pynrc.nrc_utils.zodi_spec

pynrc.nrc_utils.zodi_spec(zfact=None, ra=None, dec=None, thisday=None, **kwargs)[source]

Zodiacal light spectrum.

New: Use ra, dec, and thisday keywords to call jwst_backgrounds to obtain more accurate predictions of the background.

Creates a spectrum of the zodiacal light emission in order to estimate the in-band sky background flux. This is primarily the addition of two blackbodies at T=5300K (solar scattered light) and T=282K (thermal dust emission) that have been scaled to match literature flux values.

In reality, the intensity of the zodiacal dust emission varies as a function of viewing position. In this case, we have added the option to scale the zodiacal level (or each component individually) by some user-defined factor ‘zfact’. The user can set zfact as a scalar in order to scale the entire spectrum. If defined as a list, tuple, or np array, then the each component gets scaled where T=5300K corresponds to the first elements and T=282K is the second element of the array.

The zfact parameter has no effect if jwst_backgrounds is called. Representative values for zfact:

  • 0.0 - No zodiacal emission

  • 1.0 - Minimum zodiacal emission from JWST-CALC-003894

  • 1.2 - Required NIRCam performance

  • 2.5 - Average (default)

  • 5.0 - High

  • 10.0 - Maximum

Parameters

  • zfact (float) – Factor to scale Zodiacal spectrum (default 2.5).

  • ra (float) – Right ascension in decimal degrees

  • dec (float) – Declination in decimal degrees

  • thisday (int) – Calendar day to use for background calculation. If not given, will use the average of visible calendar days.

Returns

pysynphot.spectrum – Output is a Pysynphot spectrum with default units of flam (erg/s/cm^2/A/sr). Note: Pysynphot doesn’t recognize that it’s per steradian, but we must keep that in mind when integrating the flux per pixel.

Notes

Added the ability to query the Euclid background model using zodi_euclid() for a specific location and observing time. The two blackbodies will be scaled to the 1.0 and 5.5 um emission. This functionality is deprecated in favor of jwst_backgrounds.

Keyword Arguments

  • locstr – Object name or RA/DEC (decimal degrees or sexigesimal). Queries the IPAC Euclid Background Model

  • year (int) – Year of observation.

  • day (float) – Day of observation.