NACO P2PP Tutorial

This tutorial provides a step-by-step example of the preparation of a set of OBs with NACO, the near-infrared adaptive optics assisted imager and spectrograph on UT4 of the VLT.  The specifics of this tutorial pertain to the preparation of OBs for Period 91.

To follow this tutorial you should have a P2PP (Version 3.4.0) installation on your computer and be familiar with the essentials of the use of P2PP (Version 3.4.0).  Please refer to the P2PP Webpage for detailed installation instructions, and to the P2PP User Manual for a general overview of P2PP and generic instructions on the preparation of Observing Blocks (OB).  Finally, please note that the P2PP screenshots shown below were made with a previous version of P2PP (3.2.1).  While there are some differences between that version and the version for P94 (3.4.0), the appearance of the screens will be the same as those shown below, apart from the different version number at the top of some of the screenshots course.

0: Goal of the Run

In this tutorial we will prepare OBs for a simple example observing run, consisting of broadband imaging and spectroscopy of the pre-main sequence star LS-RCrA 1 (RA (2000) = 19:01:33.7, Dec (2000) = -37:00:30).  The AO reference target for this observation is the nearby visibly bright K0 star V709 CrA (RA (2000) = 19:01:34.3, Dec (2000) = -37:00:55, V=11.24).  Note that in spite of the fact that the Strehl ratio you could achieve on LS-RCrA 1 would be higher if you were using the Laser Guide Star Facility (LGSF), we here consider the case where the LGSF was not requested in the observing proposal. This means you are not allowed to use it; hence we will ignore it for this Phase 2 Tutorial.

The following OBs will illustrate the use of a variety of features of P2PP and the NAOS Preparation Software (NAOS PS) and they will illustrate the kind of decisions to be taken at the time of preparing an observing run, as well as some aspects that are specific to the preparation of OBs for NACO.

1: Getting started

The Phase 2 process begins when you receive an email from the ESO Observing Programmes Office telling you that the allocation of time for the coming period has finalized and that you can view the results by logging into the User Portal and clicking on "Check the webletters." Note that the username and password that you need to use for the User Portal are the same as those you will use to prepare your OBs.

Following the instructions given by ESO, you find that time was allocated to your run with NACO. Therefore, you decide to start preparing your Phase 2 material.

First, you collect all the necessary documentation:

and you proceed with the installation of P2PP and the NAOS PS on your machine, if necessary.

to the top

2: Your First OB

You decide to start with the somewhat simpler of the two science aspects, the imaging portion. So, off you go to define those observations.

2.1: First Things: The NAOS PS

Since NACO is actually comprised of two separate instruments (NAOS and CONICA), you must configure each of these in turn. A number of aspects of NACO OBs depend on how the adaptive optics part (NAOS) is configured, so you should start with the NAOS PS first.

After starting the PS (by entering the command jnps) you will see the following Graphical User Interface (GUI)

new-jnps_scr1

to the top

2.1.1: Configuring the Target & Instrument Setup

Start filling the box in the upper left of the interface (Target & Instrument Setup).  The fields in this box are

  • CONICA filter: Here is where you should select the wavelength at which you wish to compute an estimate of the resulting Strehl ratio.  Since this Run will have Ks observations you may leave the pulldown menu with its default value.  This results in the field Observing Wavelength showing 2.18 microns.  (Had you chosen free for the filter you would then fill in the wavelength manually.)
  • Dichroic: This is the place where the selection of the dichroic is made.  This is the component that directs some portion of the light to NAOS and some to CONICA.  If you want to force the PS to use one of the available dichroics you can select it from the dropdown menu.  For purposes of this tutorial, let's leave the choice of the dichroic up to the PS, hence leave the dropdown menu as FREE.
  • Target Name: Here you should put the name of the source to be observed, LS-RCrA.
  • RA: Enter the Right Ascension into the three fields (19, 01, and 33.7, respectively).  This R.A. is in the J2000.0 equinox.
  • DEC: Enter the J2000.0 Declination into the three fields (-37, 00, and 30, respectively).
  • Epoch: Since this is not a high proper motion target you can leave this to the default, 2000.0.
  • Equinox: As mentioned above, you've already entered the coordinates in the J2000.0 equinox.  Hence, this, too, can remain as the default, 2000.0.
  • Prop. Mot. RA: Since this is not a high proper motion target you should enter 0.
  • Prop. Mot. DEC: Since this is not a high proper motion target you should enter 0.

to the top

2.1.2: Configuring the Reference Object

Continue filling in items in the PS interface by entering values in the box on the right of the GUI (Reference Objects).  Note that since the science target is different from the AO reference object these fields must be filled in manually.  The entries in this box are:

