VISIR P2PP Tutorial

This tutorial provides a step-by-step example of the preparation of a set of OBs with VISIR, the VLT spectrometer and imager for the mid-infrared. The specifics of this tutorial pertain to the preparation of OBs for Period 75. To follow it, you should have a P2PP installation (version 2.9) in your computer and be familiar with the essentials of the use of P2PP. Please refer to the P2PP Web page 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.

0: Goal of the Run
1: Getting Started
2: Your First OB - Starting with P2PP
- 2.1: Define an imaging OB with P2PP
- 2.2: Define a spectroscopic OB with P2PP
3: Finishing the preparation and submitting the OBs

0: Goal of the Run

In this tutorial we will prepare two OBs, one imaging OB and one spectroscopic OB. In both cases the target is a young stellar object named He3-298 possessing a circumstellar disk. We assume you wish to image He3-298 with a PAH filter at 11.25 micron and observe it spectroscopically at low resolution. The target has the following coordinates: RA(2000) = 09 36 44.4, Dec(2000) = -53 28 00. We will start with the construction of the imaging OB, followed by a long-slit spectroscopy OB.

The sample OBs will illustrate the use of a variety of features of P2PP and illustrate the kind of decisions to be taken at the time of preparing in advance an observing run, as well as some aspects that are specific to the preparation of OBs for VISIR.

To the top

1: Getting started

The Phase 2 process begins when you receive an email from the ESO Visiting Astronomers Section telling you that the allocation of time for the coming period has finalized and that the results can be obtained in the corresponding Web page. The communication from ESO contains a login ID and password that you need in order to consult that Web page, but it is also your ID and password for the use of P2PP. You follow the instructions given by ESO and find that time was allocated to your run with VISIR. Therefore, you decide to start preparing your Phase 2 material. First, you collect all the necessary documentation:

The VISIR User Manual
The VLT and ESO-MPI 2.2m Service Mode Guidelines
The P2PP Documentation referred to above.
Consult the VISIR service mode specific webpage

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

To the top

2: Your first OB - Starting with 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 this account to prepare actual OBs intended to be executed.

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

Runs for a number of instruments appear in the Folders area, since the same tutorial account is used for all of them. Similarly, if you log in with your own P2PP ID, you will get the list of all the runs in which you are PI.

Select the folder corresponding to the VISIR tutorial run, 60.A-9253(I). In this tutorial we assume that time was allocated in Service Mode. This is indicated by the SM letters that appear next to the Run ID of the VISISR run.

To the top

2.1: Define an imaging OB with P2PP

Once you have selected the VISIR folder in the Folders area, you can start defining your first OB.

First, click on the New icon on the upper left side of the P2PP main GUI. This creates an entry under the Summaries area. The red dot next to the OB name means that the OB fails to pass some fundamental verification criteria, as may be expected from the fact that no template has been attached to the OB yet.

Click on the View icon. The View OB window appears:

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

To the top

2.1.1: Filling in the Basic Information

OB Name

First, you define the OB name. Preferentially, you like to be able to identify later, that this OB is associated with the target He3-298 and that it is an imaging OB. Therefore, you choose the OB name He3-298-ima. Type this name in the Name field.

User Priority

Next, assign this OB a priority. In case your run contains of more than one OB (very likely), you can select a priority for this OB from the drop-down User Priority menu.

OD Name

It may be useful in many cases to have an easy way of identifying an OD, like when having observations of a number of targets performed with identical instrument configuration and observation template parameters. 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 Summaries area of the P2PP main GUI, thus allowing the identification at a glance of all OBs having ODs with the same name. In this tutorial OB the observation description will define the use of the PAH2 filter at 11.25micron. Thus, we enter the name Imaging_PAH2 in the OD Name field

User Comments

The User Comments field can be used for any information you think is important for the night astronomer at the time the OB is executed (e.g. to keep further track of the characteristics of the OB, to alert the staff on Paranal to special requirements (but also see the reference below to the Calibration Requirements field)).

To the top

2.1.2: Defining the acquisition template

The first template that must be part of any science OB is the acquisition template, so let us define it next. In the

Template
Type

list, make sure that the acquisition entry is highlighted. This will list all the acquisition templates available for VISIR in the Template list next to it.

After reading the description of the templates in the User Manual, you have noticed that the VISIR_ima_acq_MoveToPixel template is your choice, because you are using the small pixel scale (pfov 0.075arcsec) and you want to make sure that your target gets very well centered. You thus click on this template in the Template list, and then on the Add button next to it. The window should now look like this:

To the top

Now, you need to decide on the acquisition parameters, and if necessary, modify the default values given in the acquisition template.

