コード例 #1
0
    def test_sm(self):
        """Test the session metadata utilties."""

        sm = metabundle.get_session_metadata(mdbFile)

        # Make sure all of the observations are done
        self.assertEqual(len(sm.keys()), 1)
コード例 #2
0
    def test_metadata(self):
        """Test the observation metadata utility."""

        fileInfo = metabundle.get_session_metadata(mdbFileOld1)
        self.assertEqual(len(fileInfo.keys()), 1)

        # File tag
        self.assertEqual(fileInfo[1]['tag'], '056492_000000094')

        # DRSU barcode
        self.assertEqual(fileInfo[1]['barcode'], 'S10TCC13S0007')
コード例 #3
0
    def test_metadata(self):
        """Test the observation metadata utility."""

        fileInfo = metabundle.get_session_metadata(mdbFile)
        self.assertEqual(len(fileInfo.keys()), 1)

        # File tag
        self.assertEqual(fileInfo[1]['tag'], '056742_000440674')

        # DRSU barcode
        self.assertEqual(fileInfo[1]['barcode'], 'S15TCV23S0001')
コード例 #4
0
def main(args):
    # Get the site and observer
    site = stations.lwa1
    observer = site.get_observer()

    # Filenames in an easier format
    inputTGZ = args.filename

    # Parse the input file and get the dates of the observations.  Be default
    # this is for LWA1 but we switch over to LWA-SV if an error occurs.
    try:
        # LWA1
        project = metabundle.get_sdf(inputTGZ)
        obsImpl = metabundle.get_observation_spec(inputTGZ)
        fileInfo = metabundle.get_session_metadata(inputTGZ)
        aspConfigB = metabundle.get_asp_configuration_summary(
            inputTGZ, which='Beginning')
        aspConfigE = metabundle.get_asp_configuration_summary(inputTGZ,
                                                              which='End')
    except:
        # LWA-SV
        ## Site changes
        site = stations.lwasv
        observer = site.get_observer()
        ## Try again
        project = metabundleADP.get_sdf(inputTGZ)
        obsImpl = metabundleADP.get_observation_spec(inputTGZ)
        fileInfo = metabundleADP.get_session_metadata(inputTGZ)
        aspConfigB = metabundleADP.get_asp_configuration_summary(
            inputTGZ, which='Beginning')
        aspConfigE = metabundleADP.get_asp_configuration_summary(inputTGZ,
                                                                 which='End')

    nObs = len(project.sessions[0].observations)
    tStart = [
        None,
    ] * nObs
    for i in range(nObs):
        tStart[i] = utcjd_to_unix(project.sessions[0].observations[i].mjd +
                                  MJD_OFFSET)
        tStart[i] += project.sessions[0].observations[i].mpm / 1000.0
        tStart[i] = datetime.utcfromtimestamp(tStart[i])
        tStart[i] = _UTC.localize(tStart[i])

    # Get the LST at the start
    observer.date = (min(tStart)).strftime('%Y/%m/%d %H:%M:%S')
    lst = observer.sidereal_time()

    # Report on the file
    print("Filename: %s" % inputTGZ)
    print(" Project ID: %s" % project.id)
    print(" Session ID: %i" % project.sessions[0].id)
    print(" Observations appear to start at %s" %
          (min(tStart)).strftime(_FORMAT_STRING))
    print(" -> LST at %s for this date/time is %s" % (site.name, lst))

    lastDur = project.sessions[0].observations[nObs - 1].dur
    lastDur = timedelta(seconds=int(lastDur / 1000),
                        microseconds=(lastDur * 1000) % 1000000)
    sessionDur = max(tStart) - min(tStart) + lastDur

