Instrument Science Report NICMOS 2005-005
NICMOS Cycles 13 and 14
Calibration Plans
Santiago Arribas, Eddie Bergeron, Roelof de Jong, Sangeeta Malhotra, Bahram
Mobasher, Keith Noll, Al Schultz, Tommy Wiklind, Chun Xu.
November 17, 2005
ABSTRACT
This document summarizes the NICMOS Calibration Plans for Cycles 13 and 14. These
plans complement the SMOV3b, the Cycle 10 (interim), and the Cycles 11 and 12 (regular) calibration programs executed after the installation of the NICMOS Cooling System
(NCS).. These previous programs have shown that the instrument is very stable, which has
motivated a further reduction in the frequency of the monitoring programs for Cycle 13. In
addition, for Cycle 14 some of these programs were slightly modified to account for 2
Gyro HST operations. The special calibrations on Cycle 13 were focussed on a follow up
of the spectroscopic recalibration initiated in Cycle 12. This program led to the discovery
of a possible count rate non-linearity, which has triggered a special program for Cycle 13
and a number of subsequent tests and calibrations during Cycle 14. At the time of writing
this is a very active area of research. We also briefly comment on other calibrations
defined to address other specific issues like: the autoreset test, the SPAR sequences tests,
and the low-frequency flat residual for NIC1. The calibration programs for the 2-Gyro
campaigns are not included here, since they have been described somewhere else. Further
details and updates on specific programs can be found via the NICMOS web site.
Introduction
Since the installation of the NICMOS Cooling System (NCS) during the Servicing Mission 3b, NICMOS has shown a very stable behavior as a consequence of its well
controlled operating temperature (Wiklind & Wheeler, 2006; Bergeron 2006), which has
facilitated greatly its calibration. This stable behavior has had an important impact on the
Copyright© 1999 The Association of Universities for Research in Astronomy, Inc. All Rights Reserved.
NICMOS Cycles 13 and 14 Calibration Plans
calibration plans, which have evolved into three main directions. First, the frequency of
some of the monitoring programs have been gradually reduced. Second, due to the higher
instrument’s stability, the systematic errors in the calibration have become relatively more
important. Consequently a reduction in the systematic errors in zero points and grism sensitivity curves has been pursued. Third, we have also studied the behavior of the
instrument at extreme count rate regimes (e.g. UDF, very high S/N spectrophotometry).
Apart from these generic lines, other calibrations to address specific problems (e.g. autoreset, new multi-accum sequences, etc.) have been also implemented. In the following
paragraphs we will briefly comment on each of these categories, pointing out the most
relevant aspects of the Cycles 13 and 14 Calibration Plans.
1- Monitor programs:
As a consequence of the stable behavior shown by the instrument, the frequency of the different monitoring programs, which track the stability of key properties of the instrument
(i.e.darks, flats, focus, photometry), have been gradually reduced between Cycles 10 and
13. Although it was discussed the possibility of reducing the frequency of some programs
even further by combining their information (i.e. photometric stability could, in principle,
be checked using the photometric monitoring data), it was considered important to maintain homogeneity in the programs across cycles. During Cycle 13 the major reductions
affected to the flat and focus programs, whose frequency were cut by factors of 2 and 1.5,
respectively. During Cycle 14 we maintain the same frequency as in Cycle 13 for all monitor programs. However, the change to a 2 Gyro operating mode for HST has reduced the
visibility period of some of the objects traditionally used for some of these programs, like
the photometric and focus monitor. Consequently we have added new objects to these programs (G191B2B as new photometric standard and 47Tuc as a new focussing cluster).
2- Photometric and Spectrophotometric recalibrations:
The more stable behavior of the detectors has made the systematic errors to have a relatively more important role in limiting the actual accuracy of standard observations.
Consequently we launched in Cycle 12 two programs (photometric and spectrophotometric re-calibrations) aimed at improving the systematic errors associated with the
photometric zero-points and sensitivity curves with respect to those achieved during Cycle
7 and 7N. The photometric re-calibration expanded the number and type of stars used for
obtaining the zero points for all filters. Similarly, the spectroscopic recalibration allowed a
reanalysis of the sensitivity curves for the three grisms using a larger number and variety
of stars. Several of the selected objects were common for the two proposals. Therefore,
these data allowed a spectro-photometric recalibration by cross-checking results obtained
independently from these modes (i.e. imaging/filters and spectroscopy/grism).
