The upper section of the status window gives information about the telescope/dome systems. The left column gives the current RA, DEC, hour angle of the telescope, coordinate epoch, and position angle. The next column gives the azimuth, altitude, rotator, focus positions for each of the three focus motors, and tertiary port. The rightmost column gives the current UT, local sidereal time, airmass, and the focus position in a coordinate system which gives mean focus, xtilt, and ytilt.
Other entries give the dome position and status (initialized/unitialized, slaved/not slaved, open/closed), and mirror cover status (open/closed).
If any of the items appear in reverse video, there is likely to be something configured such that you will have significant problems with your observations (e.g., the dome is closed!). Note that no mirror covers are currently installed, so the status of these can be ignored.
The telescope positions are not absolutely encoded, so the status only reports where the computer thinks the item is, which is not necessarily where it really is, although if things are working well, the computer should correctly know where things are. However, if something seems peculiar, it is important to check with the remote video cameras and/or by going out and looking at the telescope/dome!
If you hit a key in the status window, it will toggle into engineering mode, where some additional information is displayed, and where a graphical window will come up which shows a running plot of the current encoder positions relative to the desired positions. If you accidentally do this, you can minimize the plot window, and switch back to normal mode by hitting a key again in the status window.
All commands should be entered in the command window. For all commands, you will not get a command prompt until the previous command completes.
The software allows you to write simple scripts in an external file which can be read in by the program to issue a series of commands automatically. Input script files should have commands which are identical to what you would need to type in the command window. To execute a script, you use the command:
where filename is the name of the file with the commands to execute. Our convention is to use .inp as the extension for script files. A script can call another script, up to 5 layers deep.
If for some reason things appear to hang up (i.e., nothing returns for several minutes after you'd really expect it to, you can restart the tcomm programs after issuing a CTRL- in the command window. This should kill all of the windows, and then retyping tcomm should start everything up again. However, if this is necessary, please inform Jon of the circumstances - we would really like to get things working without ANY hangups.
The OD command will open the upper dome slit. It will prompt for a confirmation before opening.
The CD command will close the upper dome slit.
OLD will open the lower dome slit. The upper dome slit must be opened first, since it has a lip over the lower dome slit. Normally, we do not open the lower dome slit unless we are doing absolute (all-sky) photometry; the reason for this is that the lower dome slit is not on a hardware watchdog circuit, so in case of a failure, it will likely not get closed.
OLD will close the lower dome slit. The lower dome slit must be closed before the upper dome slit is closed.
ODS will open both upper and lower dome slits in conjunction. However, normally we do not open the lower dome slit unless we are doing absolute (all-sky) photometry; the reason for this is that the lower dome slit is not on a hardware watchdog circuit, so in case of a failure, it will likely not get closed.
CDS will open both upper and lower dome slits in conjunction.
DS toggles dome slaving on/off, i.e. the tracking of the dome position to the telescope azimuth position.
DA will move the dome to the requested azimuth position (0 degrees is N, and az increases towards the east). DA will turn off dome slaving automatically (otherwise the dome would just rotate back to where the telescope is pointed!).
The following commands can be used to move the telescope:
The CO command will move the telescope to some user-specified coordinates. If you do not specify a position on the command line, the program will prompt for an RA and DEC, and then ask you to confirm the move. The coordinates will be interpreted using the current epoch, which defaults to 1950 (the default epoch can be changed using the NE command which will prompt you for a new epoch). Format is hh mm ss, separated by spaces (you can omit the mm or ss if they are zero).
Move the telescope to an SAO star. The program will ask whether you want an SAO near near the current telescope position (T), near some other specified RA/DEC (O), or some specified ALT/AZ (A). If you choose one of the latter two options, you will be prompted for coordinates. You will then be prompted for an acceptable magnitude range for the SAO star (CR to allow any brightness). Note that the on-line SAO catalog only contains stars down to 7th magnitude and does not have fainter catalog members at this time. The program will find the nearest SAO star to your coordinates, and ask if you want to move there; enter Y to move.
Same as SA, but for a SAO catalog sample that contains only fainter stars with .
Move the telescope to specified azimuth and altitude.
Move the telescope to the position of star id in an open user coordinate file (see section ??). If not specified on the command line, id will be prompted for.
Recalls the last 5 previously commanded moves and allows you to select one to move back to.
Offset the coordinate by arcseconds in right ascension and arcseconds in declination. If not specified on the command line, the offsets will be prompted for.
Offsets the telescope by pixels along rows and pixels along columns of the CCD. If not specified on the command line, the offsets will be prompted for. These allow ``instrument plane'' offsets, i.e., in the coordinate system of the CCD even if the instrument is rotated with N no longer oriented along columns. Unlike the 3.5m, the instrument plane offsets are specified in pixels, not arcseconds. The offset is for the telescope, so stars will move by ( ).
Move the telescope such that a marked location on the CCD frame will be moved to the center of the CCD frame. This requires that an image has already been obtained. If you use this command, you will be prompted to mark the location of an object in the CCD frame; use C to centroid on the position of the cursor, or I to just take the integer pixel location of the cursor.
