Overview on data reduction, calibration and analysis -...
Transcript of Overview on data reduction, calibration and analysis -...
![Page 1: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/1.jpg)
Overview on data calibration, reduction and analysis
Spectral Lines
Andrea TarchiPhoto by G. Alvito
![Page 2: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/2.jpg)
Outline
![Page 3: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/3.jpg)
Outline• Calibration
Everything else matters To move or not to move? Through the mist Good ol’ Jansky!
![Page 4: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/4.jpg)
Outline• Calibration
Everything else matters To move or not to move? Through the mist Good ol’ Jansky!
• Reduction Breaking the waves Summing up Would you buy this?
![Page 5: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/5.jpg)
Outline• Calibration
Everything else matters To move or not to move? Through the mist Good ol’ Jansky!
• Reduction Breaking the waves Summing up Would you buy this?
• Analysis Bright enough One moment in time Spectral presences 3-D
![Page 6: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/6.jpg)
CalibrationEverything Nothing else matters
![Page 7: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/7.jpg)
CalibrationEverything else matters
We observe a point source with our (radio)telescope
The source has a certain power
We replace the telescope feed with matched load (resistor)
We adjust the load temperature until the power received = source power
The temperature reached is = to the Antenna Temperature
![Page 8: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/8.jpg)
What do we measure?
• ON the source, we have:
Tmeas,ON(α,δ,Az,ZA)= Tsrc(α,δ,Az,ZA) + Telse
• OFF the source, we have:
Tmeas,OFF(α,δ,Az,ZA)= Telse
Where Telse=Tsys=TRX+Tgr(Az,ZA)+Tcel(α,δ,t) +TCMB+Tatm(ZA)
CalibrationEverything else matters
![Page 9: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/9.jpg)
Tsrc + Telse Telse
OFFON
CalibrationEverything else matters
![Page 10: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/10.jpg)
Tsrc + Telse Telse
OFFON
CalibrationEverything else matters
![Page 11: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/11.jpg)
(Tsrc + Telse) - (Telse)
=
ON - OFF
CalibrationEverything else matters
(TON - TOFF)
![Page 12: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/12.jpg)
[(Tsrc + Telse) - (Telse)]/ Telse
=
(ON – OFF)/OFF
CalibrationEverything else matters
This is what is typically provided during a line observation
(TON - TOFF) / TOFF
A spectrum in Tsys units
Conversion to K (or Jy) required
Telse=off = Tsys
Estimate required
![Page 13: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/13.jpg)
A spectrum in Tsys units (counts, so far)
Conversion from counts to K (or Jy)
required
CalibrationEverything else matters
• Theory
• Noise Diodes
• Hot & Cold Loads
• Astronomical Measurements
See also next section
![Page 14: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/14.jpg)
Noise diodes (frequency dependence; precision in diodes meaurements affects calibration accuracy)
Astronomical sources (quite accurate; knowledge in the flux cal. Intensity influences calibration accuracy)
Tsource aka TA of the source in K can be obtained
CalibrationEverything else matters
![Page 15: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/15.jpg)
CalibrationTo move or not to move?
![Page 16: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/16.jpg)
CalibrationTo move …?
Position Switching
ON
![Page 17: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/17.jpg)
CalibrationTo move …?
Position Switching
ON OFF
![Page 18: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/18.jpg)
CalibrationTo move …?
Position Switching
Pros• good baselines(typically)• Iittle a priori infos required
Cons• requires to move the telescope• source cannot be too extended
![Page 19: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/19.jpg)
Calibration… or not to move?
Frequency Switching
ON OFF
ON-OFF
![Page 20: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/20.jpg)
Calibration… or not to move?
Frequency Switching
![Page 21: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/21.jpg)
Calibration… or not to move?
Frequency Switching
Pros• does not require to move the telescope• rapid ON-OFF switching (good efficiency)
![Page 22: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/22.jpg)
Calibration… or not to move?