    print(" ")
    print(" Total Session Duration: %s" % sessionDur)
    print(" -> First observation starts at %s" %
          min(tStart).strftime(_FORMAT_STRING))
    print(" -> Last observation ends at %s" %
          (max(tStart) + lastDur).strftime(_FORMAT_STRING))
    if project.sessions[0].observations[0].mode not in ('TBW', 'TBN'):
        drspec = 'No'
        if project.sessions[0].spcSetup[0] != 0 and project.sessions[
                0].spcSetup[1] != 0:
            drspec = 'Yes'
        drxBeam = project.sessions[0].drx_beam
        if drxBeam < 1:
            drxBeam = "MCS decides"
        else:
            drxBeam = "%i" % drxBeam
        print(" DRX Beam: %s" % drxBeam)
        print(" DR Spectrometer used? %s" % drspec)
        if drspec == 'Yes':
            print(" -> %i channels, %i windows/integration" %
                  tuple(project.sessions[0].spcSetup))
    else:
        tbnCount = 0
        tbwCount = 0
        for obs in project.sessions[0].observations:
            if obs.mode == 'TBW':
                tbwCount += 1
            else:
                tbnCount += 1
        if tbwCount > 0 and tbnCount == 0:
            print(" Transient Buffer Mode: TBW")
        elif tbwCount == 0 and tbnCount > 0:
            print(" Transient Buffer Mode: TBN")
        else:
            print(" Transient Buffer Mode: both TBW and TBN")
    print(" ")
    print("File Information:")
    for obsID in fileInfo.keys():
        print(" Obs. #%i: %s" % (obsID, fileInfo[obsID]['tag']))

    print(" ")
    print("ASP Configuration:")
    print('  Beginning')
    for k, v in aspConfigB.items():
        print('    %s: %i' % (k, v))
    print('  End')
    for k, v in aspConfigE.items():
        print('    %s: %i' % (k, v))

    print(" ")
    print(" Number of observations: %i" % nObs)
    print(" Observation Detail:")
    for i in range(nObs):
        currDur = project.sessions[0].observations[i].dur
        currDur = timedelta(seconds=int(currDur / 1000),
                            microseconds=(currDur * 1000) % 1000000)

        print("  Observation #%i" % (i + 1, ))
        currObs = None
        for j in range(len(obsImpl)):
            if obsImpl[j]['obsID'] == i + 1:
                currObs = obsImpl[j]
                break

        ## Basic setup
        print("   Target: %s" % project.sessions[0].observations[i].target)
        print("   Mode: %s" % project.sessions[0].observations[i].mode)
        print("   Start:")
        print("    MJD: %i" % project.sessions[0].observations[i].mjd)
        print("    MPM: %i" % project.sessions[0].observations[i].mpm)
        print("    -> %s" % get_observation_start_stop(
            project.sessions[0].observations[i])[0].strftime(_FORMAT_STRING))
        print("   Duration: %s" % currDur)

        ## DP setup
        if project.sessions[0].observations[i].mode not in ('TBW', ):
            print("   Tuning 1: %.3f MHz" %
                  (project.sessions[0].observations[i].frequency1 / 1e6, ))
        if project.sessions[0].observations[i].mode not in ('TBW', 'TBN'):
            print("   Tuning 2: %.3f MHz" %
                  (project.sessions[0].observations[i].frequency2 / 1e6, ))
        if project.sessions[0].observations[i].mode not in ('TBW', ):
            print("   Filter code: %i" %
                  project.sessions[0].observations[i].filter)
        if currObs is not None:
            if project.sessions[0].observations[i].mode not in ('TBW', ):
                if project.sessions[0].observations[i].mode == 'TBN':
                    print("   Gain setting: %i" % currObs['tbnGain'])
                else:
                    print("   Gain setting: %i" % currObs['drxGain'])
        else:
            print(
                "   WARNING: observation specification not found for this observation"
            )

        ## Comments/notes
        print("   Observer Comments: %s" %
              project.sessions[0].observations[i].comments)
コード例 #5
0
ファイル: createConfigFile.py プロジェクト: lwa-project/eLWA
def main(args):
    # Parse the command line
    filenames = args.filename

