COMPUTER TO TCS ASCII COMMUNICATIONS : Detailed descriptions
Jim Harwood
Revised May 17, 1996
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Argument:
n=0 for requesting immediate reply.
n=1 for requesting wait for any offset-type motion to complete.
Request current telescope position data. The data returned for RA, dec, HA, airmass, and epoch are from the same variables that are read out on the monitor display.
Returns:
Current telescope coordinates as follows-
RA DEC HA AIRMASS EPOCH
hh:mm:ss.ss dd:mm:ss.s hh:mm:ss.ss a.aaa yyyy.y
Example: 1 TPD
Returns from the TCS, after any offsetting has finished,
14:26:11.84 32:56:38.6 -01:44:29.21 1.187 1950 -OK
Argument:
n=0 for requesting immediate reply.
n=1 for requesting wait for current slew to complete.
Request last-entered slew position and epoch. In case the last-entered slew was aborted, the data returned are 0 0 0.
Returns:
Last entered slew coordinates and epoch as follows-
RA DEC EPOCH
hh:mm:ss.ss dd:mm:ss.s yyyy.y
Example: 1 LSP
Returns from the TCS, after the current slew is finished, its coordinates and epoch as-
9:23:41.84 41:19:55.6 1950.0 -OK
Argument:
Year in tenths. (0.0 for APPARENT.)
Requests a change of epoch, or if the argument is 0.0, a change from MEAN to APPARENT. If the original state was APPARENT, and a non-zero epoch is requested, the state will change to MEAN.
The TCS sends back as confirmation the new epoch preceded by the telescope coordinates corresponding to the shift in epoch.
Returns:
Telescope coordinates corresponding to the new epoch-
RA DEC HA AIRMASS EPOCH
hh:mm:ss.ss dd:mm:ss.s hh:mm:ss.ss a.aaa y.yy
Example: 1950.0 C.EPOCH
Returns from the TCS-
14:26:11.84 32:56:38.6 -01:44:29.21 1.187 1950.0 -OK
Calls for positioning the telescope to the A-beam or B-beam logical position. (See >BEAM< for altering the logical to physical beam relationship.)
No data are returned from the TCS, except the usual -OK.
Positions the telescope at one of the beam positions. These two commands generate a notification over the serial port to the external workstation that a beamswitch is happening, so tip-tilt operations can anticipate the beamswitch. The notification also occurs if a beamswitch button is pressed at the console. It consists of the requested beam letter (A or B) and the "-OK" prompt.
Returns the current beam state.
Example: ?BEAM
Returns from the TCS-
ABEAM -OK
or BBEAM -OKToggles the current beam designation without moving the telescope, and reports back the logical beam state. Thus, the first time>BEAM< is used, logical beam A becomes physical beam B and vice-versa. The second time >BEAM< is used, the logical and physical beams are the same.
The logical beam is the designation within the program, and the physical beam is the actual telescope's beam position.
Example: >BEAM<
Sends back from the TCS, if the current beam is B, without moving the telescope-
ABEAM -OK
Returns the current beamswitch position as a displacement from the beamswitch base position. The units are tenths arcseconds, positive for North and East. The RA coordinate difference has been multiplied by cos(dec) to produce the returned on-sky RA beamswitch displacement.
Returns:
Current telescope beamswitch displacement (after any pending beamswitch motion) as follows-
RA DEC
sss.s sss.s
Example: ?BS
Returns from the TCS-
0.0 -10.5 -OK
The return says that the telescope is currently zero arcseconds RA and 10.5 arcseconds south of the beamswitch base position.
Arguments:
ra.s is desired right ascension displacement in arcseconds.
dec.s is desired declination displacement in arcseconds.
Sets entered displacements in beamswitch thumbwheel locations as if the displacements were in the console thumbwheels. The displacements are positive for East and North. Subsequent beamswitch commands will cause the displacements to occur, such as pressing the beamswitch pushbutton or calling ABEAM or BBEAM. The right ascension displacement given is assumed to be an on-sky displacement, not coordinate difference. The value is divided by cosine(dec) prior to being applied to the telescope HA axis.