Frequency Switching
Pros• does not require to move the telescope• rapid ON-OFF switching (good efficiency)
Cons• frequency of the line has to be well known• requires time- and frequency- stable baselines
![Page 23: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/23.jpg)
Calibration…or not to move?
Beam Switching
Pros• does not require to move the telescope
Cons• requires hardware• source cannot be too extended
![Page 24: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/24.jpg)
Calibration…or not to move?
Beam Switching
Pros• does not require to move the telescope
Cons• requires hardware• source cannot be too extended
![Page 25: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/25.jpg)
Calibration… or not to move?
Beam Switching with 2 beams (NODDING)Pros• does not require to move the telescope• ON and OFF at the same time
Cons• requires hardware• source cannot be too extended
![Page 26: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/26.jpg)
CalibrationTo move or not to move?
Further methods
• Baseline fitting (simple but requires good baselines)
• Baseline fitting with average fit (for extended sources)
• Double position switching (to remove residual standing waves due to strong continuum)
![Page 27: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/27.jpg)
CalibrationThrough the mist
![Page 28: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/28.jpg)
CalibrationThrough the mist
When νobs ≥ 15 GHz, it is necessary to correct for atmospheric absorption/attenuation!
Path length through the atmosphere for the radiation from a celestial source
![Page 29: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/29.jpg)
CalibrationThrough the mist
![Page 30: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/30.jpg)
CalibrationThrough the mist
Tsys and AM can be determined
Tatm can be assumed ≈ to the air temperature (on ground level) or calculated through approximated relation
A number of measurements Least-square fit
τ (& T0) can be estimated
![Page 31: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/31.jpg)
CalibrationThrough the mist
Average opacities measured at Effelsberg.
Zenith opacity applied as the default in the GBTIDL procedures for quick-look calibration of GBT data.
Warning: τ depends on the weather conditions; especially at high frequencies!
![Page 32: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/32.jpg)
CalibrationThrough the mist
Sky-dip procedures and Water-Vapour Radiometers installed at the telescope sites and/or on the telescopes allow to derive (quasi) real-time τ estimates.
Left: Opacity at 22 GHz measured with the microwave radiometer (in the circle of the picture above) at the SRT site (Courtesy: F. Nasir, F. Buffa, G. Deiana, and collaborators)
![Page 33: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/33.jpg)
CalibrationGood ol’ Jansky
![Page 34: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/34.jpg)
CalibrationGood ol’ Jansky
![Page 35: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/35.jpg)
CalibrationGood ol’ Jansky
When moving at higher or lower Elv, the dish loses sensitivity due to small-scale deformations, viz.the telescope Gain changes.
![Page 36: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/36.jpg)
CalibrationGood ol’ Jansky
When moving at higher or lower Elv, the dish loses sensitivity due to small-scale deformations, viz.the telescope Gain changes.
![Page 37: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/37.jpg)
CalibrationGood ol’ Jansky
To convert from Antenna Temperature (K) to Flux Density (Jy)
Γ is typically determined though observations of know calibrators (and tabulated)
A correction factor, Cs, has to be applied if the source is not point-like
![Page 38: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/38.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
![Page 39: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/39.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
![Page 40: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/40.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
T A[K] = counts·T cal[K]
T cal depends on freq
![Page 41: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/41.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
T A[K] = counts·T cal[K]
T cal depends on freq
![Page 42: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/42.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
T A[K] = counts·T cal[K]
T cal depends on freq
![Page 43: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/43.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
T A[K] = counts·T cal[K]
T cal depends on freq
Atm. contributionRequires opt. depthand source Elv
![Page 44: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/44.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
T A[K] = counts·T cal[K]
T cal depends on freq
Atm. contributionRequires opt. depthand source Elv
![Page 45: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/45.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
T A[K] = counts·T cal[K]
T cal depends on freq
Atm. contributionRequires opt. depthand source Elv
