User's Guide to ShARCS

Table of Contents

Summary Table
Detector Characteristics
Filters, Grisms, Apertures, Polarimeter
Software Overview
Data Taker GUI
Filter & Aperture Wheel GUI
Image Display GUI
Sound server
Temperature Monitor
Observing Procedures and Tips
FITS Header Keywords

Data Archive
Mt. Hamilton Homepage

Data Taker Software

Main GUI | Menu Bar | Exposure Palette | Take Darks

The data taking software, sharcs_fe, runs on the computer covert and is started by typing sharcs_fe at the command line. This will open two windows, an xterminal with messages (which can be ignored unless there are problems) and the GUI shown in Figure 1 below. Exposure parameters, such as exposure time and number of coadds are controlled from this GUI, as well as the status of exposures in progress.

Figure 1: ShARCS data taking GUI, sharcs_fe.

The top section (just below the menu bar, which will be discussed later), is the status section. This section will update with exposure status, progress, and any messages or errors, as well as displaying the elapsed and remaining exposure times. When an exposure is not in progress (as shown in Figure 1), the status area will be green with the first line of text showing the Object name and Secs: is the seconds remaining for the exposure (in this case 0, as there is no exposure in progress). The next line of text will display any messages concerning status or errors. Also, to the far right will be displayed to total amount of elapsed exposure time (including overhead, but not the about 12 seconds of time it takes to write the FITS file to the data directory, /data/sharcs/.) The bottom line of text will display the name of the exposure in progress or the last exposure completed if an exposure is not in progress.

When an exposure is in progress (see Figure 2a), the green bar will advance as the exposure progresses, as well as display status updates on how many reads and coadds have been completed. Secs: will display the number of seconds remaining for the exposure (including overhead) and immediately below it will be the elapsed time (in seconds) for the exposure. The exposure, when completed, will be written to the file name listed at the bottom of the status panel. When the exposure is completed, it takes about 12 seconds to write the file to the data directory, /data/sharcs/. That time is designated with a blue background for the status panel (Figure 2b).

Figure 2a: Exposure in progress status bar.

Figure 2b: Blue background indicates FITS file is being written to data disk.

Below the status region, some helpful information is listed for the observer's reference. This information will be updated any time the exposure parameters are updated.

Min ITime= is the minimum exposure time per coadd allowed with the current detector configuration. For most programs, this will be 1.46 seconds (as shown in Figure 1). If the detector is windowed to a small region (refer to Window GUI below), the exposure time may be less, e.g. 0.11 seconds for a 100x100 pixel region.

Actual= is the actual exposure time in seconds for the exposure. One may enter any desired exposure time, but the actual exposure time will be an integral number times the Min ITime. The software will automatically take the entered Exposure time and figure out the maximum Actual exposure time that fits in the entered Exposure time. The Actual exposure time is always less than or equal to the entered Exposure time.

Total= displays (in seconds) the actual exposure time plus overhead from the number of reads plus the time it takes to write the file to disk. Note that the Actual and Total exposure times are for a single coadd and will not be adjusted if Coadds is greater than 1.

The middle section of the sharcs_fe GUI (see Figure 1 above), is the one that observers will interact with most, as this is where exposure parameters are specified and exposures can be started.

Exposure time may be entered in Seconds or Milliseconds, as specified by the radio buttons immediately above the Exposure entry box. The default is seconds. When a new exposure time is entered the background of the entry box will turn yellow and it will not be used until the Set button is pressed. When Set is clicked, the new exposure time will be displayed to the right of Exposure and the background of the entry box will return to its default white color.

NReads is the number of reads of the detector. As displayed in Figure 1, its Set button is greyed out because the default mode for the GUI is Auto Mode where the appropriate number of reads for the dectector is calculated based on the entered exposure time (up to a maximum of 16 reads). The default mode is useful for the vast majority of observing programs. Those wishing to use non-standard number of reads can go to the File menu (see Figure 6) and select Normal Mode to enable the Set button for the Number of reads. To return to the default settings for NReads, select Auto Mode from the File menu. Normal Mode is displayed in Figure 3. Behavior of the Set button is the same as for setting the Exposure.

NCoadds is the number of coadds for each exposure. This number must be an integer 1 or greater. The Set button behaves the same as for the Exposure entry.

Obs # is the observation number and will be part of the file name. ShARCS data files are stored in the directory /data/sharcs/. File names are sXXXX.fits where XXXX is the observation number prepended with zeros to make a 4 digit number.

All of the above exposure parameters (plus many others, see FITS header keywords for more informaiton) are written into the FITS file header.

One may enter a number of parameters then set them all at once using the Set All button. If a mistake was made, one can clear the entry fields by clicking the Clear All button.

Once the exposure parameters are set, one starts the exposure by pressing the Expose button.

If one needs to abort an exposure (due to improper paramter settings, change in weather, or other issue), the Abort button can be used. When one clicks on Abort a menu is displayed (see Figure 4 ). The options are No, Abort Now, After Read, After Group, or After Coadd. No will cancel the abort (in case Abort was clicked by accident). Abort now will stop the exposure immediately. After Read will stop the exposure after the current read is done. After Group will stop the exposure after the current group of reads is completed. After Coadd will stop the exposure after the current coadd is done. In all cases a file is written to disk, though the value of the data from the aborted exposure will be suspect if not stopped after a group or coadd.

