NACO p2 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 102.  Please note that all the figures shown below can be clicked on to get higher resolution versions.

To follow this tutorial you should have familiarity with p2 : the web-based tool for the preparation of Phase 2 materials.  Please refer to the main p2 webpage (and the items in the menu bar on the left of that page) for a general overview of p2 and generic instructions on the preparation of Observing Blocks (OB).  Screenshots for this tutorial were made using the demo mode of p2, but should not differ in any way from one's experience in preparing your own OBs under your run.

0: Goal of the Run

In this tutorial we will prepare OBs for a simple example observing run, consisting of broadband imaging 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).

The following OBs will illustrate the use of a variety of features of p2 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 time allocation information" (within the Phase 1 card). 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 the NAOS PS on your machine, if necessary.

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2: Your First OB

You decide to start with the observations of the target (and not the PSF reference --- see below).

2.1: First Things First: 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 NAOS PS (by entering the command jnps) you will see the following Graphical User Interface (GUI)

new-jnps_scr1

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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 NAOS 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 NAOS PS, hence leave the dropdown menu as FREE.
  • Wavefront Sensor: Here you must specify the IR-WFS wavefront sensor, due to the following two facts.  Fact 1: Since July 2018 the VIS-WFS has been decommissioned due to hardware issues that could not be overcome.  Hence, you must not select the VIS WFS.  Fact 2: Since the move of NACO to UT1 meant the loss of the usage of the LGSF for NACO observations you should never select LGS from this pull-down menu.  While not the best situation (the fact that the NAOS-PS still lists the two now-forbidden WFS choices) it was unavoidable.
  • 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.

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2.1.2: Configuring the Reference Object

Continue filling in items in the NAOS 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: This tick-box was used when NACO was mounted on UT1 and hence had the LGSF at its disposal. It enabled use of the LGS without a tip-tilt star. Since NACO can no longer be used with the LGSF and since the selection of the Wavefront sensor should thus never be LGS this tick-box should always be grayed-out and un-tickable.
  • 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.

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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.

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2.1.4: Optimization and Exporting to p2

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 NAOS 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 p2 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 (yes, it still says P2PP even though the file will be used within p2).  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.

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2.2: Next Stop: p2

For the sake of this tutorial, we will use the p2 demo facility: https://www.eso.org/p2demo

This is a special facility that ESO has set up so that users who do not have their own p2 login data can still use p2 and prepare example OBs (for example, while writing a proposal to get the overheads right!).  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 p2 (with http://www.eso.org/p2).

After directing your browser to the p2 demo facility the main p2 GUI will appear as follows:

p2_Fig_1

Runs for a number of instruments appear in the lefthand column, since the p2 demo facility is used for all of them.  Similarly, if you log into p2 (instead of p2demo) with your own ESO User Portal credentials, you will get the list of all the runs for which you are PI, or for which you have been declared as a Phase 2 delegate by one of your colleagues.

Select the folder corresponding to the NACO tutorial run, 60.A-9252(H) by clicking on the + icon next to it.  In this tutorial we assume that time was allocated in Service Mode.  This is indicated by the small wrench icon that appears next to the RunID.  "Inside the run" you will see (at least) one folder, called "NACO Tutorial".  That folder contains the final product of the tutorial you are now reading.  You can refer to the contents of that folder at any time, perhaps to compare against your own work.

You can now start defining your observations.  In the p2 demo you must first start by creating a folder, within which you will put your own content.  Because the p2 demo is online and accessible to anyone you may see folders belonging to other people here, though after-the-fact cleanup is encouraged and possible.  

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 p2 help 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 clicking on the newly created OB you will be able to edit its contents on the right hand side of the GUI, and you should see the following window (here note that, in anticipation of the appearance of the overall OB, we have adjusted the number of templates/row (tpl/row) from the default (2) to 4 on the righthand side of the window):

p2_Fig_2

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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, like when having observations of a number of targets performed with identical instrument configuration and exposure times.  The Observing Description Name field within the Obs. Description tab allows you to define such names.  The Observing Description name appears in turn in p2 after clicking on the Overview tab at the very top (left), thus allowing the identification at a glance of all OBs having Observing Descriptions with the same name.

In this example OB, the Observing Description 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 Observing Description 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."

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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 Template Type pulldown menu make sure that acquisition is selected.  This will result in the second pulldown menu (to the right) listing all the acquisition templates available for NACO.

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 Template 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, some time 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 indicating "no"
  • Pupil tracking mode: box remains indicating "no"
  • 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 it cannot be a Laser Guide Star-assisted observation (given that the LGSF is on UT4 and NACO is on UT1).  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 upload button 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 Choose.  The acquisition template is now complete, and the window should now look like this:

p2_Fig_3

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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 just below the top of the OB display.

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 p2, as it will then be incompatible with the settings of NAOS.

