All-Day Synthesis Issues - Revision history

Dgary: /* Implementation */

2022-01-11T13:28:49Z

Implementation

@@ Line 64: / Line 64: @@
 === Implementation ===
-I have written a routine to use the above table for this specific date and overwrite the data in a copy of a UDB ms with a unit source amplitude and the correct shifted phase. The two figures below show the comparison of the original psf and the smeared one.  It should be noted that the smeared psf has the caustic sort of shape that looks like the residuals in the full-disk maps.  However, more tests are needed to see if this result is correct.
+I have written a routine to use the above table for this specific date and overwrite the data in a copy of a UDB ms with a unit source amplitude and the correct shifted phase. The two figures below show the comparison of the original psf and the smeared one.  It should be noted that the smeared psf has the caustic sort of shape that looks like the residuals in the full-disk maps.
-[[File:20180623_7-14_originalpsf.png|thumb|400px|'''Fig. 1:''' Original PSF for an mfs image of bands 7-14 on 2018 Jun 23 has unit amplitude and is only three pixels wide, with relatively small and symmetric sidelobes.  Each cell here is 2.5".]]
+[[File:20180623_7-14_originalpsf.png|thumb|200px|'''Fig. 1:''' Original PSF for an mfs image of bands 7-14 on 2018 Jun 23 has unit amplitude and is only three pixels wide, with relatively small and symmetric sidelobes.  Each cell here is 2.5".]]
-[[File:20180623_7-14_smearedpsf.png|thumb|400px|'''Fig. 2:''' Smeared PSF for the same data as in Fig. 1 has a peak amplitude of about 0.34 and has sidelobes with a caustic pattern much like what we see in the full-disk images.]]
+[[File:20180623_7-14_smearedpsf.png|thumb|200px|'''Fig. 2:''' Smeared PSF for the same data as in Fig. 1 has a peak amplitude of about 0.34 and has sidelobes with a caustic pattern much like what we see in the full-disk images.]]

Dgary: /* Implementation */

2022-01-10T15:42:25Z

Implementation

← Older revision		Revision as of 15:42, 10 January 2022
Line 68:		Line 68:
	[[File:20180623_7-14_originalpsf.png\|thumb\|400px\|'''Fig. 1:''' Original PSF for an mfs image of bands 7-14 on 2018 Jun 23 has unit amplitude and is only three pixels wide, with relatively small and symmetric sidelobes. Each cell here is 2.5".]]		[[File:20180623_7-14_originalpsf.png\|thumb\|400px\|'''Fig. 1:''' Original PSF for an mfs image of bands 7-14 on 2018 Jun 23 has unit amplitude and is only three pixels wide, with relatively small and symmetric sidelobes. Each cell here is 2.5".]]

	[[File:20180623_7-~~14_originalpsf~~.png\|thumb\|400px\|'''Fig. 2:''' Smeared PSF for the same data as in Fig. 1 has a peak amplitude of about 0.34 and has sidelobes with a caustic pattern much like what we see in the full-disk images.]]		[[File:20180623_7-14_smearedpsf.png\|thumb\|400px\|'''Fig. 2:''' Smeared PSF for the same data as in Fig. 1 has a peak amplitude of about 0.34 and has sidelobes with a caustic pattern much like what we see in the full-disk images.]]

Dgary: /* Implementation */

2022-01-10T15:41:19Z

Implementation

← Older revision		Revision as of 15:41, 10 January 2022
Line 65:		Line 65:
	=== Implementation ===		=== Implementation ===
	I have written a routine to use the above table for this specific date and overwrite the data in a copy of a UDB ms with a unit source amplitude and the correct shifted phase. The two figures below show the comparison of the original psf and the smeared one. It should be noted that the smeared psf has the caustic sort of shape that looks like the residuals in the full-disk maps. However, more tests are needed to see if this result is correct.		I have written a routine to use the above table for this specific date and overwrite the data in a copy of a UDB ms with a unit source amplitude and the correct shifted phase. The two figures below show the comparison of the original psf and the smeared one. It should be noted that the smeared psf has the caustic sort of shape that looks like the residuals in the full-disk maps. However, more tests are needed to see if this result is correct.

			[[File:20180623_7-14_originalpsf.png\|thumb\|400px\|'''Fig. 1:''' Original PSF for an mfs image of bands 7-14 on 2018 Jun 23 has unit amplitude and is only three pixels wide, with relatively small and symmetric sidelobes. Each cell here is 2.5".]]

