This tutorial provides a step-by-step example of the preparation of a set of OBs for AMBER, the near-infrared interferometric phase-closure instrument for the VLTI. The specifics of this tutorial pertain to the preparation of OBs from Period 82 onwards. To follow it, you should have the newest P2PP installation (since P82, version 2.13) on your computer and be familiar with the essentials of the use of P2PP. Please refer to the P2PP page for links to the P2PP manuals.
1: Goal of the Run
In this tutorial we will prepare an OB that performs the acquisition of a science target and its fringe observation in medium spectral resolution mode. The example consists ofobserving the star alf Ori (Simbad coordinates RA (2000) = 05 55 10.31, Dec (2000) = +07 24 25.4, proper motions RA 27 mas/year, Dec 11 mas/year) with the baseline configuration A0-G0-H0 and within the LST range 06h...09h. Following the science OB for alf Ori, we will construct a second OB that defines the observation of a calibrator target for alf Ori.
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 ofpreparing in advance an observing run, as well as some aspects that are specific to the preparation of OBs for VLTI and AMBER. If you have prepared OBs for MIDI before, you will see that many aspects regarding interferometric calibrators, the definition of the baseline configuration, and the setting of sidereal time constraints are very similar for MIDI and AMBER.
2: Getting started
The Phase II process begins when you receive an email from the ESO Observing Programmes Office (OPO) telling you that the allocation of time for the coming period has finalized and that you can view the results by logging into the UserPortal 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.
You follow the instructions given by ESO and find that time was allocated to your run with AMBER. Therefore, you decide to start preparing your Phase II material. First, you collect all the necessary documentation:
- The AMBER User Manual
- The AMBER Template Manual
- The VLT Service Mode Guidelines
- The P2PP Documentation referred to above.
and you proceed with the installation of P2PP on your machine if necessary.
3: Your First OB
You decide to start with the definition of an OB for your science object.
3.1: Define an OB 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 no thave 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 AMBER Tutorial run, 60.A-9253(J). 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 of the AMBER run.
You can now start defining your OBs.
First, click on the New button on the upper left side of theP2PP main GUI. This creates an entry in 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 button. The View OB window appears:
This is the window where you will define the contents of your OB.
3.1.1: Filling in the basic information
OB Name
First, you define the OB name, where the name of the OB must follow the specific OB naming convention for VLTI/AMBER: a science target OB must begin with SCI_ and should preferentially contain the target name. Therefore, the OB name is SCI_alfori. Type this name in the Name field.
User Priority
Next, assign this OB a priority. In case your run will contain more than one science OB (very likely), you can select a priority for this OBfrom the drop-down User Priority menu.
OD Name
It may be useful in many cases to have an easy way of identifying an OD (Observation Description), 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 the observation description will define the use of the low resolution mode for the fringe observations (while the medium resolution modes would be the other option). Thus, we enter the name Fringe_obs_medres in the OD Name field.
User Comments
The User Comments field can be used for any special requirements that you want the staff on Paranal to be alerted to, however, in most cases, this information should be part of the ReadMe attached to this OB, or should be included in the Calibration Requirements tab (see below). Since we don't have any special comments for this example, we leave this field blank.
Instrument Comments: name of associated OB of the SCI/CAL pair
The VLTI specific field Name of associated OB of the SCI/CAL pair must be used to insert the name of the calibrator OB associated with your science OB SCI_alfori. Thus, you enter CAL_hd39400 in the Name of associated OB of the SCI/CAL pair field.
3.1.2: Defining the acquisition template
The first template that must be part of any science OB is the acquisition template, so let us define it now. In the TemplateType list, click the acquisition entry.This will list all the acquisition templates available for AMBER in the Template list next to it (of which thereare currently just one). Highlight the AMBER_3Tstd_acq template and click the Add button next to it.The window should now look like this:
Now, you need to decide on the acquisition parameters, and if necessary, modify the default values given in the acquisition template.
