CUTE Signal to Noise CALCULATOR Help Page

Overview

This is the online help pagefor the CUTE signal to noise calculator. Please note that this calculator provides only approximate estimates for CUTE observations. Please report inconsistencies and bugs.

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Source Parameters

Temperature

Temperature of a star in kelvin. The stellar models are selected based on temperature and will set the shape of the stellar spectral energy distribution (SED). The SED is then scaled at earth employing the distance information provided by the user.

  • Allowed Range: 3500 to 104
  • Data type: float

Radius

Radius of the star in solar radii.

  • Allowed Range: 0.9 to 13
  • Data type: float

Right ascension

Right ascension of the star in degrees in J2000.

  • Allowed Range: 0 to 360
  • Data type: float

Declination

Declination of the star in degrees in J2000.

  • Allowed Range: -90 to 90
  • Data type: float

Distance

Distance to the star as parallax in milli arc-seconds.

  • Allowed Range: 1 to 1000
  • Data type: float

Stellar activitiy index

Stellar avtivity index (logR'HK) of the star. This input is used for setting the strength of Mg II line core emission.

  • Allowed Range: -3.5 to -5.5
  • Data type: float

Line core emission

Select this option to add line core emission at the position of Mg II lines in the CUTE band. MgII h&k resonance lines with chromospheric emission cores is added in late-type stars with a strength proportional to the activity of the star. To account for this we implemented the emission assuming that the behaviour of the MgII h&k emission with stellar temperature is the same as that of the CaII H&K emission.

Interstellar medium absorption

The calculator adds extinction following the method described in Sreejith et al. 2019. To add ISM Mg and Fe ISM absorption at the position of the MgI (2852.127 A), Mg II (2795.528 A and 2802.705 A), and Fe II (2599.395 A) resonance lines, please check the add ISM absorption box and specify their coresponding column densities.

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Instrument Parameters

Spectral Resolution

Spectral resolution of CUTE in Angstroms.

  • Allowed Range: 0.001 to 100
  • Data type: float

CCD readout noise

CUTE CCD readout noise in electrons/pixel.

  • Allowed Range: 0.001 to 100
  • Data type: float

CCD dark noise

CUTE CCD dark noise in electrons/pixel/s.

  • Allowed Range: 0.001 to 100
  • Data type: float

CCD gain

CUTE CCD gain in photolectrons/ADU.

  • Allowed Range: 1 to 100
  • Data type: float

Spectrum width

Expected width (in the cross-dispersion direction) of the CUTE spectrum in pixels.

  • Allowed Range: 1 to 512
  • Data type: float

CCD exposure time

CUTE CCD exposure time per observation in seconds.

  • Allowed Range: 1 to 1000
  • Data type: float

CCD read time

CUTE CCD read time per observation in seconds.

  • Allowed Range: 1 to 1000
  • Data type: float

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Transit Parameters

Transit duration

Transit duration of the planet in hours.

  • Allowed Range: 0.01 to 24
  • Data type: float

Number of transit Observations

Number of transits observed.

  • Default: 10
  • Data type: float

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Wavelength Parameters

By default the SNR calculator calcucates SNR in seven bands

  • Full Band : 2518.9-3331.1 A
  • Lower Band: 2518.5-2788.84 A
  • Mid Band : 2789.24-3059.57 A
  • Upper Band: 3059.97-3331.1 A
  • MgII Band : 2792.81-2804.72 A
  • MgI Band : 2849.97-2853.54 A
  • FeII Band : 2582.81-2586.78 A

In addition to the above bands, the user can specify a maximum of 20 wavelength bands.

Output

The Output of the CUTE SNR is SNR in seven bands (plus those given by the user), together with counts noise and SNR per pixel. CUTE SNR calculator works on a scaled version of CUTE data simulator described in Sreejith et al. 2019. The software package for SNR calculator is avaliable for dowload at https://github.com/agsreejith/CUTE-SNR. Please contact us (sreejith.aickara@oeaw.ac.at) for stellar model files.

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Versions, Changelog and Upcoming

Present Version: 1.0.0

Release Date: 20th November, 2020

Versions are denoted using a standard triplet of integers: MAJOR.MINOR.PATCH. The major version will be updated with any changes in the instrument parameters - from calibration results or other updates. Minor version changes with updates in the backend software packages or inclusion of new components. Minor version shall reset to "0" with a change in major version. Finally, the patch gets updated with modifications/bug-fixes in the cgi/scripting components. Patch will be reset to "0" whenever minor or major version gets an update.

Changelog

  • Initial Release: 1.0.0, 20th November, 2020

Upcoming

Here is a list of additions which would be incorporated in the future releases:

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