SAMI Observing

 

Focusing the Spectrograph

File type to be dummy.

Click the “Auto Focus – Hartmann” button in the “AAOmega Spectrograph Control”

Exposure time 10 seconds.

Accept the results.

Repeat until the focus has converged.

If you need a starting point and lost the original value try the one below

Focus settings as of 16/02/2015 (A good starting point, but still run the focus script):

CCD Arm Spatial Tilt Spectral Tilt Piston
Blue 1563 3414 155
Red -308 1362 615

 

Day-time Calibrations (Biases, Darks and Long-slit Flats)

BIAS –  (AAOMEGA slides closed) 50 per run

Darks -25/30 per run [good abitude take a dummy exposure to avoid residual current]

Long-slit Flats/Detector flats – 30 per run

  • Defocus both the spectrographs TO ~4000  in piston
  • When software asks about lamp, keep top-end flats
  • 120 sec exposure
  • In blue, peak 15000, in read peak 40000 cnts

 

Near-zenith dome flat – 80 sec

Fiber flat at “near zenith” with the new screen (1 per plate). If plate is re-mounted need to get a new one!

 

Twilights

  • TIPS: if unsure check previous logs
  • Point 1 hr away from zenith in the direction opposite the sun .
  • If it is dusk, start immediately as the sun hits the horizon. A short exposure (~ 2-5 s).
  • “Offset Sky” as the observation type. DO NOT SELECT OFFSET FLAT!
  • 30,000 – 40,000 are good numbers for the highest values. .
  • Offset the telescope between frames by 60″ in a random direction.
  • For the next frame increase your exposure time.
  • Aim to keep the counts constant-ish between twilight frames. just note down in the log if you saturate one or if one has too few counts.
  • If observing dawn twilights, reverse the procedure, starting with your longest exposure about 15 mins before sunrise.

 

Focusing the Telescope

Point a star

Calculate offsets to move star

sami.utils.other.offset_hexa(‘/instsoft/2dF/config/SAMI_CurrentRun/CurrentDate/file.csv’)

The CSV file path should point to the allocation CSV file that describes the current plugging. It will output something like:

———————————————————————-
Move the telescope 192.26 arcsec W and 465.29 arcsec S
The star will move from the central hole
to guider 1 (G1 on plate)
Move the telescope 45.43 arcsec W and 268.23 arcsec S
The star will move from guider 1 (G1 on plate)
to object probe 6 (P6 on plate)
———————————————————————-

Give the offsets to the assistant, now s/he should see the star in the guide.

import sami
focus_values_list=[[focus1, fwhm1], [focus2, fwhm2],[..]]
sami.centroid.guider_focus(focus_values_list)

 

Updating and Loading the SAMI Allocation File

On aatlxy: /instsoft/2dF/config/SAMI_CurrentRun

Alternatively, you will find the file on the wiki http://sami-survey.org/wiki/target-selection-overview under “Plate Configurations By Run”.

aatmacb can see this instsoft directory and hence the csv files can be updated directly, make a subdirectory with the UT date to avoid accidentally overwriting the csv files.

The file names take the following form:

run_?_galaxy_plate?_f?.allocated.csv

ipython –pylab
In [1]: import sami
In [2]: sami.update_csv.allocate(“infile.csv”, “outfile.csv”)

Copy the output file to /instsoft/2dF/config/SAMI_CurrentRun/CurrentDate if it is not already there.

Upload the file into the AAOmega CCD Control Window, using the button at the bottom of the window. Once you have selected the correct file click Load Positions from SAMI File into Input Fields.

IMPORTANT – Double check that you clicked the Load Positions from SAMI File into Input Fields button!! This step is prone to human error.

