Principal: Chad Engelbracht
Deputy: Dean Hines, Dave Frayer, Susan Stolovy
Data Monkey(s): James Muzerolle, Kate Su, Casey Papovich
Priority: Necessary
Downlink Priority: Normal
Analysis Time: 72h
Last Updated:
The purpose of this task is to compare the output of the MIPS 24µm calibration stimulator (preferably the flat-field stimulator) to the output of a calibration star. It will also check the stimulator stability on short timescales.
Small field photometry AOT data on a standard star will be collected, interspersed with stim flashes recorded using the 24µm stim flash IER, MIPS-IER-120. The sequence is as follows: 1) Observe the star using the photometry AOT with 3 second integrations and small field dither (2 cycles). 2) Observe the stimulator (MIPS-IER-120). 3) Repeat 1 and 2 five times. The observation needs a S/N in photons of 100:1 in the stimulator and star so that the uncertainty is dominated by repeatability (4-5%).
The AOR listed here takes 349 seconds and the stim IER takes 71 seconds, so the total duration of this task is 5 * (349 + 71) / 60, or about 35 minutes. This is well within the 50 minutes allocated for this task. If we have to use a fainter star for calibration, we'll use 10-second DCEs, pushing the total time up to about the allocated 50 minutes.
The target is HD 159330, a K2III which is about 515 mJy at 24µm and is visible from April 16 to Nov 23.
This task will generate 150 observations of the standard star, 35 observations of the stimulator, and 15 dark observations for a total of 200 DCEs. The stellar and stimulator observations will both be 3-second DCEs. The stimulator observations will be generated using the 24µm stimulator IER (MIPS-IER-120), while the standard star observations will be generated using a standard AOR, as below:
# Please edit this file with care to maintain the
# correct format so that SPOT can still read it.
# Generated by SPOT on: 3/4/2003 10:41:54
HEADER: FILE_VERSION=6.2, STATUS = PROPOSAL
AOT_TYPE: MIPS Photometry
AOR_LABEL: MIPS-120
AOR_STATUS: new
MOVING_TARGET: NO
TARGET_TYPE: FIXED SINGLE
TARGET_NAME: HD 159330
COORD_SYSTEM: Equatorial J2000
POSITION: RA_LON=17h30m43.57s, DEC_LAT=+57d52m36.6s, PM_RA=0.012", PM_DEC=-0.014"
OBJECT_AVOIDANCE: EARTH = YES, OTHERS = YES
MICRON_24: FIELD_SIZE = SMALL, EXPOSURE_TIME = 3, N_CYCLES = 2
SPECIAL: IMPACT = none, LATE_EPHEMERIS = NO,SECOND_LOOK = NO
RESOURCE_EST: TOTAL_DURATION=349.4, SLEW_TIME=7.2, SETTLE_TIME=5.0, SLEW_OVERHEAD=180.0, SPECIAL_OVERHEAD=0.0, UPLINK_VOLUME=594, DOWNLINK_VOLUME=2537774, VERSION=S6.5.2
INTEGRATION_TIME: MIPS_24=92.27469,MIPS_70=0.0,MIPS_160=0.0
The IER is listed here:
// EXP_WRITER_VERSION=630
// ****************************************************************************
//
// Creation Date: Thu Jan 16 16:34:05 PST 2003
//
// Expansion File: /epi02/mipsier/iers/Other/v65/mips_ier120.exp
//
//
// ****************************************************************************
//
//
// Keyword Section
//
IERID 0x000000000000 // IER Identifier
IERType MIPS // Type of IET
IERVersion 6.5.0 Final // Spotier Version
IERTitle 'mips_ier120' // Title of IER
Target 'mips_ier120' // Target Name
IERTargetType Any // Target type of IER
Ra // Target RA
Dec // Target DEC
NaifId // NaifId for this IER
TotalExposureTime 29.359679999999997 // seconds
TotalExecutionTime 70.99999999999999 // seconds
TotalSlewTime 0.0 // seconds
TotalSettlingTime 0.0 // seconds
Slew Tax 0.0 // seconds
Special Overhead 0.0 // seconds
TotalUplinkLoad 303 // bytes
TotalCommandStorageLoad 112 // bytes
TotalStringStorageLoad 133 // bytes
TotalNumberOfInstructions 24 // Instruction count
TotalDownlinkLoad 845924 // bytes
CommandDCE 10 // Number of DCEs commanded
TotalDCE 30 // Number of DCEs in database
VisibilityRadius 0.0 // Visibility radius for this IER
Expedited 'false' // Expedited for downlink processing
StartTime 2003-049T03:02:30.000 // StartTime for this IER
BodyStartTime 2003-049T16:36:22.805 // BodyStartTime for this IER
Author 'A.Noriega-Crespo' // Name of IER author
Version '2.1 MIPS-120' // Version number (set by Author)
Purpose '24um Stim Calib w/ Sources' // Purpose of this IER
Notes 'DMK+DLP+DH concept' // General notes
//
// Expansion Section
//
00:00:00.000 START // Meta command indicates start of expansion
00:00:00.000 VML_EVAL // Place holder for VML EVAL construct
GV_ACTIVE_AORID_FLAGS // global variable name
0x0000 // value or expression
00:00:00.100 VML_EVAL // Place holder for VML EVAL construct
GV_ACTIVE_AORID_KEY // global variable name
0x00000000 // value or expression
00:00:00.200 VML_EVAL // Place holder for VML EVAL construct
GV_AOR_START_TIME // global variable name
NOW // value or expression