There are three parameters related to the telescope nodding and the secondary mirror chopping. Since your target is relatively little extended (less than 4 arcs in diameter) and also an isolated source, you decide to chop on the array, without changing the default chopping position angle. Furthermore, since you will choose a perpendicular relative chop/nod direction in your later science observations, you also select a perpendicular relative chop/nod direction for the acquisition. Thus, you enter the parameters (or select from the drop-down menu):

Relative Chop/Nod Direction: PERPENDICULAR
Chopping Position Angle: 0 (Default value)
Chopping Amplitude: 10 (Default value)

The next parameter to enter is the total integration time that will be necessary to clearly identify your target. Since He3-298 is bright, the minimum of 30sec is sufficient for that purpose. Hence, you enter

Total integration time: 30.0

You will also have to make a choice on the filter used during the acquisition, which should, in general, be selected in such a way that a high signal to noise on the target is achieved in relatively short time. In our tutorial example the continuum filter next to the PAH2 filter is the right choice. Furthermore, you wish to use the finest pixel scale. Therefore, you select from the drop-down menus:

Imager filter: PAH2_2
Imager pixel scale: 0.075

For the rest of the parameters in the acquisition template you can leave the default value.

2.1.3: Inserting Target Information

At the bottom of the view window you find the Target field where to insert your target name and coordinates. Here please insert the target name, which can be (for easy cross-identification purposes) the same name as used in the OB naming, in other words, insert Name: He3-298 Also, enter the right ascension and declination for He3-298. Furthermore, edit the entry in the Target-tabbed subpanel Class. In our case , choose YSO (Young Stellar Object).

The acquisition template including the target information is now complete, and the window should look like this:

To the top

2.1.4: 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 set of constraints, which indicate under which conditions your OB can be executed. You can do this by clicking on the Constraint Set tab and filling the entries under it:

Name:

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 OBs of this target, you type He3-298-imaCons in the Name field.

Sky transparency:

Since we assume that your imaging observations aim at constraining as accurate as possible the mid-infrared luminosity of He3-298 and its circumstellar disk, you need very good atmospheric conditions. You request Photometric conditions in the Sky Transparency entry.

Seeing:

As for the seeing constraint, you know that the image quality at 10 microns is diffraction-limited if the optical seeing is better than ~0.8arcsec, and since spatial resolution is a key issue for your study, you enter 0.8 in the Seeing field.

Airmass:

The airmass is not a stringent parameter for the imaging part of your programme, you thus enter 2.0 in the Airmass field.

Lunar Illumination and Moon Angular Distance

The moon has essentially no effect at all on the VISIR data quality, and constraints related to the moon are not considered for OB qualification. The default values are hence simply accepted.

Note that in your Phase 1 proposal you already specified some of these constraints (sky transparency, seeing). 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

2.1.5: Setting the time intervals

We will assume now that your VISIR observations are part of a larger multi-wavelength project and that the VISIR observations should be carried out simultaneously with some satelite observations that are performed between March 01-31 2005. You can specify this, i.e. the execution of your VISIR OB between March 01-31 2005 under the

Time
Intervals

tab:

Click on the checkbox at the far right next to the first row of the time intervals.
Modify the lower boundary (the left-hand side entry) of the time interval to the specified starting date of your time window, keeping the same format. In the present case, the entry should read 2005-03-01T00:00:00.
In the same way, modify the upper boundary of the time interval to 2005-03-31T00:00:00.

If your observation could be executed in other, non-contiguous time windows, you could define up to five intervals in the same way as described. However, we also wish to remark that setting time intervals for an OB, and thus narrowing the possible execution time dates, limits the possibility that your OB will be successfully executed during the observing period.

2.1.6: Setting the Calibration Requirements

The Calibration Requirements field is the place where you should enter any information relevant to the calibration requirements of your programme. If standard calibrations, as done by the VISIR calibration plan are sufficient, you can enter here: Standard calibrations

To the top

2.1.7: Defining the Observation Description

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

On Template Type, select now science. The existing VISIR science templates will appear. Select the template VISIR_img_obs_AutoChopNod and click on Add. The template will be attached to the grid below next to the acquisition template selected and filled previously.

Several parameters have to be defined for this template. In the following we discuss each of them and justify a certain choice based on the properties of the target He3-298 and the scienctific goal of this imaging OB. First, you have to decide if you prefer to nod perpendicular or parallel to the direction of the chop. From the manual you extract that for not very extended sources and observations that aim at high spatial resolution, the perpendicular relative chop/nod is recommended. From the pull-down menu you therefore select:

Relative Chop/Nod Direction: PERPENDICULAR

Several bad pixels or cosmics will produce an errornous response at some parts of the array. Therefore you want to avoid the target's signal falling permanently on a bad pixel and you choose to jitter on the nod positions by setting:

