The Coude Echelle Spectrographs

3.3 Controlling the Detector

Sections: CCD startup | Commands to take an exposure | Other commands | Error handling
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CCD Startup

 
Login to observer on aat40A (VAX 4000) (see whiteboard) then type:

$ CCD_U_VAC or
$ CCD_LVAC
specifies the controller in use - see the night assistant's whiteboard.

$ CCD_ n
where n = 1 or 2, specifying controller. This creates OBSERVER CCD_n display on terminal.
Have patience! It takes some time to start up. At the end the prompt should become IDLE>.
In the event of a fatal error, seek expert help.

INSTRUMENT NUMBER?
is used by the on-line log to add instrument-specific header items.
DATA USHORT
required if a large CCD (e.g. MITLL3) is used, in order to minimise readout time and disk storage.

WINDOW windowname
sets the readout area and on-chip binning of the CCD. A number of CCD windows are available in the default directory (GIVE)

ADD TABLE OF WINDOW NAMES
TEK1K_SETUP 121 x 1024, central columns; for UCLES setup.
TEK1K_SX2 (512+13) x 1024; binned x 2 along slit; usual for UCLES.
TEK1K_DIRECT (1024+26) x 1024
UHRF_X4 spatial binning x4 (256+4) x 1024
UHRF_X8 spatial binning x8 (128+4) x 1024

Custom windows can be created on request - ask your support astronomer or technician.

SPEED (SLOW, XTRASLOW, NORMAL, FAST, or NONASTRO)
sets the readout speed. Higher speeds introduce greater readout noise, so the correct choice depends on the anticipated count rate (see Section 1.4)
COLOUR (GRAY, CONTOUR, FALSE, GREY, or GRJT)
sets greyscale for XMEM display. GRAY turns red for pixels where the ADC is saturated.

Commands to Take an Exposure

TIME t
sets the default exposure time to be t seconds.
GLANCE [t]
takes an exposure for t in command or set by TIME. The exposure is displayed on the XMEM but not written to disk unless you type KEEP GLANCE (becomes an archival frame).

DUMMY [t]
takes an exposure for t in command or set by TIME. The exposure is displayed on the XMEM and written to a temporary storage area: DISK$DATA:[CCD_n.yymmdd]LETTER.SDF, or /vaxdata/ccd_n/yymmdd/letter.sdf where letter is a letter of the alphabet - filenames repeat after 26.

RUN [t]
takes an exposure for t in command or set by TIME. The exposure is displayed on the XMEM and written to an archival storage area: DISK$INST:[CCD_n.yymmdd]ddmmmnnnn.SDF, or
/vaxinst/ccd_n/yymmdd/ddmmmrrrr.sdf. (e.g. [CCD_1.010103]03JAN0034.SDF for the 34th run taken on 3/1/2001.)

DARK [t]
takes an exposure with slit shutter closed for t in command or set by TIME.

BIAS
0 second exposure with slit shutter closed

REPEAT [n]
repeat the next RUN style command indefinitely or n times in total.

SINGLE
end REPEAT mode at end of next exposure.
HOLD
close slit shutter and pause timer. Note that cosmic rays will continue to accumulate!
CONTINUE
continue paused exposure
STOP
terminate exposure, readout CCD
ABORT
terminate exposure or readout, trash data. Requires confirmation of YES or Y.

Other Commands

OBJECT text string
adds object name into header; can be done during exposure and/or readout
ADD COMMENT
EXIT
Exit at end of night, returning to DCL
$ LOGOUT
At end of each night; a new directory has to be created for next night and this requires OBSERVER to be logged in each day after 10.00 EST.

Error Handling

CTRL/P or CTRL/N
Scrolls previous/next message window
SHOW
shows CCD technical data. Observer automatically switches to this mode if detector status is red.
ENDSHOW
Return to normal operating screen.
RECOVER XMEM
Attempt to recover from error.
RECOVER CCD
Attempt to recover from error.
RESET
Clear system
RESET HARD
Clear system, including CCD & microcode.


Ray Stathakis (ras@aaoepp.aao.gov.au)
Last Update: 27 March 2000