1. The 24um ''read-2'' effect can produce a slight gradient across the frame. This will be corrected in the next software build.
2. The 1st DCE of every commanded sequence of observations (data with DCENUM=0) is calibrated differently than the rest of the data (extra boost frame). Best results in the short term may be obtained by ignoring all DCENUM=0 DCEs. BCD's with DCENUM=0 are omitted from the POSTBCD mosaics.
3. Saturating point sources and bright cosmic rays can produce enhanced jailbars (pattern every 4th row/column associated with the readouts). Extremely saturated sources may have a high background in the frames surrounding them due to inability to correctly account for the droop effect in regions which saturate during the first read.
4. The 24um photometry in a BCD can vary by about 2% across the array as the data is not corrected for distortions (the distortion correction is applied in the post-BCD pipeline).
5. Bright sources will leave a bright latent at the less than 1% level which fades over a timescale of seconds. Extremely saturated sources (tens of Jy) will leave latents at the several % level which may take hours to fade. These long-lived latents will be first bright, then dark as they fade away. Although we are trying not to schedule bright source photometry adjacent to faint source photometry, it is possible to see these latents from previous AORs in unusual cases.
MIPS-Ge:
1. Beware of the MIPS-160 light ''leak'' when observing objects that are bright in near-infrared.
2. MIPS-Ge data show stim latents which depend on background and appear to increase with the time since anneal. The stim latents linger longer for 70um than 160um, since the decay time constants associated with the stim latents are larger at 70um. The stim latents can also be mitigated by median filtering the data (but this is not yet implemented in the pipeline).
3. Due to a bad cable outside the instrument, there is a strong pattern noise on side-B of the 70um array.
4. Due to other cabling Items, there is one bad 4x8 pixel readout on the side-A of the 70um array and one bad 5x1 pixel readout on the 160um array.
S9.1 Calibration Items for MIPS
All Channels:
1. The data have preliminary flux calibration. We have not fully quantified the accuracy of the absolute calibration of MIPS.
2. The uncertainty images have not been validated.
MIPS24:
1. The 24um flats depend on the scan mirror position and scan rate due to contamination (''dust spots'') on the pickoff mirror. The S9.1 software uses scan-mirror dependent flats (a unique flat field for every commanded scan mirror position) in an effort to correct for this effect and should improve the flat fielding markedly compared to pre-S9.1 software. However, there is evidence that these spots may shift on the array (in the in-scan direction) somewhat randomly by approximately 1/2 24 micron pixel, which would cause a mismatch between the flat fields and the science observations. If this is the case, a dark/light pair of spots/streaks will appear in each BCD wherever a ''spot'' appears. Currently, there are no scan mirror dependent flats for the ''parallel'' 24 um data taken during Ge photometry.
2. The 24um linearity calibration is based on pre-launch solutions.
MIPS-Ge:
1. The Ge electronic non-linearity correction is based on pre-launch calibration.
2. MIPS-Ge data are calibrated using the stims to track the variation of the short-term response of the detections. The stim calibration does not completely remove long-term transients for the MIPS-Ge detectors. The measured ''illumination correction'' used to remove pixel to pixel response variations appears to vary as a function of time and background and this time variation is not taken into account in this current version of the pipeline. Starting with the BCDS, users can build separate ''flats'' as a function of time (e.g., one scan leg at a time) to help mitigate these effects. The variations of the ''illumination correction'' as a function of time can also be mitigated by median filtering the data, if users are only interested in point sources (but this is not yet implemented in the pipeline and the effects of calibration on median filtered data have yet to be quantified).
3. Flux calibration has yet to be fully derived as a function of source brightness and background. Information quantifying the flux non-linearities will be available when the archive opens, i.e., MIPS-Ge absolute calibration should be considered very preliminary at this time.
S9.1 Pipeline Items for MIPS
All Channels:
1. Less than <0.1% of the DCEs may not have pointing reconstruction applied the data. BCDs with USEDBPHF=F indicate that the Boresight Pointing History File was not used, and the RA and DCE 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.
