24 µm Cosmic Ray Limits on Integration Time

Principal: Deborah Padgett
Deputy: Susan Stolovy
Data Monkey(s):
Priority: Necessary
Downlink Priority: Normal
Analysis Time: 5 hours
Last Updated:

Objective

To determine the maximum useful MIPS Si:As array integration times in the presence of cosmic-ray hits

Description

While observing a region of the sky with a reasonably faint zodiacal/cirrus background, take images at many different integration times up to the maximum allowed value to evaluate the trade off between "background limited" and "completely swamped with particle hits." This program has been broken into two parts: MIPS-250 for Si:As and MIPS-251 for Ge:Ga.

Data Collected

This task is accomplished by executing a series of photometry AORs over a range of integration times from 10 to 60 seconds, stepping by 10 seconds.



NOTE: THIS AOR WILL BE MODIFIED FOR THE NON-STANDARD EXPOSURE TIMES

#  Please edit this file with care to maintain the
#  correct format so that SPOT can still read it.
#  Generated by SPOT on:  6/12/2002     14:50:38

HEADER: FILE_VERSION=6.1, STATUS = PROPOSAL

      AOT_TYPE:  MIPS Photometry
     AOR_LABEL:  MIPS-250-10s
    AOR_STATUS:  new

 MOVING_TARGET:  NO
   TARGET_TYPE:  FIXED SINGLE
   TARGET_NAME:  CVZ-Dark-N
  COORD_SYSTEM:  Equatorial  J2000
      POSITION:  RA_LON=17h15m50.00s,  DEC_LAT=+65d25m37.0s
OBJECT_AVOIDANCE:  EARTH = YES, OTHERS = YES

    MICRON_24: FIELD_SIZE = SMALL, EXPOSURE_TIME = 10, N_CYCLES = 1
SPECIAL_OVERHEAD: IMPACT = none, LATE_EPHEMERIS = NO
RESOURCE_EST: TOTAL_DURATION=414.6, SLEW_TIME=5.4, SETTLE_TIME=5.0, SLEW_OVERHEAD=180.0, SPECIAL_OVERHEAD=0.0, UPLINK_VOLUME=817, DOWNLINK_VOLUME=2513280, VERSION=S6.1.B5
INTEGRATION_TIME: MIPS_24=165.675,MIPS_70=0.0,MIPS_160=0.0





      AOT_TYPE:  MIPS Photometry
     AOR_LABEL:  MIPS-250-20s
    AOR_STATUS:  new

 MOVING_TARGET:  NO
   TARGET_TYPE:  FIXED SINGLE
   TARGET_NAME:  CVZ-Dark-N
  COORD_SYSTEM:  Equatorial  J2000
      POSITION:  RA_LON=17h15m50.00s,  DEC_LAT=+65d25m37.0s
OBJECT_AVOIDANCE:  EARTH = YES, OTHERS = YES

    MICRON_24: FIELD_SIZE = SMALL, EXPOSURE_TIME = 10, N_CYCLES = 1
SPECIAL_OVERHEAD: IMPACT = none, LATE_EPHEMERIS = NO
RESOURCE_EST: TOTAL_DURATION=414.6, SLEW_TIME=5.4, SETTLE_TIME=5.0, SLEW_OVERHEAD=180.0, SPECIAL_OVERHEAD=0.0, UPLINK_VOLUME=817, DOWNLINK_VOLUME=2513280, VERSION=S6.1.B5
INTEGRATION_TIME: MIPS_24=165.675,MIPS_70=0.0,MIPS_160=0.0





      AOT_TYPE:  MIPS Photometry
     AOR_LABEL:  MIPS-250-30s
    AOR_STATUS:  new

 MOVING_TARGET:  NO
   TARGET_TYPE:  FIXED SINGLE
   TARGET_NAME:  CVZ-Dark-N
  COORD_SYSTEM:  Equatorial  J2000
      POSITION:  RA_LON=17h15m50.00s,  DEC_LAT=+65d25m37.0s
OBJECT_AVOIDANCE:  EARTH = YES, OTHERS = YES

    MICRON_24: FIELD_SIZE = SMALL, EXPOSURE_TIME = 30, N_CYCLES = 1
SPECIAL_OVERHEAD: IMPACT = none, LATE_EPHEMERIS = NO
RESOURCE_EST: TOTAL_DURATION=748.6, SLEW_TIME=5.4, SETTLE_TIME=5.0, SLEW_OVERHEAD=180.0, SPECIAL_OVERHEAD=0.0, UPLINK_VOLUME=817, DOWNLINK_VOLUME=6719408, VERSION=S6.1.B5
INTEGRATION_TIME: MIPS_24=501.2,MIPS_70=0.0,MIPS_160=0.0





      AOT_TYPE:  MIPS Photometry
     AOR_LABEL:  MIPS-250-40s
    AOR_STATUS:  new

 MOVING_TARGET:  NO
   TARGET_TYPE:  FIXED SINGLE
   TARGET_NAME:  CVZ-Dark-N
  COORD_SYSTEM:  Equatorial  J2000
      POSITION:  RA_LON=17h15m50.00s,  DEC_LAT=+65d25m37.0s
OBJECT_AVOIDANCE:  EARTH = YES, OTHERS = YES

