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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
STIS Status Report, 16 May, 2002
•STIS Calibration Plan for Cycle 11
•MAMA Dark Current since SMOV3B
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
STIS Calibration Plans for Cycle 11.
Considerations for Cycle 11
• Approved STIS GO orbits are down significantly for cycle 11 (1040 prime GO
orbits rather than the 1800 to 1900 orbits in cycles 7 through 10). In particular,
STIS imaging now accounts for only 2.7% of HST science.
• Most detector modes are now well understood, so the frequency of some
external monitors can be decreased without affecting the quality of calibration.
• There are some uncertainties in the absolute and relative flux calibration of the
E1 positions now supported for 1st order spectra near row 900 of the CCD.
• Monitor programs run for 13 months (Sep 1 2002 to Sep 30 2003) to give
more flexibility for Cycle 12 planning.
• Fewer special calibration programs.
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STIS Status
TIPS 16-May-2002
Charles R. Proffitt
SPACE TELESCOPE SCIENCE INSTITUTE
STIS Orbit Allocations by Cycle
Cycle
Prime
GO
STIS/Cal STIS/
Prime
Cal Par.
STIS/Cal
Internal
7
1829
300
526
2244
8
1919
135
182
1761
9
1925
84
232
1658
10
1814
108
220
1503
11
1040
70
232
1700
Above numbers do not include side-2 recommissioning programs, contingency orbits,
or other additions not included in the calibration plans.
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
STIS Cycle 11 Calibration Plan
Estimated Time (orbits)
ID
Proposal Title
Frequency
“External” “Internal”
Prime
& Parallel
CCD Monitors
9604 CCD Performance Monitor
2 per year
42
9605 CCD Dark Monitor
9606
14 per week
760
9607 CCD Bias Monitor
9608
daily
395
9609 CCD Read Noise Monitor
monthly
26
9612 CCD Hot Pixel Annealing
monthly
168a
9613 CCD Spectroscopic Flats
monthly
68
9614 CCD Imaging Flats
monthly
17
9617 CCD Spectroscopic Dispersion Monitor
annually
7
9620 CCD Sparse Field CTE Internal
annually
96a
9621 CCD Sparse Field CTE External
annually
12
9622 CCD Full-Field Sensitivity Monitor
annually
1
9626 Slit Wheel Repeatability
annually
9627 CCD Spectroscopic Sensitivity Monitor
4 per year
1
8
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
Estimated Time (orbits)
ID
Proposal Title
Frequency
“External” “Internal”
Prime
& Parallel
MAMA Monitors
9618 MAMA Dispersion Solutions
annually
36
9623 MAMA Full-field Sensitivity
annually
3
9628 MAMA Sensitivity & Focus Monitor
bi-monthly
16
9615 MAMA Dark Monitor
twice weekly
226
9629 MAMA Fold distribution
2 per year
4
9624 MAMA FUV flats
annually
10
9625 MAMA NUV flats
annually
10
9630 MAMA FUV/NUV Anomalous Recovery
As needed
N/A
Special Calibration Programs
9616 E1 Pseudo-Aperture Sensitivity and Throughputs once
4
9610 Spectroscopic PSF
once
3
9611 CCD Side-2 Gain Ratio Test
once
2
9631 Faint Standards Extension (FASTEX)
once
19
9619 Echelle Blaze Shift vs. MSM Monthly Offset
once
2
2
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
Changes to Monitoring Programs
• Decreased frequency of MAMA spectroscopic sensitivity monitors. L modes
reduced from 12 to 6 times per year, and M modes from 6 to 4 times per year,
saving a total of 8 prime orbits/year.
• Decreased frequency of full field sensitivity monitors. Will only do once per
year, rather than twice, saving 4 prime orbits.
• Add annual NUV-PRISM observations to MAMA spectroscopic sensitivity
monitor. Prism sensitivity was last measured in 2000, but had significant usage
in cycles 10/11 (2 extra orbits this year, 1 per year continuing).
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
Added Support for E1 Positions
• E1 aperture positions were defined to allow spectroscopy to be done closer to
the CCD readout, thereby reducing charge transfers and CTI effects by a factor of ~ 5. CCD sensitivity at this position differs by a few percent, and focus
and PSF differences may alter relative throughputs of narrow slits.