    # Check if the first argument on the command line is a directory.  If so,
    # use what is in that directory
    if os.path.isdir(filenames[0]):
        filenames = [
            os.path.join(filenames[0], filename)
            for filename in os.listdir(filenames[0])
        ]
        filenames.sort()

    # Convert the filenames to absolute paths
    filenames = [os.path.abspath(filename) for filename in filenames]

    # Open the database connection to NRAO to find the antenna locations
    try:
        db = database('params')
    except Exception as e:
        sys.stderr.write("WARNING: %s" % str(e))
        sys.stderr.flush()
        db = None

    # Pass 1 - Get the LWA metadata so we know where we are pointed
    context = {
        'observer': 'Unknown',
        'project': 'Unknown',
        'session': None,
        'vlaref': None
    }
    setup = None
    sources = []
    metadata = {}
    lwasite = {}
    for filename in filenames:
        # Figure out what to do with the file
        ext = os.path.splitext(filename)[1]
        if ext == '.tgz':
            ## LWA Metadata
            try:
                ## Extract the SDF
                if len(sources) == 0:
                    try:
                        sdf = metabundle.get_sdf(filename)
                    except Exception as e:
                        sdf = metabundleADP.get_sdf(filename)

                    context['observer'] = sdf.observer.name
                    context['project'] = sdf.id
                    context['session'] = sdf.sessions[0].id

                    comments = sdf.project_office.sessions[0]
                    mtch = CORR_CHANNELS.search(comments)
                    if mtch is not None:
                        corr_channels = int(mtch.group('channels'), 10)
                    else:
                        corr_channels = None
                    mtch = CORR_INTTIME.search(comments)
                    if mtch is not None:
                        corr_inttime = float(mtch.group('inttime'))
                    else:
                        corr_inttime = None
                    mtch = CORR_BASIS.search(comments)
                    if mtch is not None:
                        corr_basis = mtch.group('basis')
                    else:
                        sys.stderr.write(
                            "WARNING: No output correlation polarization basis defined, assuming 'linear'.\n"
                        )
                        corr_basis = 'linear'
                    if corr_channels is not None and corr_inttime is not None:
                        setup = {
                            'channels': corr_channels,
                            'inttime': corr_inttime,
                            'basis': corr_basis
                        }
                    else:
                        sys.stderr.write(
                            "WARNING: No or incomplete correlation configuration defined, setting to be defined at correlation time.\n"
                        )

                    for o, obs in enumerate(sdf.sessions[0].observations):
                        if type(obs).__name__ == 'Solar':
                            name = 'Sun'
                            intent = 'target'
                            ra = None
                            dec = None
                        elif type(obs).__name__ == 'Jovian':
                            name = 'Jupiter'
                            intent = 'target'
                            ra = None
                            dec = None
                        else:
                            name = obs.target
                            intent = obs.name
                            ra = ephem.hours(str(obs.ra))
                            dec = ephem.degrees(str(obs.dec))
                        tStart = mjdmpm_to_datetime(obs.mjd, obs.mpm)
                        tStop = mjdmpm_to_datetime(obs.mjd, obs.mpm + obs.dur)
                        sources.append({
                            'name': name,
                            'intent': intent,
                            'ra2000': ra,
                            'dec2000': dec,
                            'start': tStart,
                            'stop': tStop
                        })

