floyds: a robotic spectrograph for the faulkes telescopes
TRANSCRIPT
FLOYDSA Robotic Spectrograph
for the Faulkes Telescopes
Griffin HosseinzadehLCOGT/UC Santa Barbara
Hotwired-IV ― MJD 57157.74
An acronym, but barely
Folded
Low-
Order
Yte-Pupil (“white”)
Double-Dispersed
Spectrograph
Optical Design
fold mirror
grism
slit
collimator camera
fiber from calibration lamps
Raw Images
Why FLOYDS?
● Supernova classification and follow-up– Low resolution
– Wide wavelength range in a single shot
Basic Specifications
Spectrograph
Wavelength Coverage 320 – 1000 nm
Resolving Power 315 – 690
Slit Size 1.2, 1.6, 2.0, and 6.0 × 30 arcsec
Typical Exposure Times 30 min for 16 mag (S/N ~ 30 in r-band)
1 hour for 19 mag (S/N ~ 10 in r-band)
Readout + Write Time 25 s
Arc + Flat Exposure Time 100 s
R =λΔ λ
Guiding Camera
Field of View 6.4 × 4.3 arcmin
Pixel Scale 0.5 arcsec
Exposure Time 10 s
Acquisition Time 30 s (in clear conditions)
Why FLOYDS?
● Supernova classification and follow-up– Low resolution
– Wide wavelength range in a single shot
● Robotic scheduling and control
ASAS-SNLSQ
Pan-STARRS
iPTF
Why FLOYDS?
● Supernova classification and follow-up– Low resolution
– Wide wavelength range in a single shot
● Robotic scheduling and control– Can be triggered on discovery alerts
– Available all night every night of the year, weather permitting (even full moon!)
Robotic Pointing
supernova
slit
Robotic Pointing
But it's not always so easy
● Seeing & slit width ≈ 2.0 arcsec● Coordinates can be inaccurate● Weather● Flexure in instrument (slit moves)
But it's not always so easy
supernova
slit
bright galaxy core
Improvements
● Dynamically locate slit (implemented)● Acquire on brightest (now being tested)● Bad weather dissipation system
(early planning phase)
Automatic Data Reduction
● floydsspec pipeline by Stefano Valenti
● Written in Python, based on IRAF routines● No human intervention needed:
– Image pre-processing
– Aperture extraction
– Host & sky subtraction
– Wavelength calibration (HgAr arc lamp)
– Flux calibration (standard star)
– Supernova classification! (SNID)
It Works!
adsabs.harvard.edu/cgi-bin/nph-abs_connect?library&libname=FLOYDS
Robots Triggering Robots
● iPTF survey camera takes an image● iPTF software identifies a new source● iPTF software notifies LCOGT SNEx robot● SNEx schedules a FLOYDS spectrum● FLOYDS gets a spectrum in Hawai'i● LCOGT cronjob ingests and reduces data● SNID gives a classification● SNEx sends an alert & schedules follow-up
● Dave Sand● Tim Brown● Joe Tufts● Stefano Valenti● Rachel Haynes● Matt Dubberly● Eric Hawkins
Credit Where Credit Is Due
Summary
● FLOYDS is a fully robotic low-resolution long-slit spectrograph.
● This allows for immediate classification and automatic follow-up of transients.
● Currently, our biggest challenge is achieving continuous sub-arcsecond pointing accuracy.