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Дата изменения: Thu Mar 1 19:02:29 2012 Дата индексирования: Mon Oct 1 22:27:07 2012 Кодировка: |
This bug has now been fixed BUT ONLY for CIMA version 2.3. The version number of the CIMAFITS-files has been updated from '1.09' to '1.10' to reflect this correction.
To see the full announcement, click here.
5 January 2008: Correction of new CRVAL1, CDELT1 and UPPERSB bug
A bug has been found that might have caused the CRVAL1 header array
parameter to contain the wrong center frequency for data taken
immediately after a Doppler correction. In extremely rare cases, also
the CDELT1 and UPPERSB header array parameters could be wrong
indicating the wrong sideband. The data itself has been taken at the
right frequency and with the right sideband - it is just the
information in the header that can be wrong. The problem is that
CRVAL1 has not been updated but contains the previous frequency value
that was used before the Doppler correction. The error is thus
typically small.
This bug has now been fixed. The version number of the CIMAFITS-files has been updated from '1.08' to '1.09' to reflect this correction.
To see the full announcement, click here.
7 December 2007: Upgrade and bug fixes of CIMAFITS and WAPP pulsar headers
Several bugs in the CIMAFITS headers have been fixed. DETAILS TO COME ...
The WAPP pulsar headers have also been modified with some bug corrections and the adaptation to handle dual board observations.
The version number of the CIMAFITS-files was changed from '1.07' to
'1.08' after the bug was corrected. The header version of the WAPP
pulsar files was incresaed from '8' to '9'. The version number of the
CIMA WAPP software itself was incremented to 1.4.00.
7 March 2007: Correction of UT midnight roll-over bug
A bug has been found that caused the last telescope positions to be
repeated during the first second after UT midnight roll-over (20:00
AST). The solution was to remove the bug fix added to the code on 4
April 2006. It seems that the change may have occurred with the
recompilation of the CIMA WAPP software on 6 February 2007.
The version number of the CIMAFITS-files was changed from '1.06' to
'1.07' after the bug was corrected. The version number of the CIMA
WAPP software itself was incremented to 1.3.06.
15 February 2007: Correction of CRVAL1, CDELT1 and UPPERSB bug
A bug has been found that caused the CRVAL1 header array parameter to
contain the wrong center frequency for certain combinations of
frequency set-ups. In some cases, also the CDELT1 and UPPERSB header
array parameters could be wrong indicating the wrong sideband. The
data itself has been taken at the right frequency and with the right
sideband - it is just the infromation in the header that can be
wrong. CRVAL1 is typically off by several hundred MHz when it is wrong.
Pulsar observations could also be affected since the sideband indicated by IFLO_FLIP has been affected by the same bug.
This bug has now been fixed. The version number of the CIMAFITS-files has been updated from '1.05' to '1.06' to reflect this correction.
To see the full announcement, click here.
8 February 2007: Change of WAPP Doppler calculations
The formulae used for Doppler calculations when observing with the
WAPPs have been changed to include the second-order term that so far
has been omitted (for a PostScript page with details, click here). New
code was also added to make sure that OFF_RA,
OFF_DEC, OFF_AZ and OFF_ZA are
calculated correctly when observing in galactic coordinates. Also, a
bug affecting calculations of the galactic coordinates
(CRVAL2G and CRVAL3G) that was introduced on
6 February 2007 was fixed. The version number of the CIMAFITS-files
has been updated from '1.04' to '1.05'
29 September 2006: New cal tables for L-Band Wide and C-Band installed
The new calibration tables for L-Band Wide and C-Band have been
installed. These values go into the FITS-tables TCAL_FRQ
and TCAL_VAL. The new L-Band Wide table is valid from 16
July 2006 while the new C-Band table is valid since 25 May 2006. For
more details see Phil's pages for the L-Band
Wide and the C-band.
10 May 2006: Correction of PARA_ANG header array parameter
The PARA_ANG header array parameter containing the
parallactic angle has up until now been calculated wrongly. It has
been calculated using J2000 coordinates instead of using coordinates
for the current epoch. This has now been corrected and the version
number of the CIMAFITS-files has been updated from '1.03' to '1.04' to
reflect this correction.
4 April 2006: Correction of UT midnight roll-over bug
There has been a problem with coordinate interpolations at UT midnight
roll-over (20:00 AST). During 20 seconds after UT midnight roll-over,
coordinate parameters have been calculated incorrectly. This bug has
now been fixed. The version number of the CIMAFITS-files has been
updated from '1.02' to '1.03' to reflect this correction.
