RC80 control

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Foreword: the RC80 telescope is controlled via CCDSH. As for another telescopes, CCDSH provides the frontend to the telscope and its instruments while customized modules are available for specific functionality regarding to this particular telescope.

Please read this manual before using the telescope, either in an interactive way or via the scheduler.

Contents

Before observations

Login to the computer m51.konkoly.hu with your own account and start the CCDSH frontend using the the command ccdsh. Normally, the CCD> prompt should pop up within a second without any warnings or errors. If another user is using the telescope, the system would be locked via one of the logger modules and an error is reported. In this case, CCDSH would not start at all.

Initialization

Load the RC80-specific initialization script: CCD>source /usr/local/ccdsh/scripts/load-asa.ccdsh. Besides the essential backends, this command also loads and defines the camera and filter wheel modules. Filters are defined as follows:

define filter 1 u Sloan_u
define filter 2 B Bessel_B
define filter 3 g Sloan_g
define filter 4 V Bessel_V
define filter 5 r Sloan_r
define filter 6 i Sloan_i
define filter 7 z Sloan_z

Comment: Unlike on other telescope at Piszkéstető, this script also loads the module which communicates with the TCS. Thus, nothing will work without this step.

The fine-tunings of the alt-azimuth mount ASA800 telescope can be controlled via the asa command. Use the CCD>asa --help command to see the command options:

Usage:     asa [-h|--help] <command> [...]
        status
        slew taudec <hour_angle>,<declination>
        slew radec <right_ascension>,<declination>
        cover {upper|lower} {open|close|stop}
        rotator auto|<rotator_angle>
Internal commands - use when you know what are you doing:
        force respawn

Preparations: opening the telescope covers and dome slit

Open the telscope covers and the dome slit using the following steps:

  • Open the dome slit door: CCD>set dome slit open.
  • Open the telescope covers: CCD>asa cover upper open, CCD>asa cover lower open. Warning: Open the upper cover first! Check asa status before opening the lower one! These covers open/close fully within ~5 seconds.
  • Switch off the IR light of the camera: CCD>set dome light 2 off.

Preparations: automatic derotation and automatic dome tracking

Initialize the automatic modes as follows:

  • Set the rotator on auto: CCD>asa rotator auto. Currently there is no home position for the derotator. CCD>asa rotator 213.1 can be used as a "home position". This is the standard position of the derotator (i.e., when asa rotator is on auto) when the telescope is looking at the meridian, providing images with the normal view orientation (north is up, west is to the right, etc.).
  • Set the dome on auto (the dome will follow the telescope): CCD>set dome auto on.

Note: all of the three main "moving parts" of the whole telescope system (i.e. the telecope mount, the derotator and the dome) starts to move their intended position once the telescope is commanded to slew.

Checking the system

Use the CCD> asa status to check telescope status. The output should be something like this:

ASA_mount: sidereal_time:               289.11738
ASA_mount: number_of_controlled_axes:   2
ASA_mount: right_ascension:             289.08803
ASA_mount: declination:                 12.96731
ASA_mount: azimuth:                     0.04978
ASA_mount: altitude:                    55.04869
ASA_mount: is_slewing:                  0
ASA_mount: is_tracking:                 0
ASA_mount: is initializing:             0
ASA_mount: are_motors_started:          0
ASA_ACC: focuser: position:             7.94
ASA_ACC: derotator: angle:              213.072
ASA_ACC: cover: upper: position:        0.0
ASA_ACC: cover: lower: position:        0.2
MOD_ASA800: auto_derotation:            0
MOD_ASA800: auto_dome_azimuth:          0

If covers are opened properly:

ASA_ACC: cover: upper: position:        88.0
ASA_ACC: cover: lower: position:        87.7 

Some notes:

  • The are_motors_started line corresponds to the presence of the hold current on the stepper/servo motors and does not relate to any particular movement. Use the is_slewing and is_tracking to check whether is there any motion, or compare subsequent values of azimuth and altitude accordingly.
  • These lists above might be extended in the future. The outputs are intended to be both machine-readable and human-readable (i.e. easy-to-interpret).

Slewing

Slewing can be done with CCD>slew ra=hh:mm:ss,dec=+-dd:mm:ss, or in a fixed coordinate system (i.e., 1st equatorial), asa slew taudec tau_value,dec_value, where the values are decimal. Like in all of the CCDSH-based environments, the command slew accepts all of the objects whose coordinates can be resolved. The currently available resolve modules are:

  • CDS/Sesame: resolves mainly all of the "static" celestial objects (Messier catalogue, NGC objects, ...).
  • MPC/Ephemerides: resolves mainly all of the moving solar system objects in accordance with the naming conventions of the IAU Minor Planet Center
  • MPC/Natural satellites: resolves the irregular moons of the giant planets using the Natural Satellites Ephemeris Service of the Minor Planet Center.
  • CCDSH/active targets: this resolver uses the CCDSH target database of the TAO project: https://ccdsh.konkoly.hu/supernovae. Any objects listed here can therefore be resolved using the corresponding coordinates. Note that this resolver is case-sensitive.

Just check the coordinates of your favourite object using the CCDSH built-in command resolve. If this resolve command cannot resolve the target name, then slew ... won't do either.

Important comment: There is no set mount track [on|off] for this telescope. The command slew automatically starts the mount tracking, while asa slew taudec does not. Therefore, stopping the telescope movement is equivalent to send the telescope to some fixed position via this latter command.

If in doubt, check mount status with asa status:

ASA_mount: right_ascension:                289.08803
ASA_mount: declination:                 12.96731
ASA_mount: azimuth:                     0.04978
ASA_mount: altitude:                    55.04869
ASA_mount: is_slewing:                  0
ASA_mount: is_tracking:                 0

The image orientation set by the derotator is always absolute, however, images between the zenith and pole (i.e. having declinations larger than the latitude, i.e. ~49 degrees) are rotated by 180 degrees.

Imaging

From then the usual acquire, set filter ... and sequence commands can be used. For example: CCD>sequence -n SN2019odp-%N -V -x 3*([B,180],[V,180],[g,180],[r,180],[i,180],[z,180]).

Closing

Close the telescope after observations using the following procedure:

  • Send the telescope to home position: CCD>asa slew taudec 0,10. Mount tracking will not start this way.
  • Send the dome to home position: if dome tracking is not turned off, the dome should rotate to its home position after the upper command. Otherwise: CCD>set dome azimuth=0.
  • Close the telescope covers: CCD>asa cover lower close, CCD>asa cover upper close.

Warning: Close the lower cover first! Check asa status before closing the upper one!

  • Close the dome and set it to manual mode: CCD>set dome slit close, CCD>set dome auto off.

Finding the right focus

  • Slew to your favorite open cluster.
  • Run this script: source /data/rszakats/rc80/focus-longrange.ccdsh
  • Check the result from a terminal: display-focus.sh focus*.fits
  • Apply the best focus value when observing or running the scheduler: TCS80_generate.sh --start now --plot --verbose --sequential --focus 7.77 --already-open

Known issues

See also this page for further minor issues. Issues stroke out like this have already been solved, you can ignore those.

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