TIPS
COS Status: SMOV update III
STScI/CU COS Team
17 September 2009

 Science enabled on 14 September

All COS SMOV observations (except one dark) planned to be completed by end of 264 SMS (27 Sep 2009)
 Many COS Cycle 17 calibration programs have begun; all are now activated in LRP
 FUV focus updated after second focus sweep
 NUV Internal Flat Fields
– No change from ground structure; on-orbit combined with ground for better S/N; updated reference file delivered including vignetting function
 NUV/FUV Internal/External Wavecals
–
–
FUV spectrum templates, dispersion relations, and extraction boxes delivered to pipeline
NUV extraction boxes delivered to pipeline; new dispersion relations and template spectra reference files in preparation (est 9/30 delivery)

 Sensitivity
– Initial on-orbit PSA reference files in processing for delivery

Target Acquisition
–
–
Imaging plate-scales, WCA/PSA/BOA offsets, subarrays all updated
Spectroscopic plate-scale, BOA parameter updates expected
– All TA modes working well
– New recommendations for BOA imaging mode S/N

Structural / Thermal Stability
– 5-orbit CVZ-like exposures for NUV/FUV spectroscopy, NUV imaging
– Highest S/N NUV COS data; presently in analysis
 FUV External Flats; FUV High S/N recently obtained
--- courtesy Kevin Fance, COS IDT

• S/N Recommendation for ACQ/IMAGE
– PSA MIRRORA and MIRRORB: S/N=40 (no change)
– BOA MIRRORA and MIRRORB : S/N=60 (change from 40)
• FUV Dispersed-Light Acquisition subarrays updated after optical alignment
– avoid airglow contamination for ACQ/SEARCH, ACQ/PEAKXD, and ACQ/PEAKD
4

•
Sk155 is an O9 star in SMC with STIS E140H observations using 0.2X0.09 aperture giving R~114,000
•
ISM lines are both narrow features and broad saturated lines with sharp edges
Left: COS G130M spectrum compared with the STIS E140H spectrum convolved with a gaussian of R=15,000 (dotted)
Right : COS G130M spectrum compared with the STIS E140H spectrum convolved with a gaussian of R=7,000 (dotted)
5

Comparison of COS LSF model at 1309 A with (dotted line) and without (solid) OTA mid-frequency WFE.
•
• a)
Models were calculated for G130M at
1309Å (G.Hartig, STScI), including:
COS optics, using Code V model
(T.Delker, Ball) b) c) d)
COS/FUV detector blur kernel, empirically matched to TV06 data
(T.Delker, Ball)
OTA low-frequency errors
(spherical and astigmatism, in
Code V model)
OTA mid-frequency errors
When d) is left out, these models fit the data from TV06.
•
•
•
OTA WFE effect on the
COS FUV LSF
Effective resolving power (from FWHM) changes from
R ~ 20,000 to
R ~ 16,000
(~20% effect)
Line depth (LSF amplitude) decreases
(~30% effect)
6
LSF develops broad wings out to ~4
FWHM (~9 sigma)

COS G130M spectrum of previous region (solid) compared with the STIS E140H spectrum convolved with a gaussian of R=20,000 (dotted line) and with the LSF model containing OTA WFE effects (full line).
Note the good agreement with the LSF model containing OTA WFE effects which fits weak and strong features and correctly predicts cores of lines.
7

• The COS G130M spectrum of Sk155 cannot be reproduced with a simple gaussian LSF
• The filling in of the saturated cores of the ISM lines is indicative of broad wings on the LSF
•
An LSF with broad wings from a model that includes known COS and OTA properties gives an excellent fit to the COS G130M spectrum.
• The apparent finding of a different COS/FUV LSF on-orbit than during
TV06 is expected from the fact that RAS/Cal did not include OTA midfrequency WFE
– Spectral resolution (~20%), line depth, and line shape are impacted.
• The broad LSF wings suggested by both the LSF model and the data are consistent with:
– Prior expertise on HST with e.g. STIS
• Team in process of investigating further including examination of
G160M, NUV, focus quality
8

The FUV B-segment “Friends”
N132D G130M/1318/FUVB (1310 s)
--- courtesy Brian Keeney, COS IDT

N132D G130M/1318/FUVB (1310 s)
--- courtesy Brian Keeney, COS IDT

N132D G130M/1318/FUVB (1310 s)
--- courtesy Brian Keeney, COS IDT

Danforth, Keeney, France, et al.

OVI z=0.18269
?
?
COS/G13
0M
STIS/E14
0M

--- courtesy Winter, Keeney, Froning,
Penton, Danforth, France, COS IDT