25 May 2005: Correction of BEAM_OFFRAJ header array parameter
The BEAM_OFFRAJ header array parameter has up until now
been calculated wrongly. It has been given as decimal hours corrected
for the declination ( *cos(Dec) ). This has been changed
to be decimal degrees not correcting for the declination. The
version number of the CIMAFITS-files has been updated from '1.01' to
'1.02' to reflect this correction. Several comments in the FITS-files
have also been updated.
20 May 2005: Correction of OBSERVER header parameter
The OBSERVER header parameter does no longer contain the
string 'unknown'. It is is supposed to provide the
name(s) of the observer entered when a CIMA observing sessions starts,
and the bug that has prevented this from happening has now been fixed
in the 1.2.02 version of CIMA. Earlier versions of CIMA have not been
corrected.
29 April 2005: Correction of PATTERN_ID header array parameter
The PATTERN_ID header array parameter that is supposed to
hold a unique ID for each observation pattern (i.e. a
complete observation cycle like the pair of ON and OFF scans in an
ON-OFF observation) has usually been set up to a constant value at the
beginning of an observation sequence and then keeping the same value
throughout all loops in the observation sequence. This has been
corrected in the 1.2.02 version of CIMA so that
PATTERN_ID now gets a unique number for each
loop. Earlier versions of CIMA have not been corrected.
22 February 2005: Correction of CRVAL5 data timestamp bug
A bug affecting the timestamps of the data has been found and
corrected. Synchronisation errors between 1PPS pulses and
NTP-controlled system clocks have frequently caused the timestamps
indicating the start of each subscan (CRVAL5) to be off
by one second. A typical indication of this is that the parameters
ENC_TIME and OFF_TIME are one second off
from the time given by CRVAL5 and that positional
parameters differ between the WAPPs for the same CRVAL5
timestamp. This bug has randomly affected one or more WAPPs. The
timestamps given by CRVAL5 up until now should thus not
be trusted. The correct time can instead be obtained from
OFF_TIME or ENC_TIME (after rounding to
nearest integer).
This bug has now been fixed. The version number of the CIMAFITS-files has been updated from '1.00' to '1.01' to reflect this correction.
To see the full announcement, click here.
3 February 2005: CIMAFITS version 1.00 installed
A new version of CIMAFITS known as version 1.00 was installed on the
WAPPs, replacing the old version which didn't have a version
number. The new version does not contain any changes to the data
format or to the main FITS-header (except for changes of some
comments). However, a number of important changes have been made to
the binary table header.
The modifications also correct some problems with the FITS-files:
CRVAL4 and IFVAL have been
showing the codes for polarization A when polarization B was
chosen. Furthermore, the data recorded was always polarization A!
Several other header array parameters (mostly engineering ones) have
also been set with values from the wrong channel.
CRVAL4, IFVAL and INPUT_ID have
been incorrectly set for full Stokes mode when using the ALFA
receiver. Several other header array parameters (mostly engineering
ones) have also been set incorrectly. Note though, that some of these
engineering parameters will still not be set correctly even with the
new version.
CROFF2B & CROFF3B: The header array
parameters CROFF2B and CROFF3B were set up
incorrectly for non-ALFA observations. The value that was supposed to be
written to CROFF3B was instead written to
CROFF2B, while CROFF3B was set to 0.0.
CRVAL2 and
CRVAL3 have been changed from giving the requested
position to the actual position in order to comply with the
WCS-standard. This change affects the three alternative coordinates
given by the four systems CRVAL[23] (the requested
coordinates in the requested epoch), CRVAL[23]C (the
requested coordinates expressed in J2000), CRVAL[23]A
(the actual coordinates for each beam expressed in J2000), and
CRVAL[23]B (the actual coordinates for each beam
expressed in azimuth and zenith angle):
CRVAL2, CRVAL3, and
EQUINOX) have been moved to REQ_RA,
REQ_DEC, and REQ_EQUINOX. The new header
array parameter REQ_RADESYS has also be introduced for
this system.
CRVAL2C and CRVAL3C) have been
renamed to REQ_RAJ and REQ_DECJ.
CRVAL2A and
CRVAL3A have been moved to CRVAL2 and
CRVAL3. The keyword EQUINOX now refers to
this system and is always '2000.0'. It has thus been changed from
being a header array parameter to a header parameter. The new header
parameter RADESYS has been introduced to define the
coordinate system.
CRVAL2B and
CRVAL3B have been replaced by AZIMUTH and
ELEVATIO. While CRVAL3B used to give the
zenith angle, it is now replaced by a parameter giving the elevation.
