ETC Request ID: STIS.sp.835737

Exposure time (seconds) = 500.0000 at wavelength 2796.00 Å

gives: SNR = 63.5493 (per resolution element)

Exposure time calculation HAD WARNINGS.

WARNING MESSAGE: MAMA Bright limits: total count rate per image 157470 exceeds limit for irregularly-variable sources 40 percent of the bright limit 200000 counts per second

WARNING MESSAGE: Buffer time 12.7008 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 4.158 4,157.98 64.48
    Background 0.011 10.50 3.24
        Sky 2.125e-11 2.12e-08 1.46e-04
        Dark Current 0.011 10.50 3.24
Total in selected region 4.168 4,168.48 65.43
Brightest Pixel (single exposure) (at 2914.00 Å) 6.537 3,268.49
Count rate entire detector 157,469.779
Buffer Time (sec) 12.70
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 138,329.592 69,164,795.935
    Background (sky+dark) 1,572.864 786,432.11
Encircled energy fraction 0.93

Instrument name: STIS
Mode: spectroscopic
Detector: NUVMAMA
Central Wavelength: 2812
Grating: [E230H] R ~ 114000
Aperture: 31X0.05NDC


Target: [point source]
Spectrum: User uploaded spectrum: h_alp-cen-a_uvsum_1x_51277-57029_etc.dat
Extinction E(B-V): None
Normalization: None
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