                        ### Alternate phase centers
                        comments = sdf.project_office.observations[0][o]

                        alts = {}
                        for mtch in ALT_TARGET.finditer(comments):
                            alt_id = int(mtch.group('id'), 10)
                            alt_name = mtch.group('target')
                            try:
                                alts[alt_id]['name'] = alt_name
                            except KeyError:
                                alts[alt_id] = {
                                    'name': alt_name,
                                    'intent': 'dummy',
                                    'ra': None,
                                    'dec': None
                                }
                        for mtch in ALT_INTENT.finditer(comments):
                            alt_id = int(mtch.group('id'), 10)
                            alt_intent = mtch.group('intent')
                            try:
                                alts[alt_id]['intent'] = alt_intent
                            except KeyError:
                                alts[alt_id] = {
                                    'name': None,
                                    'intent': alt_intent,
                                    'ra': None,
                                    'dec': None
                                }
                        for mtch in ALT_RA.finditer(comments):
                            alt_id = int(mtch.group('id'), 10)
                            alt_ra = ephem.hours(mtch.group('ra'))
                            try:
                                alts[alt_id]['ra'] = alt_ra
                            except KeyError:
                                alts[alt_id] = {
                                    'name': None,
                                    'intent': 'dummy',
                                    'ra': alt_ra,
                                    'dec': None
                                }
                        for mtch in ALT_DEC.finditer(comments):
                            alt_id = int(mtch.group('id'), 10)
                            alt_dec = ephem.degrees(mtch.group('dec'))
                            try:
                                alts[alt_id]['dec'] = alt_dec
                            except KeyError:
                                alts[alt_id] = {
                                    'name': None,
                                    'intent': 'dummy',
                                    'ra': None,
                                    'dec': alt_dec
                                }
                        for alt_id in sorted(alts.keys()):
                            alt_name, alt_ra, alt_dec = alts[alt_id]
                            if alt_name is None or alt_ra is None or alt_dec is None:
                                sys.stderr.write(
                                    "WARNING: Incomplete alternate phase center %i, skipping.\n"
                                    % alt_id)
                            else:
                                sources.append({
                                    'name': alt_name,
                                    'ra2000': alt_ra,
                                    'dec2000': alt_dec,
                                    'start': tStart,
                                    'stop': tStop
                                })

                ## Extract the file information so that we can pair things together
                fileInfo = metabundle.get_session_metadata(filename)
                for obsID in fileInfo.keys():
                    metadata[fileInfo[obsID]['tag']] = filename

                ## Figure out LWA1 vs LWA-SV
                try:
                    cs = metabundle.get_command_script(filename)
                    for c in cs:
                        if c['subsystem_id'] == 'DP':
                            site = 'LWA1'
                            break
                        elif c['subsystem_id'] == 'ADP':
                            site = 'LWA-SV'
                            break
                except (RuntimeError, ValueError):
                    site = 'LWA-SV'
                for obsID in fileInfo.keys():
                    lwasite[fileInfo[obsID]['tag']] = site

            except Exception as e:
                sys.stderr.write("ERROR reading metadata file: %s\n" % str(e))
                sys.stderr.flush()

    # Setup what we need to write out a configuration file
    corrConfig = {
        'context': context,
        'setup': setup,
        'source': {
            'name': '',
            'ra2000': '',
            'dec2000': ''
        },
        'inputs': []
    }

    metadata = {}
    for filename in filenames:
        #print("%s:" % os.path.basename(filename))

        # Skip over empty files
        if os.path.getsize(filename) == 0:
            continue

        # Open the file
        fh = open(filename, 'rb')

        # Figure out what to do with the file
        ext = os.path.splitext(filename)[1]
        if ext == '':
            ## DRX
            try:
                ## Get the site
                try:
                    sitename = lwasite[os.path.basename(filename)]
                except KeyError:
                    sitename = 'LWA1'

                ## Get the location so that we can set site-specific parameters
                if sitename == 'LWA1':
                    xyz = LWA1_ECEF
                    off = args.lwa1_offset
                elif sitename == 'LWA-SV':
                    xyz = LWASV_ECEF
                    off = args.lwasv_offset
                else:
                    raise RuntimeError("Unknown LWA site '%s'" % site)

                ## Move into the LWA1 coordinate system
                ### ECEF to LWA1
                rho = xyz - LWA1_ECEF
                sez = numpy.dot(LWA1_ROT, rho)
                enz = sez[[1, 0, 2]]  # pylint: disable=invalid-sequence-index
                enz[1] *= -1