  • Distance to Target: This field will be filled in automatically when you enter the AO reference object coordinates (see below).
  • Seeing Enhancer: If you had the idea to observe a target that itself was too faint for adative optics correction, and that had no suitable nearby object to use as a tip-tilt reference you could still have proposed to use the LGS in "seeing enhancer" mode.  This is a mode in which the LGS is used to correct higher-order atmospheric distortions, at the expense of having no tip or tilt correction applied.  The resulting FWHM is better than seeing-limited, but not as good as "full blown" LGS correction.  If the NAOS PS was being used for such a purpose you would have selected the LGS wavefront sensor in Section 2.1.1.  Then, the Seeing Enhancer option would be selectable.  In this case, since you have a perfectly good AO reference object, and have not applied for LGS observations, this remains greyed out.
  • Name: Here you should put the name of the AO reference object, V709CrA.  Note that spaces are not allowed in this field.
  • RA (2000): Enter the J2000 Right Ascension into the three fields (19, 01, and 34.3, respectively).  Note that the NAOS PS tacitly assumes that the equinox of the reference object coordinates is the same as for the target itself, so here you had to use the J2000 Right Ascension.
  • DEC (2000): Enter the J2000 Declination into the three fields (-37, 00, 55, respectively).  When both RA (2000) and DEC (2000) fields are filled in, you should see 26.01 in the Distance to Target field. This is the separation between the target and the AO reference object. The fact that it is 26.01 and not 26.00 is inconsequential, and is the result of a very small java arithmetic inaccuracy.
  • Prop. Mot. RA: Since this is not a high proper motion source you should leave this as 0.
  • Prop. Mot. DEC: Since this is not a high proper motion source you should leave this as 0.
  • Tracking Table: Since this is not a solar system object this box should remain unticked.
  • Morphology: The AO reference object for this example is a star, so you should leave the default (Point-like) for this field.
  • Photometry: Since the magnitude and spectral type of the AO reference object is known, leave this as the default (Mag. + Spectral Type).
  • Magnitude: Enter the known (V) magnitude, 11.24.
  • Band: Here you should select the Band which the magnitude corresponds to.  In this example the default (V) is fine.
  • Spectral Type: Select here the spectral type of the AO reference object (K0V) from the dropdown menu.
  • AV: Here you decide to use a modest value of 5 for the extinction at V.

Next, you must register this object by clicking on the Register Object button at the bottom of this subpanel.

to the top

2.1.3: Configuring the Sky Conditions

One more subpanel, Sky Conditions must be configured before the NAOS PS can be asked to determine the optimal instrument configuration for these observations.  Here you must enter the poorest sky conditions which will return useful scientific data.  However, note that in your Phase 1 proposal you already specified the seeing constraint.  You must make sure that the seeing constraint specified here is no more stringent than the corresponding one specified at Phase 1.  The fields to be filled in for Sky Conditions are:

  • Seeing at zenith: This is the optical seeing toward the zenith.  Since average conditions will suffice for this project, and since the reference target is not too far from the science target, you decide not to relax the value you used in the proposal but instead select 0.8 arcseconds from the dropdown menu.
  • Airmass: Since this field goes almost straight overhead you can set a reasonably tight constraint for the airmass and not compromise your chances of having the source being observed.  Keep the default value of 1.2.
  • Seeing on reference object: This automatically contains the resulting optical seeing at the airmass you've specified.  Nothing to enter here.
  • r0 on reference object: This automatically contains the resulting size of the Fried parameter equivalent to the telescope diameter.
  • Theta0 on reference object: For the assumed model atmosphere, this is the corresponding angle subtended by r0.  This field is automatically filled and nothing need be entered here.

to the top

2.1.4: Optimization and Exporting to P2PP

Having entered all of the information required for the NAOS PS to determine an optimal NAOS configuration, you should now click on the Optimize button in the lower left of the PS GUI.  After a brief wait the GUI will look like this

new-jnps_scr2

(You should not worry if the Strehl Ratio (Sr) numbers in the lower left panel (Resulting Performance) do not exactly match the values shown in the above image.  It can be that there are small differences in the returned values, even when running the exact same set of values through the optimisation.  This is because the software uses a realistic, and random, simulation of the atmosphere.)

Next, you must export the NAOS configuration to P2PP in the form of a NAOS parameter file (the so-called '.aocfg' file).  To do this click on the Export to P2PP button on the bottom of the GUI.  A small browser window similar to the one shown below will pop up.

new-jnps_scr3

For the File name you should enter something that you can remember.  Here the default (LS-RCrA.aocfg) is fine.  Pick a suitable (sub-)directory for the file using the browser, and click on Save.

to the top

2.2: Next Stop: P2PP

For the sake of this tutorial, we will hereafter use the following P2PP information:

  • P2PP ID: 52052
  • password: tutorial

This is a special account that ESO has set up so that users who do not have their own P2PP login data can still use P2PP and prepare example OBs.  You cannot use it to prepare actual OBs intended to be executed.  When you prepare such OBs you should use your ESO User Portal credentials for P2PP.

After logging in using the tutorial account, the P2PP main GUI will appear as follows:

p2pp-1

Runs for a number of instruments appear in the Folders and Summary area, since the same tutorial account is used for all of them.  Similarly, if you log in with your own ESO User Portal credentials, you will get the list of all the runs for which you are PI.

Select the folder corresponding to the NACO Tutorial run, 60.A-9252(H).  In this tutorial we assume that time was allocated in Service Mode.  This is indicated by the SM letters that appear next to the RunID.

