Fix DEIMOS Slitmask Comb Errors More Easily with New Script (2013-May-13)
To aid in the recovery from DEIMOS slitmask “comb” faults, we have released a new script (fix_slitmask_comb_error) which will check the state of the comb; if it senses a comb problem, the script will rotate DEIMOS, re-check the system, and continue these steps until the comb sensor no longer indicates that the slitmask system is OK. It is safe to invoke this command both when DEIMOS is on sky and when it is not. The script can be run by the observer, OA, or SA. You can launch the script from the DEIMOS workspace menu via: 
DEIMOS Troubleshooting > DEIMOS Trouble Recovery > Fix Slitmask Comb Error

Care Required When Changing DEIMOS Slitmasks (2013-May-08)
DEIMOS has been experiencing a rash of failed slitmask moves when attempting to change masks while the mask mechanism is in the “up” position, corresponding to an angle of 180° (or -180°) on the DEIMOS dashboard rotator subpanel, or to 270° (or -90°) on FACSUM. Such moves can cause slitmasks to get caught in the changer mechanism, triggering the comb sensor and causing the slitmask system to hang; manual intervention is often required to recover the slitmask system. The default orientation of DEIMOS during the daytime (-30°) is far from this problem area; however, running the select_slider script to move to slider 4 will leave DEIMOS in this problematic position, and nighttime observations may take place at any angle. Thus, we ask observers to check the DEIMOS rotator panel before making a slitmask move, and if the clock diagram on that panel indicates that the slitmask is within 30° at the 12-o'clock position, please rotate at least 90° away from 12-o'clock, then change your slitmask, then rotate back and proceed with mask alignment and observation.

BAL12 Order Blocking Filter Returned to Service (2013-May-06)
The BAL12 filter has been refurbished at UCO/Lick and is now again available for use in DEIMOS. This is the only filter which allows DEIMOS observers to access wavelengths below 4000 Å. Observers may now request use of this filter on their runs by updating their DEIMOS configuration forms to include BAL12.

Updated Webpages Centralize Throughput Data and Plots (2013-Apr-06)
Ricardo Schiavon's throughput plots have been brought over to the Keck webpages from their former location at UCO/Lick and made available on the new DEIMOS Spectroscopic Throughput webpage. Furthermore, the DEIMOS Grating Summary webpage is now updated with links to these same plots, plus helpful information on dispersion and accessible wavelength range.

Switching to DEIMOS Slider 4 May Require Rotating (2012-Sep-13)
DEIMOS is having trouble clamping up on slider 4 at certain orientations. Sliders 2 and 3 can be clamped at all rotator positions. In contrast, slider 4 is only clamping up successfully for DEIMOS physical drive angles (ROTATVAL) between 135 and 360; for 0<ROTATVAL<135, clampup may fail. When switching to slider 4, continue to rotate DEIMOS to ROTATVAL=180°.

New DEIMOS Exposure Time Calculator Released (2012-Jul-13)
Xavier Prochaska and Brad Holden of UCO/Lick have released a nice web-based exposure-time calculator for DEIMOS.

New Script Helps Deal with DEIMOS Flexure (2012-Jun-19)
The DEIMOS grating system continues to exhibit excess flexure when the grating system is clamped up at certain DEIMOS rotator positions. Conversely, when DEIMOS is rotated to the optimal clamp-up position for a given grating, the flexure should be sufficiently small that the flexure compensation system can correct for it at all rotator positions. To assist observers in clamping up DEIMOS gratings at the bext rotator positions, observers are encouraged to use the select_slider script. From the DEIMOS background menu, simply click on DEIMOS Engineering > Select slider... and select from the available options to move to slider 2, 3, or 4. The script can also be run from the command line on the DEIMOS host computer; from an xterm window on polo, simply enter select_slider 3 to rotate and clamp up slider 3, or select_slider 4 to rotate and clamp up slider 4.

Flexure Found to Affect All DEIMOS Sliders (2012-Jan-14)
Our continuing investigation of flexure on DEIMOS has revealed that all three grating sliders are experiencing anomalously large amounts of flexure, with the magnitude of the flexure dependent on the instrument rotator position at which the grating is clamped up. We believe that all three sliders remain usable if the observer takes care to clamp up the slider at the optimal angle for that slider. Current optimal values are shown below:

Recommended Clampup Positions to Minimize DEIMOS Flexure
Slider ROTATVAL1 ROTPPOSN2
2 0° 90°
3 0° 90°
4 180° 270°

1Displayed as "Physical PA" on DEIMOS Dashboard Rotator Subpanel
2Displayed as "Drive" on FACSUM

Please note that the only impact on your program is that you need to put DEIMOS into the orientations listed above when changing to a particular slider. Once the grating is in place, you may freely rotate the instrument to any desired position angle. There is also no restriction on the telescope pointing.