                ## Read in the first few frames to get the start time
                frames = [drx.read_frame(fh) for i in xrange(1024)]
                streams = []
                freq1, freq2 = 0.0, 0.0
                for frame in frames:
                    beam, tune, pol = frame.id
                    if tune == 1:
                        freq1 = frame.central_freq
                    else:
                        freq2 = frame.central_freq
                    if (beam, tune, pol) not in streams:
                        streams.append((beam, tune, pol))
                tStart = frames[0].time.datetime
                tStartAlt = (frames[-1].time - 1023 // len(streams) * 4096 /
                             frames[-1].sample_rate).datetime
                tStartDiff = tStart - tStartAlt
                if abs(tStartDiff) > timedelta(microseconds=10000):
                    sys.stderr.write(
                        "WARNING: Stale data found at the start of '%s', ignoring\n"
                        % os.path.basename(filename))
                    sys.stderr.flush()
                    tStart = tStartAlt
                ### ^ Adjustment to the start time to deal with occasional problems
                ###   with stale data in the DR buffers at LWA-SV

                ## Read in the last few frames to find the end time
                fh.seek(os.path.getsize(filename) - 1024 * drx.FRAME_SIZE)
                backed = 0
                while backed < 2 * drx.FRAME_SIZE:
                    try:
                        drx.read_frame(fh)
                        fh.seek(-drx.FRAME_SIZE, 1)
                        break
                    except errors.SyncError:
                        backed += 1
                        fh.seek(-drx.FRAME_SIZE - 1, 1)
                for i in xrange(32):
                    try:
                        frame = drx.read_frame(fh)
                        beam, tune, _ = frame.id
                        if tune == 1:
                            freq1 = frame.central_freq
                        else:
                            freq2 = frame.central_freq
                    except errors.SyncError:
                        continue
                tStop = frame.time.datetime

                ## Save
                corrConfig['inputs'].append({
                    'file':
                    filename,
                    'type':
                    'DRX',
                    'antenna':
                    sitename,
                    'pols':
                    'X, Y',
                    'location': (enz[0], enz[1], enz[2]),
                    'clockoffset': (off, off),
                    'fileoffset':
                    0,
                    'beam':
                    beam,
                    'tstart':
                    tStart,
                    'tstop':
                    tStop,
                    'freq': (freq1, freq2)
                })

            except Exception as e:
                sys.stderr.write("ERROR reading DRX file: %s\n" % str(e))
                sys.stderr.flush()

        elif ext == '.vdif':
            ## VDIF
            try:
                ## Read in the GUPPI header
                header = vdif.read_guppi_header(fh)

                ## Read in the first frame
                vdif.FRAME_SIZE = vdif.get_frame_size(fh)
                frame = vdif.read_frame(fh)
                antID = frame.id[0] - 12300
                tStart = frame.time.datetime
                nThread = vdif.get_thread_count(fh)

                ## Read in the last frame
                nJump = int(os.path.getsize(filename) / vdif.FRAME_SIZE)
                nJump -= 30
                fh.seek(nJump * vdif.FRAME_SIZE, 1)
                mark = fh.tell()
                while True:
                    try:
                        frame = vdif.read_frame(fh)
                        tStop = frame.time.datetime
                    except Exception as e:
                        break

                ## Find the antenna location
                pad, edate = db.get_pad('EA%02i' % antID, tStart)
                x, y, z = db.get_xyz(pad, tStart)
                #print("  Pad: %s" % pad)
                #print("  VLA relative XYZ: %.3f, %.3f, %.3f" % (x,y,z))

                ## Move into the LWA1 coordinate system
                ### relative to ECEF
                xyz = numpy.array([x, y, z])
                xyz += VLA_ECEF
                ### ECEF to LWA1
                rho = xyz - LWA1_ECEF
                sez = numpy.dot(LWA1_ROT, rho)
                enz = sez[[1, 0, 2]]  # pylint: disable=invalid-sequence-index
                enz[1] *= -1

