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There are, at the moment, 2 data displays; one the "standard" which is what you see initially with the quick-look web display; the "alternate" which you can see by clicking the butterfly.
In the "quick-look" web display one may click the links "Calibrated", "Raw Ascii", etc, to download tables of data.
Here are explanations of the information in these text files.
The first 5 columns are always the same:
For LOWRES data, there are 2 columns of brightness data labelled XL1 and YL1 or XX1 and YY1. For HIRES, there are 4 channels for the 2 frequencies and 2 polarization channels: XL1, XL2, YR1, YR2, ( or XX1,XX2,YY1,YY2).
For LOWRES calibrated, standard processing, the minimum values have been subtracted. These minimums are given by the Keyword "MINS=". Otherwise, the brightness values are given in Kelvin.
For each time step, the spectrum has been averaged over the frequency range STRTCHAN to STOPCHAN.
The "CAL" column:
The "Sweeps" columns:
the "On/Off" column:
There is special processing for the ON/OFF scan case when the alternate processing (butterfly) is selected. In this case the on-source spectrum is the average over spectra with the "ON" flag and sweep-valid is "1"; the off-source spectrum is the average having the "OFF" flag, and sweep-valid "1". The "on-off/off" spectrum is displayed and the corresponding text file may be downloaded.
Keyword | Comments | Typical value |
---|---|---|
FILENAME | Name of this text file | "Skynet_57566_CAS-A_21903_22008.txt" |
BASENAME | MJD, object name, ID number, scan number concatenated. | "Skynet_57566_CAS-A_21903_22008" |
SRC_NAME | The name of the source, as specified by the user. | "CAS-A" |
OBSERVER | The user's name and user ID number | "fghigo_2839" |
DATE_OBS | UT date and time of the start of the observation. | "2016-06-27 15:00:23.00" |
OBSID | Skynet assigns a unique ID number to each observation. | "21903" |
SCANNUM | Cyborg scan number (can be more than one scan number per observation) | "22008" |
MJD | Modified Julian date (days since Nov 17, 1858) | "57566" |
UTC | UT seconds since last UT midnight | "54022" |
SCANTYPE | Type of scan pattern, e.g. "Daisy", "Map", "Track", "OnOff" | "Track" |
DATAMODE | Type of observation: LOWRES, HIRES, or PSR_SEARCH | "HIRES" |
RECEIVER | Type of receiver: Rx1_2(1.3-1.8 GHz) or Rx8_10 (8-10 GHz) | "Rx1_2" |
OBSFREQ | Center frequency for the selected filter in MHz | "1395" |
Actual_FREQ1 | In HIRES mode, actual band center for frequency 1, in MHz | "1668" |
Actual_FREQ2 | In HIRES mode, actual band center for frequency 2, in MHz | "1418" |
LO1freq | Frequency setting of the LO synthesizer in MHz | "7000" |
RFFILTER | Selected filter | "1355_1435" |
OBSBW | Spectrometer bandwidth (minus means lower sideband mix) | "-500" |
EFFBANDW | Effective bandwidth of the selected filter, in MHz | "80.00" |
NCHAN | number of spectral channels | "1024" |
STRTCHAN ** | Starting channel number | "747" |
STOPCHAN ** | Ending channel number | "911" |
TAVE | User-specified integration time, in seconds | "0.300" |
TINT | Integration time, in seconds. Actual integration time may differ slightly from TAVE because it is an integral number of TBINs | "0.3020" |
TBIN | Spectrometer dump interval, seconds. | "0.00419430" |
FOCUS | Focus setting, mm | "37.071" |
RA,DEC | Right Ascension, Declination of the start of the scan. | "23:38:54.48, 58:50:11.75" |
RA(deg) | Right Ascension of start of scan (degrees) [***] | "350.91371" |
DEC(deg) | Declination of start of scan (degrees) [***] | "58.83721" |
WIDTH(deg) | Extent of mapping pattern (degxdeg) [***] | "4.024x4.0058" |
AZIM(deg) | Starting azimuth [***] | "318.7034" |
ELEV(deg) | Starting elevation [***] | "41.6813" |
COORDREF | User-selected coordinate mode [note zz] | "RA_DEC" |
HREF | User-specified "horizontal" coordinate [note zz] | "350.8785" |
VREF | User-specified "vertical" coordinate [note zz] | "58.8370" |
IFattens | Attenuator settings
the system adjusts the attenuators prior to each observation to set nominal power levels to the spectrometer inputs. | "7.00, 10.00" |
ACCLEN | Accumulation length used by the spectrometer.
Depends on the TAVE specified by the user. | "2048" |
WARNING | Warning message if there are hardware errors. | "None" |
TSYS | System temperature | "YY1:32.50, XX1:32.00" |
TCAL | Temperature of noise calibration at the observing frequency | "YY1:8.47, XX1:7.28" |
TRX[L|R] | Receiver noise temperature at the observing frequency | "12.4285" |
PRECAL | Length of noise calibration at the start of the scan, seconds | "3" |
POSTCAL | Length of noise calibration at the end of the scan, seconds | "3" |