2. Users should note that the keyword PRIMEARR is now present in both the MIPS BCD and POSTBCD headers. Data with PRIMEARR=1 correspond to the user's requested primary array observations. Scan mode data in all 3 arrays are always prime and have PRIMEARR=1. POSTBCD mosaics are also made for MIPS-24 data taken while MIPS-70 and MIPS-160 photometry data are primary; currently, a single mosaic is made of all non-prime data with PRIMEARR=2 for each AOR. This mosaic may not be scientifically useful. Data with PRIMEARR=3 (MIPS-70 and MIPS-160 data taken during MIPS-24 primary data) are not scientifically valid because proper stim flashes are not taken.
MIPS-Ge:
1. The pixels in the bad half of the 70um array show zero flux instead of being replaced by NaNs as they should.
2. The online 160um mosaics may show bright rows/columns associated with the stim DCEs. The stim DCEs should be rejected in the coadds/mosaics, but these are not always rejected currently due to a software bug which affects the bmasks for 160um. Users could make updated mosaics offline by ignoring the stim DCEs; 160um stim DCEs can be identified from the keyword STMFL160>0.
S9.0 (Release Date: 29 Dec 03)
S9.0 Data Items for MIPS
MIPS24:
1. The 24um ''read-2'' effect can produce a slight gradient across the frame. This will not be fixed until S9.0 and may be somewhat mitigated with corrections to the flats in the short term.
2. The 1st DCE of every commanded sequence of observations (data with DCENUM=0) are calibrated differently than the rest of the data (extra boost frame). Best results in the short term may be obtained by ignoring all DCENUM=0 DCEs.
3. Saturating sources and bright cosmic rays can produce enhanced jailbars (pattern every 4th row/column associated with the readouts).
4. The 24um photometry in a BCD can vary by about 2% across the array as the data is not corrected for distortions (the distortion correction is applied in the post-BCD pipeline).
MIPS-Ge:
1. Beware of the MIPS-160 light ''leak'' when observing objects that are bright in near-infrared.
2. MIPS-Ge data show stim latents which depend on background and appear to increase with the time since anneal. The stim latents linger longer for 70um than 160um, since the decay time constants associated with the stim latents are larger at 70um. The stim latents can also be mitigated by median filtering the data (but this is not yet implemented in the pipeline).
3. Due to a bad cable outside the instrument, there is a strong pattern noise on side-B of the 70um array.
4. Due to other cabling Items, there is one bad 4x8 pixel readout on the side-A of the 70um array and one bad 5x1 pixel readout on the 160um array.
S9.0 Calibration Items for MIPS
All Channels:
1. The data have very preliminary flux calibration. We have not fully quantified the accuracy of the absolute calibration of MIPS.
2. The uncertainty images have not been validated.
MIPS24:
1. Due to contamination on the pickoff mirror the 24um flats depend on the scan mirror position and scan rate. We currently do not have all the calibration data collected as a function of scan mirror and are using the non-mirror position dependent flat (default flat). Deep observations will show dark spots and will appear blotchy with the current calibration. Users with sufficient data could make their own flats from the BCDs sorting the data by the scan mirror position (CSM_PRED) for photometry mode and by scan mirror position and scan rate (SCANRATE) for scan observations.
2. The 24um linearity calibration is based on pre-launch solutions.
MIPS-Ge:
1. The Ge electronic non-linearity correction is based on pre-launch calibration.
2. MIPS-Ge data are calibrated using the stims to track the variation of the short-term response of the detections. The stim calibration does not completely remove long-term transients for the MIPS-Ge detectors. The measured ''illumination correction'' used to remove pixel to pixel response variations appears to vary as a function of time and background and this time variation is not taken into account in this current version of the pipeline. Starting with the BCDS, users can build separate ''flats'' as a function of time (e.g., one scan leg at a time) to help mitigate these effects. The variations of the ''illumination correction'' as a function of time can also be mitigated by median filtering the data, if users are only interested in point sources (but this is not yet implemented in the pipeline and the effects of calibration on median filtered data have yet to be quantified).
