ITC Release Notes

Updated August 30, 2024, by astephens

Content owned by astephens

2024B.1.1.4 released 2024-Aug-30

Update IGRINS-2 throughput to match on-sky measurements.
Display the IGRINS-2 peak signal + background for both H and K detectors
Return a multiple of 4 exposures when calculating the IGRINS-2 integration time to achieve a S/N

2024B.1.1.1 released 2024-Jun-04

Set the GMOS read noise according to the read mode
Update the GNIRS HR-IFU throughput
Initial support for IGRINS-2
Fix minor bug where the F2 ITC fails to calculate peak signal with R3K + Y or H
Fix error in displayed final S/N when specifying the S/N and using coadding
Fix bug where GMOS ITC showed incorrect analysis method when requesting S/N at λ

2023B.1.1.1 released 2022-Jun-06

Add support for GNIRS IFUs
Update GMOS B480 grating curves
Support calculating exposure time & number of exposures to achieve S/N (GMOS)
Fix Flamingos-2 R3K m=5 throughput
Fix sampling of redshifted SEDs
Fix broken help link

2022B.1.1.1 released 2022-Jun-01

Support using exact IQ and CC and display the equivalent percentile bin
New Flamingos-2 JH and HK filter curves
Add NIRI telescope port selector which defaults to up-looking

2021A.1.1.1 released 2020-Dec-09

Fix the GMOS summed IFU S/N plot so that it includes the background from all the fibers
Fix the overhead calculation when supplied a S/N and a source fraction less than 1
Give an error if the GMOS IFU spatial binning is not 1
Add support for the GMOS B480 gratings
Show the input AO parameters and field lens configuration in the output

2020A.1.1.1 released 2019-Dec-03

Display the GMOS detector ROI in the web output
Relabel "Total Time" in ITC output as "Program Time"

2019B.1.1.1 released 2019-Jun-03

Show GSAOI estimated FWHM even with uniform surface brightness sources
Add cool star model SEDs
Add planet SEDs
Add warning when read noise limited

2019A.1.1.1 updated 2018-Dec-11

Change ITC plot colors to be the same for all instruments
Add support for GMOS-N ri filter

2019A.1.1.1 released 2018-Sep-14

Include observing overheads (all instruments except GSAOI)
Add support for summing GMOS-S IFU elements
Include cloud extinction in Altair Strehl calculation
Fix the printed output units for power-law SED

2018B.1.1.1 released 2018-May-31

Remove unnecessary WFS selection
Add support for summing GMOS IFU elements
Fix exposure time for GMOS Nod-and-Shuffle observations in OT interface
Automatically set GSAOI Strehl in the ITC web form
Clean up the ITC web forms
Relabel obsolete components in the ITC web forms
Fix NIRI filters in which require unnecessarily wide input SED
Fix failures with power-law input SED
Fix failure when user-supplied SED range is too large

2018A.1.1.1 released 2017-Nov-28

Add support for GNIRS spectroscopy with Altair
Add support for GMOS IFU-2 observations with the Hamamatsu detectors
Updated mirror reflectivity data
Display GMOS peak counts as fraction of saturation limit
Fix bug with redshifted emission lines
Fix bug with GNIRS XD 111 l/mm grating

2017A.1.1.2 released 2016-Dec-7

A bug in calculating the peak signal for GMOS-S with the Hamamatsu detectors has been fixed
Update NIFS gain and linearity limits

2016B.2.1.1 released 2016-Jul-26:

Fix the ITC spectroscopy 1-pixel signal to correctly account for slit width

2016B.1.1.2 released 2016-Jun-3:

