1. How to start up the CCD
2. How to start up UHRF
3. How to set up at a given wavelength
4. How to focus the collimator
5. Taking observations
6. Choice of filters
7. Copying AAT data
To start up the CCD, check the white board in the control room for the controller in use (upper or lower) and type either:
vax: CCDU_VAC
or
vax: CCDL_VAC
Then start the CCD with
ccd: CCD_n
where n is the CCD number written on the whiteboard.
When the idle prompt appears set the window, speed and colour for the detector. For example,
ccd: WINDOW UHRF_X4 for TEK window binned x 4 in
x-direction
ccd: WINDOW MITLL_FULL_B1X4 for MITLL window binned
x 4 in x-direction
ccd: SPEED SLOW
ccd: COLOUR GRAY
To start up the UCLES/UHRF software type:
vax: UCLES
and answer the questions. For the question, "Start set up procedures (Y/N)" you must answer N (or just hit return).
For the question "UCLES or UHRF?" answer UHRF
uhrf: FETCH filename
uhrf: CONFIG
uhrf: ARC THAR
Now take a dummy frame so see how the arc lamp looks:
ccd: DUMMY 20
If neccessary, make adjustments to the grating angles UT (dispersion direction) and UG (spatial direction) to recenter the order on the CCD. With the TEK ccd window uhrf_x4, the full CCD frame is 800 x 400 ADU. To shift order right on XMEM display increase gamma. To shift upwards in y-direction decrease theta.
Examples:
uhrf: UG 56500 # sets UG to 56500
uhrf: UT 14400 # sets UT to 14400
Make sure that there are at least two identified arc lines that can be used for wavelength calibration. Also check that the central wavelength is corrected for the velocity shifts of your sources.
The collimator focus procedure is done with a Hartmann test by taking two frames with the ThAr lamp with the upper and lower Hartmann shutters closed. For example:
ccd: WINDOW UHRF_X4
uhrf: ARC THAR
uhrf: UHU SHUT (shut the upper Hartman shutter)
ccd: DUMMY 15
uhrf: HP OTHER (swaps them round)
ccd: DUMMY 15
To determine the focus shift needed, set up a figaro command file which plots the two spectra on top of each other and gives the cross-correlation shift in pixels between them.
A command file with the following lines will do this process with a YSTRACT for the x-axis pixel range 30 to 180:
ystract $D/$1 030 180 sp=$1f
ystract $D/$2 030 180 sp=$2f \\
scross $1f $2f xs=min xe=max rec=no
splot sp=$1f wh=y au lab="focus_test" bu=n ha=n col=r
ax er \\
splot sp=$2f wh=y au bu=n ha=n col=g noer noax \\
An example file with these lines can be copied from the unix file /epping/ras/uhrf/foc_unix.com. Modify this file so that the x-start and x-end values cover the order.
To run the command file:
unix: setenv D /vaxdata/ccd_2/date
unix: figaro
figaro: figdisp
figaro: soft /xdisp
figaro: foc_unix.com a b
where a and b are the two Hartmann exposures taken with the upper and lower shutters closed respectively.
The cross-correlation routine will give the shift between the two spectra in 'pixels'. To convert to ADU values used by UHRF, use the following conversion scales.
For the TEK CCD:
@1E6, 1 pixel = -50 ADU
@6E5, 1 pixel = -80 ADU
@3E5, 1 pixel = -170 ADU
For the MITLL2 CCD:
@1E6, 1 pixel = +31.25 ADU
@3E5, 1 pixel = +106.3 ADU
The collimator focus for UHRF has two different drives, giving coarse (UFC) and fine (UFF) control.
To set the focus, first use the coarse control. This sets the focus position to within about 30 ADU. Then use the fine control (UFF) to adjust it to the final value. The UFF control has a maximum range of around +/- 100 ADU and can be driven out of range. If this happens then reset the focus value using the coarse control. It is possible to set the focus position to an accuracy of 5 ADU.
> R UF
It may be necessary to repeat the focus procedure if the initial focus was poor. After focusing, open both the Hartmann shutters. Note that the instrinisc instrumental resolution for UHRF can only be measured using the laser lamp which gives a spectral line at 6328 Angstroms, as the ThAr lines are resolved at such high resolutions.
Calibration observations generally include ARC frames, bias frames, flat fields (taken with SLIT) and spectrophotometric standard stars or radial velocity standards if needed.
ccd: WIN name
ccd: SPEED SLOW
ccd: BIAS
ccd: REPEAT N
uhrf: SLIT SLIT
uhrf: SL MAX
uhrf: SW 2 arcsec
uhrf: LOF
uhrf: ARC QUARTZ
uhrf: LO QUARTZ (this selects the correct quartz
lamp)
ccd: OBJECT QUARTZ_l
ccd: RUN 3
ccd: REPEAT N
when this is finished remember to put the slicer back in.
uhrf: SLIT SLICER
uhrf: ARC THAR
ccd: OBJECT thar_line # set name
ccd: RUN 20 # for 20 second exposure
For wavelength calibration - ensure that at least two well identified ThAr lines are present. If not take an extra frame with an offset in theta until there is a second line that can be used for interpolation.
uhrf: SF1 7 # sets the filter in position 7 of slit filter wheel 1
For blue wavelengths it is advisable to use a bandpass filter to cut out scattered red light. Examples are UG11 centred at 3300 and BG12 centred at 4000. Note that the blue filters have some transmission losses and may also have strong red leaks.
For red wavelengths, it is advisable to use a 'cut-on' filter such as RG630. These have a sharp cut-off profile at low wavelength edge.
The response of different filters can be plotted using Steve Lee's programme curves.
Information, written by Chris Tinney, on how to copy AAT data is given in the CCD imaging manual.