ETC Request ID: COS.sp.1009365

Exposure time (seconds) = 1,300.0000 at wavelength 2000.00 Å

gives: SNR = 15.3187 (per resolution element)

Exposure time calculation HAD WARNINGS.

WARNING MESSAGE: For faint sources, the S/N calculated by the ETC for COS/NUV observations may overestimate the S/N in the standard reduction of the data provided by the archive, because of a difference in the extraction box size. Customized reductions may be necessary to achieve the S/N predicted by the ETC (please see the COS Data Handbook or contact the STScI Help Desk for more information).


Table of Source and Noise Counts per Pixel

Plots

Detailed Information Count rate Total counts Associated noise
(counts/s) (counts) (counts)
Counts (box 8 pixels high) (1 pix x 8 pix) (3 pix resel x 8 pix)
    Source 0.066 258.02 16.06
    Background 0.007 25.68 5.07
        Sky 2.977e-07 1.16e-03 0.03
        Dark Current 0.007 25.68 5.07
Total in selected region 0.073 283.69 16.84
Brightest Pixel (single exposure) (at 2099.58 Å) 0.039 51.22
  Brightest Pixel in Stripe A (at 2099.58 Å) 0.039
  Brightest Pixel in Stripe B (at 2800.38 Å) 0.029
Count rate entire detector 954.015
    Count rate Stripe A 55.254
    Count rate Stripe B 35.784
Buffer Fill Time (sec) 2,472
For APT purposes, the recommended buffer time is 2/3 of the buffer fill time calculated above. Please refer to Chapter 5.4 in the COS Instrument Handbook for more details.
Encircled energy fraction 1.00

Instrument name: COS
Mode: spectroscopic
Detector: NUV
Central Wavelength: 3000
Grating: [G230L] Grating (R ~ 1,550 - 2,900)
Aperture: Primary Science Aperture


Target: [point source]
Spectrum: Flat in units of Fλ
Extinction E(B-V): None
Normalization: Renormalized to abmag = 17.27 in filter Galex/NUV
Redshift: None
Emission Lines: None


Selected background:
  Sky Background:
    Level:

Table of Source and Noise Counts per Pixel

Plots

These results were computed using: ETC version 25.2