beforehand the mask design because you can design all slits interactively within the MDP program. However, we recommend to prepare the basic design beforehand and then revise it using the program because, though it is rare, the inaccurate positioning case has ever been reported.

• Mask design file ( *.mdp ) is a simple ASCII file specifying object coordinates (or the slit center in X, Y), slit width, length (all in pixels), and the slit angle.
• Format of the MDP file:

Obj1-X[PIX] Obj1-Y[PIX] Length1[PIX] Width1[PIX] Angle1[DEG] 1 B, comments...
Obj2-X[PIX] Obj2-Y[PIX] Length2[PIX] Width2[PIX] Angle2[DEG] 1 B, comments...
Obj3-X[PIX] Obj3-Y[PIX] Length3[PIX] Width3[PIX] Angle3[DEG] 1 B, comments...
.
.
.
Star1-X[PIX] Star1-Y[PIX] 30(HoleSize)[PIX] 30(HoleSize)[PIX] 0 0 C, Alignment Hole
Star2-X[PIX] Star2-Y[PIX] 30(HoleSize)[PIX] 30(HoleSize)[PIX] 0 0 C, Alignment Hole
Star3-X[PIX] Star3-Y[PIX] 30(HoleSize)[PIX] 30(HoleSize)[PIX] 0 0 C, Alignment Hole
.
.
.

• The form must be one object per line.
• Slit angle is defined in the detector coordinates (not in the SKY coordinates) and is expressed in degree whose positive/negative direction is in a normal geometry (counter-clockwise). For example, Angle = 0 for normal slit (perpendicular to the dispersion axis), and 45 degree for the tilted slit whose right side is raised by 45 degree in the MDP program^(Note1).
• Although angle for the alignment holes has no meaning, explicitly specify "0" in the file for consistency. Also, you need to specify two diameters for the alignment stars. Please use the diameter of 30 ( pixels = about3.5" diameter ) for alignment hole.
• Slit/Hole shape is specified by "B," for box=slit or "C," for circular=alignment hole.
• All remaining characters after the shape parameter (B, or C, ) are regarded as a comment. But please keep a space after ",". Comments can be reviewed within the MDP while editing the mask, and might be useful in deciding which slits to be chosen.
• Alignment holes can be added within the MDP program, and you do not have to specify the alignment holes in *.mdp file.
• For the alignment stars, you must put "Alignment Hole" in the comment fields.
• MDP's coordinates start from one ( 1 ). FITS viewers such as SAOimage and Skycat also use the coordinate start from one ( 1 ), but some softwares such as IDL use the coordinate start from zero ( 0 ). Therefore be careful in making the *.mdp file based on the coordinates measured with these viewers.
  Note 1:
  If you want to put the tilted slits on your mask, you will need a special care for the design because your targets on tilted slits will run away when we do the dither observation. To avold it and to observe in maximum effeciency, you can put the identical tilted slits in the same separation as the dither length along the spatial direciton synmetrically to the pointing position, in order to keep the target always on either of these tilted slits during the dither.
  In case of the tilted slit, the slit width defined here (Width#) means the slit width projected into the dispersion direction (to keep the effective velocity resolution to the same for all slits with various tilt angle), and the slit length (Length#) means the projected length on the X coordinate. Be careful.

  In order to avoid possible mistakes, please proceed the design under the discussion with the SA.

2. MDP start-up

1. Type "idl -vm=wmdp_moircs.sav" in your computer.
2. Click IDL logo window, and the MDP program window shows up.
3. Select [ File ] - [ Read FITS image ] from the pull-down menu, and select a mosaicked FITS image in a pop-up window.
4. A FITS image will show up when you click "Auto-Intensity Scale". You can change the display range by "Change Intensity Scale".
5. Select [ File ] - [ Read MDP file ], and select a MDP file you created as shown above in "Input MDP file" window.
   If you do not have a MDP file, just push "Cancel" button for interactive mask design for all slits. In this case, one dummy slit will be set.
6. Select [ Option ] - [ Grism select ], and select an appropriate grism in "Grism Selection" window.
7. Click on "Redraw" or "Draw Slit" buttons to see the image and the slits.
8. Now you are ready to start editing the masks.

