floyds: a robotic spectrograph for the faulkes telescopes

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.