The "Signal" graph is now for 1-pixel
Display spectroscopy peak counts in ADU, electrons, and % full-well
Give nonlinearity and saturation warnings for spectroscopy
Add support for GNIRS imaging
Support binning in the GMOS IFU-2 pixel-space graph
Give a warning when the GMOS IFU uses 4x spectral binning
Increase NIRI + Altair maximum guide star distance to 45"
Add Y-band to the brightness normalization options
Add IFU details to GMOS ITC web interface
Add links to the GMOS IFU-2 pixel-space graph data
Fix F2 optimal aperture with uniform surface brightness spectroscopy
Fix ITC K0III star SED
Discourage spatial binning with the GMOS IFU

2016A.1.1.2 released 2015-Dec-2:

2012-Sep: GSAOI ITC initial release

2012-Jan: F2 ITC initial release, inactive options removed

2012-Jan: Default GMOS-N CCD type set to "EEV DD array", inactive options removed

2011-Sep: Default GMOS-N CCD type set to "EEV array"

2011-Feb: Changed CC90 to CC80. Added GMOS-N Hamamatsu CCD options.

2007-May-24: Added LGS support for NIRI. Merged NIRI and NIRI+Altair. Added support for NIFS + P2. Minor form changes.

2006-May-24: Fixed bug with minimum emission line width that affected all the instruments. Also added HK notch filter for NIRI.

2006-Feb-28: NIFS added to the list of available ITC's. Added support for Michelle Polarimetry in the imaging mode. New filters added for GMOS South.

2005-Jun-23: All v4.0 ITC running on new server for improved calculation speed. New near-IR and mid-IR background files and updated throughputs provide improved match to observed performance. Background and atmospheric transmissions models are high resolution for Michelle echelle. Michelle spectroscopy re-enabled. Background and atmospheric transmissions models are high resolution for GNIRS R=18000. T-ReCS re-enabled.

2005-Mar-2: Gemini North ITCs (GMOS North, NIRI including Altair, Michelle) now default to silver (primary and secondary) mirror coating

2003-Aug-29: Added Altair + NIRI ITC, implemented as a modification to the NIRI ITC.

2003-Jun-25: Updated T-ReCS "extra low frequency noise" parameter with on-telescope measured performance, better by a factor of 2.

2003-Apr-17: major changes to T-ReCS ITC. Detector properties now correspond to pre-ship AT performance which shows significantly elevated "extra low frequency noise" (ELFN). Updated filter list and filter transmission profiles. Added spectroscopy options (gratings, slits).

2003-Apr-17: added image quality data at 1.2um when using PWFS to improve interpolation accuracy. See the observing condition constraints for details.

Bug discovered 2003-Mar-5: the GMOS South ITC output incorrectly reports that it is using the GMOS North CCD properties. It is actually using the correct file. [fixed in v3.0]

2003-Mar-4: updates for semester 03B Call for Proposals. Added GMOS-S (currently assumes same optical properties as uses same files as GMOS-N but with blue-optimised detectors). NIRI (v3.1) spectroscopy internal background degraded to take account of grism scattering, predominantly at L but also some performance degradation at K and M).

2002-Sep-4: new releases for all instruments and added Michelle (all v3.0). Revised image quality percentiles (was [20%, 50%, 80%, any] to [20%, 70%, 85%, any]). New graphics package.

2002-Mar-11: new releases for NIRI, GMOS, T-ReCS and AcqCam (all v2.0). Changes include: revised 80%-ile image quality and 70%-ile, 90%-ile and "any" cloud cover constraints, GMOS multiple IFU elements, upload of user-defined input spectra, plus many other changes. See the v2.0 release notes for details.

2002-Mar-8: Changes included in the v2.0 releases:

2001-Oct-26: corrected GMOS R400 grating dispersion to 0.0673nm/pixel (was 0.0852nm/pixel)

Bug discovered 2001-Sep-13: when GMOS spectral binning of 2 or 4 is selected, the wavelength range is not calculated correctly [fixed 2001-Sep-19]

2001-Sep-12: updated releases of NIRI (v1.2) and GMOS (v1.1) ITCs. Both include ASCII output spectra; GMOS includes first IFU implementation and R831 grating. First release of T-ReCS ITC (v1.0).