The first four fields in the acquisition template are the uncorrelated magnitude and minimum source visibility, for the H and K bands respectively. The numbers for the H-band, Source uncorrelated H magnitude and H minimum source visibility, are important parameters if the H-band fringe tracker FINITO is to be used as the fringe sensor (see below). We insert the values for alf Ori, which are-4.0 and -4.4 for the uncorrelated magnitudes in H and K band, respectively, as well as 0.15 and 0.2 for the minimum visibilities (on the two shorter baselines), respectively:
- Source uncorrelated H magnitude: -4.0
- H Minimum source visibility: 0.15
- Source uncorrelated K magnitude: -4.4
- K Minimum source visibility: 0.2
The next two fields in the acquisition template are the Diff RA tracking and Diff Dec tracking fields, which are only needed for Solar System objects, so we keep the default value of 0:
- Diff RA tracking: 0. (Default value)
- Diff DEC tracking: 0. (Default value)
The next fields are related to the source used for Coude guiding. Since your science target, alf Ori, is at V=0.6 sufficiently bright in the visual it can be used for coude guiding itself. Therefore you choose the following parameters in your acquisition template:
- RA of guide star if COU guide star is setupfile: 0. (Default value)
- DEC of guide star if COU guide star is setupfile: 0. (Default value)
- COU guide star: SCIENCE (Default value)
- GS mag in V: 0.6
The values for "RA/DEC of guide star if COU guide star is setupfile" are used in cases where the science target is not bright enough to serve for coude guiding and an off-axis guide star within a radius of 1 arcmin is provided. In that case "COU guide star:SETUPFILE" is chosen. The parameter "GS mag in V" is set to the V magnitude of the target that is used for Coude guiding, whether it is the target itself or an off-axis guide star.
Since P80, the fringe tracker FINITO can be used if the target is bright enough in the H-band and has sufficient fringe contrast. Since that is the case for Alf Ori, we select it:
- Fringe sensor: FINITO
The next field to fill out in the acquisition template is Scienceor calibrator, which obviously must be SCIENCE since this is your science OB.:
- Science or calibrator: SCIENCE
The last field Standard spectral configuration sets the spectral configuration for your whole OB. Since in this example we write an OB for the medium resolution mode, we choose
- Standard spectral configuration: Medium_1_2.1
3.1.3: 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 should be the same name as used in the OB naming, in other words, insert Name: alfori. Also, enter the right ascension and declination for alf Ori. In the case of VLTI observations, coordinates as precise as possible are essential, so that the optical path difference to find the fringes can best be predicted. Therefore, please enter as well the proper motions of the target in arcsec/year (unless not known). Furthermore, edit the entry in the Target-tabbed subpanel Class. In our case, choose Supergiant.
The acquisition template including the target information is now complete, and the window should look like this:
3.1.4: 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 fringe observations, you type Fringe_obs_constraints in the Name field.
Sky transparency:
Since we assume that your observations are typical AMBER near-infrared observations, your target is rather bright in the near-infrared and optical, we do not need exceptional atmospheric conditions and request Variable, thin cirrus conditions in the Sky Transparency entry.
Seeing:
Since we will be using the FINITO fringe tracker, a seeing better than 1.2 arcseconds is recommended.This value is well below the standard operational limit of 1.5 arcseconds for the MACAO systems as given in the user manual. Hence we insert a Seeing value of 1.2.
Baseline:
Let's assume that time has been allocated for your programme on the baseline configuration A0-D0-H0. You must therefore choose A0-D0-H0 from the baseline drop-down menu.
Note that in your Phase I proposal you already specified some of these constraints (sky transparency and seeing). You must make sure that none of the constraints specified in Phase II is more stringent than the corresponding ones specified at Phase I.
3.1.5: Setting the time intervals
We will assume now that your AMBER observations are part of a larger multi-wavelength project and that the AMBER observations should be carried out simultaneously with some satelite observations that are performed between December 02-12 2007. You can specify this as follows:
- Select the Time Intervals tab
- Click on the checkbox at the far right of the first row oftime intervals.