2
NICMOS Cycles 13 and 14 Calibration Plans
This program (which included new faint calibrating stars) has led to the discovery of a
possible count rate non-linearity. This effect, the so called ‘Bohlin effect’, is described in
detail in Bohlin, Lindler, & Riess (2005). As a response to this effect, a special calibration
program was implemented in Cycle 13, and several tests and calibrations have followed
during Cycle 14. Since this effect is more significant at a very low count rate regime, it
will be briefly commented in the following section. The new data obtained with the photometric re-calibration program (as well as the larger set of data collected with the
photometric monitoring programs) also suggested the possibility of some systematic
residual associated to the position of the object in the field of view. During Cycles 7 and
7N the possible variation of the response (after flat-fielding) as a function of the position
in the field of view was estimated to be small compared with the actual uncertainties in
the photometry. However, with the current higher precision data this is unclear, and a
study to analyze the low frequency flat residuals has been implemented in the Cycle 14
Calibration Plan. This will be done initially for camera 1 since the intra-pixel sensitivity
effect on the photometry is smaller. Depending on the results of this program it could be
also implemented in cameras 2 and 3 (which require extensive dithering to average out this
effect; Xu & Mobasher, 2003).
3- Calibrating the extremes: From the very high S/N regime to the UDF
During Cycles 12-14 the behavior of NICMOS at extreme count rate regimes has been
investigated. On one hand a Cycle 12 calibration proposal lead by R. Gilliland was aimed
at investigating the relative spectrophotometric accuracy of the instrument at very high S/
N regime. It was found that NICMOS can reach a relative precision of around 10-4 or even
higher in time series observations (Gilliland and Arribas, 2003). Further details can be
found in Gilliland (2006) . On the other extreme, the Hubble Ultra Deep Field observations imposed new calibration challenges. Details on these particular calibrations are
discussed in Mobasher & Riess (2005) and Thompson (2006). Provided that objects in
the UDF are observed at extremely low count rates, their calibration may be affected by
the ‘Bohlin effect’ mentioned above. In order to understand better the origin of this
reported non-linearity, a program which includes several tests has been implemented in
the Cycle 14 Calibration Plan. These tests include: i) the measurement of the wavelength
dependence of the persistence decay after an exposure of a bright star in a series of multiaccum dark frames, ii) the measure of the non-linearity dependence on the count rate by
observing a field of stars in a sequence of lamp off/on, and so artificially increasing the
background level (this will be done in imaging and grism modes), and iii) the photometric
measurements of the faint standard stars SNAP-2 and WD1657+343, (on which the NICMOS non-linearity was originally discovered using grism observations) will be repeated
to obtain higher S/N. All these observations should clarify the origin of the non-linearity
effect, and its possible relation with the UDF calibrations (de Jong 2006)
3
NICMOS Cycles 13 and 14 Calibration Plans
4- Specific calibrations:
Some programs implemented in the calibration plans just addressed very specific issues
like:
i) Delta-T program: The goal of this program was to study the effects of the detector temperature on the darks. (This was a Cycle 12 calibration program implemented to late to be
included in the standard calibration plan for this cycle) .
ii) Autoreset test: This Cycle 13 calibration program is aimed at testing the short term temperature ripples in the NICMOS dewar.
iii) New SPARS sequences: This Cycle 14 program had the goal of testing the darks of the
newly implemented SPARS multiaccum sequences.
Further details on the individual proposals may be found in the tables and text below, and
via the standard HST and NICMOS web sites. The reader may also want to check the proceedings of the Calibration Workshop held at the STScI in October 26-28 (Eds. A.
Koekemoer, Dressel, L., Goudfrooij, 2006).
