ScanBlock

A ScanBlock is a list of ScanBase objects. As illustrated by the diagram below, it serves to hold together a series of scans. One of its purposes is to facilitate working with groups of scans, as it allows time averaging them together (using ScanBlock.timeaverage), or subtracting a baseline from the integrations in a group of scans (using ScanBlock.subtract_baseline).

        flowchart TD

subgraph newLines[GBTFITSLoad
    50 Scans
    Position Switching
    Dual Linear Polarization
    1 Beam
    4 Frequency Windows
    100 integrations each
    ]




end


newLines -- getps( scan=45, plnum=1, ifnum=0, fdnum=0 ) --> ScanBlock1
newLines -- gettp( scan=[17,18,19], intnum=np.r_[50:100], ifnum=2, plnum=0,fdnum=0 ) --> ScanBlock2



subgraph ScanBlock1[ScanBlock]
        psscan["spectra.scan.PSScan<br />scans = 44,45<br />plnum = 1<br />ifnum = 0<br />fdnum = 0<br />intnum = (0,100)"]
    end
subgraph ScanBlock2[ScanBlock]
        tpscan1["spectra.scan.TPScan<br />scan=17<br />plnum = 0<br />ifnum = 2<br />fdnum = 0 <br />intnum=(50,100)"]
        tpscan2["spectra.scan.TPScan<br />scan=18<br />plnum = 0<br />ifnum = 2<br />fdnum = 0 <br />intnum=(50,100)"]
        tpscan3["spectra.scan.TPScan<br />scan=19<br />plnum = 0<br />ifnum = 2<br />fdnum = 0 <br />intnum=(50,100)"]

    end

ScanBlock1[Scan Block] -- timeaverage() --->spectrum1[Spectrum]
ScanBlock2[Scan Block] -- timeaverage() --->spectrum2[Spectrum]
    

Fig. 1 The contents of a ScanBlock are a series of ScanBase objects. ScanBlock are the return of the calibration routines (e.g., getps, getfs or gettp)

The return object of all calibration methods (e.g., getps, getfs or gettp) is a ScanBlock. Since a ScanBlock is a list, it is possible to append to a ScanBlock. This can be useful when working with different observing procedures or for combining polarizations and/or spectral windows (IFs). For example, you can do the following:

# Calibrate plnum 1 and 2 data, then average.
sb0 = sdfits.getps(scan=1, ifnum=0, plnum=0, fdnum=0)
sb1 = sdfits.getps(scan=1, ifnum=0, plnum=1, fdnum=0)
sb0.extend(sb1)
pol_avg_spectrum = sb0.timeaverage()