			[[File:20180623_7-14_originalpsf.png\|thumb\|400px\|'''Fig. 2:''' Smeared PSF for the same data as in Fig. 1 has a peak amplitude of about 0.34 and has sidelobes with a caustic pattern much like what we see in the full-disk images.]]

Dgary: /* Correcting for Solar Rotation */

2022-01-10T15:34:45Z

Correcting for Solar Rotation

← Older revision		Revision as of 15:34, 10 January 2022
Line 63:		Line 63:
	The above hourly positions can be interpolated to finer timescales.		The above hourly positions can be interpolated to finer timescales.

	=== ~~CASA commands for accessing the data~~ ===		=== Implementation ===
	~~The following commands give access~~ to a copy of ~~the~~ ms as a ~~table:~~		I have written a routine to use the above table for this specific date and overwrite the data in a copy of a UDB ms with a unit source amplitude and the correct shifted phase. The two figures below show the comparison of the original psf and the smeared one. It should be noted that the smeared psf has the caustic sort of shape that looks like the residuals in the full-disk maps. However, more tests are needed to see if this result is correct.
	~~!cp -r /data1/eovsa/fits/UDBms/201806/UDB20180623.ms .~~
	~~msfile = 'UDB20180623.ms'~~
	~~tb.open(msfile)~~
	~~tb.browse()~~

	~~The browser shows that there are columns for UVW, TIME,~~ and ~~DATA, which are~~ the ~~ones we need~~. ~~We also need~~ the ~~list~~ of ~~frequencies from~~ the ~~SPECTRAL_WINDOW sub-table. One can then convert UVW in ns to U, V in wavelengths, interpolate the dRA~~ and ~~dDec to~~ the ~~relevant time, calculate <math>\phi</math> for each time, and overwrite the data as <math>e^{i\phi}</math>~~. ~~The resulting database can then~~ be ~~used to create images which will represent~~ the psf of the ~~smeared point source~~.

Dgary: /* CASA commands for accessing the data */

2022-01-08T18:48:19Z

CASA commands for accessing the data

← Older revision		Revision as of 18:48, 8 January 2022
Line 64:		Line 64:

	=== CASA commands for accessing the data ===		=== CASA commands for accessing the data ===
	The following commands give access to the ms as a table:		The following commands give access to a copy of the ms as a table:
	!cp -r /data1/eovsa/fits/UDBms/201806/UDB20180623.ms .		!cp -r /data1/eovsa/fits/UDBms/201806/UDB20180623.ms .
	msfile = 'UDB20180623.ms'		msfile = 'UDB20180623.ms'

Dgary: /* CASA commands for accessing the data */

2022-01-08T18:47:45Z

CASA commands for accessing the data

← Older revision		Revision as of 18:47, 8 January 2022
Line 65:		Line 65:
	=== CASA commands for accessing the data ===		=== CASA commands for accessing the data ===
	The following commands give access to the ms as a table:		The following commands give access to the ms as a table:
	~~msfile = '~~/data1/eovsa/fits/UDBms/201806/UDB20180623.ms'		!cp -r /data1/eovsa/fits/UDBms/201806/UDB20180623.ms .
			msfile = 'UDB20180623.ms'
	tb.open(msfile)		tb.open(msfile)
	tb.browse()		tb.browse()

	The browser shows that there are columns for UVW, TIME, and DATA, which are the ones we need. We also need the list of frequencies from the SPECTRAL_WINDOW sub-table. One can then convert UVW in ns to U, V in wavelengths, interpolate the dRA and dDec to the relevant time, calculate <math>\phi</math> for each time, and overwrite the data as <math>e^{i\phi}</math>. The resulting database can then be used to create images which will represent the psf of the smeared point source.		The browser shows that there are columns for UVW, TIME, and DATA, which are the ones we need. We also need the list of frequencies from the SPECTRAL_WINDOW sub-table. One can then convert UVW in ns to U, V in wavelengths, interpolate the dRA and dDec to the relevant time, calculate <math>\phi</math> for each time, and overwrite the data as <math>e^{i\phi}</math>. The resulting database can then be used to create images which will represent the psf of the smeared point source.