References
Bergeron, E. 2006, The 2005 HST Calibration Workshop. Eds. A. Koekemoer, L. Dressel,
P. Goudfrooij (in press
Bohlin, R., Lindler, R., & Riess, A. 2005, NICMOS-ISR-2005-002
Gilliland, R., and Arribas, S. 2003, NICMOS-ISR-2005-001
Gilliland, R. 2006, The 2005 HST Calibration Workshop. Eds. A. Koekemoer, L.
Dressel, P. Goudfrooij (in press).
de Jong, R. 2006, The 2005 HST Calibration Workshop. Eds. A. Koekemoer, L. Dressel,
P. Goudfrooij (in press).
Mobasher, B., and Riess, A. 2005 NICMOS-ISR-2005-003
Thompson, R. 2006, The 2005 HST Calibration Workshop. Eds. A. Koekemoer, L.
Dressel, P. Goudfrooij (in press)
Wiklind, T, and Wheeler, T. 2006, The 2005 HST Calibration Workshop. Eds. A.
Koekemoer, L. Dressel, P. Goudfrooij (in press).
Xu, C., and Mobasher, B. 2003 NICMOS-ISR_2003-009
4
NICMOS Cycle 13 Calibration Plan
Estimated Time (orbits)
ID
Proposal Title
Frequency
Resources
Scheduling
Accuracy
Required Products
Required
Required
“External” “Internal”
(FTE)
Notes
Routine Monitoring Programs
10380
Multiaccum Darks
monthly
10382
Focus Stability
NIC1 and
NIC2
every 3
months
10381
Photometry Stability
10379
Flats Stability
36
0.2
CDBS
4-5%
Same as in Cycle 12
0.3
ISR
1mm
Same as in Cycle 12, but NIC1 or NIC2
every 45 days (instead of monthly)
1 NIC3 execution.
bi-monthly 12
0.5
CDBS
2%
Same as in Cycle 12
quarterly
0.2
IR / ISR
0.5%
Same as in Cycle 12, but quarterly
(instead of bi-monthly)
9
3
Special Calibration Programs
10383
Grism Recalibration: follow up
once
2
0.3
ISR
1%
Observations of BD+17 4708
10454
Extreme count rates linearity test
once
12
0.5
ISR
1%
Response to the discovery of a possible
non-linearity effect
10465
NICMOS Autoreset Test
once
0.3
ISR
1%
Test of the short term temperature ripples in the NICMOS dewar
TOTAL TIME (including all executions)
2
38
38
2.3
NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10380: NICMOS Cycle 13: MA DarksProposal ID 10454:
Plan
Purpose The purpose of this proposal is to monitor the dark current, read
noise, and shading profile for all three NICMOS detectors
throughout the duration of Cycle 12. This proposal is a continuation of PID 9321 and 9636 which cover the period between
the end of SMOV3B and the end of Cycle 11.
For SPARS64, NSAMP has been changed from 19 to 23, in
order to provide Superdarks for proposal 9803 (UDF).
Description Each iteration of this proposal consists of ten dark exposures of
1088s (sample sequence of SPARS64 and NSAMP=23) for all 3
cameras. In addition, a set of 3 SCAMRR, NSAMP=25
sequences for each camera will be obtained in order to set an
accurate estimate of the read noise. Finally, in order to characterize the shading profile of the NICMOS detectors, a set of 5
STEP256, NSAMP=12 sequences for each camera will be
taken. These contain all commonly used NICMOS Delta-times,
except the shortest one (0.2s) which is covered by the SCAMRR
sequences. As an additional benefit, the dark exposures will
allow us to estimate the cosmic ray rates outside the SAA. This
sequence will be repeated once a month for 12 months to allow
the monitoring of NICMOS detector behavior as a function of
time and temperature throughout Cycle 12.
FractionGO- 100%
Supported
Resources R: Each monthly visit will require 3 internal orbits.
Observation Therefore 36 orbits are required to cover the cycle
Resources : 0.3 FTE
Analysis
Products Darks for all readout sequences. Direct superdarks for SPARS64
(NSAMP=23)
Accuracy 4-5 % per visit for the linear component of the dark current. In
Goals principle S/N ~ 50, but degradation due to CR lower this figure.
S/N ~ 35 (12) for the amplifier glow at the corner (center).