Random Jitter Box Width: 3

After using the exposure time calculator for VISIR in imaging mode, you know that 600sec of total integration time is needed on He3-298 in order to reach the signal to noise ratio you want. Thus,

Total integration time: 600

The next two parameters, again, are related to chopping and we will make the same selection as in the acquisition template, because the same rules apply here:

Chopping Position Angle: 0 (default)
Chopping Amplitude: 10 (default)

Then, you have to select the imaging filter for this observation. In principle, you are interested in imaging the PAH feature at 11.25micron, which implies the filter PAH2. But of course, it is also necessary to perform the same observations with a reference filter, close by in wavelength and centered on the continuum in order to separate the continuum contribution from the true 11.25micron emission. Since the continuum reference filter PAH2_2 is already in place (being used for the acquisition), we do the continuum imaging first and select:

Imager filter: PAH2_2
Imager pixel scale: 0.075

If you followed all the indications given so far, the View OB window should look like this now.

The observation that must now follow, and which should be defined within the same OB, is the imaging at the actual PAH filter, PAH2. In other words, you must append another VISIR_img_obs_AutoChopNod template. Select this template from the list of science templates and click on the Add button next to it on the right. Assign to the parameters exactly the same values as you did in the previous VISIR_img_obs_AutoChopNod template, with the only difference in the imaging filter, for which you select:

Imager filter: PAH2

The OB view window should now look like this:

The only other thing that you should really do at this point is to check the execution time for this OB. The fact that the displayed time does not yet reflect the execution time of the currently written OB is indicated by the small * next to the Execution Time label.

On the top right of the window, below the Add, Delete, and Duplicate buttons you will find a button labeled Recalc ExecTime. Clicking on that button has two effects. First, the small * next to the Execution Time label disappears, and second the calculated OB execution time appears in the display to the right of the label.

This (almost) completes your first OB! You can now close the View OB window by selecting File -> Close from the top menu bar and you are left with the P2PP main GUI. In there, you should see an entry under Summaries with the following contents:

Name: He3-298-ima
Dbaseid: 0
Status: (P)artiallyDefined
Target: He3-298
OD: Imaging_PAH2
CS: He3-298-ImaCons
Acquisition: VISIR_img_obs_MoveToPixel
FindingCharts: (0)

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

To the top

2.1.8: Attaching Finding Charts

The last thing to do, which finishes the preparation of a single OB, is to attach the respective Finding Chart(s) to the OB. The Finding Charts must be prepared as jpeg-files and must fulfill all general requirements for finding charts, as well as follow the specific instructions for VISIR Finding Charts outlined on the VISIR service mode specific webpage. You can use any tool of your choice to create the Finding Charts in jpeg-format. P2PP, however, does not contain such an option.

Let's assume you have prepared a jpeg-Finding Chart for this tutorial run [remember: run ID 60.A-9253(I)], which you called 60.A-9253I.he3-298.jpg, and which is saved in a sub-directory of your home directory.

Now, in the P2PP main GUI click on the OB which you want to associate with this finding chart, then select Finding Charts from the top menu bar, which opens a drop-down menu:

From the drop-down menu select Attach Finding Charts, which will open up a new window that allows you to enter path and filename of the Finding Chart you wish to attach to the selected OB. In our example you choose 60.A-9253I.he3-298.jpg and finally click on the Attach Finding Charts button (you could select more than one Finding Chart). The pop-up window will close and the Summaries area of the P2PP main GUI will show the entry

FindingCharts: (1) 60.A-92..

If you are interested in a more comprehensive explanation on how to create and attach or detach finding charts, you should have a look at this page.

To the top

2.1: Define a spectroscopic OB with P2PP

3: Finishing the preparation and submitting the OBs

With the completion of the OBs, we consider the examples developed in this tutorial to be finished. The P2PP main GUI displays the two OBs that we have prepared:

We will now submit these OBs to the ESO Database: select all of them in the Summaries list, 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.

Our tutorial with this example of creating and submitting the OBs for one imaging observation and one spectroscopic observation ends here. For the preparation of the Phase 2 material for a whole run, however, more OBs may have to be created. Furthermore, the complete Phase 2 material includes also a README file for each run. As of P75, the README file is an integral part of P2PP, it is written within the P2PP environment and also submitted along with the OBs by using the p2pp tool. A tutorial for the README file is available here . When all the OBs and the README file for a given run are submitted, the Phase 2 submission is finalized by pressing the p2pp-submit button.

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. In short,

Select Check-out... from the File menu in P2PP
In the Database Browser window that opens, type 60.A-9253(E) in the Prog ID selection criterion
Click on the Query button on the lower left
Select all the OBs that appear in the display area after the query. Normally there should be your two submitted OBs only, but if another user has submitted other OBs from this same account without removing them afterward you will see them as well.
Under the File menu in the View OB window, select Check-out

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.