                ## Set an apparent position if WiDAR is already applying a delay model
                apparent_enz = (None, None, None)
                if args.no_vla_delay_model:
                    apparent_xyz = VLA_ECEF
                    apparent_rho = apparent_xyz - LWA1_ECEF
                    apparent_sez = numpy.dot(LWA1_ROT, apparent_rho)
                    apparent_enz = apparent_sez[[1, 0, 2]]  # pylint: disable=invalid-sequence-index
                    apparent_enz[1] *= -1

                ## VLA time offset
                off = args.vla_offset

                ## Save
                corrConfig['context']['observer'] = header['OBSERVER']
                try:
                    corrConfig['context']['project'] = header[
                        'BASENAME'].split('_')[0]
                    corrConfig['context']['session'] = header[
                        'BASENAME'].split('_')[1].replace('sb', '')
                except IndexError:
                    corrConfig['context']['project'] = header[
                        'BASENAME'].split('.')[0]
                    corrConfig['context']['session'] = header[
                        'BASENAME'].split('.')[1].replace('sb', '')
                corrConfig['context']['vlaref'] = re.sub(
                    '\.[0-9]+\.[0-9]+\.[AB][CD]-.*', '', header['BASENAME'])
                corrConfig['source']['name'] = header['SRC_NAME']
                corrConfig['source']['intent'] = 'target'
                corrConfig['source']['ra2000'] = header['RA_STR']
                corrConfig['source']['dec2000'] = header['DEC_STR']
                corrConfig['inputs'].append({
                    'file':
                    filename,
                    'type':
                    'VDIF',
                    'antenna':
                    'EA%02i' % antID,
                    'pols':
                    'Y, X',
                    'location': (enz[0], enz[1], enz[2]),
                    'apparent_location':
                    (apparent_enz[0], apparent_enz[1], apparent_enz[2]),
                    'clockoffset': (off, off),
                    'fileoffset':
                    0,
                    'pad':
                    pad,
                    'tstart':
                    tStart,
                    'tstop':
                    tStop,
                    'freq':
                    header['OBSFREQ']
                })

            except Exception as e:
                sys.stderr.write("ERROR reading VDIF file: %s\n" % str(e))
                sys.stderr.flush()

        elif ext == '.tgz':
            ## LWA Metadata
            try:
                ## Extract the file information so that we can pair things together
                fileInfo = metabundle.get_session_metadata(filename)
                for obsID in fileInfo.keys():
                    metadata[fileInfo[obsID]['tag']] = filename

            except Exception as e:
                sys.stderr.write("ERROR reading metadata file: %s\n" % str(e))
                sys.stderr.flush()

        # Done
        fh.close()

    # Close out the connection to NRAO
    try:
        db.close()
    except AttributeError:
        pass

    # Choose a VDIF reference file, if there is one, and mark whether or
    # not DRX files were found
    vdifRefFile = None
    isDRX = False
    for cinp in corrConfig['inputs']:
        if cinp['type'] == 'VDIF':
            if vdifRefFile is None:
                vdifRefFile = cinp
        elif cinp['type'] == 'DRX':
            isDRX = True

    # Set a state variable so that we can generate a warning about missing
    # DRX files
    drxFound = False

    # Purge DRX files that don't make sense
    toPurge = []
    drxFound = False
    lwasvFound = False
    for cinp in corrConfig['inputs']:
        ### Sort out multiple DRX files - this only works if we have only one LWA station
        if cinp['type'] == 'DRX':
            if vdifRefFile is not None:
                l0, l1 = cinp['tstart'], cinp['tstop']
                v0, v1 = vdifRefFile['tstart'], vdifRefFile['tstop']
                ve = (v1 - v0).total_seconds()
                overlapWithVDIF = (v0 >= l0 and v0 < l1) or (l0 >= v0
                                                             and l0 < v1)
                lvo = (min([v1, l1]) - max([v0, l0])).total_seconds()
                if not overlapWithVDIF or lvo < 0.25 * ve:
                    toPurge.append(cinp)
                drxFound = True
            if cinp['antenna'] == 'LWA-SV':
                lwasvFound = True
    for cinp in toPurge:
        del corrConfig['inputs'][corrConfig['inputs'].index(cinp)]