New Soundplay System Plays DEIMOS Sounds Remotely (2011-Nov-22)
The venerable Xbeeper widget has severd us well for years, but as more astronomers make use of DEIMOS from off-island mainland observing facilities we have sought a better way to play the "exposure complete" and "readout complete" sounds remotely, rather than relying on the Polycom videoconferencing units to transmit the sounds. Will Deich at UCO/Lick has developed a set of tools which can transit instrument sounds directly to computers at mainland observing sites, as well as to our Remote Ops machines in Waimea. We are deploying the software on an experimental basis during this run with the intent of releasing it in place of Xbeeper in December. To test out the new tool, quit Xbeeper and launch the EventSounds tool from the DEIMOS workspace menu under 
    DEIMOS control menu > Subcomponents > Start Eventsounds GUI
Please note that not all remote sites are yet equipped with the external speakers required to play the sounds.

New DEIMOS Web Pages Offer Better Browsing (2011-Nov-18)
Thanks to the efforts of new Support Astronomer Luca Rizzi, the DEIMOS web pages have been reformatted and reorganized to help you find information more easily. Many pages which were previously accessible only through the index can now be accessed through submenus off the main instrument home page. For those who find it more convenient, the Old Home Page will remain available during the transition. We welcome your feedback on the organization and appearance of the new web pages.

New script obtains blue-optimized DEIMOS calibrations (2011-Oct-24)
Observing with DEIMOS in the blue (4000-5000 Å) requires a different approach to obtaining suitable calibration images, compared to using DEIMOS in the customary red wavelengths. Caltech's Evan Kirby has developed a handy script to acquire such blue-optimized DEIMOS calibration images. The calib_blue script takes separate arc and flat exposures for the red chips and the blue chips. The red-chip arc and flat images are not appropriate for the blue side and vice versa. The script employs some clever strategies to generate correctly-exposed images with the various available lamps. Please consult your Support Astronomer for assistance in customizing the script to met the needs of your observing program.

Keck starlists can now contain RA/Dec offsets (2011-Oct-24)
In response to a recent observer request, the MAGIQ guider software has been updated to allow observers to specify RA and Dec offsets to be applied after a target has been centered up. The intention is to permit starlists to contain entries for alignment stars with known offsets to a faint science target which may not be visible on the guider. As described in the starlist documentation, the new keywords to include are raoffset and decoffset. The offset values listed in the starlist file can be read directly into the MAGIQ offset fields, thus avoiding the need to verbally relay telescope offsets to the Observing Assistant (with the corresponding risk of a miscommmunication). If you have any questions about how to specify offsets in your startlist file, please contact your Support Astronomer for assistance.

DSIMULATOR bug (2011-Oct-04)
A couple of recent DEIMOS observers have been chagrined to learn on the day of their run that the alignment boxes on their DEIMOS slitmasks were not milled. In each case, the root of the problem appears to be with the operation of the DSIMULATOR software used for slitmask design. Specifically, observers should be careful NOT to use "t" option for toggling between alignment and guide stars -- it was never intended to do so. As described in the DSIMULATOR documentation, guide stars and alignment stars should be distinguished from each other by the use of different priority codes. We look forward to eventually receiving a corrected version of DSIMULATOR which eliminates the unmillable slits. Until then, all observers using custom slitmasks are responsible for sanity-checking their masks after submitting them to the slitmask database in order to ensure that they are free from design flaws. Please follow this procedure after submitting your masks and verify that the resulting slitmask plot is free of red slits that indicate problems.

Slider 3 Flexure (2011-Sep-11)
Recent engineering tests indicate that the flexure characteristics of grating slider 3, one of the two grating positions available on DEIMOS, have changed significantly since they were last tested. We are concerned that DEIMOS may have some sort of mechanical problem with that grating slider. Accordingly, we recommend that observers request their primary grating on slider 4 until further notice. Please contact your Support Astronomer for information on how to ensure that your grating is loaded in slider 4.

New deeplog option (2011-Aug-02)
A new option flag has been added to the deeplog command. The option is -loop. If specified, deeplog will not quit at the end of the current list of files: instead, it will enter a loop and wait for new images to arrive. Every 20 new images, a new copy of the column header is generated.

DEIMOS Lags LRIS in Far-Red Throughput (2011-Feb-07)
A new analysis compares the relative throughput of DEIMOS and LRIS out to 1 µm, finding that LRIS is at least twice as efficient as DEIMOS when observing with the 830 l/mm gratings on these respective instruments.

DEIMOS Begins Full-Time VNC Operation (2010-Jun-08)
Starting with the June DEIMOS run, we ask all observers to start up their DEIMOS control software within VNC desktops. Virtual Network Computing (VNC) is a technology that allows windows to be shared with observers at other computers and has been used successfully for years at Keck to provide mainland observers with access to Keck instrument controls. By expanding the use of VNC to all observers, we will thus have a single startup procedure for observers to follow regardless of whether or not they will operate with mainland observers. Operating under VNC also makes it easier for support staff to assist observers with troubleshooting and allows our observing assistants to monitor the status of observations during the night. Your support astronomer will be happy to assist you with starting your DEIMOS software under VNC.