Example: 10.0 -20.0 TW.BS
Displacements of 10.0 arcseconds east and 20.0 arcseconds south will occur when ABEAM is called. The telescope will return to the beamswitch base position when BBEAM is called.
Returns the beamswitch displacements last entered in the thumbwheels. Assumes the associated pushbuttons were pressed at the IRTF so that the beamswitch thumbwheel data would be entered into the computer.
The units are tenths arcseconds, positive for North and East. The RA coordinate difference as applied to the telescope is derived by dividing the RA beamswitch thumbwheel data by cos(dec). Thus, the RA thumbwheel data represent the on-sky RA beamswitch displacement.
Returns:
Current thumbwheel beamswitch data as follows-
RA DEC
sss.s sss.s
Example: ?TW.BS
Returns from the TCS-
-5.0 20.0 -OK
The return says that the data in the beamswitch thumbwheels is 5.0 arcseconds west and 20.0 arcseconds north relative to the beamswitch base position.
Argument:
n=0 for requesting immediate reply.
n=1 for requesting wait for current offset to complete.
Causes the telescope to offset the amount entered in the offset thumbwheels relative to the base offset position. (If the telescope is already at that position, nothing happens.)
Nothing is returned from the TCS, except the usual -OK.
Argument:
n=0 for requesting immediate reply.
n=1 for requesting wait for current offset to complete.
Places the telescope back to the offset base position. If it is already there, nothing happens.
Only the -OK is returned from the TCS.
Returns the current offset position as a displacement from the offset base position. The units are tenths arcseconds, positive for North and East. The RA offset coordinate difference has been multiplied by cos(dec) to produce the returned on-sky RA beamswitch displacement.
Returns:
Current telescope offset displacement (after any pending offset motion) as follows-
RA DEC
sss.s sss.s
Example: ?OFFST
Returns from the TCS-
44.6 -211.5 -OK
The return says that the telescope is currently 44.6 arseconds west and 211.5 arcseconds south of the offset base position.
Arguments:
ra.s is desired right ascension displacement in arcseconds.
dec.s is desired declination displacement in arcseconds.
Sets entered displacements in offset thumbwheel locations as if the displacements were in the console thumbwheels. The displacements are positive for East and North. Subsequent offset commands will cause the displacements to occur, such as pressing PB4 or calling DO.OFFST or -DO.OFFST. The right ascension displacement given is assumed to be an on-sky displacement, not coordinate difference. The value is divided by cosine(dec) prior to being applied to the telescope HA axis.
Example: 23.6 -41.8 TW.OFFST
Displacements of 23.6 arcseconds east and 41.8 arcseconds south will occur when Pushbutton 4 is pressed the first time, or n DO.OFFST is called. The telescope will return to the offset base position when Pushbutton 4 is pressed again or n -DO.OFFST is called.
Returns the offset thumbwheel settings as entered at the console or by calling TW.OFFST. The units are tenths arcseconds, positive for North and East. Note that at the IRTF the mechanical thumbwheels are not read; what is read are the memory locations that receive the thumbwheel data when the associated pushbutton is pressed.
Returns:
Console offset thumbwheel or keyboard-entered data, or equivalent entered with command TW.OFFST, as follows-
RA DEC
sss.s sss.s
-OKExample: ?TW.OFFST
Returns from the TCS-
44.6 -211.5 -OK
The return says that the previously entered offset displacement data is 44.6 arcseconds west and 211.5 arcseconds south. The telescope would displace this far from the offset base position if Pushbutton 4 were pressed or command DO.OFFST given.
OFFSET takes ra and dec displacements in 10ths arcseconds and causes the offset to occur. An offset velocity other than the default maximum can be entered with rrr.r V-OFFST where rrr.r is the desired offset velocity in tenths arcseconds/sec. Once entered, that value of velocity will be used for all subsequent offsets.
If 0. 0. OFFSET is used, the telescope will return at full speed to the offset base position. Any current V-OFFST value won't be used. You can defeat this behavior by entering 0.1 0.1 OFFSET and then 0. 0. OFFSET.