// COMMENT: start w/mobs_photo
00:00:00.300 MIPS_MOBS_PHOTO // BLOCK: SSC change MIPS state from observe to photo
0x003c99a0 // OPERCESTATE
// COMMENT: Set up the instrument for imaging
// COMMENT: csmm at 24um dark
00:00:05.500 CESCANPOS //
101 // posindex
'MIPS' // csmode
00:00:07.500 CEGERSTCON //
10 // ge160rst : 4 Ge frames
127 // ge70rst : 4 Ge frames
4 // rstdelay : 1 Ge frame
'MIPS' // csmode
00:00:08.500 CESCANCON //
'CHOP' // scanmode
'FWD' // rampdir
0 // scanpos2 : 18.901 arcsec
2048 // relpos1 : 2.3626 arcsec
2048 // relpos2 : 2.3626 arcsec
0 // stepoffset : 2.3626 arcsec
511 // rampslope : 0.1 msec/2.3626 arcsec
'MIPS' // csmode
// COMMENT: setup Si Stims
00:00:09.500 CESISTIM //
'ALLOFF' // state
'LOW' // level
'MIPS' // csmode
// COMMENT: take 3 DCEs 3sec SUR - stim off
00:00:10.500 CEMIPSUR //
0x0000 // aorid_flags
0x00000000 // aorid_key
0 // expid
'NO_COADD' // coadd
2 // framenum
3 // numdce : DCEs
'MIPS' // csmode
// EXPOSURE_INFO: Exposure_Type = 'pht'
// COMMENT: tun on Si Stims
00:00:27.500 CESISTIM //
'MIPSFLAT' // state
'LOW' // level
'MIPS' // csmode
// COMMENT: take 7 DCEs 3sec SUR - stims on
00:00:28.500 CEMIPSUR //
0x0000 // aorid_flags
0x00000000 // aorid_key
1 // expid
'NO_COADD' // coadd
2 // framenum
7 // numdce : DCEs
'MIPS' // csmode
// EXPOSURE_INFO: Exposure_Type = 'pht'
// COMMENT: turn off Si Stim
00:00:59.500 CESISTIM //
'ALLOFF' // state
'LOW' // level
'MIPS' // csmode
// COMMENT: end IER w/backto_mobs
00:01:00.500 MIPS_BACKTO_MOBS // BLOCK: SSC change MIPS state back to MIPS observe
0x003c99a0 // OPERCESTATE
00:01:10.700 VML_EVAL // Place holder for VML EVAL construct
GV_ACTIVE_AORID_FLAGS // global variable name
0x0000 // value or expression
00:01:10.800 VML_EVAL // Place holder for VML EVAL construct
GV_ACTIVE_AORID_KEY // global variable name
0x00000000 // value or expression
00:01:10.900 VML_EVAL // Place holder for VML EVAL construct
GV_AOR_END_TIME // global variable name
NOW // value or expression
00:01:11.000 END // Meta command indicates end of expansion
Array Data Desired:
24 µm
Data Reformatting Option:
Special Instructions:
N.B. This task previously depended on mips-320, the preliminary phot/SR AOT validation, but as mips-120 does not do any AOT commanding that is not already done in mips-100, I switched the dependancy to mips-100. I also added mips-115, because as far as I can tell mips-115 is the first time the 24µm stims, which this task depends heavily on, are tested. Unfortunately, mips-115 occurs in the same campaign as mips-120 and so will not serve as a useful check on whether the stims are functioning properly prior to the execution of mips-120. Thus, it doesn't make much sense to depend on mips-115 under the current schedule, but it's an important reminder that these tasks are related and may be useful if we're forced to reschedule these tasks for some other reason.
The main goal of the analysis is to determine the flux conversion factor for this campaign and to assess the repeatability of the stimulator on short timescales. It is similar to the standard 24um flux calibration (mips-920), but is repeated 5 times to improve S/N and to assess short-term variability of the stimulator.
To derive the flux conversion factor, photometry will be performed on the star in each of the 150 DCEs. The results will be averaged, rejecting any measurement greater than 3 standard deviations from the mean. The assumed flux of the star (from the tables on the MIPS IST web page) will be divided by the measured counts to compute the flux conversion factor.
A mosaic of the stellar images will be generated. This image will be examined visually for any obvious problems, such as poor matching of background levels between DCEs, missing data, asteroids in the field, etc. Photometry will also be performed on the stellar image and compared to the results derived above. If the flux conversion factors do not match within the errors, a more thorough investigation of the data will be required.
The processed stimulator images will be averaged for each of the 5 repeats of the measurement. If any image deviates by more than 3 standard deviations from the mean, the data will be investigated more thoroughly. The median value of the stimulator image will be computed for each of the repeats and examined for any trends or for greater-than-expected scatter. If the data are acceptable, the data will be averaged to form a single stimulator image and the flux conversion factor will be inserted in the header. The data will be archived and made available to the IT/IST.
If the standard anomaly response actions do result in usable data, the test must be repeated.