MI/LDSS2 Observing Procedures

IMPORTANT: START BY CHECKING THAT THE DEWAR IS PROPERLY ALIGNED (CHECK MARK)

1. Accessing Data Acquisition Computer (LLama)

• Username: obsmag1b
• Password: check with the staff
• Open an xterm window
• cd /home/obsmag1b/data
• mkdir 20020914_15 (e.g.)
• cd 20020914_15

2. Start Detector Control Window in LLama

• From xterm window type 'ccd' to open detector control window
• Before the CCD control window appears you have to select 4 parameters from the menu:
  • LDSS-2
  • Site1
  • 16
  • magellan1
• On the CCD control window select Gain 1
• On the CCD control window select Subraster and enter the following values:
  • 1 2048 380 1620
  • Save spectra.subr
  • Apply
  • Done
• Open an IRAF window and go to the recently created directory (20020914_15)
• Load the 'ldss2' package twice
• Open XImtool

3. Open Flat Field Screen Lamp Window

• From any window type 'ffs' to open Flat Field Screen Lamp Window
• From any window type 'ldss2' to open Filter Window

4. Prepare filter list

• In filter window use right button to edit filter file, aperture file, and grism file

5. Dome Flats

• Start by taking a 5 sec exposure of the mask and measure the center (xs,ys)
• In Flat Field Screen Lamp Window click IN to move screen into place, click He and Ar, and take a 2-sec arc to check that the He and Ar lamps are working and that the spectral lines are aligned with the columns
• Turn ON quartz light at the platform and adjust voltage
• Turn OFF platform lights
• In Flat Field Screen Lamp Window click IN to move screen into place
• In filter window set Filter, Aperture, Grism
• In CCD window set exposure time and object to "Dome Flat"
• Exposure times:
  • 1.03" slit (355u): 10 sec (voltage=3.0) (after sunset to avoid sunlight)
  • 3.50" slit (1200): 5 sec (voltage=3.0) (after sunset to avoid sunlight)
  • PV: 7 sec (voltage=1.5)
  • PB: 10 sec (voltage=1.5)
  • PR: 4 sec (voltage=1.5)
• Start sequence with START botton
• When the sequence of flats is complete turn OFF quartz lamp
• In Flat Field Screen Lamp Window click OUT to move screen into place
• Take a sequence of bias frames (Set Exptime=0, Imtype=zero)

6. Skyflats

At sunset you must take sky flats for direct imaging:


• SLEW telescope to the East
• In CCD window set exptime to 5 (minimum), object to "Dome Flat", Filter=PB, Aperture=Open, Grism=Open
• Start exposure with START botton
• After completing the exposure slew telescope by 20 arcsec (in any direction)
• Take 5 frames per filter with exposures longer than 5 sec and never exceeding 28000 adu
• Take a sequence with PV filter, and then PR

7. Observing

• Use 'ldss_pangle' to determine paralagtic angle and ask the NA to set the rotator angle
• In filter window set Filter=PV, Aperture=Open, Grism=Open
• Take direct image of the field
• Take a short exposure of the slit and measure (xs,ys)
• Edit parameters for 'cobject' and enter (xs,ys)
• Run 'cobject'. You will have to mark object (space bar or 'm') and offset the telescope
• In filter window set Filter=Open, Aperture=slit, Grism=Medium-Blue
• In CCD window set exposure time, object to "object name", and click START to begin exposure
• To take arc lamp click IN to move screen into place, click He and Ar, and take a 2-sec arc exposure (don't forget to remind the NA to disable guider)
• Click OUT to move screen into place, and click He and Ar to turn OFF the lamps
• If you want to take a B direct image, ask the NA to increase the telescope focus by 6 units

8. Before going to bed

• Complete Observing Run Report Form
  
  mhamuy@lco.cl