LEOsats - American Astronomical Society...Iridium satellite number 35 lit up the predawn sky west of Boston at 5 a.m. EST on February 1, 1998, S k y & Teles c o p e Satellite ﬂares

scientific impact of LEOsats:

the Rubin LSST Science Collaborations perspective

University of Delaware

Department of Physics and AstronomyBiden School of Public Policy and Administration

Data Science Institute

Rubin Legacy Survey of Space and TimeScience Collaboration CoordinatorTransients & Variable Stars Science Collaboration CoChair

federica bianco

Rubin Observatory LSST SCs

federica bianco [email protected] @fedhere

Science Collaborations

We aspire to be an inclusive, equitable, and ultimately just group and we are working withrenewed vigor in the wake of the recent event that exposed inequity and racism in our society

to turning this aspiration into action.







time-domain static skySolar Sytem transients and

moving objects

Galactic transientsand variables

planets, flaring stars

extragalactic transientsfor cosmology and

astrophysicsSNe - GW - TDE -




Morphologyof galaxies and

galactic structures

time-domain static sky

Low Surface Brightnessscience

Weakly coherent fieldsWeak lensing

LSS

Solar Sytem transients andmoving objects


planets, flaring starsGalactic structures

moving cohesively atthe edge ofdetectability

streams






time-domain static skySolar Sytem transients and

moving objects


planets, flaring starsGalactic structures

moving cohesively atthe edge ofdetectability

streams

Morphologyof galaxy and

galactic structures

Low Surface Brightnessscience

Weakly coherent fieldsWeak lensing







Time domain Rubin LSST science

1streaks 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





Iridium satellite number 35 lit up thepredawn sky west of Boston at 5 a.m. EST on

February 1, 1998, Sky & Telescope

Satellite flares



can be mitigated:- orientation of satellite,

- directing flares away fromobserver

- knowing coordinates toassociate them to alerts

if not mitigate there would

be bogus alerts andimages ruined bysaturating flares


Hainaut & Williams 2020

https://arxiv.org/abs/2003.01992


federica bianco [email protected]

Science Collaborations@fedhere

Time domain : the LSST observing strategy

fast/dense

regular/persistent

deep wide

single-filterobs density

color 8oo img over 18,000 sq deg

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

Tensions in strategy design

Deep DrillingFields

Minisurveys

Rothchild+ 2019https://arxiv.org/abs/1903.00531




Tyson+ 2020


modification to planned schedule carrylong lasting consequences on the program

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

Time domain : the LSST observing strategy



Astronomy’s Discovery Chain

Discovery Engine10M alerts/night

@fedhere

Community Brokers

targetobservationmanagers


Time domain: the astronomy discovery chain



Spectrograph and Camera forObservations of Rapid Phenomenain the Infrared and Optical(SCORPIO)designed for rapid and efficientfollow up of LSST transients8-channel imaging spectrographcurrently in development for GeminiSouth.

dynamic queue schedulingsoftware to optimize theplanning and execution ofall observations as newfollow-up targets aretriggered during the courseof the night.

follow up scheduling will have to includesatellite 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 unknownphenomena 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 prepObserving 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 sciencerequirements

cross-talk introduces systematics

twilight observations may be impossible

cross-talk suppression

Tyson et al. 2020


Static sky Rubin LSST science




Static Sky: correlated noise and cross talk

Cosmology probes are systematic dominatedmitigation: simulation of the

non-linear crosstalk to measurethe effect on precision

cosmology and effectiveness ofremoval algorithms

(image credit: Canada-France Hawaii Telescope)

Tyson et al. 2020





Static Sky: twilight observations

Twilight observation programs areneeded 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: 17Gaia magnitude limit: 17

Tyson+ 2020


Hainaut & Williams 2020





Solar System Rubin LSST science

3Science Collaborations

2l/Borisovtwilight observations lead to

NEO discoveriesComets discoveriesInterstellar objects

https://arxiv.org/pdf/1812.00466.pdfR. Seaman et al. 2018

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

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

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


Solar System Rubin LSST science


efficiency in NEO recovery peaks with images 20minutes apartany missed image would decrease detectionefficiency even extending the 10-year timeline



Rubin observations: sliver lining and conclusions

if 10-year timeline is extended the proper-motion studies would benefit

some science would benefit from 2x15

second exposures vs 1x30-sec(saturation limit is lower)

silver linings: conclusions:

to quantify the extent of the impact ofLEOsats on science requires simulationsand analysis which requires significant

resources that are currently not scoped byanyone ...


Scientific Impact of LEOsats:

the LSST Science Collaborations perspective

thank you!

Documents

LEOsats - American Astronomical Society...Iridium satellite number 35 lit up the predawn sky west of Boston at 5 a.m. EST on February 1, 1998, S k y & Teles c o p e Satellite ﬂares