Video Board Replaced (2009-Sep-30)
For many months, readout amplifier 1B (lower left corner) on the DEIMOS science mosaic has been subject to intermittent periods in which the bias level drops several thousand DN for a period of time, rendering data in the affected region unusable. After exploring non-invasive means of controlling the problem, with limited success, we have decided to replace the flaky SDSU video processing board (serial number 39) with a spare (S/N 31). Initial indications are that the new board has similar gain and readnoise to the one we removed. The flaky board is being returned to UCO/Lick for testing.

DEIMOS FCS Repaired (2009-Jun-19)
The DEIMOS flexure compensation system is working with a new piezoelectric actuator installed, and performance appears to be comparable to what it was prior to the April piezo failure. The new actuator still requires some adjustment in length, and thus the DEIMOS image is currently offset by 120 px in Y from its pre-repair location. Until we fix this, observers should realize that central wavelengths are bluer than expected by about 120 px times the dispersion of the grating. We hope to have this positioning resolved by the August DEIMOS run.

DEIMOS S/N Measurements (2009-May-23)
A new DEIMOS Spectroscopic Performance web page shows the spectral S/N achieved by the DEEP2 Survey as a function of magnitude.

DEIMOS FCS Status (2009-May-07)
We have resurrected some old software that allows us to perform flexure compensation using the grating tilt stage instead of the tent mirror. In recent testing, this software functioned well and provided flexure compensation with an RMS dispersion of 0.5 px in wavelength. Although this is about a factor of 2 worse than what DEIMOS provides with the tent mirror actuator enabled, it should be good enough that the effect of increased flexure on DEIMOS spectra will be minor. The bottom line is that the DEIMOS flexure compensation system should work well until we can replace the failed PZT actuator.

DEIMOS FCS Failure (2009-Apr-27)
On 2009-Apr-24, the DEIMOS flexure compensation system experienced a sudden and currently unexplained failure of the piezo actuator which drives the tent mirror, the key component which corrects image motion in the wavelength axis in DEIMOS images. This failure leaves DEIMOS without a working flexure compensation system. The cost and timescale for replacing the piezo unit, which is an expensive component manufactured in Europe, are currently unknown as we are awaiting information from the manufacturer. Although we hope to repair the DEIMOS FCS as soon as possible, it may not be possible to effect repairs in time for the May DEIMOS run which begins on 2009-May-23.

We are currently trying to understand why the piezo unit failed; it had functioned well since the instrument was built and was expected to last almost indefinitely. We are not aware of any event which would explain the failure. Unfortunately, due to the long expected longevity and the high cost of replacing the actuator (possibly $10,000 or more), we do not maintain a spare.

Based on measurements made this weekend, the flexure observed over a 360° rotation of DEIMOS on the science mosaic is 45 px in the spectral direction, with substantial hysteresis. This represents a tripling of the flexure measured at commissioning, possibly the result of mechanical decoupling in the piezo unit which is allowing excessive flexure to occur. Such image motion will substantially degrade spectra acquired with DEIMOS unless observers take steps to mitigate the flexure. Possible observing strategies for dealing with the flexure are to keep exposures as short as possible and to restrict observing to the range of DEIMOS rotator angles over which flexure is minimized.

If we are unable to repair the FCS by the May 2009 DEIMOS run, then a potential fallback plan would involve rewriting the FCS software to provide flexure compensation in the spectral direction using the grating tilt stage, which has much coarser resolution than the piezo-controlled tent mirror (1/3 px, vs. 1/100 px). It is not certain that we can provide the manpower to make such revisions, nor is it clear that this would provide suitable flexure compensation. If it succeeds, this approach may provide correction which is significantly worse than the piezo-based system but nevertheless far better than having no FCS at all.


DEIMOS Finder Chart Generator Now Writes Better Starlists (2009-Mar-30)
Erik Tollerup of UCI has enhanced the deimos_guider_dss script of UCSC's Dan Magee to generate starlists in the new format including rotator PA information.

DEIMOS Problems (2009-Mar-24)
DEIMOS is currently experiencing a number of problems of varying severity:

Starlists Now Allow PA Info (2009-Feb-20)
For years, observers have been forced to provide their position angle information to the OA verbally. The new starlist file format now permits you to enter the position angle for your target using the ROTMODE and ROTDEST keywords. Here is an example of how to specify the position angle: 
# slitmask with specified rotator position
PA_targ_name    00 24 00.00 +16 00 00.00 2000.0 rotdest=123.45 rotmode=pa

# target observed at parallactic angle
VA_targ_name    12 34 56.78 +01 23 45.67 2000.0 rotdest=0.0 rotmode=vertical

A Reminder About Checking Slitmasks (2008-Oct-31)
Whenever new slitmasks have been installed in LRIS, it's essential that you take direct images of all of your slitmasks in the afternoon as part of the afternoon calibration procedure for Xbox. Doing so ensures that we installed the correct masks and that the DEIMOS software is inserting the correct slitmask design information into your image headers.