Scheduling Monthly. SAA free orbits
Requirements
6
NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10382: NICMOS Cycle 13: Focus Stability
Plan
Purpose The purpose of this activity is to check the focus for the three
cameras
Description Steps:
a) Use refined target field positions as determined in cycle 7
b) Use MULTIACCUM sequences of sufficient dynamic range
to account for defocus
c) Do a 17-point focus sweep, +/- 8mm about the PAM mechanical zeropoint for each cameras 1 and 2, in 1mm steps. (10-point
focus sweep from -0.5 to -9.5 for camera 3).
d) Use PAM X/Y tilt and OTA offset slew compensations
refined from previous focus monitoring/optical aligment activities.
e) Use phase retreval algorithms to establish PAM focuss for
each camera.
Fraction 100%
GO/GTO
Programs
Supported
Resources Every visit will require 1 external orbit. (if only NIC1 or NIC2
Required: are checked) or 2 orbits is NIC3 is also done. NIC1 and NIC2
Observation will be executed 4 times during the cycle (every 3 months), and
NIC3 once. NIC1 or NIC2 will be checked every 45 days. A
total of 9 orbits are needed to cover the cycle.
Resources 0.3 FTE
Required:
Analysis
Products ISR, Update of focus as needed
Accuracy The best focus should be known within 1 mm
Goals
Scheduling& Every ~ 45 days NIC1 or NIC2 (alternate their executions).
Special One NIC3 execution
Requirements
7
NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10381: NICMOS Cycle 13: Photometric Stability
Plan
Purpose To verify the stability of the NICMOS photometric calibration
over a broad range of wavelengths.
Description Observations of a standard star (P330E) through the following
subset of filters: F090M, F110W, F160W and F190N for NIC1;
F110W, F160W, F190N, F222M for NIC2 and F110W, F160W,
and F222M for NIC3. All observations are done using a spiral
dither pattern, with 4 dither points for NIC1 and NIC2, and 7
dithers for NIC3 (to help reduce intrapixel sensitivity effects on
the photometry). The integration times are set to achieve S/N
=~ 200-350 in the standard photometry apertures for each exposure, while keeping peak pixel counts to < 66% of saturation
level. The NIC1/F190N observation has somewhat lower S/N
(~110) per exposure. NIC3/F110W may come slightly closer to
saturation (~73% according to the ETC).
Fraction 100%
GO/GTO
Programs
Supported
Resources Each bi-monthly visit will require 2 external orbits. Therefore,
Required: 12 orbits are required for the complete period.
Observation
Resources 0.30 FTE
Required:
Analysis
Products Internal Report or ISR. Updated zero pionts for CDBS
Accuracy 2-1%
Goals
Scheduling& SAA free orbits preferred.
Special
Requirements
8
NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10379: NICMOS Cycle 13: Flats Stability
Plan
Purpose A series of camera 1, 2, & 3 flat fields will be obtained to monitor the health of the cameras.
Description Each 1-orbit visit will obtain pointed flat fields in each camera
(NIC1 filters F110M, F110W, F160W; NIC2 filters F110W,
F160W, F222M; NIC3 filters F110W, F160W, F222M). Some
filters will be rotated through the sequence so that many filters
will be used during a year. A four point dither pattern will be
used to allow removal of background objects. At each dithered
position, observations will be obtained with the lamp off and
followed by lamp on observations. Every four months well
exposure observations will be taken to study the non-linearity
corrections. The Cameras 1 and 2 will be used in parallel. For
almost all the exposures, Lamp 1 (High Intensity) will be used.
Fraction 100%
GO/GTO
Programs
Supported
Resources Each quarterly visit will require one orbit. Therefore, 3 orbits
Required: are needed for the complete Cycle.
Observation
Resources 0.2 FTE
Required:
Analysis
Products Depending on the results an internal report or an ISR.
Accuracy 1-2 %
Goals
Scheduling& SAA free orbits.
