Rubin Observatory LSST SCs

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Rubin Observatory LSST SCs

Rubin Observatory LSST SCs

time-domain

Solar Sytem transients and moving objects

Galactic transients and variables

planets, flaring stars

extragalactic transients

for cosmology and astrophysics

SNe - GW - TDE -

Rubin Observatory LSST SCs

static sky

Morphology

of galaxies and

galactic structures

Low Surface Brightness

science

Weakly coherent fields

Weak lensing

LSS

Rubin Observatory LSST SCs

time-domain

static sky

Solar Sytem transients and moving objects

Galactic transients and variables

planets, flaring stars

Galactic structures moving cohesively at the edge of detectability

streams

Morphology

of galaxy and

galactic structures

Low Surface Brightness

science

Weakly coherent fields

Weak lensing

extragalactic transients

for cosmology and astrophysics

SNe - GW - TDE -

Rubin Observatory LSST SCs

Time domain Rubin LSST science

1

• streaks masking removes timestamps from time series : efficiency loss                                                                             
• avoidance algorithms prevent scheduled observations : efficiency loss                                                            
• compromises rapid follow-up                                                                                      
• flares confuse variability measurements                                                                   
• streaks correction at best decreases SNR and reliability of variablity metric                                       

Time domain Rubin LSST science

Iridium satellite number 35 lit up the predawn sky west of Boston at 5 a.m. EST on February 1, 1998,  Sky & Telescope

Satellite flares

Time domain Rubin LSST science

can be mitigated:

- orientation of satellite,

- directing flares away from observer

- knowing coordinates to associate them to alerts

if not mitigate there would be bogus alerts and images ruined by saturating flares

Hainaut & Williams 2020

https://arxiv.org/abs/2003.01992

Time domain : the LSST observing strategy

fast/dense

regular/persistent

deep

wide

single-filter

obs density

color

 8oo img over 18,000 sq deg

 pairs of observations in <1hour to track asteroid (and get transient colors)

Tensions in strategy design

Deep Drilling Fields

Minisurveys

Rothchild+ 2019

https://arxiv.org/abs/1903.00531

Tyson+ 2020

https://arxiv.org/abs/2006.12417

modification to planned schedule carry long lasting consequences on the program

ToO enabled for GW need to scan ~100 sq deg footprint upon trigger - will be compromised

Time domain : the LSST observing strategy

Astronomy’s Discovery Chain

Discovery Engine

10M alerts/night

Community Brokers

target observation managers

Time domain: the astronomy discovery chain

Spectrograph and Camera for Observations of Rapid Phenomena in the Infrared and Optical (SCORPIO)

designed for rapid and efficient follow up of LSST transients

8-channel imaging spectrograph currently in development for Gemini South.

dynamic queue scheduling software to optimize the planning and execution of all observations as new follow-up targets are triggered during the course of the night.  

follow up scheduling will have to include satellite locations 

time sensitive targets may be lost: e.g. GW

impact on follow-up

Time domain: the astronomy discovery chain

Time domain: unknown phenomena

our ability to discover unknown phenomena is compromised by gaps in observations

- get images in different filters within ~1hour

- get images in the same filter with log-uniform time gaps

Xiaolong Li, Fabio Ragosta, Will Clarkson, FBB

in prep

Observing strategy to be decided by end 2020

Lynne Jones 

Peter Yoachim

75 simulations of potential observing strategy

2

• static sky depends on achieving ~800 images on ~18,000 sq degree.          LSST may need to be extended >10 years to achieve the science requirements     

​                                

• cross-talk introduces systematics

• twilight observations may be impossible

cross-talk suppression

Tyson et al. 2020

https://arxiv.org/abs/2006.12417

Static sky Rubin LSST science

Static Sky: correlated noise and cross talk

Cosmology probes are systematic dominated

mitigation: simulation of the non-linear crosstalk to measure the effect on precision cosmology and effectiveness of removal algorithms

(image credit: Canada-France Hawaii Telescope)

Tyson et al. 2020

https://arxiv.org/abs/2006.12417

Static Sky: twilight observations 

Twilight observation programs are needed to calibrate the bright end of the color-magnitude diagram

We find that between 40 and 90% observations taken in twilight, depending on the number of satellites, have at least one trail.

LSST saturation limit: 17

Gaia magnitude limit: 17

Tyson+ 2020

https://arxiv.org/abs/2006.12417

Hainaut & Williams 2020

https://arxiv.org/abs/2003.01992

Solar System Rubin LSST science

3

2l/Borisov

• twilight observations lead to
  • NEO discoveries
  • Comets discoveries
  • Interstellar objects

https://arxiv.org/pdf/1812.00466.pdf

R. Seaman et al. 2018

https://en.wikipedia.org/wiki/2I/Borisov

Solar System Rubin LSST science

• efficiency in NEO recovery peaks with images  20 minutes apart
• any missed image would decrease detection efficiency even extending the 10-year timeline