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

Topic attachments
I Attachment Action Size Date Who Comment
mode1_rrl.psps mode1_rrl.ps manage 56 K 2013-12-11 - 16:41 AmandaKepley Mode 1 RRL reduced spectrum
mode2_offset.psps mode2_offset.ps manage 65 K 2013-12-12 - 15:09 AmandaKepley offset between recombh and mode 2 spectra
mode2_rrl.psps mode2_rrl.ps manage 169 K 2013-12-11 - 16:41 AmandaKepley Mode 2 RRL reduced spectrum (including bandpass removal)
mode3_rrl.psps mode3_rrl.ps manage 299 K 2013-12-11 - 16:41 AmandaKepley Mode 3 RRL reduced spectrum
This topic: CICADA > WebHome > GreenBankSpectrometer > CICADAGreenBankSpectrometerAug2013TestPlan > CICADAGreenBankSpectrometer2013Dec08
Topic revision: 2013-12-12, AmandaKepley
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