![Page 46: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/46.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
T A[K] = counts·T cal[K]
T cal depends on freq
Atm. contributionRequires opt. depthand source Elv
Telescope GainRequires gain curve and source Elv
![Page 47: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/47.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
T A[K] = counts·T cal[K]
T cal depends on freq
Atm. contributionRequires opt. depthand source Elv
Telescope GainRequires gain curve and source Elv
![Page 48: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/48.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
T A[K] = counts·T cal[K]
T cal depends on freq
Atm. contributionRequires opt. depthand source Elv
Telescope GainRequires gain curve and source Elv
![Page 49: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/49.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
T A[K] = counts·T cal[K]
T cal depends on freq
Atm. contributionRequires opt. depthand source Elv
Telescope GainRequires gain curve and source Elv
Flux Gain (Sensitivity)Typically tabulated
![Page 50: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/50.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
T A[K] = counts·T cal[K]
T cal depends on freq
Atm. contributionRequires opt. depthand source Elv
Telescope GainRequires gain curve and source Elv
Flux Gain (Sensitivity)Typically tabulated
![Page 51: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/51.jpg)
CalibrationGood ol’ Jansky
In summary, a good calibration procedure could be described by
For tricks and shortcuts…wait the hands-on actvities
T A[K] = counts·T cal[K]
T cal depends on freq
Atm. contributionRequires opt. depthand source Elv
Telescope GainRequires gain curve and source Elv
Flux Gain (Sensitivity)Typically tabulated
![Page 52: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/52.jpg)
ReductionBreaking the waves
![Page 53: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/53.jpg)
ReductionBreaking the waves
![Page 54: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/54.jpg)
ReductionBreaking the waves
Spectrum: Well behavingSystem and source: CollaborativeObserver: Lucky
![Page 55: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/55.jpg)
ReductionBreaking the waves
Spectrum: Well behavingSystem and source: CollaborativeObserver: Lucky
![Page 56: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/56.jpg)
ReductionBreaking the waves
Spectrum: Well behavingSystem and source: CollaborativeObserver: Lucky
Baseline fit (and subtract) by a polynomial of order 1
![Page 57: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/57.jpg)
ReductionBreaking the waves
Spectrum: Well behavingSystem and source: CollaborativeObserver: Lucky
Baseline fit (and subtract) by a polynomial of order 1
![Page 58: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/58.jpg)
ReductionBreaking the waves
Often baselines are ‘corrupted’ by ripples (instrumental and structural origin) and standing waves (mainly originating from the reflective path between the receiver feed and the reflector).
Baseline fit and subtraction require a polynomial of order > 1
…but not higher than 5-7, otherwise line features can be destroyed or fake spectral lines created!
![Page 59: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/59.jpg)
ReductionBreaking the waves
![Page 60: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/60.jpg)
ReductionBreaking the waves
Spectrum: Reasonably well behavingSystem and source: Quite standardObserver: Still Lucky
![Page 61: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/61.jpg)
ReductionBreaking the waves
Spectrum: Reasonably well behavingSystem and source: Quite standardObserver: Still Lucky
![Page 62: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/62.jpg)
ReductionBreaking the waves
![Page 63: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/63.jpg)
ReductionBreaking the waves
Spectrum: Badly behavedSystem and source: OddObserver: Probably Tarchi
![Page 64: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/64.jpg)
ReductionBreaking the waves
Spectrum: Badly behavedSystem and source: OddObserver: Probably Tarchi
Remove scan!
![Page 65: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/65.jpg)
ReductionBreaking the waves
Spectrum: Badly behavedSystem and source: OddObserver: Probably Tarchi
There are a priori ways to reduce the standing waves:• Focus modulation• Double position-switching observing mode
Remove scan!
![Page 66: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/66.jpg)
ReductionBreaking the waves
Spectrum: Badly behavedSystem and source: OddObserver: Probably Tarchi
There are a priori ways to reduce the standing waves:• Focus modulation• Double position-switching observing mode
Remove scan!
• Shaping design (SRT)
![Page 67: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/67.jpg)
ReductionBreaking the waves
Spectrum: Badly behavedSystem and source: OddObserver: Probably Tarchi
There are a priori ways to reduce the standing waves:• Focus modulation• Double position-switching observing mode
Remove scan!