Special
Requirements
9
NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10383: NICMOS Cycle 13: Grism Recalibration: follow up
Plan
Purpose All cycle 12 data for the spectroscopic recalibration (ID 9998)
were successfully acquired. One problem is that the repeatability as measured by the comparison of the cycle 11 to the cycle
12 observations of P330E is only 2%. The goal and expectation
is for repeatability to better than 1%. The somewhat poorer
results may be attributed to flat field differences between the
Thompson dither strategy during Cycle 11 and that used in during Cycle 12 (ID 9998); or perhaps, there is some synoptic
change in the system throughput. In order distinguish these possibilities and hopefully recover a repeatability of 1%, the observations of one star must be repeated as early as possible in
Cycle 13, using the same dither strategy as 9998.
Description Observations of the bright sloan standard BD+17d4708 with
G096, G141, and G206 using the same dither strategy as in
9998. This star has been previously observed on 04Jan10.
P330E would be a good choice, except that it was previously
observed too recently on 04Jun19 to measure any sensitivity
change back to 04 Jan; and the scheduling would be rushed to
get it before going into solar avoidance in October.
Fraction ~ 8% of the programs will have a direct benefit of the spectroGO/GTO scopic recalibration. However, this recalibrationl (togather with
the photometric recalibration) will provide a robust basis for the
NICMOS absolute calibration, which has a broader interest
Req.: Obs. 2 orbits are required
Re. Analysis 0.30 FTE
Products ISR, CDBS
Acc. Goals 1%
Scheduling& Ideally,to minimize the effect of any synoptic sensitivity change,
Spe. Requi. the observations should be made in September, before P330E
goes into the solar avoidance zone in mid-October.
SAA free orbits
10
NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10465: NICMOS Cycle 13: Autoreset test
Plan
Purpose Test of the short term temperature ripples in the NICMOS
dewar.
Description The test consists of running the NICMOS detectors with and
without the AUTORESET mode on. Orbits free of NICMOS
science observations are to be used and each mode (ON/OFF)
will run for approximately 24 hours. The long duration is on
order to allow the temperature in the dewar to stabilize. Normal
telemetry data will be sufficient for the temperature monitoring.
SAA passages are handled as usual when NICMOS observations are scheduled: the NICMOS detectors are turned off and
after the SAA passage, two post-SAA darks are done and the
NICMOS detectors are left in an ON mode. The remaining time
will be divided into 2 different parts, each one lasting approximately 24 hours: Visits 11, 12, 13, 21, 22, 23, 31, 32, 33, 41, 42,
43, 51, 52, 53, 61 will cover ~24 hours with AUTOFLUSH
mode OFF. These visits are grouped together. Visits 15, 16, 17,
25, 26, 27, 35, 36, 37, 45, 46, 47, 55, 56, 57, 65 will cover ~24
hours with AUTOFLUSH mode ON. These visits are grouped
together. Each set of visits should be done over a 24 hour time
period without interuption, with normal HST activities. The
two sets (AUTOFLUSH ON and OFF) do not have to be done
back-to-back, but should be scheduled as close to each other in
time as practical.
Fraction 100 %
GO/GTO
Req.: Obs. 2 internal orbits are required
Re. Analysis 0.30 FTE
Products Technical report
Acc. Goals 1%
Scheduling& See program
Spe. Requi.
11
NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10454: NICMOS Cycle 13: Extreme count rates linearity
test
Plan
Purpose To test the linearity of the detectors at count rates falling at the
low and high extremes of what is feasible.This program is a
response to the discovery that grism observations obtained with
NIC3 show a systematic offset from spectra taken with STIS
and ACS in the 0.8-1.0 micron overlap region. The observations
are consistent with a NIC3 sensitivity that depends on incident
flux, i.e. count rate.
Description By observing one bright star (BD+17D4708, the Sloan Digital
SkySurvey absolute standard) and two faint stars (SNAP-2, a
solar analog star;WD1657+343, a white dwarf) in a number of
filters we will check whether this is an intrinsic feature of the all
NICMOS detectors, something intrinsic to NIC3, or a result of a
not understood effect of the grism observations. We will furthermore be able to test whether the effect has a wavelength dependence.Photometric observations will be done for all three
NICMOS cameras, using a subset of filters for each. The filters
to be used were selected to overlap maximally with the existing
standard star observations of intermediate brightness. In addition, we will obtain extra spectroscopic data on WD1657+343,
the faintest and best modeled white dwarf of the stars on which
the original discovery of the non-linearity was made. This will
reduce the errors in this spectrum from 5% to 2% and will allow
a better estimate of the effect.