New Script Allows Drift Scanning Mode (2008-Oct-31)
In response to an observer request, we now provide a driftscan script which can be used for drift-scanning spectral observations with DEIMOS. Given the angular size of the desired scan, the script will launch an exposure, compute and apply the required non-sidereal telescope tracking rate, then restore sidereal tracking and return to the starting location at the completion of the exposure. As written, the script will only scan in RA, so the observer would typically use a north-south slit alignment.

Slitmask Plotting Tool Released (2008-Oct-23)
With the new Plotmask tool, you can answer that age-old question: which slit is my object in? Given a DEIMOS image acquired with a slitmask in place, this IDL routine will generate a plot of the slits with optional labeling of slit index number (used by QuickSlit) and/or target name. Output can be sent to the printer. Launch Plotmask via: 
	DEIMOS Utilities > Plotmask
from the DEIMOS background menu.

Grating Slider Changes (2008-Oct-20)
In an attempt to resolve the longstanding problems with clamping up on slider 4 at certain DEIMOS orientations, we have been experimenting with a slightly different clamp-up sequence for the DEIMOS gratings. The new algorithm appears to give more reliable clampups for all of the sliders, and appears to almost completely eliminate the failed clamp-ups on slider 4 (except that the behavior remains marginal over the approximate range 0° < ROTATVAL < 45°). If a clampup should fail (or you have an FCS tracking failure) the first thing to do is to unclamp and reclamp the grating. The next thing to try is to rotate to the vicnity of ROTATVAL=-30°, unclamp, and reclamp.

Real-time Data Reduction Tool Released (2008-Oct-04)
QuickSlit, a spectral quick-reduction package for DEIMOS, is now available for use on all DEIMOS numbered accounts. The software, contributed by Michael Cooper of the DEEP2 Survey Team, will perform a full reduction on a single slit from one or more science images acquired with the same slitmask and display the output in the form of both a 2-D sky-subtracted spectrum and a 1-D extracted spectrum. Online documentation is available. You can run the tool from the DEIMOS background menu under 
	DEIMOS Utilities > QuickSlit

Grating Slider 4 is Finicky (2008-Jul-30)
Slider 4 is having trouble clamping up at certain orientations, particularly at DEIMOS ROTATVAL values of +90° and -90°. Using the clampup_slider4 script is discouraged due to problems seen with alignment after running this script, sometimes requiring the observer to re-run FCS setup in order to track. Instead, we recommend that observers should rotate DEIMOS to ROTATVAL=0° (corresponding to ROTPPOSN=90°) when attempting to change to slider 4.

New Reflective Multi-Long-Slit Mask Released (2008-Apr-28)
After several years of service, the popular LngVrMir mask has worn out and been replaced by a new and slightly different mask called LVMslits ("LVM" = "Long Variable Multi"). Like LngVrMir, this new mask features a reflective slit area and a series of 20-arcsec-long slits of various widths. Whereas the old mask offered 4 slit choices, the new mask has 5 (0.7, 0.8, 1.0, 1.2, and 1.5 arcsec). The LVMslits mask now appears in the default list of available masks on the DEIMOS run configuration form.

DEIMOS FAQ Page Upgraded (2008-Apr-21)
Tips and tricks on observing with DEIMOS have been added to the DEIMOS FAQ (frequently asked questions) page. Go there for those handy tips your friendly neighborhood support astronomer is always reminding you about!

DEIMOS Arcplots Widget Released (2008-Apr-06)
We are pleased to announce the initial release of the DEIMOS Arcplots widget, a GUI with which observers can generate arc line plots customized to any grating, central wavelength, and set of line lamps. This is useful for verifying the achieved wavelength range for specific slits. Please see the Arcplots Widget page for more information.

DEIMOS Mask Overlays Generating Tool Released (2008-Apr-05)
The new IDL routine dsim2regions can be used to help plot the locations of DEIMOS targets and slits on an image of the corresponding DEIMOS field. The routine reads information from the mask design files generated with DSIMULATOR and creates ds9 regions files which can be used to mark and label the locations of slits on an image with celestial coordinates encoded in the FITS header World Coordinate System keywords. Please see the dsim2regions page for further information.

DEIMOS grating slider 4 clamp-up problem (2007-Nov-03)
Grating slider 4 is unable to clamp up at certain DEIMOS rotator positions. This may indicate that some key components in the mechanism are worn and need replacement; however, we will not be able to complete that invasive work until after the November DEIMOS run. In the meantime, there are two things that observers can do if they experience problems switching to grating slider 4. The preferred option is to execute the new script called clampup_slider4, which will position the stage to a spot where it should be able to clamp up. If this fails, the fallback is to rotate the instrument by 90 degrees and try again to select the grating from the DEIMOS dashboard GUI. If this fails. try running clampup_slider4 at this new position angle.

DEIMOS imaging mirror replaced (2007-Jun-06)
The engineering-grade imaging mirror which has been used in DEIMOS since commissioning has been removed and replaced with the science-grade imaging mirror. The coating on the engineering-grade optic was in relatively poor condition due to tarnishing, but the new science-grade optic appears to be in outstanding condition (expecially considering that the coating is well over 5 years old). This change should increase the imaging throughput of DEIMOS when the mirror is used.

