VEGAS Tests 08 December 2013
Goals
- On-sky science testing of modes 1, 2, and 3
Plan
- RRL mode 1, 2, and 3
- exgal mode 1, 2, and 3
- fast map mode 1, 2, and 3
Data Location
- data location: /home/scratch/akepley/vegas_tests/mode123_test_onsky_dec082013
Details
- Session 24
- Dec08RRLXbandMode1SpecOnOff
- Scan 1-5: point, focus
- Scan 6&7: on source
- no detection, but M82 is fainter than HI region
- trying again with longer integration
- Scan 8&9
- longer integration on M82
- lots of ringing. balance problems? point/focus problems?
- also long scan may be missing a integration (299 instead of 300 integrations)
- online SDFITS filling not working. Had Kevin restart online sdfits filler on datacapture, but no joy.
- may be a detection, but lots of ringing.
- changed source to W3OH
- Scan 10-14: point, focus again
- Scan 15&16: W3OH
- Scan 17-26 : W3OH
- something wrong with LL polarization?
- try one scan later to see if ringing goes away with pol='self'. I noticed later that the configuration script has polarization='linear' and X-band is a circularly polarized receiver. that could be the problem. Might be worth checking out.
- Dec08RRLXbandMode2SpecOnOff
- source W3OH
- Scan 27- 36
- looks nice. can detect source. additional lines?
- Dec08RRLXbandMode3SpecOnOff
- source W3OH
- Scan 37 - 46
- Dec08RRLXbandMode1SpecOnOff
- source W3OH, switched polarizations to self to see if ringing goes away
- scan 47-48
- Dec08RRLXbandMode2SpecOnOff
- source W3OH, switched polarizations to self to see if ringing goes away
- scan 49-50
- Dec08RRLXbandMode3SpecOnOff
- Source W3OH, switched polarizations to self to see if ringing goes away
- scan 51-52
- Switched to L-band
- Dec08ExGalMode1SpecFsw
- scan 53
- switched sources to U2855 to keep telescope low because of snow falling in GB
- Dec08ExGalMode2SpecFsw
- scan 54
- Dec08ExGalMode3SpecFsw
- scan 55
- Dec08LbandMode1fastmap
- Scan 56-57
- aborted because map is too big
- Dec08LbandMode1fastmap
- Scan 58-74
- cut down size of map in non-scanning direction
- Dec08LbandMode2fastmap
- Scan 75-91
- Dec08LbandMode3fastmap
- Scan 92 - 108
- Dec08ExGalMode1SpecFsw
- Scan 109
- 3 min scan
- Dec08ExGalMode2SpecFsw
- Scan 110
- 3 min scan
- Dec08ExGalMode3SpecFsw
- Scan 111
- 3min scan
- snow dump
- switch back to X-band for another quick scans to check whether polarization='Linear' for X-band was causing problems.
- Dec08RRLXbandMode1OnOff
- Scan 112-113
- tried with "cross" and "Circular"
- Dec08RRLXbandMode2OnOff
- Scan 114 - 119
- tried with "cross" and "Circular"
Analysis
- analysis was performed in gbtidl-test
- log of data analysis in mode123_test_onsky.analysis
- detected RRLs in modes 1, 2, and 3
- mode 1 has significant ringing in LL polarization that swamps the RRLs
- mode 3 has significant ringing in the RR polarization.
- GBTIDL is reading the polarizations as RR and LL even though for many of these cases we requested linear polarization.
- mode 2 has the best detection, but there are some small features that I don't know if they are real or not. Looks like the RR polarization is less stable.
- HI data turned out not to be useful because of the large amounts of RFI in band
- didn't look closely at continuum map data, but did check the header info and overall number of integrations and they look appropriate. I'm planning on taking a closer look at the continuum map data next week to test out some software on another project I'm working on.
- RRL frequencies off?
- could be due to problems with assumed source velocity (assuming W3(OH) has an LSR velocity of -50.7 km/s based on Sams+ 1996)
- could be GBTIDL problem
- could be VEGAS problem.
- using procedure that Richard used previously to get lines properly placed when source velocity isn't right in the header:
fileout, 'mode2_rrls_reduce.fits'
kgetrec, 3
recombh
show
!g.s[0].source_velocity=-50700 ; km/s from Sams+ 1996
!g.s[0].velocity_definition = 'RADI-LSRK'
show
recombh
- When I flag the center channel, I get a type conversion error when I do a getps & accum on the data:
for i = 15, 26 do flag, i, chans=512
getps & accum
% Type conversion error: Unable to convert given STRING to Long.
% Detected at: IO_SDFITS::FIND_FLAGGED_INDEX_DATA 2692