Tips and Tricks

0) Save all the steps done in a reduction attempt

Before you start reduction of a source. Run the script command as shown in the example below

script LogOfMyReductionOfM31.txt

This command will will save everything that is typed or printed in that terminal to the file LogOfMyReductionOfM31.txt while you are reducing data. At the end of reduction, press Cntrl+D to stop and exit the recording.

1) List all the observations done so far on a particular object

Say, you are looking for a source with keyword M31 in it.

Running all the following commands standing in directory containing all the night's raw data.

Following command will list details of all observations which has the keyword M31.

grep M31 201*/SlopeimagesLog.txt

If you suspect, some nights the name used might be Andromeda instead of M31, you can combine all the keywords in grep as shown below.

grep 'M31\|Andromeda' 201*/SlopeimagesLog.txt

Once, you have all the list related to observation of your source, one can use the power of pipes in gnu/linux to extract out the details just you want.

Some examples are given below.

2) Use flats from a different night

There are three ways to do it. All are equally good ways to do it.

  1. Copy those files as well as the lines corresponding to those images from SlopeimagesLog.txt of that night to new night directory. It is very important to append the SlopeimagesLog.txt with the new additions in directory.

  2. To save hardisk space, instead of actually copying the data, you can instead create a symbolic link to those images from one directory to other. But do append the SlopeimagesLog.txt with the new additions.

  3. But if your hardisk is ntfs you may not be able to create symbolic links. You can use flats form other nights still by appending those images in SlopeimagesLog.txt, but replace the filename in the first column with the relative path. Eg: ../20140329/Slope-Flat_J-23.fits. That way, you can avoid copying those fits file to each night's directory.

Note: Do not change anything in other columns of the SlopeimagesLog.txt they are all vital to run the code. When you are copy pasting the image lines from one directory to other, care should be take to preserve all the columns while pasting.

3) Continue the pipeline run, only on a subset of directories initially chosen

Due to some evil reason, your script might have crashed while reducing some particular night's data. You don't want to run all the successful runs upto that directory again, when you rerun the piepeline.

All you have to do is to backup the OUTPUTDIR/directories text file. And then remove the name of directories you don't want to run the pipeline. After finishing the run on remaining directories, you can choose to restore the directories list.

Note: In Stage 9 of Photometry pipeline (the last actual photometry part). You may want to choose at image level instead of directories. The file you have to backup and edit is OUTPUTDIR/Images4Photo.in file. After Step 6 in Photometry pipeline, OUTPUTDIR/directories does not have any role in deciding the pipelines action.

4) Some general tips which will help users