2.1 Explanation of the Main MDP window

Click for detail.


1. Pull-down menus
   - File : Tasks for file I/O.
   - Option : Grism selection, Set parameters for slits and holes, etc.
   
2. Main window
   Your FITS image is shown in the detector coordinates (pixel), not in the sky coordinates (NSEW).
   Wavelength is in vertical direction. See also this figure.
   upper detector ( detector 2 ) : upper=redder, lower = bluer)
   lower detector ( detector 1 ) : upper=bluer, lower = redder)
   Items shown in above figure:
   - Main FITS image display (entire view of the image at reduced size)
   - Slit marker (small elongated rectangle on targets)
   - Spectra marker (long rectangle elongated vertically)
   - Slit ID number (small number just right of the slit markers)
   - Slits available area (large circle showing the available area for slit cutting)
   - Center line of FOV (Continuous line at the center)
   - Edge line of detectors (Dashed lines upper and lower of the center line. Upper one is a edge line of the detector 1 and lower one is that of the detector 2.)
3. Mode selection switches
   - Object pick-up mode (apply Gaussian fitting on the image around the clicked position, or simply adopt the clicked position as a final position)
   - FOV circle display switch
   - "Slit ID display" switch does not work, and the slit IDs are always shown on the main display.
4. Zoom image display
   Display for zoomed (non-reduced) FITS image around the selected region for slit review. This display is also used for object selection by mouse.
5. Buttons for controlling the image display
   Display intensity adjustment, image redraw button, etc.
6. Buttons for slit editing
   Buttons for editing slits and alignment holes.
   
7. Information panel
   Panel showing default slit parameters and current mouse positions.

3. Mask Design

In the followings, detailed procedures on how to design the mask interactively is described. We recommend to design your masks following the order as we show below. Of course, you may repeat any tasks until you are satisfied with your design.

3.1 Adjusting intensity scale

You may want to adjust the intensity scale of the FITS image display to see faint targets. In this case, push "Change Intensity Scale" button, and input new MIN and MAX cut-off levels for the image display. This setting is for both the main and sub (zoom) windows.

3.2 Set pixel scale and the mask center position

From version 2007-07-04, the default pixel scale has been set to 0.1170. So you do not need to care about it if you reduce the data using QMCS package. But if your preimage data is not regular one, you MUST change the pixel scale value manually from "Option" -> "Pixel Scale".

If you are using the older version of wmdp_moircs, you first have to set the pixel scale. Select "WCS" then "SET FOV CENTER" from the menu. You will see the pixel scale box at the bottom. Edit here accurately to 0.1170. As wmdp_moircs also calculates the pixel scale from the wcs information on the image header, sometimes very close values may already be there. But please anyway change the scale accurately to 0.117.

Set the center coordinates of the mask. Currently the default values for FOV center has been set to (X=1084, Y=1786) considering the actual spectral data, rather than the center of the mosaicked image (1024, 1786). Sometimes you may want to shift the mask FOV center position for optimal slit distributions within a mask, e.g., to avoid any spectra fall out of the detectors or on the insensitive gap between the chips and to maximize the number of slits. You can change the mask center position, but huge shift is not recommended (try under your own risk).

If you change the FOV center position, then the RA, DEC coordinates for the MOS pointing in the observing nights also need to be modified accordingly. You will have to measure the field center coordinates by yourself ^(note). The wcs value shown on the wmdp_moircs display also doesn't work correctly in current version. You will need to submit a list of new RA, DEC coordinates together with mask design files (see below) to the SA when they are ready.

Note:
Currently the FITS WCS coordinates of the mosaicked image is not accurate and do not work correctly. Please check the coordinates carefully.

Operation

1. Click a "Draw FOV" button. (Sometimes you need to click it twice.)
2. Input center coordinates ( X, Y in pixels ) of the FOV in Xcen and Ycen boxes.