You can now start defining your observations.  Since you will have a PSF reference OB which is to be associated with the science imaging OB, you must include both into a concatenation container.  Refer to the P2PP User Manual for details on creating a concatenation and populating it with OBs.  Here we will assume that you have created a concatenation called 'Imaging + PSF' and have started by populating it with an OB called 'LS-RCrA 1 - JHKs.'

After double-clicking on the newly created OB you will then be in editing mode, and you should see the following window:

p2pp-2

This is the window where you will define the contents of your OB.

to the top

2.2.1: Filling in the Basic Information

It may be useful in many cases to have an easy way of identifying an Observation Description (OD), like when having observations of a number of targets performed with identical instrument configuration and exposure times.  The OD Name field in the View OB window allows you to define names for the ODs.  The OD name appears in turn in the Folders and Summary area of the P2PP main GUI, thus allowing the identification at a glance of all OBs having ODs with the same name.

In this example OB, the OD will consist of a sequence of three jittered exposures through the J, H, and Ks filters. We can thus appropriately name it 'JHKs jitters.'  We enter this name in the OD Name field.

Next, the User Comments field can be used for any information you wish (to keep further track of the characteristics of the OB, to alert the staff on Paranal to special requirements, ...).  For this tutorial you can try it out by entering the text "NACO Tutorial Imaging OB."

Finally, there is the Instruments Comments field.  This field is not in use for NACO for Period 91.

to the top

2.2.2: Defining the acquisition template

The first template that must be part of any OB is the acquisition template, so let us define it next.  In the TemplateType pulldown menu make sure that acquisition is selected.  This will list all the acquisition templates available for NACO in the Template list below it.

After reading the description of the templates in the NACO User Manual, you have determined that the NACO_img_acq_MoveToPixel template is the most suitable one for this particular observation.  You thus click on this template in the Template list, and then on the Add button next to it.

You need to decide now on the acquisition parameters.  This acquisition template simply sets a filter and takes exposures in open loop presenting in the Real Time Display at the telescope console the image obtained after NDIT integrations of DIT seconds each, to allow the identification of the target field.  Since you have decided to obtain the images in the J, H, Ks filters in this order, sometime will be saved if you set the J filter already in the acquisition template, so that the filter setup is already done by the time that the first science observation starts.  Moreover, since your target is fairly bright (but not bright enough to warrant a neutral density filter) the images for acquisition do not need to go very deep, meaning that DIT and NDIT can be small, say, 5 sec and 2 exposures, respectively.  As to the other parameters, after checking the manual you decide that the S13 camera is the one most suitable for your observations and that the default orientation of the frames, with North at the top, is alright.  Further, these observations will not be used to obtain a comparison PSF observation.  Finally, you decide that you would rather keep the field rotation fixed and rotate the pupil than the other way around.  The set of parameters that you choose in your acquisition template is thus:

  • DIT: 5
  • NDIT: 2
  • Type of AO Observation (LGS/NGS): NGS
  • PSF reference? (T/F): box remains unchecked
  • Pupil tracking mode: box remains unchecked
  • RA offset: 5
  • DEC offset: 5
  • Position Angle on Sky: 0.
  • Filter: J
  • Neutral density filter: Full
  • Camera: S13

Type of AO Observation is set to NGS (Natural Guide Star) since this is not a Laser Guide Star-assisted observation.The values for RA offset and DEC offset are used to make an offset to a "sky" position for better source recognition. The default values are fine for this example.

For the remaining acquisition parameter, NAOS parameter file, you should supply the file (LS-RCrA.aocfg) created in Step 2.1.4 above.  To do this, click on the read NO DEFAULT field next to NAOS parameter file and browse until you find the file you just generated.  Once you have found the file, highlight it and click on Open.  The acquisition template is now complete, and the window should now look like this:

p2pp-3

to the top

2.2.3: Inserting Target Information

Let us for a moment take a break from inserting templates into this OB and turn our attention to a few more general aspects of this OB.  We start by clicking on the Target icon in the icon bar at the top of the view window.

Here you will see that that the Name, coordinates (including epoch and equinox), and proper motions of the science target appear in their respective fields already!  This is as a result of having attached the .aocfg file.  This information must never be edited within P2PP, as it will then be incompatible with the settings of NAOS.  The only entry in the Target View which may be edited at this point is the Class to which this object belongs, for archival purposes.  In this case, choose pMS* (pre-main sequence star).

to the top

2.2.4: Setting the Constraint Set

As stated in Section 1, we assume for the purposes of this tutorial that the program has been allocated time in Service Mode.  You thus need to specify a Constraint Set for your OBs.  You can do this by clicking onthe Constraint Set icon and filling the entries in the Constraint Set View:

