Subaru Ground-Layer AO Simulation

Presentation on theme: "Subaru Ground-Layer AO Simulation"— Presentation transcript:

1 Subaru Ground-Layer AO Simulation
Shin Oya (Subaru Telescope) Subaru Next Generation AO Working Group Sapporo

2 Basic idea of GLAO Corrects only turbulence close to the ground
Improves seeing over wide-filed of view GLAO correction (simulation) Effective for wide field of view

3 Subaru GLAO configuration
f = 15 arcmin r = f/2 DM: 32 act. Across @ -80m LGS: 10 mag TTFGS: 18mag Subaru seeing: good: 0.56” moderate: 0.73” bad: 0.97” (at 0.5 mm) 1 reconstruction layer (0m) by averaging GL ★: HoGS ＋: TTF-GS (between LGS) ■: PSF eval.(toward GS) ▲: (between GS) ＊: DM fitting

4 Seeing dependence of FWHM
@zenith Stalibiy ≡ std / ave GLAO: 1~7% Seeing: 2~10% 実際にmoffatでフィットしたFWHM。NEAは積分しているので、そのstdからFWHMのstdを計算しても正しくないので。%tileは±5% GLAO: solid , Seeing: dotted; error bars shows standard deviation along time axis

5 Seeing dependence of Ensquared Energy
@zenith Gain ≡ GLAO / Seeing ~ 1.5 to 2 時間変動は、エラーバーでプロットされているがほとんど見えない。std/ave ~1% (<3%) width: blue: 0.24"、green: 0.36"、red: 0.48“ GLAO: solid lines, Seeing: dotted line

6 Uniformity of FWHM over FoV
@zenith r = 7.5 arcmin ■ ▲ +3 s/m K-band moderate s/m = std/ave along time ~ 3% -3 s/m normalized by the average over the field

7 FWHM Uniformity for other bands
R (s/m=1.2%) J (s/m=2.4%) +10% @zenith NIR +/-5% H (s/m=2.8%) K (s/m=3.6%) R=0.0117, J=0.0240, H=0.0280, K=0.0362 NIRでは、<~5% (Jの角は10%,Kは3%) difference by seeing condition < 6% -10%

8 Zenith angle dependency: GLAO / Seeing
effective height increases COSOS > 18° SXDS > 25° G.C. > 48° seeing: good moderate bad FWHM NEAから計算したFWHM。45degで10%減、60degで20%減 R: J: H: K: loss by 10% at 45°and by 20% at 60°

9 Seasonal Variation of Seeing
Subaru IQ 13N site, profile Els+09,PASP,121,527(Fig.5) どうも8kmのゆらぎ強度が影響している。 Characteristic months Sep (good) & Mar (bad). 25%-ile Sep (50%-ile) 50%-ile Mar (50%-ile) 75%-ile 0.49" 0.54" 0.64" 0.74" 0.84" Subaru AG

10 Seasonal Variation of FWHM
@zenith Variation +/-30% NEAから計算したFWHM。基本的にシーイングの変化の形が、そのままGLAOに反映される。つまり、シーイング強度がGLAOの性能に一番効く。各月のGLAO補正結果のMedianが、MedianシーイングのGLAO補正より良いのは、シーイングが悪い時は、GLが強いから? あるいはRAVENモデルがGLを過小評価しているから? どのバンドでも季節変動幅は差分で表すとGLAOとシーイングで同じ、R:0.185, J:0.124, H:0.130, K:0.103 GLAO: R: green、 J: blue、 H: magenta、K: red; Seeing: black moderate: dotted line

11 FWHM ratio (GLAO/Seeing) Map
@culmination SXDS (UKIDSS-UDS); RA, DEC (J2000): 02:18:00 -05:00:00; 2020/11/01 peak elevation: ~65 deg COSMOS; RA, DEC (J2000): 10:00: :12:21; 2020/02/15 peak elevation: ~72 deg. Gal. Cntr (glon=0 glat=0); RA, DEC (J2000): 17:45:37 -28:56:10; 2020/06/25 peak elevation: ~42deg. culmination at late ← midnight → early shift the map:

12 Sky coverage B-configration ★:LGS ●: TTFGS preliminary
diameter of the dotted circle is 7.5' ★:LGS ●: TTFGS preliminary Number of TTFGS in each of 4 pink region 18mag: 19mag: 17': In .conf: 800Hz & effectively half for EM-CCD, i.e. actually x8 LGS(32x32SA): 10mag ⇒ x 8 = TTF(4SA): 18mag ⇒ => x 8 = D. Simons, Gemini technical notes TN-PS-G0030, (1995). r(in, out) = r_circ TTFGS(R-band) b: 10~20 deg 30~50 deg 60~90 deg (7' ,8') = 1.6' < 18 mag > 6.7 > 3.0 > 1.8 standard < 19 mag > 10.7 > 4.8 > 2.8 1mag dim (7', 8.5') = 2.0' < 18mag > 34.7 > 7.4 > 4.3 1' larger dia 12

13 Summary Expected FWHM is 0.2" in the K-band under moderate seeing condition. Stability (std/ave) along time axis is same or better than seeing. Gain of ensquared energy is ~ 1.5 to 2 Uniformity of FWHM over FoV is ~ <5 % in NIR Gain of FWHM deceased with zenith angle by 10% at 45deg and by 20% at 60deg Seasonal variation of FWHM is ~30% Even at galactic pole, expected number of an 18mag star in each of 4 TTFGS of f15' case is > 1.