3.3 Design of alignment holes

Bright stars are used for pointing the MOS slits on fainter targets. For this purpose, "alignment holes" are used to find the "alignment stars" at the center of each hole during pointing the MOS mask. Therefore, designing the alignment holes is as important as designing the slits. We recommend to design the alignment holes before starting the slit design since MOS observation is impossible without such stars/holes. You can change them later if you wish.

Please select stars with 15 mag < Ks < 18 mag. Stars brighter than Ks=15 mag may saturate on the detectors, which makes the accurate measurement difficult. And also, fainter stars or the use of galaxies may make the alignment less accurate because of the larger errors in the positional measurement. We usually use the sky-subtacted image by taking a set of the nodded images. If the alignment star still does not seen in the image, we can make the exposure longer by using the "coadd" option. The alignment process will be much efficient if you can choose a set of brighter alignment stars. On the contrary, if you choose only faint stars and then the seeing on your observation may awfully bad, the star may become too faint to do the alignment. In this case we may just lose time.

Diameter of the alignment holes should be 3.5" (or 30 in the *.mdp file) for best pointing accuracy.




3.3.1 Operation

Case 1

Place the alignment star information in *.mdp file as shown above.

Case 2

For interactive selection,
1. Select [ File ] - [ Change Default Slit Params ] from the pull-down menu, and set as follows.
   Alignment Hole Size ( Diameter in pixel ) = 30 ( equivalent of about 3.5 arcsec )
   Then, click "OK".
2. Click "Add Alignment Hole"
3. Click on the alignment star in a main image display for choosing the region around the star.
4. Click again on the alignment star in a zoom image display. Position of the alignment star is determined by Gaussian fitting with the initial guess of the clicked position.
5. Selected star is displayed at the center of the zoom display as well as a small square (not a circle) if the fitting was successfully done.
6. "Click-object" mode is not available for the alignment star since Gaussian fitting is required for better accuracy.
7. "Alignment Hole" comment is shown in a comment field of *.mdp file for holes which is generated interactively in the MDP program.





Tips for designing the alignment holes

To find out the RA, DEC, and angle offsets between the mask and the targets with better accuracy, we recommend the followings . . .
1. Choose at least six ( 6 ) stars within the FOV. Try to locate alignment stars evenly over the FOV, i.e., locate at least three stars per detector. There is no upper limit on the number of alignment stars/holes. See the following illustrations.
2. We use the first Alignment star in your .mdp file as the marker of the initial guess during alignment process. So please choose the brightest alignment star first.
3. Alignment stars should be isolated to avoid confusion.
4. Alignment hole spectra will be very bright on spectrum data due to its wide aperture size relative to the slit width. So, in some cases the leaked light from the hole may contaminate the spectrum of the adjacent slitlets. Having the space of a few arcseconds from the alignment hole for these slitlets may be safer.
5. Stars beyond 3.0 arcminutes from the pointing center cannot be chosen as the alignment stars. Avoid locating stars closer to the FOV edge or near the region that two channel images are glued together (at least in 6" in width). Stars located near each quadrant boundaries should be avoided because 1-pixel raws/columns are blank at each boundary (see Fig.2a).
6. If there are troubles during the mask alinment process, we may restart alinment sequence without storing the mask to the stocker. Also, if you want to reduce the overhead of the MOS exchange, we may try the MOS alignment without storing the robot arm to the rest position. In this case, the robot arm will stay over the FOV and so the central 350 pixel region from the guled line among channel 1 and 2 will become unavailable (see the example). Therefore, at least >4 alignment stars should be out of these unavailable region. The area will be 1415 < Y < 2095 pixel if the preimage has the dimension of [2048,3569] (the preimage will be that size if the data is mosaicked using the SA-supplied distortion-correction script dismosimg.cl).
7. Try placing alignment holes isolated. If holes are located at very close to the adjacent holes/slits, MOS pointing software may easily fail to detect them automatically. Place a hole 3.5" (which is a default hole diameter) or more away from its nearest hole/slit.

   Example of BAD alignment hole distribution. Distribution of stars are biased in the FOV.

   Example of GOOD alignment hole distribution Stars are evenly distributed over entire FOV.

