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LBT Resources

 

The Large Binocular Telescope

  • Two 8.4 meter primary mirrors
  • Alt-Az mount (lower tracking limit ~ 25 degrees above horizon)
  • All currently available instruments are mounted on the telescope.
  • Instrument changes between MODS and LUCI takes ~10 min.  Changing between LBC and either MODS or LUCI on the SX (left) mirror takes up to 30 min. This is because LBC is prime focus and requires moving the secondary int place for LUCI or MODS.
  • Currently Available Instruments:
    1. Large Binocular Camera (LBC) - Red & Blue (right and left mirrors, respectively).  23'x23' FOV with 0.23"/pixel resolution.  LBC blue covers 0.32-0.5 microns, LBC red covers 0.5-1microns.  Simultaneous use available.  A summary of the capabilities of both LBCs can be found here.
    2. LUCI 1 - Near-Infrared Spectrograph and Imager covering 0.85-2.5 microns.  Spectroscopic modes include longslit (0.25", 0.50", 0.75", and 1" wide) and Multi Object Spectroscopy (slitmasks).  Moderate spectral resolution (R = 4100-8500 depending on grating) and 0.25"/pixel spatial resolution (f/1.8 with a 4'x2.8' FOV).  Imaging mode is currently f/3.75 with 0.12"/pix and a 4'x4' FOV.  Can be used simultaneously with LBC Red.  A summary of LUCI's capabilities can be found here.
    3. Multi-Object Double Spectrographs (MODS 1) - Imager and spectrograph covering 0.32-1.1 microns with a 6'x6' FOV.  Longslit and MOS modes are available with R~2000 or R=150-500 prism mode.  NOTE:  There is no atmospheric dispersion correction for MODS, so parallactic angle is important to keep in mind.  A summary of the current capabilities of MODS can be found here.
 

 

LBT WIKIs and Contact Information

  • LBT Observer's Reference Page (WIKI) This is the central source for the most up-to-date information about the telescope and it's instrumentation.  Users and prospective users are encouraged to check this site first.  The latest versions of the instrument manuals are available here.  *Link Temporarily Down*
  • LBTB Wiki.  This site contains the schedule for past, current, and upcoming observing runs for the German partnership for LBT (LBTB).  It also hosts the nightly observing logs (useful for seeing conditions, issues with instrumentation, weather, etc).  The site is password protected, please see B. Rothberg or J. Storm for access.
  • LBT Staff Contact Information.  If you have any questions about using the LBT instruments.  General questions go to LBTO Science Ops.  Specific questions about instruments should be relayed to the appropriate support scientists (see webpage).  The staff is very friendly and knowledgeable, do not hesitate to contact them.
  • NEW Science Operations Cookbook.  This is a new resource page being compiled by LBT Science Operations.
 

 

LBT & Mount Graham International Observatory Information

 

 

Phase I & Phase II Resources

 

Exposure Time Calculators

  • LBC Exposure Time Calculator.
  • LUCI Exposure Time Calculator.
  • MODS: Sensitivity Information can be found here (latest version).  The imaging mode Exposure Time Calculator can be found here.  MODS does not have the ability to compensate for atmospheric diffraction.  To estimate the effects The Ohio State University provides a tool for calculating the parallactic angle.
 

Planning Your Observations

  • Target Visibility Planning. This site allows users to estimate the visibility of their targets for specific nights or longer periods of time. Users can output charts of airmass vs. time. IMPORTANT:  The LBT cannot observe below an elevation of 25 degrees. It also has difficulty tracking at elevations that are nearly overhead (e.g. ~88-90 degrees).
  • Finder Chart Generator.  Resource for generating multi-wavelength finder charts (DSS, SDSS, 2MASS).
  • Telluric Standard Finder.  This webpage allows users to find A0V or G2V stars close to their targets for telluric corrections.  Please use this for LUCFER spectroscopic planning.
  • Optical Spectro-Photometric Standards.  This is a resource for finding optical spectro-photometric standards for flux calibration and removing the instrumental signature from observations.  This is a resource for MODS planning. There is a MODS website with additional information on Spectro-Photometric calibration with MODS.
  • Near-IR Photometric Standards.  The extended UKIRT list provides J,H,K photometric standards for large-aperture telescopes.  Users may wish to these standards for photometric calibrations of LUCI observations.
  • Landolt Photometric Standards.  List and finder charts for Landolt photometric standards (equatorial tarets, ideal for Arizona). The standards listed can be used with large-aperture telescopes. Useful for LBC and MODS imaging.
  • ATRAN:  Synthetic Atmospheric Transmission Simulator.  Web-based generator for ATRAN used to estimate the atmospheric transmission from 0.85 microns and longward. Useful for LUCI observation planning.
 

