DEIMOS and LRIS configurable elements
- Carlos Alvarez
DEIMOS and LRIS are MOS optical instruments that contain configurable elements. The configurable elements can be filters, gratings, grisms and slitmasks. Observers are required to submit their desired configuration before their scheduled observing date. The day crew at the summit will load the required configuration on the date of observing. Observers are also required to submit their MOS slitmask designs well in advance to their observing run. The slitmask designs are stored in a database. The day crew will mill the masks with a CNC machine located in the instrument lab at the summit. They will make sure that the masks are milled before the day of observing.
This page describes the different components we use to manage the DEIMOS and LRIS configurations, including the slitmask. The timeline to submit instrument configurations and slitmask designs is also discussed.
Slitmask and configuration submission and use timeline
The life cycle of a slitmask and instrument configuration for LRIS and DEIMOS is as follows:
Observers design slitmasks using software tools provided by the observatory. Observers are expected to start preparing the masks designs more than 4 weeks before the observing date.
Observers submit mask designs to the slitmask database via web interface. Ideally, observers are required to submit the mask designs at least 4 weeks before the observing date.
Observers submit configuration including slitmaks in addition to other optical elements. First reminder is sent by e-mail to observers 5 weeks before the observing run. There are subsequent persistent e-mails sent to observers regarding overdue configurations starting 4 weeks before the observing run, if a configuration has not been submitted by then. Additional reminders of the upcoming observing run are sent 3 days before the observing date.
Observatory summit staff mills the slitmasks and stores them until they are needed. Masks designs are placed on a milling queue as they are submitted by the observer. The milling queue automatically gives priority to the designs corresponding to the closer observing dates.
Observatory summit staff loads the slitmasks, filters and gratings/grisms on the instrument. This typically takes place on the date of observing in the morning. It can take place 1 or 2 days before the observing date, on the first date of an observing run.
Observers perform science observations using the loaded slitmasks. On observing runs lasting multiple nights, observers are allowed to make decisions during the night on which maks they may want use the following night. Configurations previously submitted for the next night on an observing run may need to be modified depending on events on the current night that may impact the science output. Examples are adverse weather conditions, technical problems that may affect the observing efficiency or desire to expose longer on a field than initially planned. Any configuration submitted during the night for the night of observing should be submitted before 7am HST.
Observatory summit staff unloads the slitmask and stores them. This typically takes place the day after the observing, unless it is the last night of an observing run or the same configuration is planned for the following night.
Used slitmask designs are automatically purged from the database. This occurs automatically 6 months after a slitmask has been used. An automatic e-mail warning is sent to the slitmask owner 15 days before the purging takes place. If the slitmask owner wants to keep the mask design for longer
Observatory summit staff disposes unused masks for recycling, typically twice per year. When requested by the instrument engineers, the instrument master sends them an inventory of all the masks that are active in the database. Any slitmask on the summit storage facility that are no active in the database will be packed and sent for recycling.
Configuration form
Observers are requested to use the following web-based configuration form. The welcome page of the configuration form is shown in the following figure.
Observers will receive a confirmation e-mail when the configuration is submitted. The SA group also gets the confirmation e-mail.
We can access the configuration form to help troubleshooting possible issues observers may encounter. For troubleshooting purposes, the best option is to insert in the Principal Investigator box the PI last name as shown in the column Principal on the telescope observing schedule, and to insert your e-mail address in the PI E-mail box instead of the PI’s e-mail address. Any changes made to the configuration form this way will still take place, but the SA making the changes will receive the confirmation e-mail, not the PI.
Once the configuration is submitted, the SIAS database and web page will be updated. Automatic SIAS updates take place daily at 7am and 9am HST. This is the reason why any last-minute configuration change must be submitted no later than 7am HST on the date of observing.
Configuration submission reminders
Observers will receive configuration submission reminders from the instrument@keck.hawaii.edu account with the subject “Your Keck DEIMOS configuration is X days overdue” from 5 weeks before the observing date until the observing date while a configuration is not submitted.
Slitmask design software
The software used to design slitmasks for DEIMOS is dsimulator. The software used to design slimaks for LRIS is autoslit. Dsimulator is IRAF based and autoslit is based on FORTRAN and PGPLOT.
One of the outputs of the slitmask design software is a FITS table (slitmask design file) that contains the following information in multi-extension format:
Mask ownership details.
Planned observing date details.
Field pointing coordinates and orientation.
Sky coordinates of the objects to be placed on the mask. These include science targets and alignment stars.
Slitmask geometry including location shape and orientation of each of the slits.
Observers are requested to submit slitmask configuration files to the slitmask database at least 4 weeks before the observing date.
Slitmask database
The slistmask database is the interface between the Keck observing community and the observing support staff to manage the slitmask designs for LRIS and DEIMOS.
There are two copies of the database:
Master copy hosted by UCO/Lick
Secondary copy hosted by WMKO (host machine waiaha)
Syncing between the master and the secondary database occurs as follows:
Daily at 06:00 HST the contents of the Keck database on waiaha are wiped ("stomped") and the contents of the Lick database are transferred to Keck.
Hourly from 08:00 to 17:00 HST new slitmask information is transferred from slitmaskpc to waiaha.
On the half hour from 08:30 to 19:30 HST the new slitmask information is transferred to Lick.
Twice daily at 05:00 PT and 18:00 PT the MaskKeeper process runs at Lick and sends updates to mask maintainers and observers on the status of slitmasks.
The syncing process and timeline are described in detail on the DEIMOS database updating information web page.
The slitmask database interface to is hosted at UCO/Lick. Every new database user needs to send a requests for access to the slitmask database administrator (Steve Allen - slitmaks@ucolick.org). Staff astronomers get database administrative privileges, which include the possibility to inspect mask designs for any observer, amongst others. Observers can, of course, only see slitmask designs owned by themselves.
The following figure shows the welcome page to the web-based slitmask database interface:
The machines used to access the slitmask database also need to registered by the database administrator.
A useful resource to help observers with slitmask database questions is the slitmask database FAQs page.