DEIMOS bias problems (2006-Dec-20)
Since the October 2006 earthquake, the DEIMOS science CCD mosaic has shown signs of low-level pattern noise and bias level variations which change from chip to chip. We have started troubleshooting the problem in partnership with experts at UCO/Lick Observatory and our preliminary finding is that the gain level on the science mosaic CCD controller has excess noise. Troubleshooting will continue in January 2007; until then, observers should expect somewhat higher noise in their images.

DEIMOS desktop changes (2006-Apr-22)
DEIMOS has become the first Keck instrument to change from the OLVWM window manager, no longer supported by Sun, to the FVWM window manager. A recent internal technical review concluded that FVWM was a preferred solution to alternatives such as GNOME and CDE. In addition to changing the window manager, we have also changed the way that observers will access instrument software: instead of using the window manager's pulldown menu, observers will now use the InstrMenu widget to run DEIMOS-related tasks. We welcome your feedback on these changes, which will soon migrate to the other Keck instruments.

DEIMOS computer and disk changes (2006-Apr-07)
The Sun Solaris E450 workstation which has run the DEIMOS user interface software since the commissioning in 2002 has been replaced by a more modern, faster SunFire V240. Also, the new DEIMOS machine (known as polo, like its predecessor) now features a Triton RAID-6 array offering nearly 2,000 GB of disk storage space. The new machine runs the DEIMOS software significantly faster than before, and with the new RAID array the time to write a full DEIMOS image to disk has decreased from 35 sec to 2 sec.

Update: Problem with science CCD mosaic amp 1B (2006-Mar-25)
Troubleshooting prior to the late March DEIMOS run failed to reproduce the amp 1B dropouts seen during the early March DEIMOS run. Until this problem resurfaces, observers are advised to return to using the default 2-amp readout mode for direct imaging.

DEIMOS motor controller failure (2006-Mar-21)
One of the two Galil motor controllers on DEIMOS failed during the downtime between the DEIMOS runs. The symptom of the failure was that the unit would not communicate and displayed a red FAULT lamp when powered on. We replaced the failed controller with a spare, which appeared to operate normally until we tried to move the grating select mechanism; all attempts to move the grating select stage resulted in motor shut off - positioning error. We replaced the failed spare with a new spare, which worked fine. All systems now operate normally.

Problem with science CCD mosaic amp 1B (2006-Mar-01)
The B amplifier on CCD 1 is occasionally failing to read out properly, resulting in lost data on this CCD. This amplifier is used when reading out all spectral images, plus direct images acquired in 2-amp mode. Until we resolve this problem, observers are advised to use 1-amp mode for direct image readout in order to avoid losing data. The controls for 1-amp and 2-amp mode can be accessed on the User Config panel from the main DEIMOS dashboard.

newday command now invoked automatically (2006-Mar-01)
It is no longer necessary for observers to execute the newday command to allocate new data directories and configure FCS files when starting up the instrument. The newday command is now invoked automatically when the instrument software is launched. This change allows the fcstrack script to write its logfile to the FCS subdirectory.

DEIMOS RAID array crash (2006-Feb-01)
The RAID-5 disk array which hosted most of the DEIMOS data directories has suffered physical damage and is now unreadable. Two of the 5 disks in the array were lost, preventing us from reading the data from the other disks.

Change in the operation of GO ZERO/GO BACK buttons (2006-Jan-27)
The logic controlling GO ZERO button (used to tilt the current DEIMOS grating to the zeroth-order imaging position) has changed. Until now, the logic has been to store the current grating tilt and restore to this value when GO BACK is pressed. We recently learned that this can cause problems if the GO ZERO button is pressed during a telescope slew: the instrument rotator will typically be slewing, and as a result the grating may be slightly out of position at the time the position is recorded. Hence, GO BACK ends up restoring the grating to the wrong position, which causes FCS to remain idle instead of tracking. The logic has now been changed so that when the GO ZERO button is pressed, if the actual and user-requested grating tilts are close but not the same, the requested position is the one to which the grating will return via GO BACK. If the actual position is not close to the demanded position, the GUI will generate an error message.

Gratings refuse to unclamp (2005-Dec-26)
DEIMOS is experiencing occasional problems with gratings refusing to unclamp when they have not been exercised for a few days. We believe this is because the air pressure that drives these pneumatic clamps bleeds off over time, leading to insufficient pressure to unclamp the grating. If this happens to you, see the troubleshooting guide for tips on fixing the problem.

