################################################################################### This README file contains a description of the Arp 220 Band 5 ALMA 2016 Science Verification data, scripts and data products. Spectral windows include continuum and H2O, HNC, CS and most likely CH3OH. The array included 12 antennas in a configuration with baseline lengths between ~30 and 480 m. The resolution achieved is ~0.7 x 0.6 arcseconds. The RMS achieved is: * 0.2 mJy/beam (continuum) * <3 mJy/beam / 20km/s bin on the 183-GHz water line image Additional information can be found in the comments section included in this README. The Calibrated Data and Reference Images provided here were produced using CASA version 4.7.0-1 ################################################################################### Arp220_Band5_Scripts.tgz contains the calibration and imaging scripts: * uid___A002_Xb56f17_X164.ms.scriptForCalibration_noplots.py * Arp220_scriptForImaging.py Arp220_Band5_UncalibratedData.tgz contains the raw data: One ASDM dataset: * uid___A002_Xb56f17_X164 Arp220_Band5_CalibratedData.tgz contains the calibrated uv-data: * uid___A002_Xb56f17_X164.ms.split.cal To produce this calibrated dataset you will need to execute the calibration script(uid___A002_Xb56f17_X164.ms.scriptForCalibration_noplots.py) provided in Arp220_Band5_Scripts.tgz Arp220_Band5_ReferenceImages.tgz contains the line and continuum image products: * Arp220-B5-cont-afterSelfCal.image.pbcor.fits * Arp220-B5-spw0.image.pbcor.fits * Arp220-B5-spw1.image.pbcor.fits * Arp220-B5-spw2.image.pbcor.fits * Arp220-B5-spw3.image.pbcor.fits * Arp220-CS_4-3.image.pbcor.fits * Arp220-CS_4-3.mom0.fits * Arp220-CS_4-3.mom1.fits * Arp220-CS_4-3.mom2.fits * Arp220-H2O_313-220.image.pbcor.fits * Arp220-H2O_313-220.mom0.fits * Arp220-H2O_313-220.mom1.fits * Arp220-H2O_313-220.mom2.fits * Arp220-HNC_2-1.image.pbcor.fits * Arp220-HNC_2-1.mom0.fits * Arp220-HNC_2-1.mom1.fits * Arp220-HNC_2-1.mom2.fits The reference images can be re-created by executing the imaging script (Arp220_scriptForImaging.py). Some benign warnings can be ignored. Arp220_Band5_SelfCalibration.tgz This contains the self-calibration table that is produced as part of the imaging script. Users can use this table to self-calibrate the provided calibrated data. Alternatively, users can perform self-calibration and generate this table by following the provided imaging script. --------------------------------------------------------------- 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#2011.0.00018.SV. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada) and NSC 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." ################################################################################### COMMENTS: Data were obtained on 2016 July 16th, during science verification of ALMA Band 5. The weather conditions were excellent, with a precipitable amount of water vapor of ~0.3 mm. The array included 12 antennas in a configuration with baseline lengths between ~30 and 480 m. One antenna (DA58) was found to have slightly higher system temperatures than the others, and was flagged. The tuning was set with four spectral windows to cover mainly the 183.310-GHz water line, but also includes the strong lines of HNC~2-1 (181.324~GHz), CS~4-3 (195.954~GHz) and most likely CH3OH (a blend of several transitions around 193.4 GHz). There are some other fainter lines in the frequency coverage, but without robust identification at the moment this readme was written. The resulting synthesized beam is of 0.7''x0.6'' with Briggs weighting (robust parameter set to 0.5). The two cores of Arp 220 are thus well resolved. The continuum emission of Arp220 is strong enough for self-calibration of the data. A model of the source was constructed after a shallow clean, using line-free channels in spectral windows 2 and 3 (upper sideband). Then, gain phase solutions were determined for each integration and applied to the whole data (including lower sideband). Note however, that the channels used for determining the continuum do apparently cover some weak lines toward the western core of Arp 220. While this does not affect the self-calibration procedure, it results in an imperfect removal of the continuum level over the western core. Toward the weaker eastern core, which also has narrower linewidth, the continuum subtraction with the current channel selection is good. The sensitivity, after self-calibration of the data, is 0.2 mJy/beam for the continuum image, and better than 3 mJy/beam per 20 km/s bin for the image of the water line. ################################################################################### HOW TO EXECUTE THE CALIBRATION SCRIPT (1) Put the ALMA raw data and the calibration script in the same directory (2) In CASA 4.7 execfile('uid___A002_Xb56f17_X164.ms.scriptForCalibration.py') HOW TO EXECUTE THE IMAGING SCRIPT (1) Put uid___A002_Xb56f17_X164.ms.split.cal and the imaging script in the same directory (2) In CASA 4.7 execfile('Arp220_scriptForImaging.py')