Preparing Scripts & Masks for Observations

LBT observations are executed using scripts (for MODS and LUCI) and observing blocks (for LBC).  Users are required to generate their own scripts and verify they will work.  Users must also include any calibration scripts (dark frames, arc lamps, flats, biases, etc) they want executed. Please submit your scripts to B. Rothberg for verification before the Phase II Deadline.  They will then be submitted to the LBTB Program Coordinator.  IMPORTANT - Make sure the scripts have the correct partner information: LBTB.  Otherwise you will NOT be able to access your data from the archives.

  • LBC Observing Blocks.  This webpage presents information for generating and visualizing observing blocks (OBs) for LBC Red & Blue.  Software can be downloaded from here.
  • LUCI Scripts.  This webpage hosts example scripts for LUCI (including calibration scripts).  Spectroscopic observations require two scripts, one for acquisition, the second for the actual observations.  The LUCI manual provides additional information on syntax and settings for various configurations.  There is a script generator available from MPIA here. IMPORTANT:  Make sure all imaging, including spectroscopic acquisition, uses the N3.75 camera, and NOT the N1.8 camera. Provide ALL calibration scripts required, even if one is using a "standard" observatory script.
  • LUCI Masks.  This webpage provides information and software (LMS) for generating multi object slit masks for LUCI.  There is a separate manual for information on LUCI masks.
  • MODS Scripts.  This webpage provides information and software (modsTools) for generating imaging and spectroscopic scripts for MODS.  There is separate manual for MODS scripts that users are encourage to read. Calibration scripts and information can be found here.  IMPORTANT:  Provide ALL calibration scripts required, even if one is using a "standard" observatory script.
  • MODS Masks.  This webpage provides information and software for creating masks for use with MODS.
  • Dual Instrument Mode (MODS or LUCI + LBC-Red):  If LBC-Red is used as the secondary instrument, then the OB blocks must be modified from the standard syntax to avoid cross-talk between the two instruments and the telescope. Currently, the method is to create two OBs for each target.  The first is a single OB giving the target information (coordinates, instrument configuration, etc) but with NDIT=1 and a short exposure.  After execution of this OB, a second OB is used which provides the number of exposures, dithers, etc.  This second OB must have dec=-90deg.  The telescope interprets this as a flag to not send a preset to the telescope (i.e. to avoid moving the telescope).  In this scenario, only MODS or LUCI sends presets.   If you have an approved dual-mode program please contact the LBT Support staff well in advance of the run.  This mode is still in "beta" testing.
 

Visualizing Your Observations & Script Checking

  • LBTView.  Tcl/Tk plugin for ESO Skycat.  NOTE:  This utility is no longer supported and users are encouraged to migrate to the newer, Python based luciView and modsView.
  • MODSView. Python visualization tool for planning MODS observations.  Allows you to view targets and guidestars overlaid with various MODS slits and multi-object slit masks (requires mms mask files).  Use this to select guidestars for your program and to verify that your observing scripts will operate correctly at the LBT.  *UPDATE* in MODSView do not use the bottom 1/3rd of the guidebox (cyan) that sticks out beyond the green FOV of the MODS array to select guidestars - this is actually beyond the guideprobe patrol area.
  • LUCIView Python visualization tool for planning LUCI. Allows you to view targets and guidestars overlaid with various LUCI slits and multi-object slit masks (requires lms mask files) or imaging field.  Use this to select guidestars for your program and to verify that your observing scripts will operate correctly at the LBT.
  • LUCI-Check.  Python script checker.  This software will load DS9 to visualize the placement of guidestars and verify that all aspects of the acquisition and instrument scripts will operate.
  • LBC. Please use the LBC Observing Blocks webpage for more visualization and verification information.
 

 

Retrieving Your Data

 

 

Data Reduction

Currently, there is no official pipeline software for LBT instruments.   The main LBT Wiki has some information on scripts provided by LBT partner members.  This section will be continually updated to provide users guidance with reducing and analyzing their data.  IRAF scripts have been created by some AIP users, see B. Rothberg for more information about LBT data reduction with IRAF.

