ETC Request ID: STIS.sp.1044073

Exposure time (seconds) = 218.1000 at wavelength 6500.00 Å

gives: SNR = 5,551.8457 (per resolution element)

gives: Time to Saturation (for a single exposure) = 3.65 seconds

Exposure time calculation HAD WARNINGS.

WARNING MESSAGE: CCD Full Well limits: total counts per native pixel 7.1785e+06 exceeds bright limit 120000 for selected gain

WARNING MESSAGE: "Electrons per pixel due to background (4.2) is less than the recommended threshold of 20 electrons to avoid poor charge transfer efficiency (CTE). We suggest you consider CTE mitigation strategies described in the STIS Instrument Handbook."

Table of Source and Noise Counts per Pixel


Detailed Information Count rate Total counts Associated noise
(e-/s) (e-) (e-)
Counts (box 7 pixels high) (1 pix x 7 pix) (2 pix resel x 7 pix)
    Source 70,664.817 30,823,993.14 5,551.94
    Background 0.141 61.69 7.85
        Sky 0.015 6.73 2.59
        Dark Current 0.126 54.96 7.41
    Read Out 30.68
Total in selected region 70,664.958 30,824,054.83 5,552.03
Brightest Pixel (single exposure) (at 5828.90 Å) 32,913.793 7,178,498.26

Global Count Rates
    Source only 47,796,763.680 10,424,474,158.707
    Background (sky+dark) 20,299.709 4,427,366.56

Encircled energy fraction 0.91

Instrument name: STIS
Mode: spectroscopic
Detector: CCD
Central Wavelength:
Grating: [G750L] R ~ 500
Aperture: 52X2
Gain: 4.0
# Frames: 1
Binning: dispersion: 1, spatial: 1
Dark: medium

Target: [point source]
Spectrum: Castelli-Kurucz Models G8V 5500 4.5
Extinction E(B-V): None
Normalization: Renormalized to vegamag = 5.4 in filter Johnson/R
Redshift: None
Emission Lines: None

Selected background:
  Sky Background:
    Earth Shine: Average
    Zodiacal Light: Average
    Air Glow: Average

Table of Source and Noise Counts per Pixel


These results were computed using: ETC version 25.2