CRVAL2 --> REQ_RA: the header array
parameter CRVAL2 (the requested RA pointing) has been
moved to REQ_RA. The keyword CRVAL2 now has
a new meaning containing the true J2000 RA pointing.
CRVAL3 --> REQ_DEC: the header array
parameter CRVAL3 (the requested Dec pointing) has been
renamed REQ_DEC. The keyword CRVAL3 now has
a new meaning containing the true J2000 Dec pointing.
EQUINOX --> REQ_EQUINOX: the header
array parameter EQUINOX (the requested epoch) has been
renamed REQ_EQUINOX. The keyword EQUINOX now
has a new meaning specifying the J2000 system for the new
CRVAL2 and CRVAL3. It has also been changed
from being a header array parameter to a header parameter. It is
always set to 2000.0.
RADESYS: a new header parameter RADESYS
has been added. It is a string parameter specifying the primary
coordinate system used for CRVAL2 and
CRVAL3. It is always set to 'FK5'.
REQ_RADESYS: the new header parameter
REQ_RADESYS (the definition of the coordinate system used
for CRVAL2 and CRVAL3) has been added.
CRVAL2A --> CRVAL2: the header array
parameter CRVAL2A (the true J2000 RA pointing for this
beam on sky) has been moved to CRVAL2. The unit has also
been changed from hours to degrees.
CRVAL3A --> CRVAL3: the header array
parameter CRVAL3A (the true J2000 Dec pointing for
this beam on sky) has been moved to CRVAL3.
CRVAL2C --> REQ_RAJ: the header array
parameter CRVAL2C (the requested RA J2000 pointing) has
been renamed REQ_RAJ. The unit has also been changed from
hours to degrees.
CRVAL3C --> REQ_DECJ: the header array
parameter CRVAL3C (the requested Dec J2000 pointing) has
been renamed REQ_DECJ.
CRVAL2B --> AZIMUTH: the header array
parameter CRVAL2B (the true azimuth pointing for this
beam on sky) has been renamed AZIMUTH.
CRVAL3B --> ELEVATIO: the header array
parameter CRVAL3B (the true zenith angle pointing for
this beam on sky) has been renamed ELEVATIO. The axis
has also been changed from being the zenith angle to the elevation.
'V' describing the frequency axis as velocities has been
removed. Several of the parameters used like CRVAL1V and
CDELT1V have so far contained nonsense values. The
'V' system is expected to be reinstalled in a later
version of CIMAFITS when the proper code to provide it (allowing the
observer to specify a rest frequency) has been implemented. Keywords
removed: RESTFRQV, CDELT1V,
CRPIX1V, SPECSYSV and
SSYSOBSV. Keywords renamed: CRVAL1V,
CUNIT1V and CTYPE1V.
CRVAL1V --> REQ_VEL: the header array
parameter CRVAL1V (the velocity or red-shift for the
source in the velocity frame) has been moved to REQ_VEL.
The unit header parameter (the TUNITxxx keyword) for the
header array parameter CRVAL1V has been changed from
m/s_orZ to a blank string. The unit (either
m/s or Z) is given by
REQ_VEL_UNIT.
CUNIT1V --> REQ_VEL_UNIT: the header
array parameter CUNIT1V (the unit for
REQ_VEL) has been moved to REQ_VEL_UNIT.
CTYPE1V --> REQ_VEL_TYPE: the header
array parameter CTYPE1V (the velocity type for
REQ_VEL) has been moved to REQ_VEL_TYPE.
The possible values have changed to comply with the WCS-standard. An
optical velocity will be given as 'VOPT-F2W' instead of
'VOPT-F2V' and an optical redshift will be given as
'ZOPT-F2W' instead of 'ZOPT-F2V'.
TDIM1: A new header array parameter
TDIM1 has been added. It is a string parameter describing
the dimensionality of the data in the heap that corresponds to the
particular entry in the header table. It has been added to comply with
the SDFITS standard. For a 4096 channel spectrum, it will have the
value '(4096,1,1,1,1)'.
NMATRIX: the obsolete header parameter
NMATRIX has been removed.
RESTFRQ: a new header array parameter
RESTFRQ (specifying the rest frequency) has been added.
SPECSYS: the possible values have changed to comply
with the WCS-standard. A heliocentric frame will be given as
'BARYCENT' instead of 'HELIOCENT' and a
geocentric frame will be given as 'GEOCENTR' instead of
'GEOCENT'.
