Discussion of observations for LOFAR CS1

This area is for more detailed comments about problems and tests done with specific observations. Start a new subsection for your favorite observation!

Studied reflected signal of Italian TV station in SB3 (channel 179). Found roughly 20 individual events of different durations (0.1-4 s) and shapes (FRED profile to broad lump). See more in presentation by Casey at August CS1 meeting.

reflections of distant TV stations seen with LBA at 200MHz on subbands 247,282,283,319

Sarod used this data set to make the deep, all-sky map named ??. The MeqTrees .tdl.conf file is below:

• Position error in images from first subband is gone. I assume reference frequency error was fixed. (casey)

• Phase wrap problem disappeared. Why?
• Dipole number 15x now works.
• First subband of each MS has shift in positions. Sarod says this is caused by an error in the reference frequency for the first subband of each MS. (casey)

• Phase wrap problem with CS016. All baselines between CS016 dipoles and non-CS016 dipoles have a rapid change in phase with frequency. About twelve turns of phase are observed across the 256*0.6 kHz subbands.
• Closure phase experiment for phase wrap problem: add phases along three baselines (e.g., 1-13 + 13-14 + 14-1). This sum is constant, which suggests that the phase wrap is related to a delay problem between CS016 and the other stations. It probably does not occur in the correlator. (Can someone confirm this?)
• Dipole number 15x is turned off.
• First subband of each MS has shift in positions. Sarod says this is caused by an error in the reference frequency for the first subband of each MS. (casey)

• Phase wrap problem first of CS016 first seen?