Figure 3: Normal Mode for exposure parameter entry.

Figure 4: Abort Menu

The bottom section of the sharcs_fe GUI (see Figure 1 above) allows the observer to enter their Name, Program, and the Science Target's name or identifier.

Observer: The observer's names or observers' names. Can be up to 64 regular characters. This information will be written to the OBSERVER FITS header keyword in your data file. The Set button behaves the same as for the Exposure time entry. The Hide... button will hide the entry box to prevent accidental changes during the night. Once pressed the Hide... button changes to Show... so that one can display the entry box again.

Program: The Program is any text one choses to enter (up to 64 regular characters) that designates the science program. The Set and Hide... buttons work as for the Observer entry box. This information is written in the FITS data file keyword PROGRAM.

Object: The Object name can be entered (up to 64 regular characters). The Set and Hide... buttons work as for the Observer entry box. This information is written in the FITS data file keyword OBJECT.

LogNote: An electronic log is kept of all significant ShaneAO actions and ShARCS exposures and scripts. The log file is saved with the data in the data directory /data/sharcs/ and named saolog_YYYY-MM-DD.log. To add a comment to the log, type it in and press the Set button.

Menu Bar

The men bar at the top of the sharcs_fe GUI (as shown in Figure 1 above, and below in Figure 5), allows one to reconfigure the GUI, ShARCS configuration files, bring up auxillary GUIs and displays status messages.

Figure 5: ShARCS Menu Bar

File Menu

Figure 6: File Menu

The File menu has a number of options for changing how the GUI is displayed.

Log... has not been implemented yet, but eventually will bring up the planned electronic log for ShaneAO and ShARCS.

Resize sets the GUI back to its default size.

Auto Mode displays the exposure parameter entry fields for typical operations, where the number of reads for the Fowler sampling is set automatically (up to a maximum of 16 reads) based on the exposure time.

Normal Mode is the same as Auto Mode except that the number of reads, NReads, for the Fowler sampling is set manually by the observer. Note that if one sets the number to reads to be more than can be covered by the exposure time, an error message will be generated when one tries to start an exposure.

Advanced Mode shows all the available exposure parameters and is the mode that must be used if one wants to do up-the-ramp sampling for the read out of the detector. Figure 7 shows the Advanced Mode options for exposure configuration.

Figure 7: Advanced Mode exposure configuration GUI

In Advanced Mode, the readout mode may be selected with the Mode button. Mode options are Single, CDS (Correlated Double Sampling), MCDS (Fowler sampled multiple reads) or UTR (Up-The-Ramp sampling). When in CDS mode, the NGroups and NReads fields are greyed out, as they are not options when doing CDS. In MCDS mode NGroups is greyed out, as the mode requires NGroups to be two. Note, nothing gets greyed out in Single mode, though most parameters (except NResets and NCoadds) are irrelevant.

Exposure, NReads, NCoadds, and Obs # are identical to the Normal Mode settings. The additional options are described below.

NGroups is the number of groups of reads to perform. For example, in MCDS mode, there will be 2 groups, one group of reads at the beginning of the exposure and another at the end. In UTR mode NGroups will be the number of groups of reads during the exposure.

NIgnored is the number of reads to ignore between the NGroup reads.

Resets is the number of detector resets performed before the exposure begins. Default value is 1, but more may be done, though this adds overhead to each exposure.

Settings are sufficiently complicated, that errors are relatively common for those new to using the Advanced Mode. However, errors in the exposure settings should generate an error message when the Expose button is pressed, so they can be identified quickly. An example of settings for an UTR exposure is ??.

The rightmost item in the menu bar is a status message. Normally the message is routine, such as "Connected" or "Fits writing complete" (as in Figure 1 above) with a grey background. However, critical messages will be displayed with a red background alerting one to a problem. For example, in Figure 5 one can see the red background with the message "Lost Server". In most cases the observer will not be able to solve the problems on their own, so contact a telescope operator or support astronomer for assistance.

Windows Menu

The Windows menu allows one to bring up auxiliary GUIs required for ShARCS setup, operations, and status reports.

Figure 8: Windows Menu

Exp Palette: TheExposure Palette is a window displaying the exposure times taken since the last clearing of the palette. Clicking on an exposure time in the exposure palette will copy those parameters to the main sharcs_fe GUI. This is a convenient way of selecting exposure parameters if one has a few different setups one wishes to use during the night. It also tracks how many exposures where taken with each set of parameters so that one may take dark frames at the end of the night with the Dark GUI.

The first column, Time, is the exposure time in seconds.
The second column, Reads, is the number of reads.
The third column, Resets, is the number of resets performed before the exposure begins.
The fourth column, Coadds, is the number of coadds for that exposure configuration.
The final column, Exposures, is the number of exposures taken with that configuration.

Note that exposure times shorter than 1.5 seconds will show up in the exposure palette, but will fail if the detector is not windowed to an appropriate size for the shorter exposure time to be valid.

