ETC Request ID: STIS.sp.827679

Exposure time (seconds) = 250.0000 at wavelength 1550.00 Å

gives: SNR = 31.7291 (per resolution element)

Exposure time calculation HAD WARNINGS.

WARNING MESSAGE: MAMA Bright limits: total count rate per image 145378 exceeds limit for irregularly-variable sources 40 percent of the bright limit 200000 counts per second

WARNING MESSAGE: Buffer time 13.7573 is less than minimum 99 seconds.


Table of Source and Noise Counts per Pixel

Plots

Detailed Information Count rate Total counts Associated noise
(counts/s) (counts) (counts)
Counts (box 7 pixels high) (1 pix x pix) (2.0 pix resel x pix)
    Source 2.178 1,088.85 33.00
    Background 0.001 0.53 0.72
        Sky 9.699e-15 4.85e-12 2.20e-06
        Dark Current 0.001 0.53 0.72
Total in selected region 2.179 1,089.38 34.32
Brightest Pixel (single exposure) (at 1394.31 Å) 1.333 333.15
Count rate entire detector 145,377.731
Buffer Time (sec) 13.76
For APT purposes, the recommended buffer time should be 4/5 of the buffer time calculated above. Please refer to the STIS Instrument Handbook for more details.
Global Count Rates
    Source only 96,813.485 24,203,371.130
    Background (sky+dark) 157.286 39,321.60
Encircled energy fraction 0.94

Instrument name: STIS
Mode: spectroscopic
Detector: FUVMAMA
Central Wavelength: 1489
Grating: [E140H] R ~ 114000
Aperture: 0.1X0.03
Glow region: low


Target: [point source]
Spectrum: Bruzual Synthetic Stellar Spectra B8 V
Extinction E(B-V): None
Normalization: Flux 1.7e-10 flam at 1360.0 Å
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 24.2