Keck LRIS/DEIMOS Slitmask Handling System

De Clarke, S. L. Allen, and Gregory D. Wirth
Version 0.1
2006-Jul-27

Abstract

Observers using Keck's LRIS and DEIMOS spectrographs submit slitmask design files via a Web interface to a database server residing at UCO/Lick. Software at Lick performs sanity checks on eack mask before adding it to the slitmask database, a shadow copy of which resides in Hawaii and is updated twice daily. Masks may be milled either in California or Hawaii. Each slitmask recevies a barcode label which serves as a unique identifier. When masks are milled in Hawaii, results are communicated back to the master server in California several times daily. Cron jobs send twice-daily email updates to maintainers in order to ensure that mask milling proceeds on schedule. Masks are retained for a default period of 180 days and then discarded and deleted from the database. Observers can extend the lifetime of their masks via the database server's web interface.

Introduction
Slitmask Submission and Verification
Slitmask Data Transfer
Slitmask Milling
Observing
Slitmask Purging
References
Appendices

Introduction

Astrometric slitmasks are commonly used by observers on the LRIS and DEIMOS spectrographs of the W. M. Keck Observatory in order to acquire spectra of multiple targets simultaneously. These masks are custom designed by observing teams and milled per their specifications at the Mauna Kea summit. Since the observatory regularly processes and uses over 100 masks per month, a system for tracking the production and disposition of these masks was required to ensure that masks are produced in a timely and efficient manner. This document describes the software and procedures involved in handling the slitmask designs and physical masks.

Slitmask Submission and Verification

Slitmasks are designed by observing teams using one of two software packages:

LRIS observers use a FORTRAN-based program called AUTOSLIT written by J. Cohen of Caltech. The output of the program includes a mask design file, an ASCII-format file which includes a minimal human-readable header plus machine code instructions for milling the mask.
DEIMOS observers use an IRAF-based program called DSIMULATOR written by A. C. Phillips of UCO/Lick. The program's output includes a FITS binary file containing tables that fully describe the targets to be observed as well as the slits to be milled.

Once an observer has designed a mask, she uploads the mask design files to a centralized database for LRIS and DEIMOS slitmasks at UCO/Lick using a web-based interface. For security reasons, observers must not only obtain an account and password prior to accessing the database but also must register their computer with the database maintainers to access the web pages.

Once logged in to the database's web interface, the observer selects the option to upload slitmask files, then specifies which files to upload from the local computer and for which instrument the files were designed (LRIS or DEIMOS). The latter step is required because of the different formats in which the data are written by the slitmask design software.

During the upload process, the acceptance software on the UCO/Lick server validates the files and requires the user to click once more to certify that the files are to be entered into the database, or "ingested". During the ingest process, the processing software converts DEIMOS files into mill code and simply copies the LRIS files (which are already in the mill code format). At this point the files are now ready to be transferred to mill in Hawaii.

Following the acceptance of one or more masks, the online database software allows the observer to:

download the FITS design file;
download the corresponding mill code;
display the full contents of the FITS tables in the mask design file;
generate and display a low-resolution plot of the slitmask layout;
modify the slitmask use date;
request that a mask be remilled;
delete the mask from the database;

Observers are restricted to performing these operations only on masks which they own, but super-users (including observatory support staff) designated by the administrator can perform these operations on any slitmask. Certain operations, such as manual deletion of a mask from the database, will trigger an email to the mask owner as confirmation of the operation.

Slitmask Data Transfer

TBD

Slitmask Milling

TBD

Observing

TBD

Slitmask Purging

Two compelling reasons exist for periodically removing slitmasks from the database and from the physical collection of masks at the summit:

If the number of records in the database grows too large, it becomes unwieldly to perform the daily database "stomp" operation which copies the database from Lick to the summit.
The physical space available at the summit for storing slitmasks is limited, and hence only a certain number of slitmasks can be retained.

Based on previous experience at Keck, LRIS and DEIMOS observers will occasionally re-use an old slitmask within 2-3 months of its original planned usage date, but after 6 months the target will be inaccessible and by the following year the mask is rarely re-used. Hence, we have adopted a 6-month expiration date for slitmasks.

