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.

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
samiupdatecsv [-h] [-z] [-b] [-c] [—noobject] [--nosky] [--noguide] infile outfile

Enter with the “-h” option and it will output help on the arguments.

samiupdatecsv  run_1_galaxy_plate1_f1.allocated.csv run_1_galaxy_plate1_f1.allocated.20130101.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

  • Go to source
  • (If new screen can be observed – rare – get ARC and fiber flat both at start and end of 7 dithers.
  • 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

  • Lamp (CuAr) 10secs
  • sami.utils.domewindscreenflat_pos(“12h17m00s -00d12m52s”)  i.e.,(“HA, DEC”)
  • Return an azimuth and zenith distance. Need just zenith
  • Ask the night assistant to move the dome to that zenith distance (rounded to the nearest whole number).
  • Fiber flat 80 sec
  • Commence slew and track

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