Figure 9: Exposure Palette

Take Darks is a GUI that enables taking dark exposures at the exposure times listed in the Exposure Palette.

The top of the GUI shows which positions the filters are currently in. If they are in the dark positions, the backgrounds will be green, otherwise yellow as a warning that they are not in the proper positions for taking Darks. Move the filters to the Dark positions by clicking on the Set Filters button in the upper righthand corner. When filters are moving the button will turn red. Once filters are in place the button will revert to the default grey color. (Note, there is currently a bug in the program and it stays red in color, do not be concerned).

The main section of the GUI summarizes the information from the Exposure Palette, indicating the number of exposures (Count), exposure time in seconds (Exp Time), number of Reads, Resets, and Coadds.

To take darks for a given exposure configuration, enter the number to exposures to take for each exposure configuration in the Takes column. Please try to keep the total time to do all darks under two hours. The total estimated time to take the requested darks is listed at the bottom of the exposures table. If darks will go beyond 8am, please email to let the observatory staff know that darks will still be in progress when the day crew comes in and please also include at what time the dark script will be completed. As darks are taken by the Take Darks script, the Taken column numbers will increment to indicate how many exposures have been completed for each exposure time. An estimate of the total time in seconds (including overhead) to perform the requested number of darks is in the final column, Total Time.

Before setting the Takes for each exposure configurations, it is advisable to click the Reload button to update the exposure information. This will make sure that all exposure times in the Exposure Palette are listed in the Take Darks GUI. The Reload button will also reset all Takes and Taken values to zero.

For convenience one can set all Takes (e.g. 10 dark exposures at each exposure time) by typing the desired number into the entry box near the bottom of the GUI and pressing the Set All Takes button. One can then manually edit any Takes to a different number, if desired (e.g. in Figure 10 all takes were set to 10, then the first exposure configuration was manually set to 0).

To reset the number of exposures taken for each exposure time (i.e., set Count to 0 for all exposure times), click the Clear Counts button. This is sometimes desirable to do at the beginning of each night so one is tracking only new exposures taken that day, rather than including the previous night's exposures.

One can also clear the Exposure Palette of all information by clicking Delete Exp Info. This is often done by the staff when configuring the system for a new observer so they start with a blank exposure palette.

Figure 10: Take Darks GUI


Observers should not need this window, however, it is documented here for completeness and Figure 11 displays what the GUI should look like during normal operations. Note that the full AsicCfg is C:\startup\SHARCSColdControlConfig.xml and the full AsicHost is These parameters should not be changed, as that could render ShARCS inoperable until reset appropriately.

If Connected is No, push the Connect button to establish connection to the detector computer. If Connected updates to yes, then press the Init button to initialize the software using the information listed below (note Initing will change to Yes immediately after the Init button is pressed and will revert to No when initialization is complete). If all works properly, SideCarInit should say Success! and the data taker should work normally. If there are problems, contact a telescope technician or support astronomer for assistance.

WriteAll is an option to write all reads to the FITS file rather than just the final MCDS or UTR data. For most programs this should be the default No. When set to Yes it takes longer to write the FITS files and files are significantly larger.

Figure 11: Setup GUI


ShARCS status of the current exposure (or last exposure if no exposure is in progress) is listed in the Status GUI. Most of this information is displayed elsewhere, but is useful for engineering or diagnosing problems.

Figure 12: Status GUI


The Action GUI is only used rarely used by the technical staff. The buttons are explained here for completeness, but observers should not use them unless instructed to by a telescope technician or support astronomer.

The Resume button attempts to resume connection to the ICE server on stealthie without initializing. The Reset button resets the detctor controller. GetAsicPower retrieves the SIDECAR power status from the hardware. The status is displayed in the AsicPwr= field, where -1 is unknown, 0 is off, and 1 is on. DLFirmware=No is a menu with two options, Yes or No, to set whether the JADE firmware is downloaded upon initialization. This becomes No if the initialization succeeds. Its default value is No. The PowerDown button turns off power to the detector controller. The Close button closes the GUI.

Figure 13: Actions GUI


The Sharcs Window GUI enables selection of a sub-region to read out on the detector. Four numbers need to be entered to define a region, start x, end x, start y, and end y. The full detector is 2048x2048 pixels, and shown as the green box if Figure 14. The the top quarter of the detector is non-functional, indicated by the red X. When new values are entered for the region vertices, the green area will alter showing exactly which portion of the detector is being read out (see Figure 15 for example). The Full button sets the start and end values to read out the entire detector. The Center Zoom is set to a 100x100 region centered on the ShaneAO optical axis.

It is important to note that exposure parameters for subarrays are stored in the exposure palette, but the size and position of the region are not. Also, after windowing the detector, the first full 2048x2048 image taken afterwards will have some undesirable bias values in the region that was last used. Hence, it is always advisable to take a quick junk full frame after windowing to clear the bias defect.

Figure 14: Window GUI

Figure 15: Window GUI with Center Zoom region set.

More information on minimum exposure times for different sized sub-region windows are in the Observing Hints and Tips.
Last modified: Sat Mar 26 15:50:49 PDT 2016