• Added exposures using 52X2E1 to the usual G230LB, G430L, G750L sensitivity monitoring program. This can be done without extra orbits.
• Added two orbits to CCD sensitivity monitor to allow the standard G230MB,
G430M, and G750M monitoring at selected wavelengths to also be done at E1
positions.
• Added a special program to observe a white dwarf standard through
52X0.05E1, 52X0.1E1, 52X0.2E1, 52X0.5E1, and 52X2E1 apertures. Prior
aperture throughput tests at the E1 positions did not use a standard star, so
absolute flux results are less certain. Doing two visits of two orbits each, separated by a few months, will test small slit throughput repeatability.
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
MAMA Dispersion Solutions (36 Internal Orbits).
• Dispersion solutions for many central wavelengths never checked on-orbit.
Will take deep wavecals at all central wavelengths this cycle.
• This data will be valuable for future ECF recalibration efforts.
CCD Dispersion Solutions (11 Internal Orbits)
• Regular line lamp has very low signal-to-noise at E1 position.
• Use HITM1 instead of usual LINE lamp to better illuminate E1 positions.
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
Special Calibrations
Faint Standards Extension (FASTEX), 19 prime orbits.
• Primarily driven by the need to provide more standard stars for other instruments and projects (ACS Sloan filters and prism, as well as COS).
• Observe two new faint WD standards (V = 16.5) and improve observations for
two more.
• Also observe primary Sloan standard with STIS CCD to cross-calibrate.
Echelle MSM Offset Test (2 prime orbits)
• The monthly spectral offsetting causes a misalignment of the wavelength scale
with echelle blaze function. This adversely affects the extracted fluxes.
• Don’t have a flux standard with multiple offsets at same CENWAVE.
• Will observe the WD flux standard HZ 43 with E230H using the 2513 Å setting at five different MSM offset positions.
• Data will allow improved test of software fix devised by Lindler & Bowers.
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
Upper panel shows blaze function misalignment. Bottom shows Lindler’s fix.
1.5
Old
1.4
Flux 10−12 erg s−1 cm−2 Å−1)
1.3
1.2
1.1
1.0
1.5
1.4
Order 313
Order 312
Order 311
1.3
1.2
1.1
1.0
E230H / 2513 (o6hb30020)
2465
2470
Lindler Algorithm
2475
2480
Wavelength (Å)
2485
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
Gain ratio test (two prime and two internal orbits)
•
•
•
•
Take high signal-to-noise spectra of external target in gain=1 and gain=4.
Will give better estimate of gain ratio (current estimate 4.08+/-0.08).
Also checks that use of the side 2 electronics hasn’t changed the gain ratio.
Also includes measurements of B amp gain and bias, which will be useful for
CTE tests done using both B and standard D amps to read out the CCD. This
will allow us to infer the impact of CTE loss on the derived gain ratio.
CCD Spectroscopic PSF Test (3 prime orbits)
• Step 52x0.1 and 52x0.2 slits across a star to measure off-axis and out of slit
PSFs using the G750L. Will do both regular and E1 positions.
• Relevant for numerous galactic and black hole dynamics programs, both current and archival, which depend heavily on the ability to model the STIS PSF
in the red and near IR.
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
MAMA Dark Current Since SMOV3B.
• NUV MAMA dark current due to phosphorescence of window impurities.
• A short term increase in the temperature, T, increases the rate at which metastable states depopulate, increasing the dark current by about 12% per ˚C. This
is seen during daily temperature cycling.
• However, a sustained increase in T also reduces the overall population of
excited meta-stable states, moderating the increase in the dark rate.
• Expected net increase of about 4% in NUV dark rate per ˚C.
• Extra heat input from new instruments after SMOV3B was expected to
increase aft-shroud T by a a few ˚C.
• STIS Heater Zone 3A (the one nearest the MAMA detectors) was stuck at max
power between Nov 30, 2001 and Feb 17, 2002.
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
Daily average of OMTUBET temperatures during Side 2 operations.
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
Dark rates during 2 periods of Side-2 STIS operations.
Despite increase in mean T of NUV MAMA, mean dark values are similar.
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SPACE TELESCOPE SCIENCE INSTITUTE
STIS Status
TIPS 16-May-2002
Charles R. Proffitt
FUV MAMA dark “glow” also tends to increase as temperature increases.
Limited data since SMOV3B indicates no new enhancement of the FUV glow.