Move the telescope such that a marked location on the CCD frame will be moved to any another desired location. Again, this requires that an image has already been obtained. If you use this command, you will be prompted to mark the location of an object in the CCD frame, then prompted to mark a second position to which the object will be moved. Mark these positions using C to centroid at the location of the cursor, or I to use the integer pixel location of the cursor.
Change the position angle to the specified PA. The position angle is measured from north to vertical on the chip when the image is displayed in sky orientation (for the PI CCD, this is (1,1) in the upper left).
Go through startup sequence that is run when starting tcomm, i.e. telescope initialization, dome initialization, and louver query.
Users can create catalogs of object positions which can be referenced by an ID number to maximize efficiency and minimize input error during the night. The format of the user catalogs is identical to that used by REMARK on the 3.5m. Each object should be put on a separate line with the following format:
object name TAB RA (hh:mm:ss) TAB DEC (dd:mm:ss) TAB epoch TAB (proper motion in RA) TAB(proper motion in DEC)
The following commands can then be used with these files:
Open a new input file. The file name will be prompted for.
Move to object id. If no id is given, it will be prompted for
The default coordinate epoch on startup in 1950. The default epoch for coordinate entry can be changed using:
Change the input epoch to a new value. The program will give the current epoch, and prompt for a new value. Note that the epoch on the display will not change until you move to an object using the new epoch.
Update coordinates, i.e. set the current position of the telescope. With the command, the telescope will display a list of the last 5 commanded positions; you enter the index of the object that the telescope is currently pointed at, and the positions of the azimuth and altitude axes will be adjusted. The normal mode of operation is to slew to an SAO star (SA command), take an exposure (EXP or QCK), center star (CENTER), then update coordinates (UC).
The telescope can be focussed by moving the position of the secondary. The secondary position is controlled by three separate motors, so the mirror can be tilted as well as pistoned. Tilting the mirrors changes the collimation and thus is not a motion which should normally be done! All focus positions are negative: (0,0,0) is when the secondary is at the home position, farthest from the primary.
Note that the focus is a function of temperature, since the telescope structure expands/contracts as a function of temperature. As the temperature increases, the focus decreases, i.e. goes more negative.
The focus commands are:
Take a series of exposures at different focus values. You will be prompted for a starting focus value, a delta focus (amount to change focus between each exposure), a number of exposures, and an exposure time. After entering these, the program will automatically take the requested number of exposures. The program will always approach a given focus value from the same direction, assuming you specify a positive delta focus value. When using FOCRUN, the CCD will automatically switch into a ``fast'' readout mode (which still isn't that fast!) which has increased readout noise; when done, the CCD will be switched back into the normal readout mode.
Move the focus to position . This command will automatically approach the desired position from the same direction.
Moves the focus by a relative amount, . If not specified on the command line, the amount to move will be prompted for
Tilt the secondary mirror to the specified angle.
Move the secondary to the home position (i.e. farthest from primary).
All camera commands are normally entered in the command window, but these are passed to the appropriate camera control program, which are usually run from separate windows on the right part of the desktop.
After images are taken, they are normally written out to disk in FITS format. The images go into directory images/yymmdd under the tcomm home directory, where yymmdd refers to the current UT date. The default filenames are yymmdd.index.fits where index is a running index number: both the root filename and the index number can be changed, see below.
The first time an image is taken, each camera program opens an Image Display window on the console; each subsequent image will be displayed in this window. Once an image has been displayed, some interactive commands are available in the display window, provided that a wait for input or any other I/O is not pending. To interact with the image, simply move the mouse onto the display window. The current pixel location of the cursor will be displayed in a frame at the base of the image display along with the pixel intensity. The arrow keys are used for fine control (one pixel at a time) of the cursor position. Note that, to maintain a small window, the image as originally displayed will likely only show every other, or even every 4th pixel (depending on the detector)
The following mouse buttons and keyboard keys are active while the mouse is located on the image display:
|LEFT||ZOOM IN, centered on the cursor|
|MIDDLE||ZOOM OUT, centered on the cursor|
|RIGHT||PAN, move the pixel under the cursor to the center|
|R||RESTORE image to the original zoom/pan|
|+||BLINK Forwards through the last 4 images.|
|-||BLINK Backwards through the last 4 images.|
|P||Find the PEAK pixel near the cursor & jump the cursor there|
|V||Find the LOWEST pixel ("Valley") near the cursor & jump the cursor there|
|#||"Power Zoom" zoom at the cursor to the maximum zoom factor|
|H||Toggle between small and full-screen cross-hairs|
|]||Clear boxes and stuff off the image display|
Color Bar Adjustment:
If you place the mouse on the color bar, these commands are available to adjust the contrast of the image:
Pressing the R key while the mouse is on the color bar restores the original color map (undoing any change of the contrast or "roll" changes made with the mouse buttons).
Note that you can also redisplay the current image with a different stretch using the SCALE command, see below.
The following commands are available:
Take an exposure of length seconds.
Same as EXP, but filename index exposure is not incremented, so next image will overwrite current one, i.e., exposure will not be permanently saved.
