Principal: Almudena Alonso
Deputy: Susan Stolovy
Data Monkey(s): Almudena Alonso, Casey Papovich, Susan
Stolovy
Priority:
Downlink Priority: Normal
Analysis Time: 2-5 days
Last Updated:
Objective
To carry out a detailed comparison of 24micron
scan flatfields as a function of the scan mirror position.
Description
We will acquire the data needed to produce flatfield
frames at 24micron in scan mode with enough DCEs taken at 33 scan-mirror
positions. This will allow us to produce a flatfield for each scan-mirror
position. If these individual flatfields are judged to be indistinguishable
they can be combined to create a single flatfield. We will perform the necessary
data reduction (median-filtering) needed to create the flatfield frames.This
activity is a companion to the ROUTINE Photometry and ROUTINE Scan AOR flatfield
activities (MIPS-917 and MIPS-914).These activities will allow us to determine
the relative efficiency and quality of flatfields created using scan and
photometry AORs.
This task is executed in MIPS Campaign Q.
Data Collected
A 5-degree long x 3 legs scan map is taken using the fast-scan AOT in
a region of sky chosen to avoid bright point-sources. The map will require
about 65.5 minutes of observing time. In each calibration cycle 33 scan mirror
positions are observed. In a 5degree long scan map observed in fast mode.
For a given leg each will observe 10DCEs per scan mirror position, so a total
of ~30DCE per scan mirror position will be available when the task is executed.
# Please edit this file with care to maintain the
# correct format so that SPOT can still read it.
# Generated by SPOT on: 10/3/2002 13:42:16
HEADER: FILE_VERSION=6.2, STATUS = PROPOSAL
AOT_TYPE: MIPS Scan Map
AOR_LABEL: MIPS-305-Feb25-Apr10
AOR_STATUS: new
MOVING_TARGET: NO
TARGET_TYPE: FIXED SINGLE
TARGET_NAME: MIPS-305-Feb25-Apr10
COORD_SYSTEM: Equatorial J2000
POSITION: RA_LON=6h40m18.6381s, DEC_LAT=+43d09m59.7558s
OBJECT_AVOIDANCE: EARTH = YES, OTHERS = YES
REQUIRE_160: YES
SCAN_RATE: fast
FAST_RESET_160: NO
STEP_SIZE: TURNAROUND=302", FORWARD=302"
N_SCAN_LEGS: 3
N_MAP_CYCLES: 1
SCAN_LEG_LENGTH: 5.0
MAP_CENTER_OFFSET: CROSS_SCAN = 0, IN_SCAN = 0
SPECIAL: IMPACT = none, LATE_EPHEMERIS = NO,SECOND_LOOK = NO
RESOURCE_EST: TOTAL_DURATION=3927.325, SLEW_TIME=37.2, SETTLE_TIME=68.625, SLEW_
OVERHEAD=180.0, SPECIAL_OVERHEAD=0.0, UPLINK_VOLUME=749, DOWNLINK_VOLUME=8247770
4, VERSION=S6.2.7
INTEGRATION_TIME: MIPS_24=15.7,MIPS_70=15.7,MIPS_160=3.1
COMMENT_START:
COMMENT_END:
Array Data Desired:
All Arrays
Data Reformatting Option:
- NORMAL
1 FITS file per AOR per array.
Special Instructions:
Task Dependencies
- MIPS-326: 24 um Scan AOT Validation - preliminary
- etc.
Calibration Dependencies
Output and Deliverable Products
Mosaic of observed field at all three wavelegths. The 24micron mosaic
may be useful for IRS to select their own flatfield regions, since they will
need to avoid bright sources.
Comparison of flatfield accuracy as a function of the scan mirror position.
Data Analysis
- Standard Pipeline reduction using the DAT and/or SSC Pipeline. If
using the DAT, we will run MIPS_SLOPER for dark subtraction.
- Use MIPS_ENHANCER to produce a mosaic of the observed field corrected
for geometrical distorsions (useful for screening of possible bright sources
present in the FOV).
- Obtain the scan mirror position from header of images (e.g., using
the IRAF 'hselect' task). The keyword we need is called: CSM_PRED.
- Median combine images obtained at 24micron (with some rejection
algorithm) using the IRAF "imcombine" task to create the flatfields as a
function of the scan mirror position. If S/N of individual flatfields is
not high enough, we could bin the scan mirror positions as needed to obtained
the desired S/N (this may be the case for 160micron data). Alternatively we
can use MIPS_ENHANCER for this.
- For each scan mirror position flatfield:
- Flatfield star 24 micron observations at different positions across
the array. For instance we can use the Focal Plane Survey observations:
MIPS-130 and MIPS-131.
- Aperture photometry on star using the IRAF "phot" task to measure
flux. We will use the tasks: photpars, fitskypars to set up the photometry
parameters (aperture, sky/background estimate).
- Comparison of star aperture photometry at different positions across
the array to determine flatfield accuracy, and comparison as a function of
the scan mirror position
- Or alternatively, ratio all different flatfields to a reference
flatfield, and look for possible variations as a function of scan mirror
position.
- This will done for all three wavelengths as long as images are
not saturated.
Software Requirements
Actions Following Analysis
Depending on the output of this task, we will have to determine whether
we need to use different flatfield frames for different scan mirror positons.
Failure Modes and Responses
Additional Notes