• Shaping design (SRT)
![Page 68: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/68.jpg)
ReductionBreaking the waves
Spectrum: Badly behavedSystem and source: OddObserver: Probably Tarchi
There are a priori ways to reduce the standing waves:• Focus modulation• Double position-switching observing mode
Remove scan!
• Shaping design (SRT)• Off-axis feed arm (GBT)
![Page 69: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/69.jpg)
ReductionBreaking the waves
Spectrum: Badly behavedSystem and source: OddObserver: Probably Tarchi
There are a priori ways to reduce the standing waves:• Focus modulation• Double position-switching observing mode
Remove scan!
• Shaping design (SRT)• Off-axis feed arm (GBT)
![Page 70: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/70.jpg)
ReductionBreaking the waves
Spikes and interferences
Our Interference-busters mobile unit
MobLab: a fully equipped mobile laboratory to seek radio interferences (Courtesy: F. Gaudiomonte, P. Bolli, F. Messina, and collaborators)
![Page 71: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/71.jpg)
ReductionSumming up
![Page 72: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/72.jpg)
ReductionSumming up
…..…..…..
+ many other more scans
Longer integration time gives a lower noise.
Observations are performed by obtaining several scans (on-off)In individual scans, there is no evident emssion…
…should we give up?
Individual scans
![Page 73: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/73.jpg)
ReductionSumming up
…..…..…..
+ many other more scans
…Not yet!
Let’s try averaging all the scans
The signal to noise ratio (SNR) would increase by √N (N=number of scans)
Individual scans
![Page 74: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/74.jpg)
ReductionSumming up
…..…..…..
+ many other more scans
…Not yet!
Let’s try averaging all the scans
The signal to noise ratio (SNR) would increase by √N (N=number of scans)
Individual scans
Sum of the scans
![Page 75: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/75.jpg)
ReductionSumming up
…..…..…..
+ many other more scans
Individual scans
![Page 76: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/76.jpg)
ReductionSumming up
…..…..…..
+ many other more scans
Individual scans
Smoothed (x4) sum of the scans
![Page 77: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/77.jpg)
ReductionWould you buy this?
![Page 78: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/78.jpg)
ReductionWould you buy this?
Gaussian or ‘normal’ distribution
![Page 79: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/79.jpg)
ReductionWould you buy this?
Gaussian or ‘normal’ distribution
68% values drawn from a normal distribution are within one standard deviation (1 sigma) away from the mean.
![Page 80: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/80.jpg)
ReductionWould you buy this?
Gaussian or ‘normal’ distribution
99.7% values drawn from a normal distribution are within three standard deviation (3 sigma) away from the mean.
![Page 81: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/81.jpg)
ReductionWould you buy this?
3σ
![Page 82: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/82.jpg)
ReductionWould you buy this?
3σ
5σ
![Page 83: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/83.jpg)
ReductionWould you buy this?
![Page 84: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/84.jpg)
ReductionWould you buy this?
Chances to publish your detection:
![Page 85: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/85.jpg)
ReductionWould you buy this?
Chances to publish your detection:
• SNR > 5 σ (very likely)
![Page 86: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/86.jpg)
ReductionWould you buy this?
Chances to publish your detection:
• SNR > 5 σ (very likely)
• SNR between 3 and 5 σ (likely)
![Page 87: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/87.jpg)
ReductionWould you buy this?
Chances to publish your detection:
• SNR > 5 σ (very likely)
• SNR between 3 and 5 σ (likely)
• SNR ~ 3 σ (more difficult; the author should be very convincing and/or having an independent measurement for confirmation)
![Page 88: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/88.jpg)
ReductionWould you buy this?
Chances to publish your detection:
• SNR > 5 σ (very likely)
• SNR between 3 and 5 σ (likely)
• SNR ~ 3 σ (more difficult; the author should be very convincing and/or having an independent measurement for confirmation)
• SNR < 3 σ (almost impossible)
![Page 89: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/89.jpg)
ReductionWould you buy this?
