On 06jul21 14 5min on/off position switches was
done on M42A using xband. This was to look at some
recombination lines. The setup was:
- On position:
- 05:32:50 , -05:25:00 B1950. taken from Effelsberg 10.5
- the beam is about 10 arcminutes
- Off position:
- was supposed to retrack the on position
(about 5min,20sec in ra).
- bug in onoff.proc had it move in the opposite ra
direction (moved 5min,20 secs to a lower ra).
- Off was still off the source
- 10 sec cal on,off
- taken in the off position after the off.
- we don't yet have accurate measurements of the cal on
the telescope (need the cherry picker to put the absorber
in front of the feed).
- If/lo setup
- recomb lines looked at:
- mock setup
- 5 boards used
- bandwidth 160Mhz/ 3=53.33 Mhz
- 2048 channels ->26 Khz channel width
- center of band was originally set 5MHz below the H lines
to stay away from the bump in the center of the complex
- the softer complained about the band centered at
8040Mhz. it was outside the allowed band
- So i switched to be band center to be 5
Mhz above the H lines
- --> unfortunately i should have been 5Mhz
above the C lines (since they are > than the H lines)
- This caused the C line to be close to the center of
the band. It wasn't too bad since the bump cancelled..
only problem was dc spike and low freq rfi around the
center of band.
- There was no doppler correction done. The band center
was a topocentric frequency.
- The data files
- the onoff proc had a bugs:
- it was not updating the pattern_id correctly (now
- it forgot to update the observation type after the
first calon,off (fixed)
- the file numbers go
- 00000 through 05500
- 000- on source
- 100 off source
- 200 - calon
- 300 - caloff
- 400 - on source
- 500 off source
- 600 calon
- 700 caloff
- ... this continues till
- 5200 on source
- 5300 off source
- 5400 calon
- 5500 caloff
- the files are stored as
- N 1.. 5
- M 0,1,2,3,4
- nnnnnn 00000 to 5200
Plotting the averages
The on/off's were averaged and plotted vs
freq and velocity. The cals were ignored for these plots. I
only plotted the 3 central line numbers. The lowest and
highest fell on the part of the bandpass that was
averages vs frequency (.ps)
- red is polA, green is polB
- the x axis is topocentric frequency.
- I've flagged the rest frequencies of the lines
- The H transition is visible in the 3 transitions.
- the C transition may be a bit below the rest freq
(although it is close to the center).
averages vs velocity (.ps) (.pdf)
- I've plotted the spectra vs helio centric velocities
(maybe i should have used lsr?)
- Need to check if the projected helio,geo velocities in the
header are being computed correctly.
- We saw the 90-92A recombination lines of hydrogen with 70
minutes on source. T
- The carbon line may be visible but it is too close the the
bump in the center to be sure.
- anish.. please check the header values when reprocessing
this data :)