Arguments:
r is a reply code:
r=0 for immediate reply.
r=1 to wait for this scan motion to complete before replying.
sss.s: RA arcseconds displacement, then dec arcseconds.
c is a command code:
c=0 for relative displacement.
c=1 for absolute displacement.
c= -1 to intitalize the current scan position without moving telescope (defines this as scan base position).
Displacements are positive for East and North. The displacement given for RA should be the on-sky displacement. This value will be divided by cos(dec) to produce a coordinate difference for output to the telescope.
Scanning patterns in the sky are done with this command. The scan motions are independent of offsetting or beamswitching. The displacements sss.s arcseconds are with respect to the scan base position when using 1 for argument c, and are with respect to the previous scan position when using 0 for this argument.
To specify the current telescope position as the scan base reference, -1 is used for argument c. In this case, the values of sss.s for RA and dec are "don't care".
To cause the telescope to return to the scan base position, the arguments should be r 0.0 0.0 1, where r is either 0 or 1.
Example: 1 21.3 -100.0 0 C.SCN
Returns the -OK from the TCS after the scan motion is complete. The telescope is moved 21.3 arcseconds east and 100.0 arcseconds south of its previous scan position.
Returns the current scan position as a displacement from the telescope's scan base position. The units are tenths arcseconds, positive for North and East. The RA coordinate difference has been multiplied by cos(dec) to produce the returned on-sky RA scan displacement.
Returns:
Current telescope scan displacement (after any pending scan motion) as follows-
RA DEC
sss.s sss.s
Example: ?SCAN
Returns from the TCS-
216.8 49.3 -OK
The return says that the telescope is currently 216.8 arcseconds west and 49.3 arcseconds north of the beamswitch base position.
Arguments:
r is a reply code:
r=0 for immediate reply.
r=1 to wait for this peak motion to complete before replying.
sss.s: RA arcseconds displacement, then dec arcseconds.
c is a command code:
c=0 for relative displacement.
c=1 for absolute displacement.
c=-1 to initialize the current peak position without moving telescope (defines this as peak base position).
Displacements are positive for East and North. The displacement given for RA should be the on-sky displacement. This value will be divided by cos(dec) to produce a coordinate difference for output to the telescope.
Peak patterns in the sky are done with this command. The peak motions are independent of offsetting, beamswitching, or scanning. The displacements sss.s arcseconds are with respect to the peak base position when using 1 for argument c, and are with respect to the previous peak position when using 0 for this argument.
To specify the current telescope position as the peak base reference, -1 is used for argument c. In this case, the values of sss.s for RA and dec are "don't care".
To cause the telescope to return to the peak base position, the arguments should be r 0.0 0.0 1, where r is either 0 or 1.
Example: 1 4.5 -10.0 0 C.PEAK
Returns the -OK from the TCS after the peak motion is complete. The telescope is moved 4.5 arcseconds east and 10.0 arcseconds south of its previous peak position.
Returns the current peak position as a displacement from the telescope's peak base position. The units are tenths arcseconds, positive for North and East. The RA coordinate difference has been multiplied by cos(dec) to produce the returned on-sky RA peak displacement.
Returns:
Current telescope peak displacement (after any pending peak motion) as follows-
RA DEC
sss.s sss.s
Example: ?PEAK
Returns from the TCS-
86.3 29.7 -OK
The return says that the telescope is currently 86.3 arcseconds west and 29.7 arcseconds north of the peak base position.
Arguments:
r is a reply code:
r=0 for immediate reply.
r=1 to wait for this autoguider motion to complete before replying.
sss.s: RA arcseconds displacement, then dec arcseconds.
c is a command code:
c=0 for relative displacement.
c=1 for absolute displacement.
c= -1 to intitalize the current autoguider position without moving telescope (defines this as autoguider base position).
Displacements are positive for East and North. The displacement given for RA should be the on-sky displacement. This value will be divided by cos(dec) to produce a coordinate difference for output to the telescope.
Autoguider motions in the sky are done with this command. The autoguider motions are independent of offsetting, beamswitching, or scanning. The displacements sss.s arcseconds are with respect to the autoguider base position when using 1 for argument c, and are with respect to the previous autoguider position when using 0 for this argument.
To specify the current telescope position as the autoguider base reference, -1 is used for argument c. In this case, the values of sss.s for RA and dec are "don't care".