CTYPE1: the header parameter CTYPE1 has
been changed from the incorrect 'FREQ-F2V' to
'FREQ'.
CTYPE2 and CTYPE3: the two header
parameters CTYPE2 and CTYPE3 have been
changed from the incorrect 'RA---TAN' and
'DEC--TAN' to 'RA' and 'DEC',
respectively.
CRDELTx: The misspelt header parameters
CRDELT2-CRDELT5 which should have been
CDELT2, CDELT3, CDELT4 and
CDELT5 for the degenerate axes have been removed.
CTYPExG,
CUNITxG and
CRPIXxG: new header parameters
CTYPExG,
CUNITxG and
CRPIXxG where 'x' is '2'
or '3' have been added for the alternative galactic coordinate system
'G'.
RESTFRQG: a new header array parameter
RESTFRQG (specifying the rest frequency for the galactic
coordinate system 'G') has been added. It will have the same value as
RESTFRQ.
SPECSYSG: a new header array parameter
SPECSYSG (describing the velocity frame used for the
galactic coordinate system 'G') has been added.
EXTNAME: The parameter EXTNAME has been
changed from being 'BDFITS' to 'CIMAFITS'.
OBS_ID --> ( PROJID & OBSID ):
The header parameter OBS_ID has been replaced by the two
header parameters PROJID and OBSID. Both are
string parameters and currently they will both get the same string
value, but that may change in future versions of CIMAFITS. The change
is made to comply with the SDFITS standard.
CUR_TOL --> CUR_ERR: the header array
parameter CUR_TOL (the current great circle tracking
error) has been renamed CUR_ERR. Note that this parameter
has not been interpolated to coincide with the timestamp of the
data. Use the new (interpolated) header array parameters
AZ_ERR and ZA_ERR if interpolated errors are
needed.
REQ_TOL --> ALLOWED_ERR: the header array
parameter REQ_TOL (the maximum allowed great circle
tracking error) has been renamed ALLOWED_ERR.
CROFF2 --> OFF_RA: the header array
parameter CROFF2 (the true RA J2000 offset to commanded
map center) has been renamed OFF_RA. Also, the unit has
been changed from hours to degrees.
CROFF3 --> OFF_DEC: the header array
parameter CROFF3 (the true DEC J2000 offset to commanded
map center) has been renamed OFF_DEC.
CROFF2B --> OFF_AZ: the header array
parameter CROFF2B (the true azimuth offset to commanded
map center) has been renamed OFF_AZ.
CROFF3B --> OFF_ZA: the header array
parameter CROFF3B (the true zenith angle offset to commanded
map center) has been renamed OFF_ZA.
GAIN --> AMPGAIN: the header array parameter
GAIN (gain of the control room amplifiers) has been
renamed AMPGAIN.
OBS_NAME --> SCANTYPE: the header array
parameter OBS_NAME (describing the current type of
observing scan) has been renamed SCANTYPE.
PATTERN_SCAN --> PATTERN_ID: the header
array parameter PATTERN_SCAN (containing a unique ID for
the current observation pattern) has been renamed
PATTERN_ID.
SCAN_NUMBER --> SCAN_ID: the header
array parameter SCAN_NUMBER (containing a unique ID for
the current observation pattern) has been renamed
SCAN_ID.
PATTERN_NUMBER --> SUBSCAN: the header
array parameter PATTERN_NUMBER (the sequential number of
the current subscan) has has been renamed SUBSCAN. It has
also been changed from being a computer programmer's counter to an
astronomer's counter, i.e. for a 60 second integration, the 60
subscans (dumps) will now be numbered from 1 to 60 instead of from 0
to 59.
TOTAL_PATTERN --> TOTAL_SUBSCANS: the
header array parameter TOTAL_PATTERN (the total number of
subscans in the current scan) has has been renamed
TOTAL_SUBSCANS.
CRVAL5: the unit of the header array parameter
CRVAL5 has been changed from hours to seconds to comply
with the normal FITS conventions. This change also affected the header
parameter CUNIT5.
LST: the unit of the header array parameter
LST (the local mean sidereal time) has been changed from
hours to seconds to comply with the normal FITS conventions.
CDELT1: the header array parameter
CDELT1 now has a negative value if the spectrum is
flipped. (This is also indicated by the header array parameter
UPPERSB).
TSYS: the header array parameter TSYS is
still not set properly. However, instead of being set to 0.0 when Tsys
is not available, it is now set to 1.0.
