ETC Request ID: STIS.sp.1038349

Requested Signal/Noise Ratio = 50.000 at wavelength 2026.00 Å (per resolution element)

gives: Time = 338.8772 seconds

Exposure time calculation HAD WARNINGS.

WARNING MESSAGE: MAMA Bright limits: total count rate per image 121418 exceeds limit for irregularly-variable sources 40 percent of the bright limit 200000 counts per second

WARNING MESSAGE: Buffer time 16.472 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 7 pix) (2 pix resel x 7 pix)
    Source 4.034 2,734.01 52.29
    Background 0.011 7.12 2.67
        Sky 1.910e-10 1.29e-07 3.60e-04
        Dark Current 0.011 7.12 2.67
Total in selected region 4.044 2,741.13 54.68
Brightest Pixel (single exposure) (at 2346.01 Å) 3.476 1,177.91
Count rate entire detector 121,418.267
Buffer Time (sec) 16.47
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 94,366.486 31,978,650.064
    Background (sky+dark) 1,572.864 533,007.75
Encircled energy fraction 0.93

Instrument name: STIS
Mode: spectroscopic
Detector: NUVMAMA
Central Wavelength: 1978
Grating: [E230M] R ~ 30000
Aperture: 0.2X0.06


Target: [point source]
Spectrum: Kurucz Models B3V 18700 3.9
Extinction E(B-V): Milky Way Diffuse (Rv=3.1) = 0.37 applied before normalization
Normalization: Renormalized to vegamag = 6.36 in filter Johnson/V
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