.. index:: Absolute Photometric Standards (NISP-S); Calibration observations .. _calobs-block-pv-nisp-spec-absolute-standards: **CALBLOCK-PV-003:** NISP-S Absolute Photometric Standards ========================================================== .. include:: definitions.rst Observation configuration file ------------------------------ | :download:`ocf_CALBLOCK-PV-003_BGS000.csv ` | :download:`ocf_CALBLOCK-PV-003_RGS000-NOM.csv ` | :download:`ocf_CALBLOCK-PV-003_RGS000-ROT.csv ` | :download:`ocf_CALBLOCK-PV-003_RGS180-NOM.csv ` | :download:`ocf_CALBLOCK-PV-003_RGS180-ROT.csv ` Scheduling ---------- Once. **The targets might not be visible during PV phase, and must be observed at a suitable time offering minimum spectra-order contamination.** In case of failure, repeat as soon as possible due to limited visibility. Time-critical ------------- Yes. Observations must be taken when the individual grism spectra of that star are not contaminated by other sources. Objective --------- Obtain measurements of a HST CALSPEC spectro-photometric standard star as a function of position for each NISP detector and grism. Observations ------------ The star is stepped across 5 positions on each detector. A NISP-S spectro-MACC exposure is taken at each position, observed with each grism. Since self-consistent catalogs require imaging data as well, the ROS_D1 is executed at each dither position. An accurate position is required for the star for the wavelength solution. The star will be saturated in NISP images, such that OU-MER must replace the NISP-P position with the expected Gaia position for that epoch of observation. **Spectra contamination is critical, i.e. each grism must be scheduled at suitable times.** This introduces a considerable launch-time dependency, as suitable targets have limited visibility. **The ROS_D1 VIS variants** are mostly NominalScience+ShortScience [NS+SS], with cases of [NS+Bias] distributed once every 6 to 8 hours. The biases provide instrumental reference. The Short Science exposures are not mandatory, but useful for VIS photometric and astrometric calibration of the NISP target. .. code-block:: python for grism in [RGS000, RGS000_rot, RGS180, RGS180_rot, BGS000]: for offset in dither_offsets: if visible without contamination: ROS_ else: schedule at another time Fulfilling ---------- :ref:`calobs-nisp-spec-absolute-standards` Targets and pointing constraints -------------------------------- :command:`Pointing`: VIS straylight supression: :math:`{\rm AA}\leq-3.5`. Scheduling must verify that no considerable order-overlap occurs for the first order. This can tightly constrain the times at which a particular grism can be calibrated. .. csv-table:: **HST CALSPEC standards**. :download:`CSV file ` :widths: 20, 18, 18, 10, 10, 10, 35 :file: tables/targets-nisp-spec-absolute-standards.dat .. csv-table:: **HST CALSPEC standards visibility**. :download:`CSV file ` :widths: 20, 50, 50 :file: tables/nisp-spec-absolute-standards_visibility.dat Instrument configuration ------------------------ Instrument: Wide survey Methodology / Uplink procedure ------------------------------ :command:`Entity`: VIS & NISP :command:`Commanding Method`: NISP: Observation, VIS: Science :command:`Dither Sequence`: ROS_RGS000, ROS_RGS000_rot, ROS_RGS180, ROS_RGS180_rot, ROS_BGS000 The dither offsets are as follows: .. |RGS000_0_WD| image:: ../images/RGS000_0_WD.png :scale: 20% .. |RGS000_-4_WD| image:: ../images/RGS000_-4_WD.png :scale: 20% .. |RGS180_0_WD| image:: ../images/RGS180_0_WD.png :scale: 20% .. |RGS180_+4_WD| image:: ../images/RGS180_+4_WD.png :scale: 20% .. |BGS000_WD| image:: ../images/BGS000_WD.png :scale: 20% +----------------+------------------+ | |RGS000_0_WD| + |RGS000_-4_WD| + | RGS000 + RGS000_rot + +----------------+------------------+ | |RGS180_0_WD| + |RGS180_+4_WD| + | RGS180 + RGS180_rot + +----------------+------------------+ | |BGS000_WD| + + | BGS000 + + +----------------+------------------+ :download:`RGS000 dither offset ` (also for the rotated position) :download:`RGS180 dither offset ` (also for the rotated position) :download:`BGS000 dither offset ` Inter-operability constraints ----------------------------- None In-orbit duration ----------------- :command:`In-orbit Duration`: 122.3 h ``80*5 = 400`` executions of a ROS_D1-like observation Data volume ----------- ``400*ROSD1 = 521200 MB`` Processing input ---------------- :command:`Ground Processing Input Data`: All calibration products to run the standard science pipeline (BPM, darks, flat, nonlinearity, etc), reference measurement of standard star, RSR curves (relative spectral response of the system (mirrors, optics, instrument) :command:`Data Description`: Processing output ----------------- Absolute spectro-photometric transmission as a function of source position in the focal plane. Required accuracy, constraints ------------------------------ The measured spectro-photometric response is within the expectations from the known system transmission and detector QE curves. Processing tools ---------------- L1 science pipeline and absolute calibration pipeline, additional offline trend analysis of flux measurements Quality control parameters -------------------------- DataModel: ``_ Contact person -------------- NISP-S calibration scientist .. raw:: latex \clearpage