Change the filter wheel to filter . You must supply a name which matches that in the current filter table. For a list of available filters, use SETFILT without any arguments. SETFILT allows you to operate without knowing the details of which filter is located in which slot. SETFILT will also adjust the telescope focus for the relative focus difference between the filters (the filter specific offset is shown in parentheses in the status window).
Initializes the filter wheel if it has gotten lost.
Change the default root file name for output images to .
Change the extension for the next filename to be the number .
Set filetype for future image stores to be FITS.
Turn off/on autosaving of images.
Turn on/off autodisplay of images after they are taken.
Redisplay the current image with greyscale scaling between and .
Sets mode for autoscaling to have black level somewhat below mean level in image, and white level above it. This is the default.
Sets mode for autoscaling of images to be from minimum pixel (black) to maximum pixel (white).
Sets mode for autoscaling of images to be identical to the current scale.
Sets CCD windowing. If 4 coordinates are given, CCD will be set to window to requested region. If FULL is specified, windowing will be set back to full chip mode. If nothing is specified, user will be prompted to mark two opposite corners on the current image display to define the window region. In all cases, the final requested window position will be displayed on the current image.
Takes a series of flat fields, adjusting exposures times to maintain good S/N, for use in taking twilight flats. A ``good'' flat is defined as one with a mean level (over bias) of somewhere between 5000 and 20000 DN, with a minimum exposure time of 1 second. The routine will start out by taking an exposure of length startexp. From this, it will compute a new exposure time which is required to obtain a mean of 10000, after multiplying by the fudge factor fudge, which accounts for the changing brightness of the twlight sky (fudge should be for evening twilight and arounge for morning twilight. In no case will the program let the exposure time be longer than 30 seconds, and any 30 second flat will be counted as a ``good'' flat to prevent a large number of unsuccessful flats being taken when it is too dark. The program will continue taking flats until it gets ndesired ``good'' flats or until it has taken ``nmax'' flats.
Several commands are available to increase your efficiency in observing standard stars. There is a full catalog of all of the Landolt standards, plus several others, in the top level observe directory, with filename standards.apo. To allow use of this catalog in conjuction with your own catalog of objects, there are separate commands to open and read from the standards file, so you can have both the standards file and a user file open simultaneously. The standards file also includes the UBVRI magnitudes of the stars, and the observing program knows about the throughput of the 1m telescope, so the program is also capable of choosing reasonable exposure times for you.
The relevant commands are:
Open the standards file (analagous to OF for user files). If you are running in a subdirectory under the top level observe login directory, you will enter: ../standards.apo
Move to standard id. If no id is given, it will be prompted for.
Take an exposure of the current standard through filter filtname. You must have already moved to the star using the RS command. The program will move the filter automatically and will take an exposure based on the known magnitude of the star and the throughput of the system.
Sets a fudge factor for the automatic expossure time calculation of the STAN commands. All standard star exposure times will be multiplied by the fudge factor specified.
The current guider CCD is a camera purchased from Finger Lakes Instrumentation; it uses a E2V 10241024 CCD with 13.5 pixels.
In general, you can issue the same commands to the guider CCD as you can to the science CCD. To do so, use the same command names but preceeded by the letter ``G'', e.g., GEXP t will take a guider exposure of length t seconds.
Since our telescope is a three-axis telescope (alt-az-rot) and a single guide star only contains two positions (x-y), the absolute quality of the guiding depends on an accurate pointing model (although less so than if there were no guider at all!). We use the guider observations to update altitude and azimuth, and assume that the rotator angle is correct. Since the guider is located off axis, errors in the rotator angle will manifest themselves as small arcs of stars in the science camera, centered around the position of the guide camera (which is off of the chip).
To start guiding, first take a guider exposure to see if there is an acceptable guide star and to determine a good exposure time. Ideally, you will have a star which has good S/N with an exposure time of less than or approximately equal to 1 second. Once you have a picture taken with a good exposure time, you can start guiding by issuing the GUIDE command. This will take a picture with your exposure time, ask you to mark the guide star in the guide CCD image, and will then start autoguiding on this star.
If your original image was taken in full frame mode (WINDOW FULL), then all guiding images will be done with a small subframe around the guide star. If your original image was taken in windowed mode, then all guiding images will be taken with the same windowing.
Guiding will continue until you do a slew with the telescope or unless you issue a GUIDEOFF command.
Other commands relevant to guiding:
Sets the number of guide exposures to average centroids from before sending a position update command to the telescope. Default is 5.
Sets the size of the box used for computing centroids. Default is 11 pixels.
Puts guider in NOSHUTTER mode where exposures are taken without using the shutter. You must remember to issue the OPEN command to open the shutter before starting to guide!
Puts guider into normal SHUTTER mode.
Opens the guider shutter.
Closes the guider shutter.
Toggles mode where each individual guide exposure is saved to disk. Default is not to save each image. Currently, this command must be issued from the guider CCD control window (not the command window).
Initializes the guider stages by moving them to their home positions. Users should not issue this command without being instructed to do so!