Instructions for GBT21A-363: Radio Recombination Lines: Constraints on the Fermi Bubble Shell (Dhanesh Krishnarao et al.)
Our observing strategy and these instructions are identical to those of GBT20A
1. Run scheduling blocks sb01, sb02, sb03, etc.
; Run these scheduling blocks in order. If a scheduling block is aborted then please re-run it.
1. Check the pointing/focus results.
If the pointing or focus scans are bad then just abort and re-run the scheduling block. If the pointing or focus scans continue to fail after two attempts, use previous pointing and focus corrections if available; otherwise zero out these corrections.
2. Check the VEGAS bandpass.
We are tuned to 64 spectral windows at 2 polarizations. Make sure we have a reasonable bandpass in all spectra. Since Astrid may crash when set to display all spectra, the best way to check the bandpasses is by opening a web browser and going to https://vegasdisplay.gb.nrao.edu
. For example, below is a screen shot of the Vegasdisplay (on the left) where all bandpasses look ok. If the bandpasses significantly deviate from the screenshot, please reset VEGAS and run the scheduling block again.
</b>Lately, the Vegasdisplay has been offline a number of times. If it is offline, please check a few spectral windows in Astrid.
3. Check the power levels.
Go to Cleo --> Launch --> Backends --> VEGAS and select VEGAS Power Monitor --> All measpwr. Power levels should be around -21 dBFS for all banks, except for one polarization in bank H for which the power level should be around -26 dBFS. Short-term spikes in the power levels are usually due to RFI and are ok as long as the power level returns to its normal value after a few seconds (see right-hand side of screenshot below). If the power levels deviate from the above values by more than ~5 dBFS for several minutes, please reset VEGAS and run the scheduling block again.