metrics( peter(yoachim( university(of(washington( cadence(workshop ... ·...

1"LSST"Cadence"Workshop"•"Phoenix"•"August"11;15,"2014"LSST"Cadence"Workshop"•"Phoenix"•"August"11;15,"2014"

Metrics((

Peter(Yoachim(University(of(Washington(

(Cadence(Workshop(August(11=15,(2014(

2"LSST"Cadence"Workshop"•"Phoenix"•"August"11;15,"2014"

LSST"Era"Astronomy"

−  Over"10"years,"LSST"will"make"around"2.5"million"visits"

−  Need"a"tool"to"analyze"~300"log"books"


The"OperaNons"Simulator"(OpSim)"and"Metrics"Analysis"Framework"(MAF)"

−  OpSim"generates"realisNc"10;year"LSST"poinNng"histories"

–  2.5"million"visits"

–  For"each"visit,"record"Nme,"airmass,"ra,"dec,"seeing,"sky"brightness,"filter,"etc."

−  MAF"provides"a"framework"for"visualizing"and"analyzing"the"

scienNfic"usefulness"of"a"survey"


Simple"Metrics"

−  Combine:"

–  Single"columns"from"OpSim"like:"

airmass,"seeing,"sky"brightness"

–  Simple"algorithms"like:"Mean,"Median,"Coadded"depth,"RMS,"etc"


Median"Airmass"


Max"Airmass"


Median"Sky"Brightness"


Coadded"depth"


Number"of"Visits"


Just"a"reminder"that"all"these"maps"come"with"histograms"and"power"spectra"


Single"Visit"Depths"


New"Cadence"Metrics"

−  Astrometry"

−  Supernova"−  Availability"of"templates"

−  Uniformity"


Proper"MoNon"Metric"

Time"

PosiNon"

Error"bar"determined"by"seeing,"image"depth,"

systemaNc"limit"

If"there"are"no"degeneracies"in"the"astrometric"fit,"the"uncertainty"in"the"proper"moNon"is"a"funcNon"of"

the"measurement"uncertainNes"and"the"observaNon"Nmes."

σ1"="FWHM/SNR"σ2"="0.01"arcsec"


Proper"MoNon"Precision"

Assuming"a"20th"mag,"flat"SED"star"and"a"systemaNc"centroiding"limit"of"10"mas"

beDer( worse(


Compare"to"an"“opNmized”"survey"PosiNon"

PosiNon"

Compare"the"observed"precision"to"the"

precision"obtained"by"moving"all"the"

observaNons"to"1st"and"last"day."""


Proper"MoNon"RelaNve"to"“opNmal”"

More(OpGmized(

Less(OpGmized(


Parallax"

PosiNon"

Again,"assume"a"20th"mag"flat"SED"star.""No"proper"moNon"or"degeneracies"in"the"parallax"fit"(not"true"for"1st"6"months"at"least!)"

RA"and"Dec"parallax"precision"calculated"independently,"then"combined."

Time"


Parallax"Precision"

beDer( worse(


Compare"to"an"opNmized"parallax"survey"PosiNon"

PosiNon"

Compare"to"a"survey"where"all"observaNons"are"taken"at"

maximum"parallax"factor"


Parallax"Precision"compared"to"“opNmized”"

90"degrees"away"from"eclipNc,"scheduling"doesn’t"majer"much"(always"at"full"parallax"amplitude).""On"eclipNc,"

scheduling"important"

More(OpGmized(

Less(OpGmized(


Blink"for"fun"


“opNmized”"

PosiNon"

PosiNon"

Note"that"the"“opNmized”"

comparison"only"moves"observaNons"in"

Nme,"and"does"not"consider"things"like"

filter"distribuNon,"

moon"phase,"etc."


Temporal"Uniformity"

CumulaNve"DistribuNon"FuncNon"

Time" 10"years"0"

uniform"

Observed"

Dmax"

0"

100%"


Temporal"Uniformity"

Value"of"zero"is"perfectly"uniform,"value"of"1"would"mean"all"the"observaNons"were"taken"on"a"single"day."

More"uniform" Less"uniform"


FracNon"of"ObservaNons"with"Good"Templates"

For"image"differencing,"we"need"a"pre;exisNng"image"taken"in"similar"or"bejer"seeing."


Supernova"Metric"

−  Say"a"SN"goes"off"every"5"days."−  Check"if"the"SN"is"“well"observed”"(criteria"from"Science"Book)"

–  ObservaNons"in"least"2"filters"near"peak"– Max"gap"of"15"days"near"peak"

–  At"least"1"early"observaNon"–  At"least"1"late"observaNon"–  At"least"7"total"observaNons"–  Only"use"filters"between"300"and"900"nm"in"SN"resnrame"

–  Signal"to"noise"criteria"(not"implemented)"


SN"Light"Curve"

≥2"observaNons"≥2"filters"No"gap"of">15"days"

≥1"obs"

≥1"obs"

≥7"observaNons"

+Only"resnrame"opNcal"filters"


That’s"a"lot"of"if;statements"

for i,index in enumerate(ind): if i <= right_side: pass else: visits = dataSlice[left[i]:right[i]] t = time[left[i]:right[i]] t = t-finetime[index]+self.Tmin if np.size(np.where(t < self.Tless)[0]) > self.Nless: if np.size(np.where(t > self.Tmore)[0]) > self.Nmore: if np.size(t) > self.Nbetween: ufilters = np.unique(visits[self.filterCol]) if np.size(ufilters) >= self.Nfilt: #XXX need to add snr cut here filtersBrightEnough = 0 nearPeak = np.where((t > self.Tless) & (t < self.Tmore)) ufilters = np.unique(visits[self.filterCol][nearPeak]) for f in ufilters: if np.max(visits[self.m5Col][nearPeak] [np.where(visits[self.filterCol][nearPeak] == f)]) \ > self.singleDepthLimit: filtersBrightEnough += 1 if filtersBrightEnough >= self.Nfilt: if np.size(nearPeak) >= 2: gaps = t[nearPeak][1:]-np.roll(t[nearPeak],1)[1:] else: gaps = self.peakGap+1e6 if np.max(gaps) < self.peakGap: result += 1 if self.uniqueBlocks: right_side = right[i] maxGap.append(np.max(gaps)) Nobs.append(np.size(t))"

1""

""

2"3"

4"

5""

"

6""

"7"

8"

"9"


Supernova"Light"Curve"Sampling"

A"new"z=0"SN"goes"off"every"5"days"at"each"healpixel.""How"many"are"“well"observed”?""(max"possible"~700,"we"get"200;300"in"the"WFD"area)"


Supernova"

For"those"well"sampled"SN,"the"median"number"of"observaNons"per"light"curve."


For"well"sampled"SN,"the"median"gap"in"days"near"maximum"light."(max"possible"is"15)"

All"of"these"maps"also"include"histograms,"power"

spectra,"and"any"summary"stats."


Conclusions"

−  We"have"lots"of"metrics"

−  We’d"like"more"


Solar"System"

TBD"


Gaps"in"Observing"

metrics( peter(yoachim( university(of(washington( cadence(workshop ... ·...

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