In practice, we follow this procedure to discard old slitmasks:

Generate future discard list. On the fifteenth day of each month, software generates a list of all slitmasks which will be 6 months past their expiration date at the end of the month.
Warn mask owner. The software then sends an email to the owners of the selected masks informing them of the masks' pending deletion from the database. See below for a template of the email message. If desired, the mask owner can postpone the deletion of a mask by up to one year at a time by visiting the Lick slitmask database web pages and modifying the "Use date" for the mask.
Generate current discard list. On the first day of the month, software generates a list of all slitmasks which are now 6 months or more past their expiration date. This list is emailed to selected personnel at Keck, and is also stored on the Lick server for future reference. See below for the format of the list.
Expunge expired masks from database. At the time the list is generated, the software expunges the expired masks from the database. Although gone, they will not be forgotten, as software at Lick will generate a backup of the mask data on some physical media (tape or DVD).
Discard old masks from summit. Upon receiving the list of masks to be discarded, personnel at the Keck summit remove the selected masks from the archive and discard them.
Inform mask owners. The software sends a message to the mask owner confirming that their masks were removed from the database. See below for a template of this message.

To assist in periodic auditing of the slitmask collection at the Keck summit, the Lick web interface to the slitmask system will provide the following capabilities:

Archived discard lists. The super-user can access any of the monthly slitmask discard lists to check when a particular mask was discarded, or to obtain an old list of discard instructions in case personnel fail to perform the operation in a given month.
Current mask inventory. The super-user can generate on-demand a list of all barcodes which should currently be in the database. Since LRIS and DEIMOS slitmasks are stored separately, and these collections are further divided into "user masks" and "engineering masks", the output list is also divided into 4 sections to accomodate the needs of summit staff. See below for the format of the inventory list.

References

"Slitmasks from Observer to Telescope: Astrometric Slitmask Manufacturing and Control for Keck Spectrographs." D. Clarke et al. Poster presented at SPIE 2004 (Glasgow, Scotland, UK)

Appendices

Expiry Email

The following message will be sent to slitmask owners approximately 15 days prior to the deletion of their masks:

Dear Dr. X:

One or more DEIMOS or LRIS slitmasks owned by you are now nearly 6
months past their "Use Date" as listed in the online database of
slitmasks for the Keck Observatory.  At the end of this month, we plan
to:

 - discard the physical slitmask currently residing at the summit
 - delete the records of these masks from the online database

The affected masks include the following:

	Instr	Mask Name	ID	Barcode	Use Date
	-----	---------------	----	-------	------------
	LRIS	foo		4321	1234	2006-Jan-01
	LRIS	bar		4322	1235	2006-Jan-01
	DEIMOS	baz		4323	1236	2006-Jan-01

If you do not plan to ever use these masks again, then no action is
required and the masks will be discarded at the end of this month.  If
you need these masks to be saved for possible future use with LRIS or
DEIMOS, please do the following BEFORE the end of the month:

  1. Log in to the online slitmask database at:

  http://spg.ucolick.org/cgi-bin/Masks//login.cgi

  2. Click on the button labeled "Show me my mask inventory" to get a
  list of your masks.

  3. Locate the listing for the mask you want to save.  Click on the
  button labeled "Edit use date" to access the "Edit mask use date"
  screen for this mask.

  4. Select the amount of time by which you wish to delay the "Use
  Date", up to a maximum of one year.  Note that you must increase the
  Use Date by at least one month to prevent the scheduled deletion of
  your mask.

  5. Repeat the previous 2 steps for each mask you want retained.

If you have any questions about the disposition of your masks, please
direct them to instruments@keck.hawaii.edu.

	Aloha,

	The Lick Slitmask Processing System

------------------------------------------------------------------------
This message was generated by the script slitmaskDiscardWarning.tcl
running on helios.ucolick.org.
------------------------------------------------------------------------

Discard Email

The following message will be sent to slitmask owners upon deletion of their masks:

Dear Dr. X:

One or more DEIMOS or LRIS slitmasks owned by you have been discarded
and deleted from the online database of slitmasks for the Keck
Observatory.  The affected masks include the following:

	Instr	Mask Name	ID	Barcode	Use Date
	-----	---------------	----	-------	------------
	LRIS	foo		4321	1234	2006-Jan-01
	LRIS	bar		4322	1235	2006-Jan-01
	DEIMOS	baz		4323	1236	2006-Jan-01

If you have any questions about the status of your masks, please
direct them to instruments@keck.hawaii.edu.

