SUNDISH Cassiopeia A archive

This archive contains the results of the absolute calibration procedure. At the moment only the SRT images, both solar and CasA, are available. The key words are slightly different respect to the one present in the Solar archive. Below are explained the modified and the new key words.

Key words and links

CasA MAP ID# is an identification number for a single CasA map. It indicates the radiotelescope (Medicina or SRT), the source CassiopeiaA (CA for short), the observation date (expressed as YYMMDD) and the order in which the map were acquired during the day (_1 indicates the first map acquired, _2 indicates the second, and so on). Here an example of MAP ID: MED_CA_191114_1 indicates the first CasA map acquired during the observation on the date 14/11/2019 with the Medicina radiotelescope.

CASA TIME (UT) illustrates the acquisition time interval of the CasA map. The time is expressed as Universal Time.

EPOCH indicates the observation date expressed as DD/MM/YYYY.

SOLAR MAP ID# is an identification number for a single solar map. It indicates the radiotelescope (Medicina or SRT), the observation date (expressed as YYMMDD) and the order in which the map were acquired during the day (_1 indicates the first map acquired, _2 indicates the second, and so on). Here an example of MAP ID: MED_191114_1 indicates the first solar map acquired during the observation on the date 14/11/2019 with the Medicina radiotelescope.

SUN TIME (UT) illustrates the acquisition time interval of the solar map. The time is expressed as Universal Time.

CENTRAL FREQ (GHz) is an abbreviation for central observation frequency.

TAU columns list the opacity values for the day used in the absolute calibration procedure and taken from the SRT radiometer or from the forecast system. The values are taken from the sites: http://www.atmosphere-monitoring.srt.inaf.it/index.html. The tau varies with time, therefore the values written in the table are referred to roughly in the middle of the CASA TIME, since CasA is the less strong source (for 2018-2019-2020 data).
From 2021 TAU has been split between TAU_C and TAU_S: the first one refers to CasA, while the second one to the Sun. Both values are extrapolated at the middle of their observing time.

SUN IMAGE (PNG) is a link to a representative map image in PNG format of the solar image at the same frequency taken in the same observing session.

SOLAR FLAGS consists of a series series of abbreviation, acronyms or words that indicate specific characteristics of the corresponding solar map:

• 1. T or S (Test or Science) indicates whether the map was acquired during a test session or in the contest of a science observation. In case the session contains both test and science observation, the flag in written as T/S;

  2. CA (Cas A). We utilize this flag in the case the Supernova Remnant CasA was observed during the session for calibration purposes;

  3. DF (Dual Frequency) flag is present when the Sun was observed at two different central frequency during the same observing session. If the Sun was observed at more than two different central frequency during the same observing session, the flag is MF (Multiple Frequencies);

  4. AR (Active Region) points out the presence of one or more Active Region in the map. For now, we identify Active Regions as approximately punctiform bright spots that stand out from the surrounding quiet region.

  5. Flags HQ, MQ or LQ give a qualitative interpretation of the final image. In general, with Low Quality (in red colour) we indicate a map image with numerous and clear artefacts (due to RFI and/or poor sky opacity conditions). When the artefacts are only a few and not remarkable we use the Medium Quality flag (in orange colour). Finally, when the image is clear or the artefacts are negligible, we assign the Quality as High (in green colour);

  6. C indicates that standard Calibrators different from CasA were observed during the session;

  7. CS is a flag used when the session Sun includes Cross Scan observations (see Loru S., Pellizzoni A., Egron E., "Investigating the high-frequency spectral features of SNRs Tycho, W44, and IC443 with the Sardinia Radio Telescope" for more detail on this technique);

  8. RA/DEC is the scan direction: Right ascension or Declination;

  9. V5 specifies the Pipeline Version used in order to analyze the raw data. At the moment the version number 5 is the most recent.

CASA and SUN IMAGES (DS9 FITS) are a link to the DS9 fits files obtained after the analysis of CasA and solar maps.

The link RAW DATA brings to the raw data of the observing session.

OBS.REPORT is a link to a report of the observing session. The reports contains details about the weather, set up parameters and others.

NOTES: it includes comments on the final results obtained after the absolute calibration procedure.

In the section EXTRACTING [REGION CENTER; RADIUS (°)] are reported the center coordinates and radius (degrees) of the circular region used in order to obtain CasA total counts.