TCAL --> ( TCAL_FRQ & TCAL_VAL ):
the header array parameter TCAL (which has been a
two-column array with frequencies and corresponding Tcal-values) has
been split up into the two new header array parameter arrays
TCAL_FRQ and TCAL_VAL. Both parameters are
floating point arrays holding a maximum of 32 values; the actual
number of entries is still given by NTCAL. The units are
Hertz for TCAL_FRQ and Kelvin for TCAL_VAL.
The old TCAL used Hz for ALFA and MHz for non-ALFA receivers.
ENC_TIME: the header array parameter
ENC_TIME has been changed from being an integer expressed
in milliseconds to a floating point value (double) expressed in
seconds. It has also been changed from being expressed in local time
(AST) to UTC.
OFF_TIME: the header array parameter
OFF_TIME has been changed from being expressed in local
time (AST) to UTC.
TUNITxxx keywords) specified in a non-standard
way, for example hours have been given as
'day' instead of 'd'. These unit
descriptions have been modified to follow the FITS-standard.
The affected header array keywords are:
MJD-OBS: 'day' --> 'd'
RATE_C1: 'deg/sec' --> 'deg/s'
RATE_C2: 'deg/sec' --> 'deg/s'
CUR_ERR (CUR_TOL): 's' -->
'arcsec' (the unit has always been arc-seconds even when listed
as seconds)
ALLOWED_ERR (REQ_TOL): 's' -->
'arcsec' (the unit has always been arc-seconds even when listed
as seconds)
CUNIT2 and CUNIT3 have also
been mdified from 'DEG' to 'deg'.
VERSION: A new parameter VERSION
has been added to the bintable
header to indicate which version of CIMAFITS is being used. The version
number is given as a floating point value.
VER_DATE: A new parameter VER_DATE has
been added to the bintable header to indicate the date when the
current version of CIMAFITS started to be used. The date is given in
the format YYYY-MM-DD.
AZ_ERR and EL_ERR: two new header array
parameters AZ_ERR and EL_ERR have been
added. They contain the tracking errors in azimuth and elevation
interpolated to the timestamp when the data was taken. Both parameters
are expressed in arc-seconds.
VEL_BARY: a new header array parameter
VEL_BARY has been added. It contains the barycentric
velocity (including the geocentric velocity VEL_GEO)
projected towards the requested source and is expressed in m/s. It has
been interpolated to the start time of each subscan.
VEL_GEO: a new header array parameter
VEL_GEO has been added. It contains the geocentric
velocity projected towards the requested source and is expressed in
m/s. It has been interpolated to the start time of each subscan.
BAD_DATA: a new header array parameter
BAD_DATA has been added. This parameter is to be used to
flag subscans where there are problems with the data or with the
information in the header. It is an unsigned integer, where the
different bits represents different error conditions. A value of '0'
indicates that everything is OK. This parameter will be used in future
versions of CIMAFITS. The error codes are described in the
COMMENT section in the bintable header.
COMMENT section): a
list of COMMENT cards have been added to the binary table
header. These COMMENT cards contain more elaborate
explanations of some of the keywords than what fits in the comment
field of the keyword card itself. A user who has questions about some
keyword should thus have a look at this COMMENT section.
CRVAL2A,
CRVAL3A, CRVAL2B, CRVAL3B,
CRVAL2G, CRVAL3G, CROFF2,
CROFF3, CROFF2B, CROFF3B,
BEAM_OFFRAJ, BEAM_OFFDECJ and
PARA_ANG). This problem was present in the software
version used before 15 November 2004, so it has affected all WAPP
FITS-files back to 16 September 2004 (and possibly earlier).
To see the full announcement, click here.
15 November 2004: Correction of bad telescope positions
A series of errors have been discovered in the routine used to
interpolate the telescope position which was introduced on 16
September 2004. As a result, a number of FITS-header keywords dealing
with calculated telescope position information contains erroneous
values. The magnitude of the error is usually of the order of 10
arcseconds or less, however occasionally, the error could be as large
as several degrees. This problem affects all FITS-files generated
between 16 September and 9 November 2004. The following keywords have
been affected by the error:
CRVAL2A and CRVAL3A: beam position on sky in
RA/Dec
CRVAL2B and CRVAL3B: beam position on sky in
Az/ZA
CRVAL2G and CRVAL3G: beam position on sky in l/b
CROFF2 and CROFF3: map center offset in RA/Dec
CROFF2B and CROFF3B: map center offset in Az/ZA
BEAM_OFFRAJ and BEAM_OFFDECJ: total beam
offset in RA/Dec
PARA_ANG: parallactic angle