- Modify the lower boundary (the left-hand side entry) of thetime interval to the specified starting date of your time window, keeping the same format. In the present case, the entry should read 2007-12-02T00:00:00.
- In the same way, modify the upper boundary of the time interval to 2007-12-12T00:00:00.
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 (remember that there are only limited service mode time windows over the period, and that VLTI baselines are scheduled block-wise at certain dates only).
3.1.6: Setting the constraints on the sidereal time
Under the Sidereal Time tab you can constrain the LST range within which your OB should be executed. In this tutorial you wish to prepare an OB that should be executed between 06h < LST < 09h, hence you do the following:
- Select the Sidereal Time tab
- Click on the checkbox at the far right next of the first row of sidereal time intervals.
- Modify the lower boundary (the left-hand side entry) of the sidereal time range to the specified starting LST of your LST range, keeping the same format. In the present case, the entry should read 06:00.
- In the same way, modify the upper boundary of the sidereal time range to 09:00.
In the same way you could define up to 4 more LST slots, as alternative(!) LST ranges, in case the OB cannot be executed duringyour prefered LST range setting which you defined in the first row. Please note that defining more than one sidereal time ranges in this field does NOT mean that the OB will be executed multiple times at each these LST ranges. Rows 2-5 indicate just the alternatives to the LST range specified in the first row.
3.1.7: Setting the calibration requirements
Under this tab, you can specify special calibration requirements, such as alternate calibrators, different sequences of SCI and CAL targets, etc. If you want to observe the calibrator both before and after the science target, it is important to include this information here and in the Special Calibration section of the ReadMe file (see below).
3.1.8: Defining the observation description
Once the acquisition and the tabbed items Target, Constraint Set, Time Intervals, Sidereal time, and Calibration Requirements, are completed, the science template(s) can be inserted.
On Template Type, select now science. The existing AMBER science templates will appear. Select the template AMBER_3Tstd_obs_1row (actually, the only template available) and click on Add. The template will be attached to the grid below next to the acquisition template selected and filled previously.
The first field of this science template is the integration time Frame integration time (DIT in s). Since in this example we are using FINITO to stabilize the fringe, the integration time can be increased above thethe default value in order increase the signal-to-noise ratio. Because your target is very bright, you enter 0.2 (if your calibrator is more than a magnitude fainter, you might haveto increase the DIT to satisfy the minimum requirement and have the same integration time for science and calibrator targets):
- Frame integration time (DIT in s): 0.2
The next two parameters of the science template are again the H and K magntiude of the target, which obviously need to be the same values that were inserted into the acquisition template:
- Source uncorrelated H magnitude: -4.0
- H Minimum source visibility: 0.15
- Source uncorrelated K magnitude: -4.4
- K Minimum source visibility: 0.2
The next two parameters of the science template are the offsets in RA and declination for taking the sky background. If you notice that the default offset would result in a position where another star (or any source of none pure sky emission) is present, you should change these parameters. In our example, we leave these values at their defaults:
- Sky telescope offset in Alpha (arcsec): 0. (Default value)
- Sky telescope offset in Delta (arcsec): 30. (Default value)
Finally, we have to define the covered wavelength range for our observation. Since the use of FINITO allows for longer integration times, the full detector can be read out, and so we enter the same range previously only available in the LR mode:
- Row1: max wavelength in um : 9999.0
- Row1: min wavelength in um : 0.0
The only other thing that you should really do at this point is to check the execution time for this OB. The factthat 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 finda 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 ofthe label. In this case the total execution time is 00:45:00.
This (almost) completes your first OB! If you followed all the indications given so far, the View OB window should look like this now.
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: SCI_alfori
- Dbaseid: 0
- Status: (P)artiallyDefined
- Target: alfori
- OD: Fringe_obs_medres
- CS: Fringe_obs_constraints
- Acquisition: AMBER_3Tstd_acq
- FindingCharts: (0)
You can resize the columns as indicated in the P2PP User Manual to view the full contents of each entry.
4: Attaching Finding Charts
The next thing to do 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 and AMBER specific requirements for finding charts. 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(J)], which you called 60.A-9253J.alfori01.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-9253J.alfori01.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.
