Atacama Large Millimeter/submillimeter Array (ALMA) ######################## Publications making use of these data must include the following statement in the acknowledgement: "This paper makes use of the following ALMA data:ADS/JAO.ALMA#2011.0.00005.E. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada) and MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ." In addition, publications from NA authors must include the standard NRAO acknowledgement: "The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc." ################################################################################### This Readme file contains a description of HL Tau Band 9 long baseline testing data, scripts and data products. There are two ALMA execution blocks (ASDMs) observed in low spectral resolution mode (TDM). Angular resolutions achieved for the continuum data are 19 x 16 mas - natural 19 x 16 mas - natural >500kl baselines 12 x 10 mas - Briggs Robust 0.5 The Calibrated Data and Reference Images provided here were produced using CASA version 5.6.1-8 ######################## COMMENTS: This is ALMA comissioning test data of the protostellar disk source HL TAU taken at Band 9 in pure TDM (continuum only) mode. This was part of the High Frequency Long Baseline campaign undertaken in 2017 (HF-LBC-2017). The overview of this work and notes on the technical tests related to the observations of HL TAU is detailed in the summary paper for the campaign: Asaki, Y., Maud, L.T. et al. 2020 ApJS 247 23A Note there are future papers to be released from the same campaign efforts. These data were taken for new imaging capaility commissioning, so several experimental functions were tested: band-to-band (B2B) phase referecing with differentail gain calibration (DGC), 90deg-Walsh phase switch for the Band~9 sideband separation. There are 2 individual datasets that make up the final combined dataset. These are band-to-band (B2B) testing data, in which scheduling blocks were used to undertake similar to science-style observations. This particular B2B mode used a high frequency (for the target) of Band 9, while the calibrator used a lower frequency, the low frequency used was Band 4. A strong source, called the Differential Gain Calibration (DGC) source is observed - changing between low- and high- frequencies to solve the band offsets and facilitate the phase transfer. In these testing datasets, there were some issue with the observations of the DGC and some flags were required. Note, phase stability conditions were marignal for Band 9 even though fast phase referencing was used, with cycle times <40s. The EBs each have slightly different observation times and cover slightly different u,v space, although due to the long baseline configuration a considerable fraction of large scale emission is resolved out as HL TAU is an extended source. A number of flags reduced the image resolution below the expected 10mas. The bandpass, flux calibrator and DGC are all the source J0522-3627 observed in seperate scans for the BP/FLUX and DGC intents. The DGC is observed over many scans. The BP/FLUX is source was used to bootstrap the correct flux scaling to the datasets. Note that the phase calibrator was observed at Band 4, as per the B2B mode and there is no amplitude calibration made for this low frequency. Only the phases are transfered. The datasets were concatenated prior to imaging. Imaging was then conducted using TCLEAN. The beam sizes for the various image weightings are listed below as well as the noise and SNR. The imaging uses a simple circular mask and a shallow cleaning for speed and ease in these representative testing data images, although those published (paper reference above) used a manually drawn clean mask, but were also processed in an older CASA version and used 'clean'. Self-calibration was not performed. The final image (HLTau_sci.spw17_19_21_23_25_27_29_31.cont.I.manual-natural.pbcor.fits) has: Beam Size = 19 x 16 mas @ -27.930 deg Peak Flux Density = 18.82 mJy/bm Noise Level = 0.525 mJy/bm Signal to Noise (Dynamic range) = 35.8 The final image (HLTau_sci.spw17_19_21_23_25_27_29_31.cont.I.manual-natural500kl.pbcor.fits) has: Beam Size = 19 x 16 mas @ -27.729 deg Peak Flux Density = 18.03 mJy/bm Noise Level = 0.433 mJy/bm Signal to Noise (Dynamic range) = 41.7 The final image (HLTau_sci.spw17_19_21_23_25_27_29_31.cont.I.manual-robust.pbcor.fits) has: Beam Size = 12 x 10 mas @ -6.430 deg Peak Flux Density = 10.23 mJy/bm Noise Level = 0.426 mJy/bm Signal to Noise (Dynamic range) = 24.0 ######################## HLTau_B9_B2B_Scripts.tgz contains the calibration and imaging scripts: * uid___A002_Xc660ef_X1b89.ms.scriptForCalibration.py * uid___A002_Xc660ef_X2046.ms.scriptForCalibration.py * HLTau_B9_B2B.scriptForImaging.py HLTau_B9_B2B_UncalibratedData.tgz contains the raw data: Two ASDM datasets: * uid___A002_Xc660ef_X1b89.asdm.sdm * uid___A002_Xc660ef_X2046.asdm.sdm HLTau_B9_B2B_CalibratedData.tgz contains the calibrated uv-data: * uid___A002_Xc660ef_X1b89.ms.split.cal * uid___A002_Xc660ef_X2046.ms.split.cal * uid___A002_Xc660ef_X1b89.ms.split.cal.flagversions * uid___A002_Xc660ef_X2046.ms.split.cal.flagversions To re-create these calibrated datasets you would need to execute the calibration scripts (e.g uid___A002_Xc660ef_X1b89.ms.scriptForCalibration.py) provided in HLTau_B9_B2B_Scripts.tgz HLTau_B9_B2B_ReferenceImages.tgz contains the continuum image products: * HLTau_sci.spw17_19_21_23_25_27_29_31.cont.I.manual-natural.pbcor.fits * HLTau_sci.spw17_19_21_23_25_27_29_31.cont.I.manual-natural500kl.pbcor.fits * HLTau_sci.spw17_19_21_23_25_27_29_31.cont.I.manual-robust.pbcor.fits * HLTau_sci.spw17_19_21_23_25_27_29_31.cont.I.manual-natural.pb.fits * HLTau_sci.spw17_19_21_23_25_27_29_31.cont.I.manual-natural500kl.pb.fits * HLTau_sci.spw17_19_21_23_25_27_29_31.cont.I.manual-robust.pb.fits The reference images can be re-created by executing the imaging script (HLTau_B9_B2B.scriptForImaging.py). Note these are slightly different from those used in the technical paper which were calibratrated and imaged with an older CASA version and using 'clean' compared with 'tclean'. ################################################################################### HOW TO EXECUTE THE CALIBRATION SCRIPTS (1) Put an ALMA ASDM and the corresponding calibration script in the same directory (2) In CASA 5.6.1-8 e.g. execfile('uid___A002_Xc660ef_X1b89.ms.scriptForCalibration.py') execfile('uid___A002_Xc660ef_X2046.ms.scriptForCalibration.py') HOW TO EXECUTE THE IMAGING SCRIPT (1) Put the two *.ms.split.cal and the imaging script in the same directory (2) In CASA 5.6.1-8 execfile('HLTau_B9_B2B.scriptForImaging.py')