Download - SALT HRS Lisa Crause for Durham CfAI & SALT Ops SALT Board Meeting #35, Chapel Hill, 5 June 2014
SALT HRS
Lisa Crause for Durham CfAI & SALT Ops
SALT Board Meeting #35, Chapel Hill, 5 June 2014
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
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
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
MODE SPECIFICATION ACHIEVED
Low Resolution 12700 12700 15000 14000
Medium Resolution 33000 33600 43400 39600
High Resolution 58000 62300 66700 73700
High Stability P-fibre
High Stability O-fibre
58000 6230058000 62300
66900 6460094600 84200
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
Instrument Throughput
• HRS fibres & comparable fibre-fed échelles
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
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
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
Arc Line Stability
• Normalised flux of internal arc lines over 3.5 days, the line stability requirement is 10% (rms) over 12 hours:
Arc Line Stability
• Line width measurements over 3.5 days, the stability requirement is 1% (rms) over 12 hours:
High Stability Frames
Sky
Flat
+ Iodin
e Cell
Simulta
neous
ThAr
Inte
rnal
HS Arc
Assorted HRS Frames
Blue
MR
ThAr+
Ar
ArcRed
LR
ThAr+
Ar
Arc
Red H
R
QTH Fl
at
V=16.5
CSPN
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
HRS SV Results & Feedback
• “HRS iodine agrees beautifully with the other FTS scans! See attached.” – David Gilbank @ SAAO
HRS MMI – Astronomer GUI
• SALT Astronomers are now running the instrument
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!
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
The Last Word...