    MICRON_24: FIELD_SIZE = SMALL, EXPOSURE_TIME = 30, N_CYCLES = 1
SPECIAL_OVERHEAD: IMPACT = none, LATE_EPHEMERIS = NO
RESOURCE_EST: TOTAL_DURATION=748.6, SLEW_TIME=5.4, SETTLE_TIME=5.0, SLEW_OVERHEAD=180.0, SPECIAL_OVERHEAD=0.0, UPLINK_VOLUME=817, DOWNLINK_VOLUME=6719408, VERSION=S6.1.B5
INTEGRATION_TIME: MIPS_24=501.2,MIPS_70=0.0,MIPS_160=0.0





      AOT_TYPE:  MIPS Photometry
     AOR_LABEL:  MIPS-250-50s
    AOR_STATUS:  new

 MOVING_TARGET:  NO
   TARGET_TYPE:  FIXED SINGLE
   TARGET_NAME:  CVZ-Dark-N
  COORD_SYSTEM:  Equatorial  J2000
      POSITION:  RA_LON=17h15m50.00s,  DEC_LAT=+65d25m37.0s
OBJECT_AVOIDANCE:  EARTH = YES, OTHERS = YES

    MICRON_24: FIELD_SIZE = SMALL, EXPOSURE_TIME = 30, N_CYCLES = 1
SPECIAL_OVERHEAD: IMPACT = none, LATE_EPHEMERIS = NO
RESOURCE_EST: TOTAL_DURATION=748.6, SLEW_TIME=5.4, SETTLE_TIME=5.0, SLEW_OVERHEAD=180.0, SPECIAL_OVERHEAD=0.0, UPLINK_VOLUME=817, DOWNLINK_VOLUME=6719408, VERSION=S6.1.B5
INTEGRATION_TIME: MIPS_24=501.2,MIPS_70=0.0,MIPS_160=0.0





      AOT_TYPE:  MIPS Photometry
     AOR_LABEL:  MIPS-250-60s
    AOR_STATUS:  new

 MOVING_TARGET:  NO
   TARGET_TYPE:  FIXED SINGLE
   TARGET_NAME:  CVZ-Dark-N
  COORD_SYSTEM:  Equatorial  J2000
      POSITION:  RA_LON=17h15m50.00s,  DEC_LAT=+65d25m37.0s
OBJECT_AVOIDANCE:  EARTH = YES, OTHERS = YES

    MICRON_24: FIELD_SIZE = SMALL, EXPOSURE_TIME = 30, N_CYCLES = 1
SPECIAL_OVERHEAD: IMPACT = none, LATE_EPHEMERIS = NO
RESOURCE_EST: TOTAL_DURATION=748.6, SLEW_TIME=5.4, SETTLE_TIME=5.0, SLEW_OVERHEAD=180.0, SPECIAL_OVERHEAD=0.0, UPLINK_VOLUME=817, DOWNLINK_VOLUME=6719408, VERSION=S6.1.B5
INTEGRATION_TIME: MIPS_24=501.2,MIPS_70=0.0,MIPS_160=0.0





CONSTRAINT: TYPE=CHAIN, NAME=Chain-MIPS-250
AORS: AOR1=MIPS-250-10s, 
      AOR2=MIPS-250-20s, 
      AOR3=MIPS-250-30s, 
      AOR4=MIPS-250-40s, 
      AOR5=MIPS-250-50s, 
      AOR6=MIPS-250-60s

Data Reformatting Requirements

Array Data Desired:

24 µm

Data Reformatting Option:

NORMAL

1 FITS file per AOR per array.

Special Instructions:

Task Dependencies

MIPS-100
MIPS-110

Calibration Dependencies

darks and/or masks (to remove hot pixels)
otherwise, should use raw data to preserve CR identity

Output and Deliverable Products

This task will produce an estimated on-orbit Si:As CR count rate for hopefully typical space weather during the mission. It also allows evaluation of exposure times longer than 30 seconds.

Data Analysis

The data analysis for this task requires ensemble processing of the photometry AOR DCEs in order to identify the cosmic rays. The images need to be registered and outlier rejection applied. This can be done using the SSC mosaicker, the DAT, or Montage.

Software Requirements

DAT and/or SSC BCD/Post-BCD pipeline
ATV - IDL image viewer
IRAF or IDL image analysis package
"fv" - Goddard "lheasoft" package
plotting package (SM, IRAF, IDL)

Actions Following Analysis

If CR count rate is too high, the 30 second exposure time might be disallowed or changed to 20 sec in SPOT. If the CR count rate is low, longer exposures might be enabled in SPOT.

Failure Modes and Responses

Presuming that data is obtained and is unsaturated, the most likely failure mode of this task is coincidental scheduling at the time of unusual solar activity. In this case, the task should be repeated at a later date. Also, the selected region of sky should not contain bright sources.