  • First, give a descriptive name to the constraint set about to be defined.  Since you have decided that this constraint set will be applied to all the imaging observations, you type Imaging constraints in the Name field.
  • Since you wish to be able to determine accurate fluxes from your images, you requested photometric observations when you wrote your proposal.  Hence, here in Sky Transparency entry you leave Photometric.
  • You may notice that the Seeing field at this point has a value in it. This value was taken from the .aocfg file in the same manner as were the source coordinates.  Since it is imperative that the seeing in the Constraint Set matches that used as the Seeing at zenith within the NAOS PS package you must never change this value in p2pp.
  • The Strehl (%) value is also extracted from the .aocfg file.  You are free to edit the value but you must never increase the value above the default.  Since you are satisfied with the predicted value of 45.94% Strehl, you should leave the default as it is.
  • The last Constraint Set parameter which is taken from the .aocfg file is the Airmass.  As with the seeing, it is imperative that the seeing in the Constraint Set matches that used as the Airmass within the NAOS PS package you must never change this value in p2pp.
  • Since you are doing broad band observations in the near-infrared, the lunar illumination has very little influence.  You can thus leave the default values of 1.0 and 30 degrees for the Lunar Illumination and Moon Angular Distance fields.
  • Finally, as of Period 90 there is a new parameter that is used at the telescope to assist in the scheduling of OBs: "Atmospheric Turbulence Model."  The Period 91 default value for this parameter is "default Paranal atmosphere model."  This implies that consideration for the atmospheric turbulence is to be considered when scheduling this OB.  Since you are using AO for these observations this is the correct value by default.  Hence it should remain as it is.

Note that in your Phase 1 proposal you already specified some of these constraints (lunar illumination, transparency). You must make sure that none of the constraints specified in Phase 2 is more stringent than the corresponding one specified at Phase 1.

to the top

2.2.5: Setting the time intervals

We will assume now that the imaging observations that you are defining are part of a photometric monitoring program of LS-RCrA 1 and that, to ensure that you have the light curve properly sampled, this particular OB needs to be executed during July 2013.  You can specify this in the Time Intervals View after clicking on the Time Intervals icon:

  • Since this is a time requirement, and not a sidereal time requirement, make sure that the Time Intervals tab is selected.
  • Click on the New TI button.
  • Modify the lower boundary of the time interval to the specified starting date of your time window.  In the present case, the two fields should read: 2013-07-01, and 00:00, respectively.
  • In the same way, modify the two fields of the upper boundary of the time interval to 2013-07-31, and 00:00, respectively.
  • Finally, click on the OK button.

If your observation could be executed in other, non-contiguous time windows, you could define more intervals in the same way as described.

to the top

2.2.6: Defining the Observation Description

Once the acquisition template is complete and the items Target, Constraint Set, and Time Intervals are filled in, the science template(s) can be inserted.

After checking with the manual and considering the scientific requirements of your program, you have decided to execute the observations using a random jitter pattern of 10 points within a 6 arcsec box, using the object frames themselves to construct a sky frame by median-filtering.  You conclude that the NACO_img_obs_AutoJitter template is the most suitable one.  After clicking on the Obs. Description icon, select science from the Template Type pulldown menu.  The existing NACO science templates will appear.  Select the chosen one, NACO_img_obs_AutoJitter, and click on Add.  The template will be attached to the grid below next to the acquisition template selected and filled previously.

Given the flux of your source and the advice on the duration of the individual DITs in each filter as given in the User Manual, you decide that an appropriate choice of integration parameters is such that at each jitter position you obtain 1 exposure of 60 sec in J, 2 exposures of 45 sec in H, and 4 of 30sec in Ks. Further, given the background you decide that the readout mode of the array should be Double_RdRstRd.  You also consider, but reject the idea of using Cube Mode observations; hence you must take full frame exposures.  You also decide to start the jitter in each filter at the reference position given by the preset coordinates, rather than at the last position observed in the previous template.  The first NACO_img_obs_AutoJitter template (the observation in J) thus has the following parameters:

  • DIT: 60
  • NDIT: 1
  • Readout mode: Double_RdRstRd
  • Window size: 1024
  • Observation Category: SCIENCE
  • Store Data Cube (T/F): box remains unchecked
  • Jitter Box Width (arcsec): 6
  • Number of exposures per offset position: 1
  • Number of offset positions: 10
  • Return to Origin ? (T/F): checked (i.e., True) (the telescope will thus not try to recenter a guide star after each offset)
  • Filter: J
  • Neutral density filter: Full
  • Camera: S13

Since this observation does not fall into the special category of those that are suited to pre-imaging, Observation Category remains at the default value (SCIENCE).

For the observations in H and in Ks, you can select again the same template, Add it, and fill the parameters in the same way as done for the template in J.  However, since the parameters of these other two templates will be very similar to those of the one just defined, you can speed up the preparation by clicking on any entry of the template for the jitter in J (thereby selecting that column), then clicking on the Duplicate button next to the list of templates, and then clicking again on the same button. In this way, you will have produced two identical copies of the first science template in which you should now only edit the parameters that change from template to template:

  • DIT must be changed to 45 and 30, respectively.
  • NDIT must be changed to 2 for the last column (the one which will be made to be Ks in the next change)
  • And Filter must be changed to H and Ks, respectively.

The only other thing that you should really do at this point is to check the execution time for this OB. To do this click the Recalculate button to the right of the Execution Time field.  It is not bad practice to click on that button whenever one or more parameters that could affect the timing of the OB are modified or added.  In this case the total execution time is 00:55:36, that is, just under the 1 hour execution time limit.

