---------------------------------------------- Checklist for IRS/SINGS validation on NGC 7331 ---------------------------------------------- ============== Critical Tests ============== The following assessments are critical for further acquisition of IRS/SINGS data to continue as currently specified by the AORs. (1) Data Accountability and Integrity - Compare requested and expected number of raw DCEs and processed BCDs, mask files, extracted spectra, and ancillary data files. (did we receive all the expected files?) RESPONSE: We received all of the expected and necessary data. HOW SHOULD BE BRING UP THE ISSUE OF CALIBRATION FILES FOR CUBISM? - Were there any corrupted data that will prevent our completion of any of the critical analysis tasks listed below (#2-4)? If so, do we need a re-transmission of data from JPL or the spacecraft? If data were corrupted on board (due to CR's, instrument anomalies, etc.) do we need to re-observe all or part of NGC 7331? RESPONSE: For the most part, the data were not corrupted so as to prevent validation. For SL, however, there is an unexpectedly large number of on-order bad pixels that translate into holes in the map. This will probably not warrant a change of observing strategy. - Were there significant saturated spectra that make validation of the data or data-taking strategy impossible? Has stray light from the peak-up arrays severly contaminated the SL2 spectra (see also #8, below)? RESPONSE: The data were not saturated so as to prevent validation, and peak-up stray light was not severe enough to prevent validation. (2) Pointing - Compare requested and reconstructed pointing for all IRS DCEs. * Is the center of the map consistent with the nucleus or HII region? Are there global offsets beyond the reported pointing accuracies of SIRTF and the IRS? These could indicate a problem with the pointing for NGC 7331 or the pointing reconstruction at the SSC. RESPONSE: The SL map from Cubism nicely shows that we are centered on the nucleus (show image & quantify). WHAT ABOUT LL, SH, LH? No, there is no global offset beyond the reported pointing accuracy. * Are the positional offsets consistent with those requested over the entire map? This should be evaluated between slit positions and also between map legs. Requested positions are indicated by header keywords (RA,DEC,PA)_RQST in the BCDs. Reconstructed positions, based upon the current Observer, are indicated by header keywords (RA,DEC,PA)_FOV and (RA,DEC,PA)_SLT in the BCD (bcd_fp.fits files). RESPONSE: The issue of commanded vs expected positions is fine, as evidenced by the structure of the contructed map of the ring. However, our plan was to use the reconstructed positions to double-check and improve the overall astrometry of the cube. IDEALLY, WE'D USE A MAP OF A STAR FIELD WITH KNOWN POSITIONS AS A CHECK--IS THERE ONE? DO WE NEED TO COMPLAIN ABOUT UNCERTAINTIES IN THE RECONSTRUCTED POSITIONS? (3) Sensitivity (and mapping redundancy) - Do the reported sensitivities of all four modules fall within the tolerances of the existing program? This can be answered without reference to NGC 7331 data. RESPONSE: The sensitivities of our data, and the signal-to-noise achieved for each IRS module, are generally in line with our expectations. (Show figure) SH: 3sigma: 2e-18 W/m^2 Goal: 5e-18 W/m^2 SOM: 2e-18 W/m^2 0.42e-17 W/m^2 for 30x2=60s + 4x redundancy S/N: 6 and 7 for [Ne III] and [Ne II] LH: 3sigma: 5e-18 W/m^2 Goal: 5e-18 W/m^2 SOM: 5e-18 W/m^2 1e-17 W/m^2 for 60s @ 34um + 4x redundancy S/N: 10 and 25 for [SIII] and [SiII] SL: 3sigma: 0.4-4 mJy for off-source ("background") Goal: 3 mJy SOM: 0.4/1.3 mJy 0.6/1.8 for 60/14s extranuc/nuc + 2x redund S/N: 5 to 20 ranging from nuc to interarm continuum LL: 3sigma: 1-10 MJy/sr Goal: 1 MJy/sr SOM: 1-10 MJy/sr 2-20 MJy/sr for 30s + 4x redundancy S/N: - Do our validation data suggest a deviation from the reported values which would compromise the program and/or force a revision in data-taking strategy (see #4 and #7, below)? RESPONSE: No. - If pointing and offsets were as commanded (see above), and the instrument response is as expected, is there adequate redundancy and slit overlap in our nominal data-taking strategy to ensure high S/N cubes and maps? This is particularly important for the SL spectral maps. RESPONSE: More redundancy and/or larger/contiguous maps for SL would be helpful. LL, SH, and LH data have plenty of overlap for our purposes. (4) Removal of Slit Backgrounds [less critical than 1-3, above] - To what extent can data in the "wings" of various spectral maps be used to assess and remove the local backgrounds? Are the LL flanking fields spatially flat? Do we need to revise our data- taking plan to include real off-galaxy spectra? RESPONSE: The LL emission from NGC 7331 drops off fast enough radially, such that our LL map is large enough to get a good estimate of local backgrounds. (quantify) ================== Non-Critical Tests ================== IRS/SINGS data can continue being taken, and non-critical issues will be addressed concurrently. (5) Cubism Functionality - Verify that CUBISM can read all the BCDs, extract the necessary header information and assemble the cubes. * Are there any artifacts in the cubes or extracted maps which cannot be explained via data-taking (e.g. stepping) anomalies addressed above? * Can anomalies in the cubes or maps be removed by modifying CUBISM in a reasonable amount of time -- without affecting our delivery schedule? * Is the pointing information for each BCD accounted for correctly, such that multiple epochs of data will not pose problems? * Are there any irregularities in the regions of order overlap? If so, are these indicative of a problem in cubism, or the IRS pipeline products - e.g. flat fielding or stray light removal, (see #8, below). Can the overlapping scan legs be "seamlessly" combined to produce a map? * Are the delivered uncertainty images useful for weighting and rejecting data from the extremities of the order/slit? * Is there a significant difference in the maps when using the reconstructed vs. the requested offsets? (6) Calibration Products - Are all requisite calibration products available in the correct formats? These include wavelength and order position solutions, permanent mask files, and flux calibration files/keywords. - Does the calibration match pre-launch expectations? If not, will significant deviations require changes to the established cube-building algorithms? RESPONSE: DO YOU MEAN LAMBDA CALIBRATION? IF NOT, HOW ARE WE SUPPOSED TO CHECK THE FLUX CALIBRATION? ISN'T THAT THE ISSUE OF #7a? (7) IRS - IRAC - MIPS cross-calibration - Verify calibration consistency through direct comparison to ISO maps. RESPONSE: HELENE PLEASE COMMENT. - Generate maps over relevant IRAC and MIPS filter bandpasses and compare to IRAC and MIPS data directly after extracting to the same projected aperture. This will require co-ordination with IRAC/MIPS groups. Is there a systematic offset in one of the derived products that is indicative of a change in sensitivity or an effect not documented by the IRAC, MIPS or IRS teams during IOC or SV? - Do the IRS flanking peak-up fields sample backgrounds match what we derive from the slit perimeter fields (see #4, above)? Use SPOT visualization to verify peak-up and slit perimeter overlap. (8) IRS Pipeline - Is fringing adequately removed by the pipeline flat-fielding? RESPONSE: The effects of fringing are surprisingly minimal. It appears that the pipeline processing will be sufficient. - Are Peak-Up stray light and high-res crosstalk removal modules functioning well enough to use corrected BCD products as inputs to cubism? RESPONSE: IS THERE A PROBLEM HERE FOR THE OFF-SOURCE POINTINGS? PLEASE EXPLAIN.