FCS problems (2005-Dec-09)
Over the last 6 months, the DEIMOS flexure compensation system (FCS) has experienced intermittent problems with loss of signal from one of the two CCDs in the system (FCS CCD 1), causing the system to fail. The problems became more frequent during the November run, culminating in a hard failure on December 2 after which the system remained in a "fail" state. Working with personnel at Lick, we opened the FCS dewar electronics box and located a connector which was not well seated. The connector is now properly seated and the FCS functions normally. As part of the troubleshooting, Bob Kibrick at Lick developed new FCS control software which can function using only 1 of the 2 FCS CCDs. Although the flexure compensation in this mode will not be as good as when 2 CCDs are used, it will be much better than having no corrections at all. Please see the FCS troubleshooting notes for further information on using this script.

DEIMOS grating system repaired (2005-Aug-25)
The grating move problem reported in the April news item has now been eliminated. Working with a team from Lick, we disassembled the grating select mechanism and located two loose screws on slider 3. These were retightened and the system laboriously retuned (modified the GRATOFFx parameters) in order to allow all gratings to clamp up at all DEIMOS rotator positions.

DEIMOS collimator mirror recoated (2005-Aug-10)
The DEIMOS collimator mirror received the same beautiful Gemini silver coating as the DEIMOS tent mirror received in the spring, thanks to Maxime Boccas and his team at Gemini. New throughput measurements are pending. The shift in image position relative to the value prior to removal of the tent mirror is -7.8 px in CCD_X and -4.1 px in CCD_Y, which is within the 10 px requirement.

DEIMOS tent mirror recoated (2005-Apr-25)
The DEIMOS tent mirror received a beautiful new silver coating at the Gemini summit coating facility thanks to Maxime Boccas and his team at Gemini. New throughput measurements are pending. A side effect of the removal and reinstallation of the tent mirror is that the optical alignment has changed by a few pixels. This means that observers should not attempt to use FCS reference files generated prior this run, since it may be impossible for FCS to maintain alignment on such data.

DEIMOS grating move problems (2005-Apr-02)
The DEIMOS grating select stage experiences mechanical interference which causes grating moves to fail at certain orientations of the instrument. The problem is worst when DEIMOS is at a physical rotator position (in DEIMOS coordinates, as displayed on the Dashboards "Rotation" panel) of 270°, and occurs when trying to move slider 3 past the in-beam position. The symptom is that the grating select move fails at this point. The solution is to rotate the instrument by 90° either diection and re-try the failed grating move. When possible, avoid changing the grating when the instrument is near 270° rotator position.

DEIMOS tent mirror receives temporary coating (2005-Apr-02)
The DEIMOS tent mirror's protected silver coating has been degrading since installation, reducing the DEIMOS throughput. After the last run, we removed the optic, stripped the old coating, and replaced it with a temporary coating of bare Al to tide us over until we can recoat with a new protected silver coating in mid-April. A side effect of the removal and reinstallation of the tent mirror is that the optical alignment has changed by a few pixels. This means that observers should not attempt to use FCS reference files generated prior this run, since it may be impossible for FCS to maintain alignment on such data.

Offsets to guider coordinates removed (2004-Nov-03)
The slitmask mill was serviced in October and this appears to have restored the original zeropoint of the slitmask coordinate system. The offsets which were previously required to align stars on the guider are no longer needed.

deeplog command updated (2003-Oct-11)
The deeplog script will now print out information on only the latest N files if you supply a numeric argument.

DEIMOS update (2004-apr-01)

Focus analysis script enhanced (2003-Oct-10)
The Analyze Focus script will now set the DEIMOS focus to the newly-determined value if you consent.

Re-arrange your GUIs automatically (2004-Oct-09)
With one click, you can now resize and move all of the DEIMOS GUI windows into their appropriate configuration. Simply go to the OpenWindows pulldown menu, select DEIMOS Utilities > Auto-arrange GUIs, and watch your windows morph into place!

Offsets to guider coordinates (2004-Sep-14)
Several observing teams report that the guider appears to have shifted, resulting in a 10-column offset between the predicted and actual positions of the stars in the guider when the mask is aligned. Observers should thus apply a +10 pixel offset to the intended x coordinates of their guide stars when completing the coarse phase of slitmask alignment; i.e., instead of typing 
	gmov 100 200 300 400
type 
	gmov 100 200 310 400

Several DEIMOS filters damaged (2004-Jun-23)
An unfortunate incident this spring has resulted in significant damage to several of the DEIMOS filters. The affected filters are: The damage was caused by a bent component in the filter wheel which grazed the surface of the filters when the optics were inserted or removed from the instrument. The scratches run along the center of the filters (covering less than 5% of the surface area) and are oriented in the spectral (not spatial) direction when the filter is in the beam. Plans for replacing the filters are on hold until we can establish the level of degredation to their performance. In the meantime, observers who would normally have used BAL12 for spectroscopy are advised to use the GG400 filter instead. Since DEIMOS transmits very little light below 4000 Å anyway, we do not expect a significant impact on observing.

FCS now runs automatically (2004-Mar-25)
The DEIMOS startup and shutdown scripts have been changed to launch the FCSTRACK script automatically, eliminating the need to perform the additional step of running FCSTRACK frm the pulldown menu during afternoon setup. Please be aware that if the DEIMOS software is shutdown and restarted, FCSTRACK will probably come up in its default (idle) configuration. Click the START button on the FCS GUI to re-enable FCS tracking.