3.4 Design of slits

During designing masks, you will find that several slits are close in both space (X) and dispersion (Y) directions, and are overlapping on each other. You may also find that some targets are out of the FOV, or on the detector gap. Slit design is to add/delete/modify slits to avoid such confections while searching for the best possible slit multiplex advantage.



Figure: Targets can be choosen up to 2-3 arcsec close to the glued boundary of fovs between chip1 and chip2 (solid line). Spectra can be obtained about 270 pixel further than the line (red and blue dashed lines for chip 1 and 2, respectively). For example, if the spectra by a slit on chip 1 extends beyond the red dashed line, the spectra beyond the line will be terminated. The same is true for chip 2 (blue dashed line).




3.4.1 Operation

Case 1: Maual Processing

Place the slitlet information in *.mdp file manually with the format shown in 1.3.

Case 2: Interactive Processing

1. Select [ Option ] - [ Change Default Slit Params ] from the pull-down menu, and input "Default Slit Width" and "Default Slit Length" in pixel unit.
   e.g.) Since a pixel scale of MOIRCS is 0.117"/pix, width = 6.84 (pix) means a slit width of 0.8".
   Both length and width of each slit can be modified after locating the slits.
2. Select a mode for the target selection at upper left of the MDP window. You may choose "pick-object" mode in which Gaussian fitting is used to find the object coordinates, or "click-point" mode in which mouse click position itself is used as the object coordinates. "Pick-object" mode is suitable for point or compact sources. For extended source the "pick-object mode" may not work properly, and in such case you can use the "click-object" mode. As the manual slit location requires the special technique to achieve a accurate positioning, the user should pay much attention to the result of the "click-object" mode. It is for diffuse and extended sources.
3. Click "Add slit by click" button.
4. Click on the object on the main image display. Region around the clicked position is shown on the zoom image display.
5. Click on the target again on the zoom display. In "pick-object" mode, Gaussian fitting is performed around the clicked position, and the detected source is shown at the center of the zoom display as well as the rectangles for the calculated slit position. In "click point" mode, click on your favorite position on the zoom display, and the image is re-displayed around the clicked position.
6. Regions occupied by the spectrum will be shown as an elongated rectangle both on the zoom and the main window. Red frames are for the spectra in the detector 1, and green frames are for the spectra in the detector 2 (the color coding may change depending on the user environment).
7. Click on "Redraw" or "Draw Slit" buttons to see the updated image and the slits.
8. "Newly Added Slit" comment is shown in a comment field of *.mdp file for slits which are generated interactively in the MDP program.





Tips for designing the slitlets

1. Again, the objects beyond 3.0 arcminutes from the pointing center cannot be chosen as targets. Avoid locating high-priority slits close to the FOV edge (should be separated by at least ~10") or near the region that two channel images are glued together (at least 6").
2. We usually use the MOS mask itself, instead of using the long slit, for the rationing star observation to save time. So the user should choose the suitable slitlet for the rationing star observation. The slit for it should have the length longer than 15", because we should choose the dither width at least twice of that for object observation to avoid the affection of the "latent" signal by the standard star obs. You can prepare the slitlet for it on each detector. If you want to take the rationing star data on one chip only to save time, please use the slit on channel 2.
3. It is recommended to put slits on a bright star on each channel. The data should become useful for the quality check (flux, FWHM, etc) or the monitor of the telluric absorption during the exposure. And also, the data will enable us to measure the position or the actual dither width accurately, which will be efffectively used for your data reduction.
4. !!! IMPORTANT !!! The actual spectra of R500 grisms is tilted by ~1 degree counter-clockwise with respect to the y axis (for R1300 grism it is ~0.3 deg clockwise for channel 1 and ~0.7 deg counter-clockwise for channel 2). Due to this, spectra may occasionally overlapped with each other depending to the rayout (see figure below). If the two adjacent slitlets are widely separated in y-direction with the left slit is up and right slit is down, the overlap will occure. Taking a margin of >15pixel per dy=1000 pixel would be better.
   




