It felt really good to be reunited with the team this morning. The tedium of running dolphot and getting huge outputs was weird to encounter at home, but I feel more confident taking on the big files dolphot spits out now that Thom and I are working together as a team. I am running dolphot on another folder of files right now, and reading a tutorial on awk, a text processing utility that dolphot recommends to interpret the output.

The meaty output of dolphot is a text file with a row for each possible star. There are 154 columns in each row and each column contains information about the star. The eleventh column in each row is the object type as detected by dolphot. This can range from 1-5 where 1 is a likely star, 2 is a faint star and 3-5 are different elongated and/or faint non-stars. Just as a test to cull the list down to what are likely stars, I am going to try to get awk to make a new file from the dolphot output of just the stars with a 1 value in the object type column. This should give a sense of how many good stars dolphot found. I hope this will be a reasonable value of a few hundred to a few thousand as opposed to the 250k+ objects that dolphot put in the output file.

This helped me figure out how to write an awk command to do what I want to do. I started by practicing with a few dummy files so that I could troubleshoot a simpler example. I moved on to the dolphot output. It took awk about 15 seconds to run, and it produced an output file: ‘goodstars.txt’ with only the objects out of dolphot that were type-one objects (stars). Unfortunately, goodstars.txt is basically an exact copy of the dolphot output. I checked this by making a ‘badstars.txt’ file with only non type-one objects, and it only had 51 objects in it (out of several hundred thousand), all of which were object type 2 (faint stars). This means we have to use something other than the object type to screen out bad stars.

I loaded the file into excel which makes column-based viewing easier. Column 19 is Chi, and it varies from 0-76 over the 250k objects in the list. there are about 500 objects with a chi of 1.00. 500 is a nice number of stars for this field, so I am tempted to use those, but I am not sure if that is fair to the rest of the stars as there could be good candidates with a different chi.

I think all the traveling is throwing my immune system off and I’m feeling like I am getting sick. I am going to go home and rest. I may be back here today. If not, it will be tomorrow.