Subtle problem with BLANK pixels (2003-Nov-21)
DEIMOS images taken between October 2002 and November 2003 are affected by a newly-discovered problem with certain data values. The problem is subtle and may be unnoticable for many observers. A full description of the problem and the simple solution is now available courtesy of Steve Allen (UCO/Lick).

spec2d version 1.1.4 released (2003-Sep-23)
The DEEP Survey team at UCB announces the release of a new version of the spec2d reduction package. Please see the release notes for full information, and consult the pipeline website for info on how to update your copy of spec2d. In addition to the revised version of the code, there are new calibration frames available; please click here for details. It is strongly recommended that all 2003 data be rerun with this new set of calibration files. Please note that an email list has been established to notify interested parties of developments related to spec2d. Email sent to this address will be directed to everyone on the spec2d_users subscription list which includes the developers here at UCB. Please contact to be added to the email alias.

AUTOPANE saves readout time (2003-Aug-25)
DEIMOS will now read out direct images and mask alignment frames faster, thanks to the new AUTOPANE keyword. When AUTOPANE is set to AlignArea (the ne default), the CCD system will readout only the illuminated rows if a direct image (without slitmask) is taken, and only those rows containing the alignment boxes if a slitmask alignment image is acquired. Spectral exposures are read out in full, as previously. Observers can control the setting og AUTOPANE using a new selector on the User Config panel of the DEIMOS Dashboard. For more information, please see this document.

DEIMOS Update (2003-Aug-07)

Use guidermon to detect guiding problems (2003-Jun-03)
The new guidermon script will monitor the guider signal-to-noise ratio (S/N) and generate an audio alarm if the S/N falls below the minimum threshold you specify. It can thus be used to detect the onset of cloudy weather and allow you to pause an exposure before it is degraded by clouds, or to be warned if the guide star wanders out of the guide box for some other reason. Once the signal has fallen below the threshold, the software will continue to monitor the guider S/N and will generate a different audio message when the guider counts exceed the threshold again. To use this script, open a local window on any machine in Remote Ops and type: 
	guidermon thresh
where thresh is the threshold at which to generate warnings. The appropriate value of the thresh parameter will depend on the brightness of the guider star and the guider integration time. A reasonable value would be 50% of the starting S/N.

Enhancements to DEIMOS IRAF package (2003-Jun-03)
The IRAF package keck.deimos has been modified to make observing with DEIMOS easier. The following tasks are affected:

"apropos" command for DEIMOS scripts (2003-May-29)
DEIMOS has a sizeable library of user scripts which can be used to control the instrument. You can now use the new apropos command on polo to search for commands related to a certain keyword.

DEIMOS slitmask imaging widget (2003-May-28)
Observers should acquire a direct image of each of their slitmasks in the afternoon and run xbox on them to verify that they function as expected. Observers can now use the DEIMOS Slitmask Imaging Tool to acquire these data rapidly and conveniently.

spec2d version 1.1.3 released (2003-May-20)
The DEEP Survey team at UCB announces the release of a new version of the spec2d reduction package. Please see the release notes for full information, and consult the pipeline website for info on how to update your copy of spec2d. The new version includes a patch for a noteworthy bug which affects all masks milled after the middle of October, 2002. The release notes provide the details of this bug, but it is important to note that all post-October masks need to be rerun using v1_1_3!

DEIMOS update (2003-may-15)

Generating DEIMOS slitmask maps (2003-May-03)
The DSIMULATOR slitmask design package can generate an optional plotfile which consist of Lick MONGO plot commands; however, few people have access to this software package. For the convenience of observers, a new IRAF task will accept the DSIMULATOR plotfile as input and will generate a plot using the STSDAS.IGI plotting program. You can download this script and run it at your home institution, or bring your DSIMULATOR files to Keck and generate the maps here.

Generating DEIMOS guider finder charts (2003-May-02)
Dan Magee (UCO/Lick) has generously donated a wonderful software package which generates nice DEIMOS guider finder charts using the Digitized Sky Survey and the output files from DSIMULATOR.

Experimental ds9 released (2003-Apr-24)
A new, "experimental" version of the ds9 image display tool is now in use for DEIMOS observing. This version features two new ways to compute image statistics, accessible under the Analysis menu:

Zeroth order imaging available on slider 4 (2003-Apr-24)
The staff of Keck and Lick Osbervatory recently completed mechanical modifications to increase the range of motion on slider 4, allowing it to reach the zeroth-order imaging position. Observers can now perform slitmask acquisition and MIRA on slider 4. Various user scripts which involve zeroth order imaging have been updated to reflect the new capability, including gozero, image_user_masks, and align_check

New script aids afternoon setup (2003-Apr-24)
Observers should acquire a direct image of each of their slitmasks in the afternoon and run xbox on them to verify that they function as expected. To speed the process of acquiring the direct images, observers can use the new image_user_masks script. By default, it will reconfigure DEIMOS for direct imaging on the current slider and acquire images of all user masks. To image only certain masks, list their names as arguments. The slitmask checklist has been updated to describe the use of this script.

spec2d version 1.1.2 released (2003-Apr-16)
The DEEP survey team at UC-Berkeley announces the release of version 1.1.2 of their IDL-based DEIMOS data reduction pipeline sofwtare. Known as spec2d, this software takes an input a set of undithered DEIMOS spectral exposures and produces a set of individual, sky-subtracted 2-D spectra for each slitlet. Please see the description of the spec2d software pipeline for further information on obtaining and using the software.

