Low-resolution

Single Raw Frame


Low-resolution Spectroscopy
count rates (ADU/s/coadd)
Filter source sp. type mag. itime (s) slit (") source sky line bkg
NIRSPEC-2 HD 89239 A0V V=6.528 4 42 x 0.76 3500 9 2
NIRSPEC-3 (J) HD 129653 A2 J=6.980 3 42 x 0.76 3900 12 -
NIRSPEC-5 (H) FS 27 G8IV/V H=13.181 5 42 x 0.76 13 25 1
NIRSPEC-7 FS 27 G8IV/V K=13.123 5 42 x 0.76 14 16 1-5

Background Subtracted Nod Pair (using positive beam only)


Low-resolution Spectroscopy
Filter source sp. type mag. itime (s) x coadd slit (") SNR/pixel
NIRSPEC-5 (H) FS 27 G8IV/V H=13.181 5 x 2 42 x 0.76 12
NIRSPEC-7
~2.0µm
FS 27 G8IV/V K=13.123 5 x 2 42 x 0.76 12
NIRSPEC-7
~2.2µm
FS 27 G8IV/V K=13.123 5 x 2 42 x 0.76 8
NIRSPEC-7
~2.4µm
FS 27 G8IV/V K=13.123 5 x 2 42 x 0.76 3


High-resolution

Single Raw Frame


High-resolution Spectroscopy
count rates (ADU/s/coadd)
Filter source sp. type mag. itime (s) x coadd slit (") seeing (") source sky line bkg
NIRSPEC-7 HR 3067 A3V K=4.362 4 x 1 0.576 x 12 ˜0.5 1760 n/a 0
NIRSPEC-7 HR 1237 A0V K=6.074 15 x 1 0.576 x 12 ˜0.5 410 n/a 0
NIRSPEC-7 HIP 53735 A0V K=8.856 150 x 1 0.576 x 12 ˜0.5 32 n/a 0

Background Subtracted Nod Pair (using positive beam only)


High-resolution Spectroscopy
Filter source sp. type mag. itime x coadd x frames slit (") typical counts SNR/pixel
NIRSPEC-7 HR 3027 A3V K=4.362 4 x 1 x 2 0.576 x 12 6000 150
NIRSPEC-7 HR 1237 A0V K=6.074 15 x 1 x 2 0.576 x 12 6000 150
NIRSPEC-7 HIP 53735 A0V K=8.856 150 x 1 x 2 0.576 x 12 4000 120


SNR/pixel values were determined by the relation:


                 Sgt                    S = source count rate (ADU/s)
SNR =   ______________________   where  B = rms in background (ADU); implicit time dependence
        ______________________          D = dark current (0.2 e-/s/pix)
       /                                g = gain (4 e-/ADU for SPEC)
      / Sgt + Bg + Dt + r^2             t = integration time (itime x coadds)
    \/                                  r = read noise ( 2 x (25 e-)^2 = 1250 e- for nod pair)

The calculated values match a "by-eye" assessment using cuts through the spectra.