5.5 HAWC+

v8.1.0

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5.5.1   Overview of AOTs

HAWC+ specific instructions and reminders of general issues are given in the following topics below. It is necessary to read the HAWC+ chapter of the Observer's Handbook before preparing detailed HAWC+ observations in USPOT. Astronomical Observation Requests (AORs) should be created as described in Chapter 3.

The USPOT Observation drop-down menu lists the four Astronomical Observation Templates (AOTs) available for HAWC+: Total Intensity, PolarizationOTFMAP, and Polarization OTFMAP. Refer to the Observer's Handbook for a complete description of available combinations of configurations and modes for HAWC+.

The USPOT HAWC+ Main AOR Window contains several frames: HAWC_PLUS and Nod & Map. Figure 5.5-1 shows an example of the Main AOR Window of a HAWC+ AOT. The instrument-specific fields are discussed in detail in this chapter. Contact the Help-Desk with any questions.

Figure 5.5-1.
Main AOR Window of a HAWC plus AOT

Figure 5.5-1. An example of a HAWC+ AOT Main AOR Window, using the HAWC+ Total Intensity AOT.

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5.5.2   AOR Fields

Tables 5.5-1, 5.5-2, and 5.5-3 list the required fields for Phase I and Phase II for each available HAWC+ AOT. Conditional fields (i.e., fields not editable unless certain parameters are specified) are denoted with a footnote, with a reference to the required field to activate the conditional field. Fields that are not listed in these tables fall under one of three categories: fields not directly editable in USPOT (but may be affected by updating other fields, which are required; for more information on how particular fields may be related, refer to the corresponding sections within the Observer's Handbook—denoted in Tables 5.5-1, 5.5-2 and 5.5-3 by OH followed by the appropriate section number), fields inteded for use only by SOFIA Support Scientists only, or optional fields.

 
Table 5.5-1.
Total Intensity Phase I Required Fields
All Observer's Handbook (OH) Reference links in the table point to the latest version of the Observer's Handbook—currently Cycle 8. Be sure you are using the version of the Observer's Handbook that corresponds to your observing cycle. The documentation for all cycles can be found on the Proposal Documents webpage.
Field Location Field Reference
Target Window Specify Target § 3.4
HAWC_PLUS Frame PassBand § 5.5.2.2OH § 7.1.2
Observing Condition & Acquisition/Tracking Window All Fields Required § 5.5.2.3§ 3.4

Total Intensity Phase II Required Fields
All Observer's Handbook (OH) Reference links in the table point to the latest version of the Observer's Handbook—currently Cycle 8. Be sure you are using the version of the Observer's Handbook that corresponds to your observing cycle. The documentation for all cycles can be found on the Proposal Documents webpage.

Field Location Field Reference
HAWC_PLUS Frame Observation Order § 5.5.2.1§ 3.4
AOR Repeats § 5.5.2.1
Example Rotation Angle OH § 7.2
Nod & Map Frame Chop Throw Chop Angle Chop Angle Coordinate Reference § 5.5.2.1OH § 7.1.2.2
 
Table 5.5-2.

Polarization Field Phase I Required Fields
All Observer's Handbook (OH) Reference links in the table point to the latest version of the Observer's Handbook—currently Cycle 8. Be sure you are using the version of the Observer's Handbook that corresponds to your observing cycle. The documentation for all cycles can be found on the Proposal Documents webpage.

Field Location Field Reference
Target Window Specify Target § 3.4
HAWC_PLUS Frame PassBand § 5.5.2.2OH § 7.1.2
Observing Condition & Acquisition/Tracking Window All Fields Required § 5.5.2.3§ 3.4

Polarization Phase II Required Fields
All Observer's Handbook (OH) Reference links in the table point to the latest version of the Observer's Handbook—currently Cycle 8. Be sure you are using the version of the Observer's Handbook that corresponds to your observing cycle. The documentation for all cycles can be found on the Proposal Documents webpage.

Field Location Field Reference
HAWC_PLUS Frame Observation Order § 5.5.2.1§ 3.4
AOR Repeats § 5.5.2.1
Example Rotation Angle OH § 7.2.2
Main AOR Window, Nod & Map Frame Chop Throw Chop Angle Chop Angle Coordinate Reference § 5.5.2.1; OH § 7.2.2
 
Table 5.5-3.

OTFMAP Phase I Required Fields
All Observer's Handbook (OH) Reference links in the table point to the latest version of the Observer's Handbook—currently Cycle 8. Be sure you are using the version of the Observer's Handbook that corresponds to your observing cycle. The documentation for all cycles can be found on the Proposal Documents webpage.

Field Location Field Reference
Target Window Specify Target § 3.4
HAWC_PLUS Frame Half Wave Plate* OH § 7.1.1.1
PassBand § 5.5.2.2OH § 7.1.2
Observing Condition & Acquisition/Tracking Window All fields required § 5.5.2.3§ 3.4

OTFMAP Phase II Required Fields
All Observer's Handbook (OH) Reference links in the table point to the latest version of the Observer's Handbook—currently Cycle 8. Be sure you are using the version of the Observer's Handbook that corresponds to your observing cycle. The documentation for all cycles can be found on the Proposal Documents webpage.