Fraction ~ 100% of the programs will benefit of this calibration
GO/GTO
Req.: Obs. 12 orbits are required
Re. Analysis 0.50 FTE
Products ISR, CDBS
Acc. Goals 1%
Scheduling& In order to ease scheduling, there are no time constraints speciSpe. Requi. fied in the proposal. However, because of the potentially important implications of this effect, it is very important that these
orbits bescheduled as soon as possible. They could be critical
for the proper calibration of NICMOS The targets have visibility
1) BD+17D4708: 16 Apr - 17 Jan 2) SNAP-2: 3 Feb-1 Mar 3)
WD1657+343: 3 Feb-26 FebThere are no SAA requirements on
this proposal, although SAA-free orbits are always prefered if
possible.
12
NICMOS Cycle 14 Calibration Plan
Estimated Time (orbits)
ID
Proposal Title
Frequency
Resources
Scheduling
Accuracy
Required Products
Required
Required
“External” “Internal”
(FTE)
Notes
Routine Monitoring Programs
10723
Multiaccum Darks
monthly
10724
Focus Stability
NIC1 or
NIC2
every 45
days
10725
10728
24
CDBS
4-5%
Same as in Cycle 13
10
0.3
ISR
1mm
Similar to Cycle 13 (4 NIC1, 4 NIC2,
and 2 NIC3 executions)
New field (47Tuc), for 2Gy operations
Photometry Stability
bi-monthly 12
0.3
CDBS
2%
Same as in Cycle 13, but new object
(G191B2B) for 2Gy operations
Flats Stability
every 3
months
0.2
IR / ISR
0.5%
Same as in Cycle 13
13
0.2
4
Special Calibration Programs
10726
Non-linearity tests
once
12
1
ISR
1%
Several tests to analyse the count rate
dependent non-linearity seen in NICMOS spectro-photometric observations
10727
Low-frequency flat residuals for
NIC1
once
2
0.5
ISR/
CDBS
1%
To better characterize the flatfielding
errors seen for camera 1 in the photometric monitoring data
10721
Test for newly implemented
SPARS sequences
once
0.2
IR
4-5%
To measure the dark currents for the
new multiaccum sequences for all three
NICMOS detectors.
TOTAL TIME (including all executions)
12
40
36
2.5
NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10723: NICMOS Cycle 14: MA Darks
Plan
Purpose The purpose of this proposal is to monitor the dark current of
the three NICMOS detectors throughout the duration of Cycle
14. This proposal is a continuation of PID 9321, 9636 and 9993
which cover the period between the end of SMOV3B and the
end of Cycle 13.
Description Each iteration of this proposal consists of ten dark exposures of
1344s (sample sequence of SPARS64 and NSAMP=23) for all
3 cameras. The dark exposures will also allow us to estimate the
cosmic ray rates outside the SAA. This sequence will be
repeated once a month for 12 months to allow the monitoring of
NICMOS detector behavior as a function of time and temperature throughout Cycle 14.
Since 2000 the (linear) darks for all 3 detectors have been stable (using data from proposals: PID 9321,9636,10064,9803
[UDF],9993,10380). Occasionally high darks are obtained due
to persistance after observations of extremely bright objects
(e.g. Mars).
FractionGO- 100%
Supported
Resources R: Each monthly visit will require 2 internal orbits.
Observation Therefore 24 orbits are required to cover the cycle
Resources : 0.3 FTE
Analysis
Products Darks for all readout sequences.
Accuracy 4-5 % per visit for the linear component of the dark current.