DVD writer available (2003-Mar-30)
DEIMOS observers can now write their data to DVD (or CD) using our automated writer and software. The observatory provides both the media and a GUI for completing the writing. Instructions are provided here . Each DVD can hold 4.7 GB of raw data, so it is generally possible to store a run's worth of data on a few discs. To access the GUI from any instrument account, select Instrument Utilities > Autobackup from the OpenWindows workspace menu.

FCS software upgraded (2003-Mar-25)
Three components of the FCS software have been upgraded:
  1. The FCS keyword library (service deifcs)
    All FCS-related keywords have been moved into the deifcs service. Previously, some FCS keywords (e.g., FCSMODE, FCSMSG) were contained within the science mosaic keyword library (service deiccd). Many new keywords have been added, providing access to the individual measurements computed for each FCS CCD. The FCSRMXxx keywords provide measurements of the FCS system's RMS tracking error during each science exposure. These new keywords are recorded in the FITS headers to provide a record of how well FCS was able to stabilize each science exposure. Note: the FCSCORRX and FCSCORRY keywords have been replaced by the FCSCORXM and FCSCORYM keywords, respectively.
  2. The FCS GUI
    The FCS graphical user interface has been completely re-worked. It provides many new features, including user-adjustable plot scales for various plots of the FCS tracking performance. Status displays provide detailed information regarding various warning and lockout conditions, and pop-up alarms notify the observer of any conditions that would degrade FCS tracking performance. The new GUI also provides features for taking FCS reference images.
  3. The fcstrack script
    The fcstrack script has been significantly upgraded to support the new capabilities of the FCS GUI. The revised correction algorithm provides improved image stabilization, especially when DEIMOS is rotating at higher velocities as occur when tracking objects near the keyhole. The revised algorithm also provides more robust handling of cosmic ray events; previously, such events would sometimes result in spurious FCS corrections.
Both the FCS Startup Checklist and the FCS Notes have been updated to reflect the changes.

FCS upgrade reduces scattered light (2003-Mar-02)
A recent upgrade to the flexure compensation system by Lick and CARA added hardware which turns the FCS lamp on only during an FCS exposure; previously, it was always on when FCS was running. Since FCS integrates for only a few seconds on each iteration, this should reduce the amount of scattered FCS light on the detector by a factor of 3 more.

Observing preparation checklist published (2003-Jan-31)
The new DEIMOS Observing Preparation Checklist tells you the things you need to know to prepare for your DEIMOS slitmask observing run and points out some key resources you should bring along.

Slitmask calibration widget released (2003-Jan-31)
The new Slitmask Calibration Widget automates the process of acquiring calibration data (arcs and internal flats) for a series of DEIMOS slitmasks. See these instructions on its use.

DEIMOS Update (2003-Jan-09)

Filter focus discipline released (2003-Jan-08)
De Clarke of Lick has written new software which will automatically adjust the focus of DEIMOS to compensate for the difference in focus values between the various DEIMOS science filters. The software takes as parameters a global shift in focus (derived from daily focus checks in the R band which you should run in the afternoon) and focus offsets for each filter relative to the R band. The DEIMOS focus is adjusted each time a filter is changed, with the changes being "invisible" to the observer.

New deeplog utility generates electronic logsheets (2003-Jan-08)
The new deeplog utility allows you to generate a listing of the images in your data directory to complement or replace your paper logsheets. The text output produced by the script isn't pretty but has the key benefit of being machine readable. See some sample output.

Flexure compensation centroiding improved (2003-Jan-01)
Bob Kibrick and Drew Phillips of Lick have developed a new cross-correlation algorithm for the DEIMOS flexure compensation system that simplifies the afternoon setup procedure and is far less prone to losing its "lock" during the night. The new algorithm is now the default and has performed perfectly since being deployed in late December.

Ghosting seen in 900-line grating (2002-Oct-22)
Drew Phillips has written a nice report on unusual ghosting seen when using the 900-line grating on DEIMOS. Until further notice, observers should use dome flats only for the 900-line grating, and other gratings that work at a similar tilt. Observers should be aware of the problem and watch for it in their data.

DEIMOS Update (2002-Oct-17)

DEIMOS slitmask design software released (2002-Aug-09)
Drew Phillips (UCO/Lick) has announced the initial release of his IRAF-based software package for design of DEIMOS slitmasks. Details on the installation and use of his software may be found at his website.