This completes your first OB! If you followed all the indications given so far, the View OB window should look like this now.

p2pp-4

and you should see an entry under Folders and Summary in the P2PP main GUI with the following contents:

  • Name: LS-RCrA 1 - JHKs
  • Status: (P)artiallyDefined
  • Target: LS-RCrA
  • OD: JHKs jitters
  • CS: Imaging constraints
  • Acquisition: NACO_img_acq_MoveToPixel
  • FindingCharts: (0)
  • EphemerisFile:

You can reshape the columns as indicated in the P2PP User Manual to view the full contents of each entry.

At this point you may notice the (0) under the heading of FindingCharts.  This is because you have not attached any Finding Charts to the OB. Following the general and NACO-specific rules for Finding Chart generation, you make your FindingChart(s).  The jpg file(s) should then be on your local disk, and you attach them one by one to the OB by highlighting the OB, selecting Finding Charts from the Menu bar, and selecting Attach Finding Chart(s) from the pull-down menu. This gives you a browser window, in which you navigate to the correct directory and select the file(s).  The P2PP Finding Chart Tutorial gives more advice on how to attach Finding Charts within P2PP.

to the top

3: Defining a PSF imaging OB

When planning your observing run, you realized that your imaging observations would require some deconvolution with a PSF reference star.  You soon realized that the requirements for this were such that you had to find another pair of stars separated by (at least roughly) the same distance as LS-RCrA 1 is from its AO reference star.  Further, one member of this pair must have the same V magnitude as the original AO reference star.  These constraints impress you as very hard to achieve!  Undaunted, you spend quite some time looking for a suitable pair of stars, in the end settling on:

  • GSC 07902-00834: R.A. (2000) = 18:33:36.875, Dec. (2000) = -38:10:27.42, V = 11.2, pma = pmd = 0
  • GSC 07902-01850: R.A. (2000) = 18:33:35.972, Dec. (2000) = -38:10:04.43, V = 11.0, pma = pmd = 0

where GSC 07902-00834 will serve as the AO reference target for the PSF calibrator GSC 07902-01850.

The calibration plan does not include PSF star observations, so you decided to apply for time within your proposal to obtain an extra observation of this specific PSF standard star in JHKs.  Now you must prepare the OB, within the same concatenation container as the corresponding imaging OB you just completed, for this star.

If principle, this observation can be very similar to the JHKs jitter described in detail before. There is one very special difference, however.  For purposes of these observations, it is imperative that the same NAOS setup is used.  This is signaled in three ways:

  1. the OB name must be prefixed with the string PSF_,
  2. the PSF reference? box in the acquisition template must be ticked, and
  3. clear instructions must be written into the README file as part of your Phase 2 package submission (though this last aspect is of lesser importance with the advent of OB containers and the fact that the two OBs will share a common OB concatenation).

The steps that you should follow to define the OB are analogous to those that you followed when preparing the LS-RCrA 1 - JHKs jitter OB before, including the NAOS PS step (see "2.1: First Things First, The NAOS PS" and "2.2: Next Stop: P2PP" above).

to the top

3.1: Back to the NAOS PS

You begin the process by making a new .aocfg file in the NAOS PS package. Note that since you will designate this as a PSF observations the NAOS configuration in this file will not be used at the time of observation. Rather, the original setting will be maintained. However, the all-important new source coordinates will be in this file, along with the (admittedly only slightly different) new Strehl value.

Making the new .aocfg file is completely analogous to the first time you have done this, except for the fact that the two sources have changed. The only other difference is that, owing to a lack of catalog information, you must make an educated guess as to the spectral type of and visual extinction towards the new AO reference target, GSC 07902-00834.  Your best guess is that it is an F0V star with AV of 1.  After you have entered all of the corresponding values into the NAOS PS GUI (including the same values for seeing and airmass as before), you optimize (you cannot export to P2PP without doing so), and as a result the GUI looks like this:

new-jnps_scr4

You must then export the NAOS configuration (which contains the all-important coordinates!) to P2PP in the form of an.aocfg file.  Click on the Export to P2PP button on the bottom of the GUI.  When the browser pops up (see above Figure) enter a filename you can remember.  Here you choose GSC07902-01850.aocfg.  Pick a suitable(sub-)directory for the file using the browser, and click on Save.

to the top

3.2: Again, P2PP

To make life simpler, you decide to simply duplicate the previously made imaging OB (LS-RCrA 1 - JHKs) and use the copy as a starting point.

3.2.1: Filling in the Basic Information

Since this OB will be the JHKs observation of your PSF reference, you must prefix its name with PSF_.  So, you decide to name it PSF_LS-RCrA 1 - JHKs (consistent with the OB Name you specified above in the Instrument Comments field of the corresponding science OB).  Type this name in the Name field, and type Corresponding Science OB = LS-RCrA 1 - JHKs into the Instrument Comments field.  Similarly, you can use PSF reference for the OD Name field.

Finally, the User Comments field can be used for any information you wish (to keep further track of the characteristics of the OB, to alert the staff on Paranal to special requirements, ...).  For this tutorial you can try it out by entering the text "NACO Tutorial PSF Calibrator OB".

to the top

3.2.2: Defining the acquisition template

The first template is the acquisition template. Since this is a calibration observation for an already constructed imaging OB, it is advisable to use the same acquisition template as before, NACO_img_acq_MoveToPixel.

