ETC Request ID: STIS.im.1939997

Exposure time (seconds) = 440.0000

gives: SNR = 21,761.8163

gives: Time to Saturation (for a single exposure) = 0.27 seconds

gives: Optimum SNR = 30,775.7889

Exposure time calculation HAD WARNINGS.

WARNING MESSAGE: CCD Full Well limits: total counts per native pixel 4.98085e+07 exceeds bright limit 120000 for selected gain

WARNING MESSAGE: "Electrons per pixel due to background (13) 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."


Plots

Detailed Information Count rate Total counts Associated noise
(e-/s) (e-) (e-)
Counts (box of 3 x 3 pixels)
    Source 1,076,318.071 473,579,951.42 21,761.89
    Background 1.023 450.25 21.22
        Sky 0.735 323.53 17.99
        Dark Current 0.288 126.72 11.26
    Read Out 53.40
Total in selected region 1,076,319.095 473,580,401.67 21,761.97
Brightest Pixel (single exposure) 452,804.530 49,808,498.32
Global Count Rates
    Source only 2,152,636.143 947,159,902.841
    Background (sky+dark) 119,222.039 52,457,697.09
Background per unit area
    Sky Background (arcsec-2) 32.680 14,379.023
    Dark Current (arcsec-2) 12.800 5,632.000
Extraction region
box of 3 x 3 pixels
    Effective Sky Area (pixels) 9.00
    Fraction of flux 0.50
    Fraction of flux in brightest pixel 0.21
Effective Wavelength 6601.42 Å

Instrument name: STIS
Mode: imaging
Detector: CCD
Aperture: 50CCD
Gain: 4.0
# Frames: 4
Binning: 1
Dark: medium


Target: [point source]
Spectrum: Flat in units of Fλ
Extinction E(B-V): None
Normalization: Renormalized to vegamag = 10.5 in filter Johnson/V
Redshift: None
Emission Lines: None


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

Plots

These results were computed using: ETC version 32.2