Observing procedure

For each field, take flat and lamp at zenith

  1. Ask the night assistant to start the telescope, dome and windscreen tracking at a position at least 25 degrees from zenith. Simply driving the telescope and windscreen to the designated position for a dome flat will not work: the telescope must be tracking as though observing. Note that the windscreen should be in its default position before starting, that is, the telescope should be pointing at the gap between windscreens, not the windscreen itself!
  2. Take a science quality exposure (‘Fibre Flat’). Select Top-end Flat. The flat lamp should automatically turn on whenever a ‘fibre flat’ exposure time is selected. Always check that the windscreen is in front of the telescope aperture.
  3. The dome flat lamp should turn off automatically, but if it doesn’t, then it can be turned off by clicking the “Clear” button on the lamp calibration system control window.
  4. Check the flat frame when it has read out – if it has ~30,000 – 40,000 counts (not more) at the highest point that’s a good flat!
  5. Click Arc in the CCD control screen. It will do the entire routine automatically. Check that the Arc lamp is off and the flaps are open after the exposure.

 

  • Go to source
  • Ask night assistant to start at position A

S/he needs to put the stars at the pre-set marks. With 3×3 binning

Guide 1:  X=86.15   Y=175.78

Guide 2: X=141.95 Y=66.60

Guide 3: X=201.34 Y=170.24

If you are using 1×1 binning, multiply all pixel values (absolute values and offsets) by 3; if 2×2, multiply them by 1.5.

  • Click “Commence Slew and Track”
  • Take quick acquisition to check that everythin is in oder
  • Object – 1800 sec
  • Dither among positions

B – [0.4N, 0.6W] – [-2.90, -1.93]

C- [0.7S, 0.0] – [-2.90, -1.93]

D – [0.4N, 0.6E] – [+2.90, -1.93]

In between the dither sequence take arc and flat with new screen

With the new windscreen this can only be done below a ZD of ~20 degrees.

Click Fibre Flat in the CCD control screen. Select Top-end Flat, and start the procedure. (80sec)

Click Arc in the CCD control screen. It will do the entire routine automatically. Check that the Arc lamp is off and the flaps are open after the exposure. (10 sec)

Continue observing the field, but don’t forget to ask the night-assistant to move the telescope to the new dither position.

E – [0.4S, 0.6W] – [-2.90, +1.93]

F – [0.4S, 0.6E] – [+2.90, +1.93]

G – [0.7N, 0.0] – [0.00, -3.38]

samidisplay  [-h] [-ifu <1..13>] [-sigma] [-linear] [-gray] [-quiet]
              [-dispfor <0..1000>] [-x <0...>] [-y <0...>]
              [-waveband <1..1000>] [-pixstart <1..2000>]
              flat_file [display_file]

 

Spectrophotometric Standards

Shortened list picked from the ESO List see the SAMI Primary Calibrators page.

“Commands->Do Standard Star”

Select the guide bundle – generally Guide 2

Select the IFU you what to use from the drop-down. Start with the closest one

Enter the standard star position and name (the name is used for the headers).

Press “Calculate”.

Work through the “Operations” at the bottom of the window.

  • Slew to star
  • Apply “Field Center to Guide Bundle offset”
  • Wait that night assistant center on the guide bundle.
  • Apply “Guide bundle to IFU offset”
  • “Run the observing script.” The script will prompt for an exposure time.

[If offset do not work, do offset by hand – night assistant – and re-run the script]

The script will take three flux calibration exposures (with offsets of 2.5 arc-seconds). It will then take a FLAT and an ARC using standard exposure times in the script (80 seconds and 10 seconds) including moving the dome windscreen to the correct position and turning on/off the lamps.

  • You then need to observe the standard through a second hexabundle. To do so you can remove the IFU to Guide offset and then select a new IFU and repeat the above procedure.

If for some reason the default 10 and 80s exposure times for the arc and flat are not giving the correct counts, then these can be changed by editing the script, but do not edit any other part of the script apart from the ftime and atime values for flat and arc respectively in

~/obsscripts/sami/sami_std_star_data_acq.obsscript

 

 

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