The standard is a relatively bright star, so you decide to add the short wavelength neutral density filter (ND_Short).  Since there is no appreciable PSF degradation when that filter is in the path this can be safely done.  Adding ND_Short has the effect of decreasing the flux by a factor of 80, so you decide to keep the DIT as it was in the acquisition for the first OB.  In addition you must check the PSF reference? (T/F) box in order to circumvent changing the current setup of NAOS!  The set of parameters that you choose in your acquisition template is thus:

  • DIT: 5
  • NDIT: 2
  • Type of AO Observation (LGS/NGS): NGS
  • PSF reference? (T/F): the box is ticked
  • Pupil tracking mode: the box remains unticked
  • RA offset: 5
  • DEC offset: 5
  • Position Angle on Sky: 0.
  • Filter: J
  • Neutral density filter: ND_Short
  • Camera: S13

The values for RA offset and DEC offset are used to make an offset to a "sky" position for better source recognition. The default values are fine for this example.

For the remaining acquisition parameter, NAOS parameter file, you should supply the file (GSC07902-01850.aocfg) created in Step 3.1 above.  To do this,click on the LS-RCrA.aocfg field next to NAOS parameter file (remember that we started with a copy of the first OB) and browse until you find the file you just generated.  Once you have found the file, highlight it and click on Open.  The acquisition template is now complete, and the window should now look like this:

p2pp-5

Note that, since you duplicated the previously created OB, the currect OB contains more than simply the updated acquisition template!

to the top

3.2.3: Inserting Target Information

As with any NACO OB, the target information obtained from the.aocfg file must never be edited within P2PP, as it will then be incompatible with the settings of NAOS.  The only entry in the Target-tabbed subpanel which may be edited at this point is the Class to which this object belongs, for archival purposes.  However, in this case there exits no suitable label, so you should reset it to Unknown.

to the top

3.2.4: Setting the Constraint Set

In order for this to be a useful measurement, the parameters of the Constraint Set must match those of the corresponding science OB.  You can do this by clicking on the Constraint Set icon and filling the entries in the Constraint Set View:

  • First, for consistency the Name field entry should remain Imaging constraints.
  • This OB, serving to provide only a PSF measurement, does not require photometric conditions.  Although it is unlikely that the sky transparency would be photometric during the science OB and degrade below that during the PSF OB, it is nevertheless true that the PSF OB does not require photomeric conditions.  Thus you should set it to Clear.
  • As before, the Seeing field at this point has a value in it.  This value was taken from the .aocfg file in the same manner as were the source coordinates. Since it is imperative that the seeing in the Constraint Set matches that used as the Seeing at zenith within the NAOS PS package you must never change this value in p2pp.
  • The Strehl (%) value is also extracted from the .aocfg file.  You are free to edit the value but you must never increase the value above the default. Since you are satisfied with the predicted value of 11.1% Strehl, you should leave the default as it is.
  • The last Constraint Set parameter which is taken from the .aocfg file is the Airmass.   As with the seeing, it is imperative that the seeing in the Constraint Set matches that used as the Airmass within the NAOS PS package you must never change this value in p2pp.
  • Since you are doing broad band observations in the near-infrared, the lunar illumination has very little influence.  You can thus leave the default values of 1.0 and 30 degrees for the Lunar Illumination and Moon Angular Distance fields.
  • Finally, as mentioned above, since this is an OB that relies on adaptive optics the atmospheric turbulence matters a great deal.  Hence, for this OB you should leave the default value,  "default Paranal atmosphere model."

to the top

3.2.5: Setting the time intervals

These must match those of the corresponding science OB (see Section 2.2.5), which will naturally be the case as you started with a copy of that OB.

to the top

3.2.6: Defining the Observation Description

Once the acquisition and the tabbed items Target, Constraint Set, and Time Intervals are completed, the science template(s) can be updated.

You decide that the best way to proceed with the PSF reference observations is to follow the same observing strategy as was done for the source itself. Therefore, the NACO_img_obs_AutoJitter template will be used in this case as well.

Since adding ND_Short has the effect of decreasing the flux by a factor of 80, you also decide to keep the DITs as they were in the science templates for the first OB.  Further, you also maintain the Double_RdRstRd readout mode.  Therefore, the first NACO_img_obs_AutoJitter template (the observation in J) must only be changed by selecting ND_Short from the dropdown list associated with the Neutral density filter field.  For the observations in H and in Ks, the same simple change of neutral density filters can be made.

Next, you can check that the Execution Time is the same as for the science OB (as you expect), by clicking on the Recalculate button.

