IRAC Instrument Handbook - IRSA - California Institute of Technology

S9.1
S9.0
Pipeline History Log 145
IRAC Instrument Handbook
\char fluxconv = 'Conversion factor in MJy/sr per DN/s'
\char fluxconvunc = 'Uncertainty in fluxconv'
|fluxconv |fluxconvunc |
|float |float |
0.195 0.020
3. HDR skydarks are now delineated from non-HDR skydarks. Skydarks are now aware of channel
4 repeats and pipelines fetch skydarks for the correct repeat. This is possible due to new fields in
the caldata tables.
4. Scattered light removal module (“slremove”) added to science pipeline and calibration
preprocessing.
5. Calibration ensemble pipelines now use “fpgen” to clean up the product header.
6. New pipeline to create subarray flats from full array flats.
7. Latent ensemble creates new request median and request average images.
8. New keywords to be added to the mosaic header: AOT_TYPE, AORLABEL, FOVID,
FOVNAME, PRIMEARR, OBJECT, PAONUM, CAMPAIGN.
Less than < 0.1% of the DCEs may not have pointing reconstruction applied to the data. BCDs with
USEDBPHF=F indicate that the Boresight Pointing History File was not used, and the RA and DEC
in the headers for these cases are based on pre-observation predictions which can be off by 5”−50".
Do not use such data if pointing is important.
1. Some AORs have been affected by long-term residual images from previous observations. For the
most part, observers have sufficiently dithered their data, so that the impact is minimal, on
processed and co-added data.
2. Note that the noise in the images and the sensitivity to point sources are not equal to our prelaunch
predictions (e.g., as available from our website until December 19, 2003, or in the
Observer's Manual versions before 4.0), although they are close. New sensitivity numbers are
available in the revised Observer's Manual (version 4.0), which was available at our website
starting ~December 19, 2003. For reference, the ratio of the new point source detection threshold
to the pre-launch advertised value, for low background observations in 30 sec frames, is 0.69,
0.75, 1.60, and 1.31 in channels 1, 2, 3, and 4, respectively.
3. Persistent images in channel 1. When a bright source (K=13 mag or brighter) is stared at for a
long time, for example, during a downlink, it will leave a persistent image in channel 1 that
decays very slowly (persists for several hours or more). A persistent image mitigation strategy
involving annealing the array after downlinks has been put in place for nominal operations. These
anneals will erase the persistent images from the array, but do not protect against persistent
images from bright object observations that can accumulate on the array before the next
downlink. Science impact: left unmitigated, you will have extra, spurious sources in your image.