3.4.2 Check the slit/hole parameters.

There are four ways to check/modify the slit/hole parameters.
1. Click the region of your interest on the main image display, and the zoom image around the selected region is shown in the zoom image display.
2. Click "Show nearest slit" button and click near your interest slit on the main image display. Nearest slit is found automatically, and the zoom image around the slit is shown in the zoom image display. A small pop-up window shows the slit information as well as the slit ID selected.
3. Click "Show slit(ID)" button and then input the slit ID number shown beside the slit. The zoom image around the selected slit is shown in zoom image window. A small pop-up window shows the slit information as well as the slit ID selected.
4. Click "Show Slit List" button to make a slit list which displays all slit information as well as comments (if any). Radio buttons at the left of each slit ID number can be used to activate/delete slits/holes. Deleted slits/holes can be re-activated from this slit list later if you wish.




3.4.3 Adjusting/modify the slit length

You may want to reduce the slit length to avoid the slit overlapping instead of deleting slits, or expand a slit length if no targets are found around it^(Note). In these cases, you can change the slit length manually.
1. Click "Change Slit Params" button and click near the slit you want to modify on the main image display. The nearest slit is automatically selected.
2. Input the new slit coordinates (X coordinates of the left and right side of the slit) and/or slit width/angle in the new popup window.
   Left = X coordinate of the left side of the slit of space direction (pixel unit)
   Right = X coordinate of right side of the slit of dispersion direction (pixel unit)
   Width ( PIX ) = Slit Width (pixel unit)
   Angle ( DEG ) = Slit Angle (degree unit)
   e.g.) Since a pixel scale of MOIRCS is 0.117"/pix, width = 6.84 (pix) means a slit width of 0.8".
   
3. Click on "Redraw" or "Draw Slit" buttons to see the updated image and the slits.
Note:
Sometimes there may be cases that the data show the reset anomaly pattern or residual of the stray lights, and you may want to remove them. In such cases, leaving some gap between slitlets may have the advantage, as you can better sample these extra component for subtraction. So, leaving some gaps as they are can be better, if it is possible to you.




3.4.4 Deleting slits/holes

There are two ways to delete slits/holes. Note that "delete" means "deactivate", and you may still see the slit information in the slit list to re-activate it.

Case 1

1. Click "Del Nearest Slit" button.
2. Click the region around the slit you want to delete on the main image display. The nearest slit is automatically selected, and deleted.
3. Click "Redraw" button to see the updated slit design.

Case 2

1. Click "Display Slit ID" button to see slit IDs on the image.
2. Click "Show Slit List" button. A slit list will show up.
3. Disable the slits you want to delete by clicking on the radio button just left of the slit. Then press "accept" button at the bottom of the list.
4. Push "Redraw" button to see the updated slit design.

3.5. Saving the results

There are two types of the output data file.

First is the *.mdp file which can be used as an input of MDP program. Users are recommended to save this file frequently to avoid the unexpected loss of the information due to MDP crush (sometimes reported), etc. You can re-start the MDP program with the *.mdp file saved during the previous MDP session.

Another is the *.sbr file which is used in the slit cutting machine. Save this file after finishing the design.

3.5.1 Save *.mdp file

Select [ File ] - [ Save MDP ] from the pull-down menu. Input the file name (*.mdp), and push "OK" button.

Users are asked whether you want to keep the information on deleted slits or not in the saved file. Comments indicating "Deleted" will be added to the *.mdp file when you keep the information. This might be useful when checking the mask design later.

Sample of *.mdp file


1646.0900 2525.9802 170.0000 8.0000 0.0000 1.0000 B, Object-1 1413.2900 3187.8088 170.0000 8.0000 0.0000 1.0000 B, Object-2 1425.0000 1307.4368 150.0000 8.0000 0.0000 1.0000 B, Object-3 1596.8900 1188.6917 133.7800 8.0000 0.0000 1.0000 B, Object-4 redshift=1.2 1790.0000 1424.0500 60.0000 8.0000 10.0000 1.0000 B, Object-5 faint 1929.3048 2935.7109 30 30 0.0000 0.0000 C, Alignment Hole 1013.9686 2216.7029 30 30 0.0000 0.0000 C, Alignment Hole 1860.3289 2637.6160 30 30 0.0000 0.0000 C, Alignment Hole 1306.7455 1371.2542 30 30 0.0000 0.0000 C, Alignment Hole 2155.8694 660.0646 30 30 0.0000 0.0000 C, Alignment Hole Deleted 1840.0000 1424.0500 60.0000 8.0000 10.0000 1.0000 B, Newly Added Slit 2722.4922 2618.4399 30 30 0.0000 0.0000 C, Alignment Hole 2805.4500 1047.8396 90.0000 8.0000 10.0000 1.0000 B, Newly Added Slit 1118.0699 1456.2828 170.0000 8.0000 0.0000 1.0000 B, Newly Added Slit