This completes your second OB (we will assume that this completes the imaging part of your run)!  If you followed all the indications given so far, the View OB window should look like this now

p2pp-6

and you should see an entry in the Folders and Summary section in the P2PP main GUI with the following contents:

  • Name: PSF_LS-RCrA 1 - JHKs
  • Status: (P)artiallyDefined
  • Target: GSC07902-01850
  • OD: PSF reference
  • CS: Imaging constraints
  • Acquisition: NACO_img_acq_MoveToPixel
  • FindingCharts: (0)
  • EphemerisFile:

You can reshape the columns as indicated in the P2PP User Manual to view the full contents of each entry.  Finding Chart generation and attachment to the OB can be done as described above.

to the top

4: Defining a spectroscopic OB

To complete this tutorial exercise with NACO with an exercise on another instrument mode, we will add a spectroscopic OB to our hypothetical run.

The purpose of this OB will be to obtain a moderate resolution H-Band spectrum of LS-RCrA 1, the main target of our tutorial run.  Unlike for the cases of the previous two OBs, you needn't start this one by running the NAOS PS program.  You can use the.aocfg file that you generated already in Section 2.1 above.  This is because, given the characteristics of the AO reference object, even if you were to re-specify the wavelength of interest as being H in the NAOS PS it would return the same configuration, and indeed the same reference Strehl ratio (the reference Strehl ratio is the Strehl ratio on the AO reference target at 2.166 microns [Brackett gamma]), as it had when using Ks as above, modulo the perhaps small variation induced by the random atmosphere modeling as described above.  Try it and see!

So, we start by generating a new OB from scratch (in the main P2PP GUI select the run folder and then click on the blue OB icon in the Icon bar).  Since this is a spectroscopic OB you can name it LS-RCrA 1 spectrum by selecting it, pressing the enter key, and editing the name (prrssing enter again when done).  Then you can edit its contents by double clicking on it.  You can start by setting the OD name to spectroscopy.

to the top

4.1: Spectroscopic Acquisition

Next, we proceed to adding the acquisition template.  You may note at this point that, contrary to what you might expect, there is no NACO_spec... template for spectroscopic acquisition.  This is due to the fact that placing the object at the position of the slit (which is known for the instrument from calibration procedures carried out by the observatory staff) is done by imaging the field, and thus the acquisition template is actually of the img type.  As described in the NACO manual, the template to be used for spectroscopic acquisition is NACO_img_acq_MoveToSlit.

Some of the parameters to be defined in this template are already familiar from previous examples.  We will assume that the acquisition is made with images through the H filter with DIT = 5, NDIT = 2, and that the slit to be used is the one with 86 milliarcsecond width (Slit_86mas).

The parameters Alpha offset from Ref. Star and Delta offset from Ref. Star offer the possibility of accurately presetting the telescope on a bright reference target close to the position of the science target, and then giving an offset to the telescope before the science observation starts so that it moves to the position of the science target.  This is useful in case of faint targets that may not be visible in the acquisition image or require an excessively long acquisition time.  In our example, the science target is bright enough and we do not need to use this indirect acquisition, so we leave these offset fields at their default zero values.

A North-South aligned slit is fine, so you leave the default position angle in.  The parameters of the acquisition template are thus as follows:

  • DIT: 5
  • NDIT: 2
  • Type of AO Observation (LGS/NGS): NGS
  • PSF reference? (T/F): box remains unchecked
  • Alpha Offset from Ref. Star: 0.
  • Delta Offset from Ref. Star: 0.
  • RA offset: 5
  • Delta offset: 5
  • Position Angle on Sky: 0.
  • Filter: H
  • Neutral density filter: Full
  • Camera: S54
  • Which Slit?: Slit_86mas
  • NAOS parameter file: LS-RCrA.aocfg

to the top

4.2: Target Information and the Constraint Set

As with any NACO OB, the target information obtained from the .aocfg file must never be edited within P2PP, as it will then be incompatible with the settings of NAOS.  The only entry in the Target View which may be edited at this point is the Class to which this object belongs, for archival purposes.  In this case, choose pMS* (pre-main sequence star).

In order for this to be a useful measurement, the parameters of the Constraint Set must match those of the corresponding science OB.  You can do this by clicking on the Constraint Set tab and filling the entries under it:

  • First, to distinguish this from the imaging OBs you decide to put Spectroscopic constraints in the Name field.
  • Let's assume that the spectroscopic part of our program can be done under less favorable conditions than for the imaging, as is usually the case with spectroscopy.  You then input Variable, thin cirrus for the Sky Transparency constraint.
  • As before, the Seeing field at this point has a value in it.  This value was taken from the .aocfg file in the same manner as were the source coordinates. Since it is imperative that the seeing in the Constraint Set matches that used as the Seeing at zenith within the NAOS PS package you must never change this value in p2pp.
  • The Strehl (%) value is also extracted from the .aocfg file.  You are free to edit the value but you must never increase the value above the default. Since you are satisfied with the predicted value of 45.94% Strehl, you should leave the default as it is.
  • The last Constraint Set parameter which is taken from the .aocfg file is the Airmass.  As with the seeing, it is imperative that the airmass in the Constraint Set matches that used as the Airmass within the NAOS PS package you must never change this value in p2pp.
  • Since the moon has no effect on the background for any NACO observation mode, and since AO reference star is bright, you can thus leave the default values of 1.0 and 30 degrees for the Lunar Illumination and Moon Angular Distance fields.
  • Finally, as mentioned above, since this is an OB that relies on adaptive optics the atmospheric turbulence matters a great deal.  Hence, you should leave the default value in place.

to the top

4.3: Spectroscopic OD

As explained in the NACO User Manual, there are two templates for spectroscopic observations with NACO, each one allowing the use of either of two detector readout modes. NACO_spec_obs_AutoNodOnSlit, suitable for point sources, moves the target between the proximities of two positions along the slit and will be our choice here.