    # Sort the inputs based on the antenna name - this puts LWA1 first,
    # LWA-SV second, and the VLA at the end in 'EA' antenna order, i.e.,
    # EA01, EA02, etc.
    corrConfig['inputs'].sort(key=lambda x: 0 if x['antenna'] == 'LWA1' else (
        1 if x['antenna'] == 'LWA-SV' else int(x['antenna'][2:], 10)))

    # VDIF/DRX warning check/report
    if vdifRefFile is not None and isDRX and not drxFound:
        sys.stderr.write(
            "WARNING: DRX files provided but none overlapped with VDIF data")

    # Duplicate antenna check
    antCounts = {}
    for cinp in corrConfig['inputs']:
        try:
            antCounts[cinp['antenna']] += 1
        except KeyError:
            antCounts[cinp['antenna']] = 1
    for ant in antCounts.keys():
        if antCounts[ant] != 1:
            sys.stderr.write("WARNING: Antenna '%s' is defined %i times" %
                             (ant, antCounts[ant]))

    # Update the file offsets to get things lined up better
    tMax = max([cinp['tstart'] for cinp in corrConfig['inputs']])
    for cinp in corrConfig['inputs']:
        diff = tMax - cinp['tstart']
        offset = diff.days * 86400 + diff.seconds + diff.microseconds / 1e6
        cinp['fileoffset'] = max([0, offset])

    # Reconcile the source lists for when we have eLWA data.  This is needed so
    # that we use the source information contained in the VDIF files rather than
    # the stub information contained in the SDFs
    if len(sources) <= 1:
        if corrConfig['source']['name'] != '':
            ## Update the source information with what comes from the VLA
            try:
                sources[0] = corrConfig['source']
            except IndexError:
                sources.append(corrConfig['source'])
    # Update the dwell time using the minimum on-source time for all inputs if
    # there is only one source, i.e., for full eLWA runs
    if len(sources) == 1:
        sources[0]['start'] = max(
            [cinp['tstart'] for cinp in corrConfig['inputs']])
        sources[0]['stop'] = min(
            [cinp['tstop'] for cinp in corrConfig['inputs']])

    # Render the configuration
    startRef = sources[0]['start']
    s = 0
    for source in sources:
        startOffset = source['start'] - startRef
        startOffset = startOffset.total_seconds()

        dur = source['stop'] - source['start']
        dur = dur.total_seconds()

        ## Skip over dummy scans and scans that start after the files end
        if source['intent'] in (None, 'dummy'):
            continue
        if source['start'] > max(
            [cinp['tstop'] for cinp in corrConfig['inputs']]):
            print(
                "Skipping scan of %s which starts at %s, %.3f s after the data end"
                % (source['name'], source['start'],
                   (source['start'] -
                    max([cinp['tstop']
                         for cinp in corrConfig['inputs']])).total_seconds()))
            continue

        ## Small correction for the first scan to compensate for stale data at LWA-SV
        if lwasvFound and s == 0:
            startOffset += 10.0
            dur -= 10.0

        ## Skip over scans that are too short
        if dur < args.minimum_scan_length:
            continue

        ## Setup
        if args.output is None:
            fh = sys.stdout
        else:
            outname = args.output
            if len(sources) > 1:
                outname += str(s + 1)
            fh = open(outname, 'w')

        try:
            repo = git.Repo(os.path.dirname(os.path.abspath(__file__)))
            try:
                branch = repo.active_branch.name
                hexsha = repo.active_branch.commit.hexsha
            except TypeError:
                branch = '<detached>'
                hexsha = repo.head.commit.hexsha
            shortsha = hexsha[-7:]
            dirty = ' (dirty)' if repo.is_dirty() else ''
        except git.exc.GitError:
            branch = 'unknown'
            hexsha = 'unknown'
            shortsha = 'unknown'
            dirty = ''

