Subaru Ground-Layer AO Simulation Shin Oya (Subaru Telescope) Subaru Next Generation AO Working Group 2013/6/13 @ Sapporo
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
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
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
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
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
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%
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: 0.7626 0.7711 0.7915 0.8269 0.8713 J: 0.6229 0.6348 0.6652 0.7215 0.8021 H: 0.5632 0.5754 0.6059 0.6641 0.7569 K: 0.5193 0.5321 0.5602 0.6154 0.7097 loss by 10% at 45°and by 20% at 60°
Seasonal Variation of Seeing Subaru IQ http://www.subaru.nao.ac.jp/Observing/Telescope/ImageQuality/Seeing/ 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
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
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): 10:00:28.6 +02:12:21; 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:
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: 34.1670 13.1761 6.7217 4.2019 3.0303 2.3584 1.9951 1.7573 1.7562 19mag: 65.2393 21.7403 10.6814 6.6279 4.7669 3.7023 3.1285 2.7500 2.7500 17': 101.1209 33.6974 16.5562 10.2732 7.3887 5.7385 4.8492 4.2625 4.2625 In .conf: 800Hz & effectively half for EM-CCD, i.e. actually x8 LGS(32x32SA): 10mag ⇒ 33.597 x 8 = 268.776 TTF(4SA): 18mag ⇒ => 5.397 x 8 = 43.1760 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
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.