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SALT HRS PowerPoint Presentation

SALT HRS

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SALT HRS

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  1. SALT HRS Lisa Crause for Durham CfAI & SALT Ops SALT Board Meeting #35, Chapel Hill, 5 June 2014

  2. HRS Timeline • 40 foot shipping container to SALT on 3 September 2013 • Unpacked & re-assembled instrument over next 3 weeks • Fibres routed to payload & connected to FIF on 27/28 September • First Light on 28 September • Commissioning & Science Verification through April • Final software arrived in April • Began fully-charged HRS science observations in May

  3. Fibre Instrument Feed & Guider • Both designed & built by SAAO/SALT • Working well & we hope to eventually replace the RSS guider with a copy of the FIF one

  4. Spectral Resolution • Resolving power (R) varies over the échellogram, due to anamorphic magnification from the grating • Table gives specified R at central blaze wavelength for each order & the median R values measured from arc spectra for the blue & red channels • All the modes comfortably beat the specification 

  5. Instrument Throughput • Measured prior to installing the fibres • From the fibre input ends to the CCDs • Used a 50 micron spot @ F/4.2 to simulate input beam from the telescope + a calibrated photodiode for a detector • 4 narrowband LEDs: 460 & 505 nm in the blue + 591 & 625 nm in the red • Also checked fibre cable transmission losses at 460 nm using HS fibres, as expected from fibre specs

  6. Instrument Throughput • HRS fibres & comparable fibre-fed échelles

  7. Total Throughput (HRS+SALT) • A V=8 K2V RV standard star was observed on a photometric night with 1.5” seeing • The blue channel performance is in good agreement with the SALT HRS Exposure Time Calculator predictions

  8. Total Throughput (HRS+SALT) • The SALT HRS Exposure Time Calculator yields estimates that are ~10% too high in the red channel • This requires investigation & the ETC will be updated as needed

  9. HRS Temperature Control • Red = inner room, blue = HRS electronics room, yellow = large spectrometer room • Bumps due to daily vacuum tank pumping • Maintaining a constant temperature in the HRS inner room is critical for RV stability, peak-to-peak amplitude now <0.5C

  10. Arc Line Stability • Normalised flux of internal arc lines over 3.5 days, the line stability requirement is 10% (rms) over 12 hours:

  11. Arc Line Stability • Line width measurements over 3.5 days, the stability requirement is 1% (rms) over 12 hours:

  12. High Stability Frames + Iodine Cell Sky Flat Internal HS Arc Simultaneous ThAr

  13. Assorted HRS Frames Blue MR ThAr+Ar Arc Red LR ThAr+Ar Arc Red HR QTH Flat V=16.5 CSPN

  14. HRS SV Results & Feedback • “We think that the spectra obtained at SALT HRS are good quality and correspond to what we expected. We will be happy to continue to use this spectrograph.” – Vladimir Elkin @ University of Central Lancashire

  15. HRS SV Results & Feedback • “HRS iodine agrees beautifully with the other FTS scans! See attached.” – David Gilbank @ SAAO

  16. HRS MMI – Astronomer GUI • SALT Astronomers are now running the instrument

  17. Technical Challenges Overcome • Installed & commissioned a whole new instrument!! • Shipping injuries: • Blue CCD misaligned  • Broken HS mode fibre  • Since being at SALT: • Mode selector failure  • Dewar warm-ups  • Temp control issues  • All of this has been Hugely educational for the local HRS instrument team!

  18. Remaining Tasks • Replace cryo-cooler filter/dryers to stop dewar warm-ups • Improve insulation & verify temp stability • Improve dewar hold times with ion pumps • Final software ATP • Upgrade SALT Cal Sys • Calibrate iodine cells • Finish documentation • Deliver Quick-Look • Issue final version of commissioning report

  19. The Last Word...