        ## Preamble
        fh.write("# Created\n")
        fh.write("#  on %s\n" % datetime.now())
        fh.write("#  using %s, revision %s.%s%s\n" %
                 (os.path.basename(__file__), branch, shortsha, dirty))
        fh.write("\n")
        ## Observation context
        fh.write("Context\n")
        fh.write("  Observer  %s\n" % corrConfig['context']['observer'])
        fh.write("  Project   %s\n" % corrConfig['context']['project'])
        if corrConfig['context']['session'] is not None:
            fh.write("  Session   %s\n" % corrConfig['context']['session'])
        if corrConfig['context']['vlaref'] is not None:
            fh.write("  VLARef    %s\n" % corrConfig['context']['vlaref'])
        fh.write("EndContext\n")
        fh.write("\n")
        ## Configuration, if present
        if corrConfig['setup'] is not None:
            fh.write("Configuration\n")
            fh.write("  Channels     %i\n" % corrConfig['setup']['channels'])
            fh.write("  IntTime      %.3f\n" % corrConfig['setup']['inttime'])
            fh.write("  PolBasis     %s\n" % corrConfig['setup']['basis'])
            fh.write("EndConfiguration\n")
            fh.write("\n")
        ## Source
        fh.write("Source\n")
        fh.write("# Observation start is %s\n" % source['start'])
        fh.write("# Duration is %s\n" % (source['stop'] - source['start'], ))
        fh.write("  Name     %s\n" % source['name'])
        fh.write("  Intent   %s\n" % source['intent'].lower())
        if source['name'] not in ('Sun', 'Jupiter'):
            fh.write("  RA2000   %s\n" % source['ra2000'])
            fh.write("  Dec2000  %s\n" % source['dec2000'])
        fh.write("  Duration %.3f\n" % dur)
        fh.write("SourceDone\n")
        fh.write("\n")
        ## Input files
        for cinp in corrConfig['inputs']:
            fh.write("Input\n")
            fh.write("# Start time is %s\n" % cinp['tstart'])
            fh.write("# Stop time is %s\n" % cinp['tstop'])
            try:
                fh.write("# Beam is %i\n" % cinp['beam'])
            except KeyError:
                pass
            try:
                fh.write("# VLA pad is %s\n" % cinp['pad'])
            except KeyError:
                pass
            try:
                fh.write("# Frequency tuning 1 is %.3f Hz\n" % cinp['freq'][0])
                fh.write("# Frequency tuning 2 is %.3f Hz\n" % cinp['freq'][1])
            except TypeError:
                fh.write("# Frequency tuning is %.3f Hz\n" % cinp['freq'])
            fh.write("  File             %s\n" % cinp['file'])
            try:
                metaname = metadata[os.path.basename(cinp['file'])]
                fh.write("  MetaData         %s\n" % metaname)
            except KeyError:
                if cinp['type'] == 'DRX':
                    sys.stderr.write(
                        "WARNING: No metadata found for '%s', source %i\n" %
                        (os.path.basename(cinp['file']), s + 1))
                    sys.stderr.flush()
                pass
            fh.write("  Type             %s\n" % cinp['type'])
            fh.write("  Antenna          %s\n" % cinp['antenna'])
            fh.write("  Pols             %s\n" % cinp['pols'])
            fh.write("  Location         %.6f, %.6f, %.6f\n" %
                     cinp['location'])
            try:
                if cinp['apparent_location'][0] is not None:
                    fh.write("  ApparentLocation %.6f, %.6f, %.6f\n" %
                             cinp['apparent_location'])
            except KeyError:
                pass
            fh.write("  ClockOffset      %s, %s\n" % cinp['clockoffset'])
            fh.write("  FileOffset       %.3f\n" %
                     (startOffset + cinp['fileoffset'], ))
            fh.write("InputDone\n")
            fh.write("\n")
        if fh != sys.stdout:
            fh.close()

        # Increment the source/file counter
        s += 1