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Space Telescope Science Institute |
Cycle 20 Phase II Proposal Instructions |
Flux information must be provided for all targets, and there can be more than one entry for a given target. STScI uses flux information to test for over-illumination of sensitive detectors. All entries are values as observed at the Earth, rather than intrinsic values.COS, ACS/SBC and STIS proposals cannot be implemented without flux information for all targets and other sources in the fields of view because of the critical requirements to protect its detectors from damage by excessively bright objects.
• Flux in V Magnitude with an uncertainty, This is required for targets observed by the FGS, STIS/FUV-MAMA, STIS/NUV-MAMA, COS and ACS/SBC. For all other instrument configurations, it’s optional.In the “Other Fluxes” field, the spectral type and color index could be provided if you think it’s important. As many additional flux values as appropriate for the requested exposures should be provided. For example, ultraviolet or emission-line fluxes should be given if the target is to be observed in the ultraviolet or through a narrow-band filter, or several magnitudes might be provided if the target is a variable star to be observed at various brightness levels. In some cases (Targets of Opportunity, variable objects, etc.) the estimated flux data may be very uncertain, but the best available estimates should nevertheless be given, along with appropriate uncertainties and comments.It may be important to specify the flux of a background source as well as the target flux. For example, a globular cluster in M87 may be seen against the bright background of the galaxy. The keyword –BKG should be appended to a background flux specification in this case (see footnote 2 to Table 3.12). Use a comma to separate entries if more than one flux value is given.where lambda is in еngstroms and F(nu) is in erg/(cm2 sec Hz). For example, if lambda = 1500е, and F(nu) = 1.0 x 10-26, then F(lambda) = 1.3 x 10-14.The flux data are to be expressed in the format shown in Table 3.12. Do not enter explicit units.If you are using the Text Proposal File, flux items in a list must be separated by commas.The following summary provides general guidelines for what flux information must be included in five general cases. See the Instrument Handbooks for more detailed descriptions of how to make the exposure time calculations.
1. Target flux: V magnitude, (B–V), E(B–V), spectral type.
Flux at specified wavelength may be substituted for V magnitude.
If no entry for E(B–V) is given, E(B–V) = 0 will be assumed.
2. Background (optional): Broad-band surface brightness or surface brightness at specified wavelength; –BKG must be specified in the name of the flux parameter.
1. Target flux: V surface brightness, (B–V), E(B–V).
Flux at specified wavelength may be substituted for V surface brightness.
If no entry for E(B–V) is given, E(B–V) = 0 will be assumed.
2. Background (optional): Broad-band surface brightness or surface brightness at specified wavelength; –BKG must be specified in the name of the flux parameter.
1. Target flux: V magnitude, (B–V), E(B–V), spectral type.
Flux at specified wavelength may be substituted for V magnitude.
If no entry for E(B–V) is given, E(B–V) = 0 will be assumed.
2. Background (optional): Surface brightness of continuum; –BKG must be specified in the name of the flux parameter.
4. Line flux and line width of brightest emission line in the wavelength range of observation.
1. Target flux: V surface brightness, (B–V), E(B–V).
Flux at specified wavelength may be substituted for V surface brightness.
If no entry for E(B–V) is given, E(B–V) = 0 will be assumed.
2. Background (optional): Surface brightness of continuum; –BKG must be specified in the name of the flux parameter.
4. Line surface flux and line width of brightest emission line in the wavelength range of observation.
1.
2. Background (optional): Broad-band surface brightness at specified wavelength; –BKG must be specified in the name of the flux parameter.
3. Note that this refers to the astronomical background and not the thermal background.
4. Flux in wavelength range of observation. Note that this must be in units of erg/(cm2 sec е)t.
Note: Details of how the above flux information was derived should have been given in the Description of Observations in the Call for Proposals. If any of the required flux data cannot be provided or are deemed to be unnecessary, these points must also be explained in that section. Incomplete flux information may delay the implementation of your proposal, especially in the case of ACS/SBC, COS and STIS/MAMA observations.
Table 3.12: Formats for Specification of Target Flux Data Broad-band magnitude1 Background Surface Brightness2 Plus whatever other fluxes are relevant to your science program. Some other examples are listed below: Flux at a specified wavelength erg/(cm2 sec е) Continuum Flux3 erg/(cm2 sec е) erg/(cm2 sec е) Line Width6 Surface Brightness at specified wavelength2 Surface Brightness at continuum wavelength2 Size (FWHM of circular region)7
The following broad-band magnitudes may be used: U,B,V,R,I,J,H,K.
You may append “–BKG” to this reference (just before the wavelength designation) to indicate that it is a background flux value (e.g., SURF-BKG(V) = 18.2 +/– 0.5; SURF-CONT-BKG(5100) = 10 +/– 3 E-15).
Whenever the S/N refers to a spectral line, W-LINE must be given along with F-LINE or SURF-LINE. Values of F-LINE and SURF-LINE outside the Earth’s atmosphere are required.
W-LINE is the full width at half maximum (FWHM).
SIZE should be included if the exposure time estimate assumed the flux was spread over an extended region; if omitted, the highest spatial resolution of the observing mode will be assumed.