Dgary: /* CASA commands for accessing the data */

2022-01-08T18:45:58Z

CASA commands for accessing the data

← Older revision		Revision as of 18:45, 8 January 2022
Line 69:		Line 69:
	tb.browse()		tb.browse()

	The browser shows that there are columns for UVW, TIME, and DATA, which are the ones we need. We also need the list of frequencies from the SPECTRAL_WINDOW sub-table. One can then convert UVW in ns to U, V in wavelengths, interpolate the dRA and dDec to the relevant time, calculate <math>phi</math> for each time, and overwrite the data as <math>e^i\phi</math>. The resulting database can then be used to create images which will represent the psf of the smeared point source.		The browser shows that there are columns for UVW, TIME, and DATA, which are the ones we need. We also need the list of frequencies from the SPECTRAL_WINDOW sub-table. One can then convert UVW in ns to U, V in wavelengths, interpolate the dRA and dDec to the relevant time, calculate <math>\phi</math> for each time, and overwrite the data as <math>e^{i\phi}</math>. The resulting database can then be used to create images which will represent the psf of the smeared point source.

Dgary: /* An Initial Test of the Idea */

2022-01-08T18:45:28Z

An Initial Test of the Idea

← Older revision		Revision as of 18:45, 8 January 2022
Line 62:		Line 62:
	24:00 -39.6388 3.98402		24:00 -39.6388 3.98402
	The above hourly positions can be interpolated to finer timescales.		The above hourly positions can be interpolated to finer timescales.

			=== CASA commands for accessing the data ===
			The following commands give access to the ms as a table:
			msfile = '/data1/eovsa/fits/UDBms/201806/UDB20180623.ms'
			tb.open(msfile)
			tb.browse()

			The browser shows that there are columns for UVW, TIME, and DATA, which are the ones we need. We also need the list of frequencies from the SPECTRAL_WINDOW sub-table. One can then convert UVW in ns to U, V in wavelengths, interpolate the dRA and dDec to the relevant time, calculate <math>phi</math> for each time, and overwrite the data as <math>e^i\phi</math>. The resulting database can then be used to create images which will represent the psf of the smeared point source.

Dgary: /* An Initial Test of the Idea */

2019-12-07T17:39:39Z

An Initial Test of the Idea

← Older revision		Revision as of 17:39, 7 December 2019
Line 49:		Line 49:
	23:00 303.809 135.161		23:00 303.809 135.161
	24:00 312.865 136.158		24:00 312.865 136.158
	and finally converted to <math>d\alpha(t), d\delta(t)</math>. Note that absolute coordinates are not needed, only the relative shift vs. time. Thus, to a good approximation, this is just <math>d\alpha(t) = -(X(t) - X_0)/\cos(\delta_0)</math> and <math>d\delta(t) = (Y(t) - Y_0)</math>, where <math>(X_0, Y_0)</math> = (276.442,132.174) is the coordinate at 20:00 UT, and <math>\delta_0 = 23.42~~</math>~~ is the declination of the Sun. This gives the following final result:		and finally converted to <math>d\alpha(t), d\delta(t)</math>. Note that absolute coordinates are not needed, only the relative shift vs. time. Thus, to a good approximation, this is just <math>d\alpha(t) = -(X(t) - X_0)/\cos(\delta_0)</math> and <math>d\delta(t) = (Y(t) - Y_0)</math>, where <math>(X_0, Y_0)</math> = (276.442,132.174) is the coordinate at 20:00 UT, and <math>\delta_0</math> = 23.42 is the declination of the Sun. This gives the following final result:
	RA/Dec shifts relative to 20:00 UT		RA/Dec shifts relative to 20:00 UT
	UT dRA dDec		UT dRA dDec

Dgary: /* Selection of date */

2019-12-07T17:38:47Z

Selection of date

@@ Line 49: / Line 49: @@
 :00      303.809         135.161
 :00      312.865         136.158
-and finally converted to <math>d\alpha(t), d\delta(t)</math>.  Note that absolute coordinates are not needed, only the relative shift vs. time.  Thus, to a good approximation, this is just <math>d\alpha(t) = -(X(t) - X_0)/\cos(\delta_0)</math> and <math>d\delta(t) = (Y(t) - Y_0)</math>, where <math>(X_0, Y_0)</math> = (276.442,132.174) is the coordinate at 20:00 UT, and <math>\delta_0 = 23.42</math> is the declination of the Sun. The above hourly positions can be interpolated to finer timescales.
+and finally converted to <math>d\alpha(t), d\delta(t)</math>.  Note that absolute coordinates are not needed, only the relative shift vs. time.  Thus, to a good approximation, this is just <math>d\alpha(t) = -(X(t) - X_0)/\cos(\delta_0)</math> and <math>d\delta(t) = (Y(t) - Y_0)</math>, where <math>(X_0, Y_0)</math> = (276.442,132.174) is the coordinate at 20:00 UT, and <math>\delta_0 = 23.42</math> is the declination of the Sun. This gives the following final result: