Creating and Scheduling Observation Files

Introduction

Though the LWA Pulsar Archive is full of past observation data that needs to be processed, we will also be creating our own new observations to add to this data collection. When we create our timing solutions, the each observation creates a point on the residuals diagram; by scheduling new observations, we are adding a new and recent data point to the timing solution.

Creating Observation Files

Follow the regular steps to log onto the LWA computers. Log onto a UCF after validating its availability at LWAUCF Operations. For example, to log onto ucf1, use the ssh shortcut:

$ ucf1

We will now create our session definition files for observing. More information can be found at the LWA observing website. Use the shortcut

$ sessionmaker

to replace the command

 /usr/local/extensions/SessionSchedules/sessionGUI.py

This pulls up a GUI for creating observation files.

Go to File > New and fill in the following information:

Observer Information

ID Number: 55

First Name: Steven

Last Name: Stetzler

Project Information

ID Code: LS012

Title:

Comments: none (leave blank)

Session Information

ID Number: 190_<internal count 1,2,3,..>

Title:

Comments: none (leave blank)

Session Type - select BEAM FORMING

Data Return Method - select COPY TO UCF

UCF Username: uvastudent

And then click Ok

Go to Observations > Add > DRX-RA/DEC and fill in across the row:

Name:

Target:

Comments: none

Start: Set the duration to 24h with 24:00:00, then check Observations > Session At A Glance

Find the peak of the pulsar using your cursor, then close the window and set the time of the peak to your start time. As for the day, pick a date about 3 days in the future. Observations must be submitted between 2 and 30 days before the scheduled time, so choose a few days in the future if you will be submitting your observations the same day as creating this file. After setting the start time, set the duration to 1 hour with 01:00:00. Reopen Session At A Glance, and the sinusoid should be replaced with an approximately horizontal line. Make slight alterations to the start time if the line has a significant slope.

If you know your pulsar is exceptionally bright, the duration can be shortened to 30 minutes, 00:30:00. Likewise, if your pulsar is exceptionally dim, set the duration to 2 hours, 02:00:00.

RA: Retrieve the right ascension from the Australia Telescope National Facility website (ATNF Pulsar Catalog). Scroll down to “Pulsar names” and enter your pulsar name, and click Get Ephemeris. You may think you are getting results for another pulsar, but the catalog simply uses synonyms for the pulsar names given in different epochs. For example, searching for PSR B0655+64 renders results for PSR J0700+6418, but these are the same object. Fill in with the value for RAJ, where the J indicated the J2000 epoch.

DEC: Likewise, retrieve the DECJ value from ATNF, making sure to add the + or - sign.

You will be creating TWO obsevation files, 1 for each tuning, with pairs (35.1, 49.8) MHz and (64.5, 79.2) MHz. All other information is the same, simply change the Session ID number n+1 for the second file.

Tuning 1: 35.1 OR 64.5

Tuning 2: 49.8 OR 79.2

Navigate to Observations > Advanced Settings. Carefully scroll down to DRX-Specific Information. Change BEAM to 1 for your first file and to 2 for the second file. This predetermines the two beams used in by the LWA. When the beam has been chosen, click Ok.

Now, you will check that all the information is correct. Navigate to Observations > Validate All. You should get a pop up: “Congratulations, you have a valid set of observations.” Click Ok to close the window. If you don’t get “Congratulations…”, the error description will be displayed in the Terminal window. Make the needed changes until validation succeeds.

Now to save the file, use File > Save As. Name the file <date>_<your name>_<pulsar name>_low.sdf OR <date>_<your_name>_<pulsar name>_high.sdf respectively for the two tunings. Be sure to add the .sdf, as this is not automatically added as the file type when saved. Before saving, navigate to your directory (/<computing ID>)in the file folder search bar. Click Create Folder and name it Observations. Open Observations and now click Save.

Great! You can now check that the SDF (Session Definition File) is in

/uva_students/<your computing ID>/Observations

Now, make the second observation file with all the same information except Session ID Number n+1, higher tunings, BEAM = 2, and file name *_high.sdf. A shortcut to doing this is to open your *_low.sdf file, make the adjustments, and resave it as a new file. This prevents having to reenter the RA/DEC and start times.

Once both files have been saved, navigate to File > Quit to close the SDF GUI.

Transferring Files

We will be submitting our SDF files to a LWA website that automatically schedules each valid observation file. However, to upload files from the LWA network, we must save the SDF files on the lwalab computer, rather than a ucf.

To transfer these files to the local system, exit the ucf via

$ logout

Your command line should now read

uvastudent@lwalab:~$

To transfer the files, we will use scp, the secure copy command. To use scp, input scp <original location of file(s)> <new location of file(s)>:

$ scp uvastudent@lwaucf[#]:/home/uvastudent/uva_students/<your computing ID>/Observations/<date>_<your name>_<pulsar name>_* /home/uvastudent/observation_files/Fall2019

Hit return/enter, and you will be prompted for the password to the ucf. Enter the password to allow the scp to go through.

Inserting the wildcard operator * into the file address allows for both tuning observations to be copied at once. The file destination (“Fall2019”) will vary from year to year.

Success! You can now check that your file is in the right place on the local lwalab server.

Scheduling Observations

To schedule observations, we must upload the files through the remote server. Open the Browser within the X2GO LWA desktop. Go to http://fornax.phys.unm.edu/lwa/validator/index.html

Click Choose File. In the pop-up window, navigate to uvastudent > observation_files > Fall2019

To choose one of your files, double click on file or single click to select and click Open. UNCHECK Schedule Valid Files and click Validate. If the file is valid, go back, reupload, and CHECK Schedule Valid Files. If the file is invalid, read the error (most likely Session Name repeat).

For Session Name repeat error, reopen the terminal. In

uvastudent@lwalab:~/observation_files/Fall2019 

you will edit the SDF file.

$ vi <date>_<your name>_<pulsar name>_low.sdf

For vi, use arrow keys to locate SESSION_ID. Type I to use INSERT function and replace the last digit with n+1. Hit ESC to close the INSERT function and type :wq to write (save changes) and quit (return to cmd line). Reupload the file and validate it, (you may need to iterate n+1 until the file is valid). Repeat with the _high.sdf file, adding +1. Validate the _high.sdf file.

Click Add Another File so that both tunings are uploaded.

Target Station: select LWA1

Target Interferometer: leave blank

Schedule Valid Files: CHECK

Click Validate. You should get green check marks on the next page!

After your observations, the data will be in

uvastudent@lwaucf[#]:/data/network/recent_data/uvastudent/<pulsarname>/<MJD of observation>

Note: you will need to cd ../.. after logging into the ucf.