Goals
Scheduling Monthly. SAA free orbits
Requirements
14
NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10724: NICMOS Cycle 14: Focus Stability
Plan
Purpose Check the focus for the three cameras
Description Steps:a) Use new target field positions (47Tuc) to account for
2Gy operations
b) Use MULTIACCUM sequences of sufficient dynamic range
to account for defocus
c) Do a 17-point focus sweep, +/- 8mm about the PAM mechanical zeropoint for each cameras 1 and 2, in 1mm steps. (10-point
focus sweep from -0.5 to -9.5 for camera 3).
d) Use PAM X/Y tilt and OTA offset slew compensations
refined from previous focus monitoring/optical aligments.
e) Phase retreval algorithms (and encircled energy) to establish
PAM focuss for each camera.
Fraction 100%
GO/GTO
Programs
Supported
Resources Every visit will require 1 external orbit. (if only NIC1 or NIC2
Required: are checked) or 2 orbits is NIC3 is also done. NIC1 and NIC2
Observation will be executed 4 times during the cycle (every 3 months), and
NIC3 twice. NIC1 or NIC2 will be checked every 45 days. A
total of 10 orbits are needed to cover the cycle.
Resources 0.3 FTE
Required:
Analysis
Products ISR, Update of focus as needed
Accuracy The best focus should be known within 1 mm
Goals
Scheduling& Every ~ 45 days NIC1 or NIC2 (alternate their executions).
Special Two NIC3 executions
Requirements
15
NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10725 : NICMOS Cycle 14: Photometric Stability
Plan
Purpose To verify the stability of the NICMOS photometric calibration
over a broad range of wavelengths.
Description Observations of the standard stars (P330E and G191B2B)
through the following subset of filters: F090M, F110W, F160W
and F190N for NIC1; F110W, F160W, F190N, F222M for
NIC2 and F110W, F160W, and F222M for NIC3. All observations are done using a spiral dither pattern, with 4 dither points
for NIC1 and NIC2, and 7 dithers for NIC3 (to help reduce
intrapixel sensitivity effects on the photometry). The integration
times are set to achieve S/N =~ 200-350 in the standard photometry apertures for each exposure, while keeping peak pixel
counts to < 66% of saturation level. The NIC1/F190N observation has somewhat lower S/N (~110) per exposure. NIC3/
F110W may come slightly closer to saturation (~73% according
to the ETC).
Fraction 100%
GO/GTO
Programs
Supported
Resources Each bi-monthly visit will require 2 external orbits. Therefore,
Required: 12 orbits are required for the complete period.
Observation
Resources 0.30 FTE
Required:
Analysis
Products Internal Report or ISR. Updated zero pionts for CDBS
Accuracy 2-1%
Goals
Scheduling& The two selected targets should cover the whole Cycle under
Special 2Gy operations, but one month. SAA free orbits preferred.
Requirements
16
NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10728: NICMOS Cycle 14: Flats Stability
Plan
Purpose A series of camera 1, 2, & 3 flat fields will be obtained to monitor the health of the cameras.
Description Each 1-orbit visit will obtain pointed flat fields in each camera
(NIC1 filters F110M, F110W, F160W; NIC2 filters F110W,
F160W, F222M; NIC3 filters F110W, F160W, F222M). Some
filters will be rotated through the sequence so that many filters
will be used during a year. A four point dither pattern will be
used to allow removal of background objects. At each dithered
position, observations will be obtained with the lamp off and
followed by lamp on observations. Every three months well
exposure observations will be taken to study the non-linearity
corrections. The Cameras 1 and 2 will be used in parallel. After
the last full well exposed image darks will be taken in the
occulted part of the orbit to measure persistence due to charge
trapping.
Fraction 100%
GO/GTO
Programs
Supported
Resources Each visit will require one orbit. Therefore, 4 orbits are needed
Required: for the complete Cycle.
Observation
Resources 0.2 FTE
Required:
Analysis
Products Depending on the results an internal report or an ISR.
Accuracy 1-2 %
Goals
Scheduling& SAA free orbits.
Special
Requirements
17
NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10726: NICMOS Cycle 14: Non-linearity tests
Plan
Purpose This program incorporates a number of tests to analyse the
count rate dependent non-linearity seen in NICMOS spectrophotometric observations.