5: Defining the Calibrator OB
Since each science OB must be combined with a calibration OB we will briefly demonstrate how to define the calibrator OB. The necessary steps are verysimilar to the definition of the science OB.
To select for each science target a calibration target, it is recommended to use the CalVin tool developed by ESO. CalVin selects suitable calibrators based on different user criteria. Ideally you would wish to have a calibrator star as close as possible to and of similar brightness as your science target. Consulting the CalVin tool you find that the star HD39400 is a suitable calibrator for your science target alf Ori.
You can either repeat the steps as outlined above, i.e. you start defining your calibrator OB by clicking on the New button on the upper left side of the P2PP main GUI, or you can duplicate the science OB by clicking on the Duplicate button. By duplicating your existing OB, the only fields that you need to modify are of course the ones related to the target, but not the instrumental setup. Calibration stars should have an LST range lasting from 30 minutes before the start of that of the science OB to 30 minutes after the end of that of the science OB. Therefore please adjust the LST range accordingly.
First, make sure the calibrator target name is updated in the OB name and in the target information section. In the latter, enter the correct target coordinates and proper motions for the calibrator.
Update the magnitude and minimum visibility information, and also enter the V magnitude of HD 39400 in the filed GS Mag in V V magnitude of HD39400, which is 4.8 (Coude guiding on the target HD39400 itself can be used again) and the H and K magnitudes, which are 2.0 and 1.8. We have to set the Science or calibrator field obviously to CALIB. You therefore enter:
- Source uncorrelated H magnitude: 2.0
- H Minimum source visibility: 1.0
- Source uncorrelated K magnitude: 1.8
- K Minimum source visibility: 1.0
- Diff RA tracking: 0. (Default value)
- Diff DEC tracking: 0. (Default value)
- RA of guide star if COU guide star is setupfile: 0. (Default value)
- DEC of guide star if COU guide star is setupfile: 0. (Default value)
- COU guide star: SCIENCE (Default value)
- GS mag in V: 4.8
- Fringe sensor: FINITO
- Science or calibrator: CALIB
- Standard spectral configuration: Medium_K_1_2.1
Concerning the actual observation, we choose as well the template AMBER_3Tstd_obs_1row, and use the same settings as for the science target alf Ori, except the H and K magntiudes, and enter:
- Frame integration time (DIT in s):0.2 (same as science target)
- Source uncorrelated H magnitude: 2.0
- H Minimum source visibility: 1.0
- Source uncorrelated K magnitude: 1.8
- K Minimum source visibility: 1.0
- Sky telescope offset in Alpha (arcsec): 0. (Default value)
- Sky telescope offset in Delta (arcsec): 30.
- Row1: max wavelength in um : 9999.0
- Row1: min wavelength in um : 0.0
Finally, your OB view window should looklike this:
You close the OB view window and perform the final step, which is attaching a Finding Chart to your calibrator OB. The name of the Finding Chart that you have created is 60.A-9253J.hd39400.jpg. This completes your calibrator OB!
6: Finishing the preparation and submitting the OBs
With the completion of the OBs, we consider the example developed in this tutorial to be finished. The P2PP main GUI displays the two OBs that we have prepared:
We will now check these OBs into 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 checking in the OBs for one science target/calibration star pair ends here. For the preparation of the Phase II material for a whole run, more OBs may have to be created. Remember, the complete Phase II material includes also the ReadMe file. The ReadMe file also has to be checked into the ESO data base (look at Readme menu). A tutorial for the ReadMe file is available here. When all the OBs and the ReadMe file for a given run are checked in, the Phase II submission must be 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. By the way, the same procedure would have to be followed should you need to modify your OBs after checking them in, because this action will also lock them. The P2PP User Manual gives you detailed indications on how todo this. In short,
- Select Check-out... from the File menu in P2PP.
- In the Database Browser window that opens, type 60.A-9253(J) 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 afterthe query. Normally there should be your two submitted OBsonly, 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 beleft 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.