  • AIP/LBT Google Groups:  This is an in-house Google Groups page for AIP users of the LBT.  The forums are for posting hints, tips, techniques and discussion about all aspects of LBT usage.  Please see B. Rothberg if you would like to join.
  • IRAF (and PyRAF) are the preferred reduction and analysis packages for many of the available scripts.  If you would like to install IRAF/PyRAF on your machine there is a Linux version (Scisoft) which is officially supported by ESO.  Scisoft/ESO includes several other software packages in addition to IRAF.  There are also a few Mac OSX versions, including Scisoft OSX (an OSX fork of the ESO software which is privately supported by a handful of individuals).  Users may also wish to manually install these software packages by going to the IRAF download and the PyRAF download pages.
 

MODS

  1. MODS data reduction scriptsPython scripts developed by The Ohio State University.  These scripts will bias subtract, trim, and apply pixel (slitless) flatfield corrections to MODS data.  In the case of Red Grating data, it will flip the x-axis so that wavelength increases towards the right.
  2. MODS is tilted in both the spectral and spatial directions.  Corrections must be made to both before extracting spectra.
  3. COMING SOON:   Wavelength calibration plots, information, and IRAF reduction scripts.
 

LUCI

Guideline to LUCI Longslit Data Reduction - this provides a general guideline for reducing LUCI longslit data with a focus on IRAF tasks and commands.

(General Notes)

  1. There has been a shift over time in the part of the array illuminated by the spectroscopic unit.   Vertically, this can be a shift as large as 40 pixels or more.  This is likely due to movement by the flexure compensation mirror in the light path. Please be sure to check that the area of the array illuminated in calibrations (flat field exposures and arc lamps) match those of your observations.  The shift has been detected on the last LBTB run (Nov 26-Dec 1).  Repeated changes in Position Angle may make the shift occur more often.  If possible, keep PA changes to a minimum.  The staff is aware of this and actively attempting a fix.
  2. It is recommended to refer to Rousselot et al. for OH skyline lists or Argon and Xenon line lists from ESO (available here) to wavelength calibrate LUCI spectra.  Preliminary plots and line lists are available below.
  3. Rectification:  Spectral lines are curved in all LUCI spectroscopic modes.  The curvature is only in the spatial direction.  Recently, we have checked for any curvature or tilt in the dispersion direction using stellar spectra obtained in 2013B. There is no evidence for a tilt or curvature.  The dispersions are straight to within +/-0.5 pixels.
  4. Telluric Corrections.  We recommend XTELLCOR, An IDL-based package used to remove the effects of atmospheric telluric absorption lines at red and near-IR wavelengths.  The software was originally designed for the Spex cross-dispersed 0.8-5 micron imager/spectrometer at the NASA Infrared Telescope Facility.  Included is the "xtellcor_general" package which can be used with any data sets. IMPORTANT: The software requires observations of A0V telluric standards to work.  It removes the telluric features and provides an approximate (+/- 20%) flux calibration for the data.  The general package takes ascii files as input.  The input must include wavelength and flux, but can also accept errors (this is highly recommended).  Input data should be in counts or DN per second in order for flux calibration to produce acceptable results.  The software can be downloaded from this link.  The README file provides general information.  For more information please see the XTELLCOR reference paper.  For questions about its use with LUCIFER, contact B. Rothberg.
  5. Resolution:  The reported resolutions for LUCI (manual and webpages) do not appear to match actual data.  At H-band, with the 0.5" slit, the measured resolution is R~5500.  At larger slitwidths in H-band the resolution scales to match this value.  Currently, we are checking other gratings and slitwidths.  It is critical that you measure the FWHM of arc lines or resolved skylines for your own data to assess the true resolution, do not simply quote the manual.  The reason for the discrepancy is that the values presented in the manual are theoretical assuming a perfect 2pixel slit and do not account for degradations due to the optics.  Empirical resolution measurements are underway for other settings.
 

LBC

  1. There are no official pipelines are IRAF scripts available for data reduction.  However, preliminary IRAF scripts are available from B. Rothberg, and another pipeline has been adapted to work with LBC with excellent results.  More information will be posted soon.
 

 

The LBT H-band Spectral Library

An LBT bad-weather program designed to provide spectra for  template matching and stellar libraries. At the central wavelength, 1.65 μm, it provides R~5500 resolution.  Version 0.1 is now available.  Anyone interested in joining this project, please contact B. Rothberg.

LBT
Last update: 15. February 2021