TAACOS - Target Acquisition Analysis for the Cosmic Origins Spectrograph

TAACOS simulates the Target Acquisition (TA) algorithm currently baselined for COS Instrument. As TA for COS uses "dispersed light", simulating the TA algorithm requires simulating the spectra at the detector for a variety of optics configurations, target locations within the PSA, and various types of target spectra. Two phases of TA simulation are currently basedlined - a quick implementation (called Phase I), to verify as soon as possible the viability of the COS TA sequence; and a more thorough simulation (called Phase II), to examine in greater detail the TA process, and the resulting estimates for efficient timing, stepsizes, and the impact on the TA process as a function of different optics, apertures and target sources.

• Requirements Document for TAACOS (PDF) completed and signed off on 2/21/2000.

• TAACOS Phase I FUV Report - Revision A distributed on 4/02/2002.

• TAACOS Phase I NUV Report - Revision A (PDF) distributed on 2/1/2001.

• Recommended TA FSW and Operations Changes, based on TAACOS Phase I Reports - Revision B (PDF) distributed on 4/11/2002.

• Software Development schedule - Updated 10/3/2000

• Diagram showing TAACOS Algorithm:
  • TAACOS Executive Loop Diagram

Preliminary results for the predicted spectra of the HST/COS/FUV G130M,G160M, & G140L configurations are now available. Photons are ray-traced to the detector plane and blurred by a ~ 25 mm radial Gaussian distribution. The target spectrum is the FOS composite QSO spectrum which has been

• Redshifted to z=0.12.
• Scaled to an observed median flux of F_l = 1E-15 ergs/cm²/s/A.
• Contaminated by Galactic and an assortment of other non-physical absorption features. (These features occur every 15A starting at the low wavelength end. The initial artificial feature has an equivalent width(EW) of 2.01A. Each additional feature has a decreasing EW in 0.1A increments down to 10mA.)
• Contaminated by geocoronal lya emission of F_l = 8E-16 ergs/cm²/s/A.

• subarrayed to +-0.25mm (G130M & G160M) or +-0.6mm (G140L) from Y=0 in the detector coordinate system (DCS),
• contiminated by a uniform noise level of 1 count/cm²/s,
• and digitized (pixelated) to 6.07x10 mm pixels.

• 10 seconds
• 20 seconds
• 40 seconds
• 60 seconds
• 100 seconds
• 1000 seconds
• 5000 seconds
• 10000 seconds

• 10 seconds
• 20 seconds
• 40 seconds
• 60 seconds
• 100 seconds
• 1000 seconds
• 5000 seconds
• 10000 seconds

• 10 seconds
• 20 seconds
• 40 seconds
• 60 seconds
• 100 seconds
• 1000 seconds
• 5000 seconds
• 10000 seconds

For these simulations, Dennis Ebbet's wavelength dependent sensitivity curves of 1/27/00 were used.

** The COS sensitivities have been updated, new simulations are currently being prepared **

• G130M
• G160M
• G140L

• G130M
• G160M
• G140L

FUV Detector cheatsheets are now available for both daytime :

• G130M
• G160M
• G140L

• G130M
• G160M
• G140L

• G185M
• G225M
• G285M
• G230L

---

Return to COS Instrument Development

Mail comments to Ken.Brownsberger@Colorado.EDU