3.5.2 Save *.sbr file

1. If you are using older wmdp_moircs, select [ WCS ] - [ Set FOV Center ], and confirm "arcsec/pix" at the bottom column is exactly set to 0.117. For version later than 2007-07-04 you do not need it unless your preimaging data is not regular one reduced by QMCS.
2. Click "Draw FOV: botton and write down the coordinate information (X, Y).
3. Select [ File ] - [ Save SBR ] from the pull-down menu. Input the file name with an extension of *.sbr and click "OK".
4. You are asked to input the coordinate of the FOV center. The (X, Y) values you can see in the "Draw FOV" button will be shown as default values, and you do not normally have to change the values.

   Note

   While writing the *.sbr file, MDP checks the slit positions whether slits are out of the FOV or on the detector gap. When MDP finds any possibly wrong slits, warning messages are shown in the warning pop-up window. However, there is a known bug on the check procedure, and the warning may pop up though there is no apparent problem. Anyway please check the slit design again to see there are any slits that are outside the MOIRCS fov if you see the message. You can ignore the message if you are confident on your design.

3.6 Quitting the MDP

Select [ File ] - [ Quit ] from the pull-down menu.

3.7 Other notes

3.7.1 Dummy slit (0th slit)

When you start the MDP without *.mdp file, a dummy slit is automatically created whose slit ID is zero (0). Delete this slit after adding other slits.

3.7.2 Coordinate system convention

MDP's coordinates start from one ( 1 ). FITS viewers such as SAOimage and Skycat also use the coordinate start from one ( 1 ), but some softwares such as IDL use the coordinate start from zero ( 0 ).

3.7.3 Care for extremely out-of-FOV slits

Slits far out of the FOV may cause a scratch on the mask holder for laser cutting machine. Though it is not dangerous, please avoid putting such wrongly-put slits. As is noted above, there is a known bug on the function of the slit position check in the software. Please ignore the warning if your mask design seems correct.

3.7.4 Other functions

• If you want to take spectra with an imaging filter, you can change the graphics of spectra on display for the filter. Select [ Option ] - [ Grism Setting ] to set the minimum/maximam wavelength of the filter which you want to use. A frame of regions occupied by the spectrum will be changed. Do not change "Straight-through Wavelength", "Dispersion ( A/pix )", "Displacement along X-axis", and "zeroth order offset".
• Select [ Option ] - [ Preference ]. You can change a color tone of the display with "color table number ( 1 - 40 )". You can also set a best resolution of the display with "demagnification factor".

4. Take a snapshot image of MDP

We ask the MDP program user to take a snapshot image of the MDP display at the end of the design. The image will be used to check the fabricated mask and be useful as a "finding chart of the alignment stars" during the MOS pointing. (rotate clockwise if you want to use it as a finding chart.)

Use your favorite snapshot software. (e.g., xv, snapshot) Any standard image formats are acceptable (such as jpg and gif).

5. Submitting the results

Submit the followings to the support scientist. E-mail submission is preferable.

• *.mdp file
• *.sbr file
• snapshot image of MDP display
• The XY and its RA, DEC coordinates of the FOV center used (especially when you moved the FOV center from the default position.)

6. Acknowledgment

We deeply appreciate Dr. Takashi Hattori for his efforts to revise the original MDP software for the application to MOIRCS. We also thank to the FOCAS Team, who have developed the original MDP software. This manual is written based on the MDP manual for FOCAS.