3. Flux calibration has yet to be fully derived as a function of source brightness and background. Information quantifying the flux non-linearities will be available when the archive opens, i.e., MIPS-Ge absolute calibration should be considered very preliminary at this time.
S9.0 Pipeline Items for MIPS
All Channels:
1. Roughly about 0.1-0.5% 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 DCE in the headers for these cases are based on pre-observation predictions which can be off by 5-50''. Do not use these data if pointing is important.
2. Some DCEs may have pointing solutions that are completely bogus (>10deg away). A software update was applied to S9.0 to fix a known S8.9 bug, but it is not clear yet if this fixed the problem in all cases. Please notify IRSA if you find any examples of strange pointing solutions in your data.
3. The POSTBCD mosaics do not have important header information, such as OBJECT and PRIMEARR. If you plan to use the SSC mosaics, you will need to check the RA and DCE to determine which fields are associated with which mosaics. PostBCD products with proper header information will not be available until S10.0 (when the archive opens).
MIPS-Ge:
1. The online 160um mosaics may show bright rows/columns associated with the stim DCEs. The stim DCEs should be rejected in the coadds/mosaics, but these are not always rejected currently due to a software bug which affects the bmasks for 160um. Users could make updated mosaics offline by ignoring the stim DCEs; 160um stim DCEs can be identified from the keyword STMFL160>0.
S8.9 (Release Date: 11 Nov 03)
S8.9 Data Items for MIPS
MIPS24:
1. The 24um ''read-2'' effect is not yet corrected which can produce a slight gradient across the frame.
2. Saturating sources and saturating cosmic rays can produce enhanced jailbars.
3. The 24um photometry can vary by about 2% across the array for data not corrected for distortions.
4. The first several 24um DCEs in a scan map are darker (have lower levels).
MIPS-Ge:
1. Beware of the MIPS-160 light ''leak'' when observing objects that are bright in near-infrared.
2. There is no correction for Ge stim latents. The effects from stim latents increase with time since anneal.
3. There is a strong pattern noise on side-B of the 70um array.
4. There is one bad 4x8 pixel readout on the side-A of the 70um array.
5. There is one bad 5x1 pixel readout on the 160um array.
6. If you are interested in weak point sources (<100 mJy) at the MIPS-Ge wavelengths, we recommend stacking the BCDs and median filtering the data as a function of time (ignoring the stim DCEs). This mitigates the effects of stim latents which are particular bad for MIPS-70.
S8.9 Calibration Items for MIPS
All Channels:
1. The data have very preliminary flux calibration. We have not fully quantified the accuracy of the absolute calibration of MIPS.
2. The uncertainty images have not been validated.
MIPS24:
1. Due to contamination on the pickoff mirror the 24um flats depend on scan mirror position and scan rate. In photometry mode, you will find dark spots, and for scan observations you will find dark streaks.
2. The 24um linearity calibration is based on pre-launch solutions.
MIPS-Ge:
1. The Ge electronic non-linearity correction is based on pre-launch calibration and is known to be somewhat inaccurate for in-flight data.
2. There is no correction for the variation of the illumination correction as a function of time.
3. There is no high-pass filter for MIPS-Ge which is useful for detecting weak point sources.
4. If you are interested in weak point sources (<100 mJy) at the MIPS-Ge wavelengths, we recommend stacking the BCDs and median filtering the data as a function of time (ignoring the stim DCEs). This mitigates the variations of the illumination correction as a function of time which are particular bad for MIPS-70.
S8.9 Pipeline Items for MIPS
All Channels:
1. The derived WCS pointing solutions are inaccurate for scan maps (nothing is wrong with the actual pointing of the telescope, software bug). Within scan legs, the offsets can vary by 5'' or so and the WCS solutions can be off by 10-20'' or more between scan legs.
2. Some DCEs may have pointing solutions which are completely bogus (>10deg away).
