# PaKo's simplest recipe

This section gives a very short and simple overview of the steps needed to start spectral line observations. Details and more explanations are in the following sections, also in user's guides for special topics.

The following simple example is for both polarizations of one sub band, LI or UO, of one band, E090, of the EMIR receiver, see the EMIR user's guide for more information.

- Prepare a source catalog file, e.g., my.sou, with one line for each source that looks like:

      W3OH EQ 2000 02:27:03.8812 +61:52:24.572 LSR -45.000

- Prepare a line catalog file, e.g., my.lin, with one text line for each line frequency like:

      CS(2-1)         97.980968       LI
      12CO(1-0)       115.271204      UO

  LI and LO refer to sub bands of the EMIR E090 band. See the EMIR user's guide for details.

- Start up PAKO (see local information how to do this).

- Enter some general options and information.

      SIC PRIORITY 1 PAKO                 ! PAKO commands get precedence
      SET LEVEL   0   0                   ! to get verbose chatter from pako
      SET Project 111-22                  ! project ID (project number)
      SET PI       "Dr. Lilo D. Doe"      ! principal investigator
      SET Observer "John Doe"             !
      SET Operator  Pako                  !
      SET Topology  low                   ! topology for azimuth
      SET doSubmit  YES                   ! allow submission to Queue
      SHOW                                ! show parameters set with set

- Specify the line catalog and the receiver setup.

      CATALOG  line my.lin                ! specify (your) line catalog
      RECEIVER /CLEAR                     ! clear any previous RX setup
      RECEIVER E090 12CO(1-0) /Horizontal /Vertical

  The options /Horizontal /Vertical mean that both polarizations will be used.

- Select your target source from your catalog; select a backend and do a calibration without sky to send the receiver setup.

      CATALOG SOURCE my.sou               !  select your source catalog
      SOURCE  W3OH                        !  source W3OH from your catalog
      BACKEND /CLEAR                      !  clear any previous Backend setup
      BACKEND WILMA /default              !  simple spectrometer setup for EMIR
      BACKEND 4MHz  /default              !  simple spectrometer setup for EMIR
      CALIBRATE /SKY NO                   !  doesn't need to move to sky position
      START                               !  start

- Let the operator tune the reciver(s)

- Do a full calibration on the source, with default parameters:

      CALIBRATE  /DEFAULT                 !  default calibration
      START                               !  start

- Look at the results and check with the operator if the receiver noise temperature is OK.

- Select a strong compact continuum source for pointing and focussing; if possible, choose a source that is smaller than your beam!

      SOURCE  2251+158 /catalog iram-J2000.sou ! pointing source from catalog
      SOURCE  Uranus                           ! OR: a “small” planet

- Select the continuum backend for pointing and focus.

      BACKEND  /CLEAR
      BACKEND  BBC  /Default

  BACKEND BBC /Default connects one part of the continuuum backend BBC to each polarization and sideband of each selected EMIR band.

- Select beam switching mode and do a pointing.

      SWBEAM                              !  to select beam switching
      POINTING /default                   !  pointing
      START                               !  start

- After a pointing the data processing software displays the results and you can enter a correction for the observed pointing offsets with the command. Let's say, the results are and [arc sec]

      SET POINTING 3.4 -1.2

- Do a focus measurement.

      FOCUS            2.0                !  length [mm]
      START                               !  start

- After a focus the data processing software displays the results and you can enter a new focus correction, e.g., mm, with the command:

      SET FOCUS -2.1

- Select a pointing source that is near your target source and do another pointing measurement and enter the resulting correction.

- Select the target source from your catalog; select a backend and do a calibration.

      SOURCE  W3OH                        !  source W3OH from your catalog
      BACKEND /CLEAR                      !  clear any previous Backend setup
      BACKEND WILMA /default              !  simple spectrometer setup for EMIR
      BACKEND 4MHz  /default              !  simple spectrometer setup for EMIR
      CALIBRATE     /DEFAULT              !  default calibration
      START                               !  start

  BACKEND WILMA /Default connects one part of the WILMA spectrometer to each EMIR sub band selected with RECEIVER. BACKEND 4MHz /Default connects one part of the WILMA spectrometer to 2 EMIR sub bands selected with RECEIVER. 4

- Select your switching and observing mode, e.g., wobbler switching and on-off, and start observing.

      SWWOBBLER -120.0 120.0 /TPHASE 2.0          !  wobbler -/+ 120 arc sec
                                                  !  2 seconds per phase
      ONOFF /NSUBSCANS 12 /SYMMETRIC /TSUBSCAN 30 !  12 subscans
                                                  !  "symmetric" subscan sequence
                                                  !  30 sec per subscans
      START

- Do a calibration at least every 15 minutes, or when you change sources, or when you change receiver and backend setups.

- Do a pointing every 2 hours or when you change to a different region of the sky.

- Do a focus every 6 hours and after sunset and sunrise.
  (Before focus, do a pointing on the focus source!)

- HAVE FUN!

  NOTES.

  PAKO has built-in help for all commands, e. g.,

      HELP SWWOBBLER
      HELP ONOFF /NSUBSCANS

  Most commands can be abbreviated substantially, e. g., the following 2 are equivalent:

      ON /NS 16 /SYM /TS 22
      ONOFF /NSUBSCANS 16 /SYMMETRIC /TSUBSCAN 22

  If you find that you enter the same command(s) very often, it is not necessary to type them every time! They can be put into command “scripts” either by editing a file or with PAKO's SAVE command, see section 2.