Subject: Re: NGST IFS-MOS trade-off for AWG Date: Mon, 1 Feb 1999 19:51:32 GMT From: Santiago Arribas To: ghasinger@aip.de, lefevre@astrsp-mrs.fr, sam@chantada.ll.iac.es, rfosbury@eso.org CC: pjakobse@estsa2.estec.esa.nl Dear Bob, I am sorry for the delay. Yes, I also think that is a good plan. Now, I am sending with this mail the tables with the numbers I presented last Thursday (now with references, etc). I have also produced a table with the values corresponding to counts of galaxies (and detector area efficiency) at a given exposure time (1 and 10 hours) for the different configurations . Note, that this has been done for some observational parameters (R=3000, S/N=10), some hypothesis (F(line)/F(continuum)=30, at the resolution considered), and (in some cases) extrapolating of the Yan et al. data. I hope to complete this over next week. In particular I would like to repeat these tables for lower resolutions (and higher S/N), getting directly into the NGST Uniqueness Space. (For some programs [e.g. 2D kinematics] a lower resolution may be partially compensated with a higher S/N). Best regards, Santiago =============================================================================== TABLE 1 Stellar Kinematics (HR/LR modes) ESTIMATED EXPOSURE TIMES ________________________________________________________________________________ H (Vega mag.) 24. 21.7 20. Yan (ApJ,503,L19,1998) r1/2 (") 0.22 0.3 0.4 " n (gal/mag/deg^2 ) 3.2e5 4.e4 1.4e4 " mu (mag/"^2 ) 22. 20.5 19. ________________________________________________________________________________ 0.8(0.01L_star) ~1 0.2-1 Cowie (AJ,112,837,1996) 4 (L_star ) IFMOS (HR mode) ________________________________________________________________________________ sampling element("^2) 0.03x0.03 0.03x0.03 0.03x0.03 NxM (pixels) 15x15 20x20 27x27 n/FOV 0.35 0.04 0.015 FOV= 3.8"x3.8" H [s.e.] (mag) 29.7 28.1 26.7 K [s.e.] (mag) 28.7 27.1 25.7 Considering (H-K)~1 H [s.e.] (AB mag) 31.1 29.5 28.1 Teplitz(ApJ,507,L17,1998) ________________________________________________________________________________ texp. (s/h/d/y) 16y 312d 23d NGST calculator (in K) R=3000, S/N=10 IFMOS (HR alternatives) ________________________________________________________________________________ Sampling element ("^2) 0.1x0.1 0.1x0.1 0.1x0.1 NxM (pixels) 4.5x4.5 6x6 8x8 n/FOV 4 (5) 0.5 (1.5) 0.17 FOV=12.6"x12.6" (16000 elements) n/FOV 20 2.5 0.85 FOV=33.3"x24" (80000 elements) H [s.e.] (mag) 27 25.5 24. K [s.e.] (mag) 26 24.5 23. ________________________________________________________________________________ texp (s/h/d/y) 40d 2.7d 4.7h NGST calculator (in K) R=3000, S/N=10 IFMOS (LR mode) ________________________________________________________________________________ Sampling element ("^2)0.18x0.25 0.18x0.25 0.18x0.25 NxM (pixels) 2x2 3x3 4x4 n/FOV 89 11 4 FOV=1'x1' H [s.e.] (mag) 25.4 23.9 22.4 K [s.e.] (mag) 24.4 22.9 21.4 _______________________________________________________________________________ texp (s/h/d/y) 2.3d 4h 1400s NGST calculator (in K) R=3000, S/N=10 ================================================================================ TABLE 2 Ionized gas Kinematics (HR/LR modes) ESTIMATED EXPOSURE TIMES ________________________________________________________________________________ H (Vega mag.) 24. 21.7 20. Yan (ApJ,503,L19,1998) r1/2 (") 0.22 0.3 0.4 " n (gal/mag/deg^2) 3.2e5 4.e4 1.4e4 " m (mag/"^2) 22. 20.5 19. ________________________________________________________________________________ 0.8(0.01L_star) ~1 0.2-1 Cowie (AJ,112,837,1996) 4 (L_star ) IFMOS (HR mode) ________________________________________________________________________________ sampling element("^2 ) 0.03x0.03 0.03x0.03 0.03x0.03 NxM (pixels) 15x15 20x20 27x27 n/FOV 0.35 0.04 0.015 FOV= 3.8"x3.8" K(Halpha) [s.e.] (mag) 25.0 23.6 22.0 Considering FHalpha/Fcont=30 ________________________________________________________________________________ texp. (s/h/d/y) 7d 13h 1h NGST calculator (in K) R=3000, S/N=10 IFMOS (HR alternatives) ________________________________________________________________________________ Sampling element (") 0.1x0.1 0.1x0.1 0.1x0.1 NxM (pixels) 4.5x4.5 6x6 8x8 n/FOV 4 (5) 0.5 (1.5) 0.17 FOV=12.6"x12.6" (16000 e.) n/FOV 20 2.5 0.85 FOV=33.3"x24" (80000 e.) K(Halpha) [s.e.] (mag) 22.3 20.8 19.3 Considering FHalpha/Fcont=30 ________________________________________________________________________________ texp (s/h/d/y) 1.5h 653s 117s NGST calculator (in K) R=3000, S/N=10 IFMOS (LR mode) ________________________________________________________________________________ Sampling element ("^2) 0.18x0.25 0.18x0.25 0.18x0.25 NxM (pixels) 2x2 3x3 4x4 n/FOV 89 11 4 FOV=1'x1' K(H ) [s.e.] (mag) 20.7 19.2 17.7 Considering FHalpha/Fcont=30 _______________________________________________________________________________ texp (s/h/d/y) 576s 106s 24s NGST calculator (in K) R=3000, S/N=10 =============================================================================== TABLE 3 - Galaxy counts/ Detector area efficiency Case: Ionized gas 2D-Kinematics , Fline/Fcont=30, R=3000, S/N=10 for the H magnitude mentioned 1) IFS (HR- current desing [s.e. 0.03x0.03"^2]) In 1 hour , n~1 galaxy of H~20, 27x27 pixels used, efficiency ~ 5% In 10 hours, n~1 galaxy of H~21.5, <27x27 pixels used, efficiency ~ <5% 2) IFS (HR- alternative desing [s.e. 0.1x0.1"^2]) In 1 hour , n~4 galaxies of H~<24, 4[5x5] pixels used, efficiency< 1% [In 10hours , n~10 galaxies of H<25.1, 10[3x3] pix used, efficiency< 1%] (*) (this desing is more sensitive and less efficent) 3) IFS (LR mode, s.e. 0.18x0.25"^2, 80000 elements]) [In 1 hour , n~300 galaxies of H< 25.3, efficiency ~1%] (*) {In 10 hours, n~500 galaxies of H<26.7, efficency ~2%} (**) (*) Requires extrapolation of the Yan et al data. (**) Requires a large extrapolation of the Yan et al data.