To cause the telescope to return to the autoguider base position, the arguments should be r 0.0 0.0 1, where r is either 0 or 1.
Example: 1 4.6 -1.4 0 C.AUTOG
Returns the -OK from the TCS after the autoguider motion is complete. The telescope is moved 4.6 arcseconds east and 1.4 arcseconds south of its previous autoguider position.
Returns the current autoguider position as a displacement from the telescope's autoguider base position. The units are tenths arcseconds, positive for North and East. The RA coordinate difference has been multiplied by cos(dec) to produce the returned on-sky RA autoguider displacement.
Returns:
Current telescope autoguider displacement (after any pending autoguider motion) as follows-
RA DEC
sss.s sss.s
Example: ?AUTOG
Returns from the TCS-
16.1 23.8 -OK
The return says that the telescope is currently 16.1 arcseconds west and 23.8 arcseconds north of the beamswitch base position.
Stores the given autoguider velocity in arcseconds/sec. This velocity will be resolved along the two axes when an autoguider displacement is executed. The RA component will be divided by cos(dec) so that the on-sky velocity is uniform anywhere in the sky. The entered velocity should be unsigned.
Returns the current autoguider velocity in arcseconds/second. Zero means maximum possible velocity.
Returns:
Current telescope autoguider velocity as follows: v.s -OK
Example: ?V.AUTOG
Returns from the TCS: 20.0 -OK
Used only by the Tip-Tilt software. Stops or enables communications from an external data acquisition program to go to the TCS. The Tip-Tilt software sees all TCS commands going over the communications link. Sometimes, for dithering for example, the Tip-Tilt system will want to inhibit data acquisition commands to the TCS and instead of letting the TCS move the telescope, use Tip-Tilt to shift the image. These two commands are specific to Tip-Tilt software and are not to be used by data acquisition programs. They are not programmed in Forth; they are defined in and only recognized by the tcsd daemon running in the workstation. They are included here for completeness.
Returns 1 if there is no offset from base motion, 0 if OFB motion is occuring. Used by the Tip-Tilt software. May also be used by data acquisition software to get around the "wait for motion complete" problem.
Arguments:
Right ascension and declination coordinates, 10,000ths seconds time per year RA proper motion, 1,000ths arcsecond per year declination proper motion, epoch.
Provides the TCS with the coordinates and epoch for a desired object. The TCS applies the proper motion to the provided coordinates and reduces the mean coordinates to apparent. If the year is 0., the TCS assumes the provided coordinates are apparent. (Always use punctuation with the entered numbers.)
Return is immediate, without waiting for the TCS to slew to the object. Only the -OK is returned.
Example: 17:24:41.78 32:08:14.2 0.0461 0.184 1950.0 C.SLEW
Returns civil HST in 50ths seconds in the format ttttttt. The count goes up to 24 hours
Returns sidereal time in the format hh:mm:ss.ss.
Example: C.STIME
Returns from the TCS the sidereal time as follows:
8:41:19.83 -OK
Returns the current total displacement from the telescope base position, including beamswitch, offset, scan, and guiding. Waits for any currently active displacing to finish. The units are tenths arcseconds, positive for North and East. The RA coordinate difference has been multiplied by cos(dec) to produce the returned on-sky displacement.
Returns:
Current telescope displacement (after any pending displacement motion) as follows-
RA DEC
sss.s sss.s
Example: ?DISP
Returns from the TCS:
44.6 -211.5 -OK
The return says that the telescope is currently 44.6 arseconds west and 211.5 arcseconds south of the base position.
Resets the current telescope position as the base position for all offset-from-base functions except SCAN. You need to explicity call C.SCN with the appropriate parameters to define the scan base position.
Returns telescope status information. Equivalent to doing: 0 TPD C.STIME C.HST . You get back the following TCS information:
RA DEC HA AIRMASS EPOCH STIME HST MOVING?
in the formats-
hh:mm:ss.ss dd:mm:ss.s hh:mm:ss.ss a.aaa yyyy.y hh:mm:ss.ss tttttt n
where the n is 0 if not moving on the sidereal sky, 1 if moving but not slewing, and 2 if in a slew.