After considering the brightness of our target and the performance of NACO, we decide to carry out the spectroscopic observation by using individual integrations of 240 sec each in positions along the slit that lie within 6 arcsec of two points (A and B), separated by 14 arcsec and symmetrically placed with respect to the center of the slit.  This defines DIT =240, NDIT = 1, Jitter Box Width = 6, Nod Throw = 14.  We will obtain one integration each time at each position (Number of exposures per offset position? = 1) and will switch 5 times between the proximities of points A and B (Number of AB or BA cycles = 5).  The array will be read out using FowlerNSamp mode, to minimize detector noise.  The dispersion element to be used is defined in the Spectroscopy Mode entry: in our case, we select S54_3_H, which will produce moderate resolution spectra covering the H-Band.  The slit to be used must be consistent with the one selected in the acquisition template, as different slits project to different positions on the detector.

This is thus the contents of the science template that composes the OD:

  • DIT: 230
  • NDIT: 1
  • Readout mode: FowlerNSamp
  • Jitter Box Width: 6
  • Number of AB or BA cycles ?: 5
  • Number of exposures per offset position?: 1
  • Nod Throw: 14
  • Return to Origin ? (T/F): checked (i.e., True)
  • Slit ?: Slit_86mas
  • Spectroscopic Mode: S54_3_SH

Next, you should click on the Recalculate button. In this case the total execution time is 00:58:55, that is, just under the 1 hour execution time limit.

This completes your last OB!  If you followed all the indications given so far, the View OB window should look like this now

p2pp-7

and you should see an entry in the Folders and Summary section of the P2PP main GUI with the following contents:

  • Name: LS-RCrA 1 spectrum
  • Status: (P)artiallyDefined
  • Target: LS-RCrA
  • OD: spectroscopy
  • CS: Spectroscopic constraints
  • Acquisition: NACO_img_acq_MoveToSlit
  • FindingCharts: (0)
  • EphemerisFile:

You can reshape the columns as indicated in the P2PP User Manual to view the full contents of each entry.  Finding Chart generation and attachment to the OB can be done as described above.

to the top

5: Finishing the preparation, prioritising things, and submitting the OBs

With the completion of the spectroscopic OB, we consider the examples developed in this tutorial to be finished.  The P2PP main GUI displays the three OBs that we have prepared, two of which appear within the concatenation called Imaging + PSF:

p2pp-8

If you did nothing further the spectroscopic OB would have the same priority (top priority, or 1) as the Imaging + PSF concatenation.  This can be seen to be the case by clicking on the Schedule tab (thereby selecting the Schedule View).  Since for purposes of this tutorial the imaging is not as important as the spectroscopy, you should decrease the priority of the spectroscopic OB.  To do this click on the spectroscopic OB, then click on its priority field.  Using the down arrow you can set the priority to 2.  

There is one other important point to stress here.  The P2PP User Manual notes, "The sequence of the execution of OBs in a concatenation cannot be specified."  But because the configuration of NAOS is not done for when the PSF reference? flag is ticked, execution of the PSF OB must follow that of the corresponding science OB!  The only control that you have over this is to ensure that the order of the OBs listed in the concatenation is the same as the order that they should be executed at the telescope (see the image above).  One should note that this will not absolutely guarantee that they are done in the correct order.  Due to human error at the telescope, they could be executed in the wrong order, though the probability of this happening is very small indeed.  If as a result of preparing the OBs within the concatenation they are in the incorrect order right clicking on an OB will bring up a context menu which will allow you to change its position within the container.

We will now submit these OBs to the ESO Database: select the concatenation and the "loose" OB, go to the File menu in the P2PP main GUI, and select the Check-in option. A dialog box will appear asking for confirmation and, if you click on OK, they will be saved in the ESO Database.

At this point, for the case of a real Run only you should edit and check in a README file (the P2PP README fileTutorial gives more advice on how to do this).  Once that is done, you would be finished with your Phase 2 submission.  To signal ESO that this is the case you would then click on the whistle icon in the Icon bar of the P2PP GUI.  This has the effect of sending a signal email to your Support Scientist that OBs have been checked in to the ESO Repository.

As a courtesy to the next user who follows this tutorial, we would like to ask you to finish these exercises by removing the OBs form the ESO Database.  The P2PP User Manual gives you detailed indications on how to do this.  The simplest way to do this is to

  • select them in your P2PP main GUI window, then
  • choose Check-out from the Fikle menu in the main P2PP GUI.

(The P2PP manual provides details on what to do in exceptional cases.)

In this way the OBs will be removed from the ESO Database and will be left in your Local Cache only.  From there you can delete them if you like by selecting them and choosing the Delete option under the File menu in the P2PP main GUI.

to the top

Instrument selector