Description It will consists of five visits. In visit 1 we will observe a few
fields with stars of a range in luminosity in NGC1850 with NICMOS in NIC1 in F090M, F110W and F160W and NIC2
F110W, F160W, and F180W. We will repeat the observations
with flatfield lamp on, creating artificially high count-rates,
allowing tests of NICMOS linearity as function of count rate. To
access the effect of charge trapping and persistence, we first take
darks (so there is not too much charge already trapped), than
take exposures with the lamp off, exposures with the lamp on,
and repeat at the end with lamp off. Finally, we continue with
taking darks during occultation. In visit 2 we will observe spectro-photometric standard P041C using the G096 and G141
grisms in NIC3, and repeat the lamp off/on/off test to artificially
create a high background. In visits 3&4 we repeat photometry
measurements of faint standard stars SNAP-2 and
WD1657+343, on which the NICMOS non- linearity was originally discovered using grism observations. These measurements
are repeated, because previous photometry was obtained with
too short exposure times, hence substantially affected by charge
trapping non-linearity. Measurements will be made with NIC1:
Visit 5 forms the persistence test of the program. The bright star
GL-390 (used in a previous persistence test) will iluminate the 3
NICMOS detectors in turn for a fixed time, saturating the center
many times, after which a series of darks will be taken to measure the persistence (i.e. trapped electrons and the decay time of
the traps). To determine the wavelength dependence of the trap
chance, exposures of the bright star in different filters will be
taken, as well as one in the G096 grism with NIC3.
Fraction 100%
GO/GTO
Req.: Obs. For external orbits for the persistence test and 4 external orbits
for the lamp off/on test, for a total of 8 orbits.
Re. Analysis 0.5 FTE
Products ISR, if necessary.refinement of pipeline
Acc. Goals 1%
Scheduling& SAA free orbits preferred
Spe. Requi.
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NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10727: NICMOS Cycle 14: L-Flat residuals
Plan
Purpose We will perform a low frequency flatfield investigation for NICMOS Camera 1 in order to better characterize the flatfielding
errors seen for camera 1 in the photometric monitoring data.
NGC1850 will be dithered in a 3x3 pattern in 4 filters: F090M,
F110W, F160W, and F190N. Each exposure will last at least 100
s to mitigate charge trapping non-linearity effects. Please schedule this at the earliest opportunity, as the problems with the
NIC1 flat field may be related to the NICMOS non-linearity
currently being investigated.
Description We will perform a low frequency flatfield investigation for NICMOS Camera 1 in order to better characterize the flatfielding
errors seen for camera 1 in the photometric monitoring data. A
spars stellar field near NGC1850 will be dithered in a 3x3 pattern in 4 filters: F090M, F110W, F160W, and F190N. Each
exposure will last at least 100 s to mitigate charge trapping nonlinearity effects. We do the 9 points offset with 9 explicit pointings to get a celestial coordinate 3x3 pattern that matches the
(somewhat linear) distribution of stars near the center of the
cluster.
Fraction 100%
GO/GTO t
Req.: Obs. 2 external orbits
Re. Analysis 0.5 FTE
Products Depending on the results, ISR, CDBS, pipeline improvement
Acc. Goals 1%
Scheduling& Early in the cycle, SAA free orbits
Spe. Requi.
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NICMOS Cycles 13 and 14 Calibration Plans
Proposal ID 10721: NICMOS Cycle 14: Dark current of new SPARS
sequences
Plan
Purpose On June 12, 2005, 4 new NICMOS multiaccum sequences
(SPARS4, SPARS16, SPARS32, SPARS128) were implemented. The purpose of this observation is to measure the darkcurrent for these new multiaccum sequences for all three
NICMOS detectors.
Description 3 internal orbits are allocated to each of the 4 new SPARS
sequences, in order to measure the dark currents for each detector (NIC1, NIC2 and NIC3). The 3 detectors are arranged to
work in parallel. Each orbit consists of multiple copies of similar exposures, with NSAMP ranging from 22 to 25, in order to
fully fill each orbit.
Fraction 10%
GO/GTO t
Req.: Obs. 12 internall orbits
Re. Analysis 0.2 FTE
Products Internal report
Acc. Goals 4-5%
Scheduling& All visits should be scheduled in SAA-free orbits in order to
Spe. Requi. avoid contamination by cosmic ray persistence.
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