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...