Bug discovered 2001-Sep-11: - found in testing T-ReCS ITC that thermal emission from telescope was not being correctly applied. Will also have affected NIRI thermal (4 and 5um) calculations [fixed 2001-Sep-12]

Bug discovered 2001-Aug-28: - in calculation of flux in 'peak' pixel for uniform surface brightness emission, flux is not updated when source brightness is changed although total signal in sq arcsec is calculated correctly (all ITCs) [fixed 2001-Sep-1]

2001-Aug-8: GMOS fixed-optics throughput file updated after initial on-telescope tests; slightly less throughput at blue wavelengths

Bug discovered 2001-Mar-14 - rarely, if the wavelength of the emission line SED is given to 3 decimal places the ITC returns "null"; the workaround is to specify with a precision of only 2 d.p. or change the wavelength slightly

2001-Mar-2: update of NIRI ITC for 2001B Call for Proposals; release of GMOS and AcqCam ITCs.

Bug discovered 2001-Feb-19 - when the noise from the source flux is larger than the background, the ITC issues the warning "not background limited", even when the background noise still exceeds dark and readout noise. Whilst strictly true, the ITC should note that the observation is source noise limited.

Bug discovered 2000-Nov-16: in NIRI ITC, 'forward' calculation of total S/N does not given the same results as the 'reverse' calculation of integration time. Forward calculation actually gives the correct result.[fixed 2001-Feb-21]

2000-Aug-30: First public release of NIRI ITC.

Support for GMOS IFU-2
Set the default number of GMOS IFU sky fibers
Support u' and Y filters as brightness normalizations
Show peak counts in ADU and full-well fraction
Support the F2 R3K grism
Remove unused sky aperture from IR instruments
Update Flamingos2 ITC filter transmission data
- User-defined source spectra can be used instead of the existing template and model SEDs. Note the following restrictions on file format:
  - Two space-separated columns: (1) wavelength in nm (2) flux density in arbitrary units. Files can have any number of comment lines, each starting with the # character, and any number of blank lines.
  - Wavelength interval need not be uniform.
  - Flux density must be in wavelength units (e.g. per nm or per um, but not per Hz).
  - Wavelength range must extend to include the requested normalization filter (or wavelength). For example, a user-defined spectrum for T-ReCS must extend to below 2000nm if the source brightness is defined in the K-band.
  - File size must be less than 1MB.
- 80%-ile image quality degraded to provide better sampling of the range of expected conditions. The corresponding image size is defined in the observing condition constraints.
- Cloud cover constraints for 70%-ile, 90%-ile and "any" bins changed to provide better sampling of the range of expected conditions. The corresponding transmission is defined in the observing condition constraints.
- Input parameters are now reported in full at the bottom of the results page.
- Performance improvements of 35-40% for imaging and spectroscopy calculations were achieved.
- NIRI changes:
  - Transmission curves updated for several narrow-band filters {specify}
  - Slid width and corresponding spectral resolution updated for 6-pixel center slit to match new physical slit. User interface now defines slit width in pixels (was in arcsec) to be consistent with PIT and OT and to avoid future updates when small changes are made.
- GMOS changes:
  - Size of IFU element corrected (hexagonal input aperture approximated by 0.19 arcsec square; was 0.21 arcsec).
  - Added radial range of IFU elements to extend previous single-element case. IFU elements have offsets of 0.20 arcsec. As before, the S/N is calculated for individual elements.
  - All gratings (including those not currently installed) made available for ITC.
- T-ReCS changes:
  - Integration time now specified explicitly, replacing specification using individual frame time and number of frames. As a placeholder, frame times of 20ms and 100ms are assumed for imaging and spectroscopy calculations.
  - Added non-stellar SEDs for planetary nebula, starburst galaxy, pre-main sequence star and the Galactic center. SEDs derived from ISO spectra.