	Aloha,

	The Lick Slitmask Processing System

------------------------------------------------------------------------
This message was generated by the script slitmaskDiscardNotify.tcl
running on helios.ucolick.org.
------------------------------------------------------------------------

Expiry List

The following message will be sent to selected Keck staff on the first day of each month:

The following slitmasks are now at least 6 months old and should
be discarded from the DEIMOS/LRIS slitmask collection immediately:

Instr	Type	Barcode	GUIname		ExpDate		Owner
-----	----	-------	--------	----------	------------------
DEIMOS	user	2234	bar		01/01/2006	jones@moo.edu
DEIMOS	user	2235	bar2		01/01/2006	jones@moo.edu
DEIMOS	user	2236	bar3		01/01/2006	jones@moo.edu
DEIMOS	user	2237	bar4		01/01/2006	jones@moo.edu
DEIMOS	user	2238	bar5		01/01/2006	jones@moo.edu
...		        
		        
LRIS	user	1234	foo		01/01/2006	smith@moo.edu
LRIS	user	1235	foo2		01/01/2006	smith@moo.edu
LRIS	user	1236	foo3		01/01/2006	smith@moo.edu
LRIS	user	1237	foo4		01/01/2006	smith@moo.edu
LRIS	user	1238	foo5		01/01/2006	smith@moo.edu
...

------------------------------------------------------------------------
This message was generated by the script slitmaskDiscardList.tcl
running on helios.ucolick.org.
------------------------------------------------------------------------

Note that the primary sort key is "instr", secondary is "type" (all masks are type "user" unless "Use Date" is set to "never expire"), tertiary is barcode number.

Inventory List

The following report can be generated by the super-user to assist with periodic inventorying of the slitmask collection at the summit:

List of all slitmasks currently in the DEIMOS/LRIS slitmask
database:

Instr	Type	Barcode	GUIname		ExpDate		Owner
-----	----	-------	--------	----------	------------------
DEIMOS	user	2234	bar		01/01/2006	jones@moo.edu
DEIMOS	user	2235	bar2		01/01/2006	jones@moo.edu
DEIMOS	user	2246*	bar3		01/01/2006	jones@moo.edu
DEIMOS	user	2237	bar4		01/01/2006	jones@moo.edu
DEIMOS	user	2238	bar5		01/01/2006	jones@moo.edu
...		        
		        
DEIMOS	eng	2234	longslit	01/01/2036	jones@moo.edu
DEIMOS	eng	2235	longslit2	01/01/2036	jones@moo.edu
DEIMOS	eng	2246*	longslit3	01/01/2036	jones@moo.edu
DEIMOS	eng	2237	longslit4	01/01/2036	jones@moo.edu
DEIMOS	eng	2238	longslit5	01/01/2036	jones@moo.edu
...		        
		        
LRIS	user	1234	foo		01/01/2006	smith@moo.edu
LRIS	user	1235	foo2		01/01/2006	smith@moo.edu
LRIS	user	1246*	foo3		01/01/2006	smith@moo.edu
LRIS	user	1237	foo4		01/01/2006	smith@moo.edu
LRIS	user	1238	foo5		01/01/2006	smith@moo.edu
...		        
		        
LRIS	eng	1254	longslit	01/01/2036	smith@moo.edu
LRIS	eng	1255	longslit2	01/01/2036	smith@moo.edu
LRIS	eng	1266*	longslit3	01/01/2036	smith@moo.edu
LRIS	eng	1267	longslit4	01/01/2036	smith@moo.edu
LRIS	eng	1268	longslit5	01/01/2036	smith@moo.edu
...

* = skip in sequence number

------------------------------------------------------------------------
This message was generated by the script slitmaskInventoryList.tcl
running on helios.ucolick.org.
------------------------------------------------------------------------

As above, note that the primary sort key is "instr", secondary is "type" (all masks are type "user" unless "Use Date" is set to "never expire"), tertiary is barcode number.

Gregory D. Wirth

Last modified: Thu Jul 27 00:10:34 Hawaiian Standard Time 2006 !DSPAM:44c89f94277863100511321!