Chances to publish your detection:
• SNR > 5 σ (very likely)
• SNR between 3 and 5 σ (likely)
• SNR ~ 3 σ (more difficult; the author should be very convincing and/or having an independent measurement for confirmation)
• SNR < 3 σ (almost impossible)
![Page 90: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/90.jpg)
AnalysisOne moment in time
![Page 91: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/91.jpg)
AnalysisOne moment in time
Moments are equally defined for T (in K)
![Page 92: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/92.jpg)
AnalysisOne moment in time
Total Intensity
![Page 93: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/93.jpg)
AnalysisOne moment in time
Mean Velocity
![Page 94: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/94.jpg)
AnalysisOne moment in time
Dispersion
![Page 95: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/95.jpg)
AnalysisBright enough
![Page 96: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/96.jpg)
AnalysisBright enough
Speak
Δν
vpeak
Gaussian FitLine peak fluxLine FWHM (Δν= √8ln2·σ)Line peak velocity
![Page 97: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/97.jpg)
AnalysisBright enough
If the distance of the emitting source is known the isotropic luminosity of the water maser can be derived:
• kilomaser or megamaser?
• star formation or AGN nature?
In two radio galaxies, water megamasers with Liso ~ 10000 Lsun has been found!!!
![Page 98: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/98.jpg)
AnalysisBright enough
Column density can be derived from the line total intensity
If the dimension of the source (or its distance from us) is known, a gas mass estimate can be obtained
![Page 99: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/99.jpg)
AnalysisBright enough
The velocity of the line provides information on the gas dynamics:
Frequency shift according to the non-relativistic Doppler equation in the optical and radio convention
νobs > νrest: the emitting gas is approching us toward the l.o.s.νobs < νrest: the emitting gas is receding from us toward the l.o.s.
For extragalactic objects, recessional velocity of the galaxy does matter
![Page 100: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/100.jpg)
Recessional velocity of the galaxy
Red-shiftedBlue-shifted NGC
4258
AnalysisBright enough
![Page 101: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/101.jpg)
AnalysisSpectral presences 3D
![Page 102: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/102.jpg)
AnalysisSpectral presences 3-D
Contour map made bya regular grid of individual pointings
![Page 103: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/103.jpg)
AnalysisSpectral presences 3-D
![Page 104: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/104.jpg)
AnalysisSpectral presences 3-D
3-D structure
…but…
Not truly source 3-D
Data cube
![Page 105: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/105.jpg)
AnalysisSpectral presences 3-D
Leiden-Argentine-Bonn (LAB) HI survey. Sweeping through the data cube;Galactic center projection. Kalberla et al.; Hartmann & Burton; Arnal et al.
![Page 106: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/106.jpg)
AnalysisSpectral presences 3-D
Leiden-Argentine-Bonn (LAB) HI survey. Sweeping through the data cube;Galactic center projection. Kalberla et al.; Hartmann & Burton; Arnal et al.
![Page 107: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/107.jpg)
Useful textbooks:• J.D. Kraus”Radio Astronomy”, 1986, Cygnus-Quasar Books • K. Rohlfs & T.L. Wilson “Tools of Radio Astronomy”, 1996, Springer-Verlag
This lecture has also taken inspiration from past lectures and talks by U.Back, D. Muders, K. O’Neil, and B. Winkel.
![Page 108: Overview on data reduction, calibration and analysis - INAFsummerschool2011.oa-cagliari.inaf.it/.../lectures/110915_02_Tarchi.pdf · Overview on data calibration, reduction and analysis](https://reader031.fdocuments.in/reader031/viewer/2022022722/5c680a3309d3f2ff5a8cd7f0/html5/thumbnails/108.jpg)
Useful textbooks:• J.D. Kraus”Radio Astronomy”, 1986, Cygnus-Quasar Books • K. Rohlfs & T.L. Wilson “Tools of Radio Astronomy”, 1996, Springer-Verlag
This lecture has also taken inspiration from past lectures and talks by U.Back, D. Muders, K. O’Neil, and B. Winkel.
Thank you…and…Happy