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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 on the Constraint Set icon (next to the Target ico) 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 Constraints 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 p2.
  • 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 46% 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 p2.
  • 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, the Atmospheric Turbulence Model is a parameter that is used for the scheduling of OBs at the telescope. The default value for this parameter is Paranal atmosphere model 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.

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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 (early) October 2018.  You can specify this in the Time Intervals View after clicking on the Time Intervals icon (next to the Constraint Set icon):

  • Since this is a time requirement, and not a sidereal time requirement, make sure that the Absolute Time Constraints tab is selected.
  • Click on the Add button.
  • Modify the lower boundary of the time interval to the specified starting date of your time window, if you like using the small calendar button to the right of the field.  In the present case, the two fields should read: 2018-10-01, and 00:00, respectively.
  • In the same way, modify the two fields of the upper boundary of the time interval to 2018-10-15, and 00:00, respectively.

Here we note two important matters:

  • If your observation could be executed in other, non-contiguous time windows, you could define more intervals in the same way as described.
  • The timeline associated with the Absolute Time Constraints tab will not display useful content for the demo of p2, but will, of course, provide useful content for "real" runs. 

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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 tab, select science from the Template Type pulldown menu.  The existing NACO science templates will appear in the second pulldown menu.  Select the chosen one, NACO_img_obs_AutoJitter, and click on Add Template.  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 set to "no"
  • Jitter Box Width (arcsec): 6
  • Number of exposures per offset position: 1
  • Number of offset positions: 10
  • Return to Origin ? (T/F): set to "yes" (the telescope will return to its first position after the last exposure of the template)
  • 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 twice on the Duplicate button ate the bottom of the science template you just finished. 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 Exec. Time button at the very top of the OB.  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 00:54:36, 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 window should look like this now (and now you see why we changed the number of templates/row above!).

p2_Fig_4
p2_Fig_5

And when you click on the Overview button at the top of the page you should see the following (where we've clipped the screenshot just below the NACO run). 

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 upload them to the OB by highlighting the OB, selecting Finding Charts tab (next to the Time Intervals tab), selecting up to 5 files, and clicking on Choose.

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3: Defining a PSF imaging OB

When planning your observing run, you realized that your imaging observations would require some deconvolution (or at least comparison with) 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 two ways:

  1. the OB name must be prefixed with the string PSF_,
  2. the PSF reference? box in the acquisition template must be ticked

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: p2 above)

 

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 did 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 p2 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 p2 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.

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3.2: Again, p2

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 name it PSF_LS-RCrA 1 - JHKs.  Type this name in the Name field.  Similarly, you can use PSF reference for the Obs. Description 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".

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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 set to "on"
  • Pupil tracking mode: the box remains "off"
  • 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:

p2_Fig_6

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

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3.2.3: Inserting Target Information

As with any NACO OB, the target information obtained from the.aocfg file must never be edited within p2, as it will then be incompatible with the settings of NAOS.

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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 p2.
  • 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 8.2% 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 p2.
  • 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."

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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.

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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 Exec. Time button (as described above).

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

p2_Fig_7
p2_Fig_8

And, when clicking on the Overview button (described above) you should then see:

4: Final Steps

With the completion of the PSF OB, we consider the examples developed in this tutorial to be finished.

There is one other important point to stress here.  Because the configuration of NAOS is not done when the PSF reference? flag is ticked (set to "on"), execution of the PSF OB must follow that of the corresponding science OB!  The 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.

In addition, for a real run you would also make sure to:

  1. click the "Check" button (to the right of the Exec. Time button) for each OB.  Check performs consistency checks on the selected OB(s).
  2. click on the Certify" button (to the right of the Check button).  Certify does the same as Check, but additionally (if the check was successful) marks the OB(s) as fully compliant and reaxdy for ESO's review.  It also marks the OB(s) as readonly.
  3. (optionally) select one or more certified OBs and click on the "Revise" button (to the right of the Certify button) to revoke the certified status and allow re-editing.  If this is done it steps 1 and 2 above should be re-done for the OB(s) in question.
  4. complete the information in the README file
  5. click on the "Notify ESO" button (to the right of the Revise button).  This will lock all certified OBs as well as the README, in preparation for ESO's Phase 2 review process.

As mentioned above, all users have access to the p2 demo facility.  And, unlike the situation that existed with p2's predessesor, P2PP3, all OBs are created directly on the ESO database (there is no longer a "check-in" requirement).  Hence, all users can see what you leave behind.  Indeed, after a while, if not properly maintained, the p2 demo runs could and would get cluttered with all manner of OBs, containers, etc.  Thus, as a courtesy to the next user who follows this tutorial, we would like to ask you to finish these exercises by deleting the OBs, containers, etc. that you make.

Finally, please note that when looking at the tutorial run in the p2 demo facility you will see that both OBs are marked as (+) Accepted (see the small screenshot below).  This is a state that these OBs have been set in (by ESO) solely to avoid them being inadvertently deleted from p2.

 

p2_Fig_9

Instrument selector