Field Location Field Reference
HAWC_PLUS Frame Observation Order § 5.5.2.1§ 3.4
Example Rotation Angle OH § 7.2
Scan Type § 5.5.2.1OH § 7.2.1
Number of iterations § 5.5.2.1
1Length of Linear Scan Element § 5.5.2.1OH § 7.2.1.1b
2Scan Amplitude(Elevation) 2Scan Amplitude(Cross Elevation) § 5.5.2.1; OH § 7.2.1.1a
Nod & Map Frame Chop Angle Coordinate Reference Chop Throw Chop Angle § 5.5.2.1; OH § 7.2

 

Polarization OTFMAP Phase I Required Fields
All Observer's Handbook (OH) Reference links in the table point to the latest version of the Observer's Handbook—currently Cycle 8. Be sure you are using the version of the Observer's Handbook that corresponds to your observing cycle. The documentation for all cycles can be found on the Proposal Documents webpage.

Field Location Field Reference
Main AOR Window PassBand § 5.5.2.2OH § 7.1.2
Observing Condition & Acquisition/Tracking Window All fields required § 5.5.2.3§ 3.4
1For Scan Type = Box
2For Scan Type = Lissajous
Return to:   Table 5.5-1   |   Table 5.5-2   |   Table 5.5-3
 

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5.5.2.1   Special Instructions

Special instructions for some of the HAWC+ fields are given in Table 5.5-4.

Table 5.5-4.

Common Mapping Parameters

Relevant AOT Field Special Instructions
All Observation Order If the accepted proposal contains observations in several passbands, it should have a correspondingly lower observation order.
All PassBand

See Table 5.5-5.

Polarization Total Intensity Dither Scale

Distance (in arcseconds) from the object's coordinates to move for the dither positions.

Note: Changing the passband will change the default dither scale value appropriately, dithers should be no smaller than these default values to ensure enough source motion on the focal plane.

Polarization Total Intensity Chop Throw The maximum chop throw is somewhat dependent on the observational field since a tracking source is required on the Focal Plane Imager (FPI) camera, but usually 400 arcseconds is routinely achievable.
Polarization Total Intensity Chop Angle SOFIA’s chop angle is counted from the north and increases in the direction of decreasing RA, which is the opposite of what an astronomer would be used to.
Polarization Total Intensity Chop Frequency Arbitrary chop frequencies are NOT supported for HAWC+: the chop frequency must be an integer multiple of the detector readout.  Therefore, only 10.2 and 16.9 Hz are supported and 10.2 Hz is the default.
OTFMAP Scan Type Choose Box for Raster or Lissajous for Lissajous.
OTFMAP Number of Iterations For SOFIA Cycle 8: Must be greater than or equal to 3.
OTFMAP (Raster) Length of Linear Scan Element Scan will always be square, so this is the length of one side of that square.
OTFMAP (Lissajous) Scan Amplitude (Elevation) Size varies per band to be comparable to the HAWC+ FOV in that band. Defaults should be used.
OTFMAP (Lissajous) Scan Amplitude (Cross Elevation) Size varies per band to be comparable to the HAWC+ FOV in that band. Defaults should be used.
OTFMAP (Lissajous) Scan Rate For amplitudes less than 100 arcseconds the scan rate should be less than 200 arcseconds/sec.

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5.5.2.2   Field of View (FOV)

All Observer's Handbook (OH) Reference links in the table point to the latest version of the Observer's Handbook—currently Cycle 8. Be sure you are using the version of the Observer's Handbook that corresponds to your observing cycle. The documentation for all cycles can be found on the Proposal Documents webpage.
 
For polarimetry observations, HAWC+ does not have a second T polarization state array; as such, the field of view is reduced to approximately half in the detector's X direction (the first element of the Field of View row in Table 5.5-5). Total intensity observations are unaffected and can use the whole field of view via the R polarization state.  To state it clearly, these are the available field of views for both Total Intensity and Polarization observations. Figures 5.5-2 and 5.5-3 illustrate and underscore this difference. In both, the HAW_A, HAW_C, HAW_D, and HAW_E FOV's are shown by the pale blue, green, orange, and red boxes respectively.
Table 5.5-5.

PassBand Characteristics

PassBand Wavelength Total Intensity FOV (arcmin) Polarization FOV (arcmin)
HAW_A 53 μm
2.7x1.7
1.3x1.7
HAW_C 89 μm 4.2x2.6 2.1x2.6
HAW_D 154 μm 7.3x4.5 3.6x4.5
HAW_E 214 μm 8.0x6.1 4.0x6.1

 

Figure 5.5-2.

HAWC FOV plot

Figure 5.5-2. The available FOV in HAWC PLUS Total Intensity observations, using a chop throw of 400 arcsec at an angle of 0 degrees in a typical C2N/NMC observation.

 

Figure 5.5-3.

HAWC FOV plot

Figure 5-3. The available FOV in HAWC PLUS Polarization observations, using a chop throw of 400 arcsec at an angle of 0 degrees in a typical C2N/NMC observation.

 

5.5.2.3   Observing Condition & Acquisition / Tracking

Complete the relevant details in the Observing Condition & Acquisition / Tracking window. Of particular importance and interest are the final six parameters in that window for tracking purposes; choose represenatitve values for targets when possible. The visible wavelength will help support scientists quickly assess whether the source itself can be used as a tracking source for the SOFIA visible tracking cameras of if an alternate tracking star/source will be necessary.

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