Photometry of a Circumstellar Disk

Objective

Description

Acquire normal photometry AOT observations at 24, 70, and 160um of an available, moderately bright, circumstellar disk with < 2' spatial extent. Use at least 3 cycles in each band regardless of whether that is needed to get the desired S/N in order to verify correct behavior of the observatory and pipeline for multiple cycles, and examine S/N as a function of integration time to verify the predicted sensitivity.

The source chosen is the F9V star HD 10647, an IRAS source with excess emission at 25 and 60 microns. This source was in the VLS GTO program, but Chas/Beth agreed to let us do it for IOC, as the IOC observation actually gave better S/N than the one they had planned. The 25 and 60 micron fluxes are roughly 250mJy and 630mJy, respectively.

The Photometry companion to this task is mips-275, which uses the same target. The flux calibration of SED mode observations is a meta-task (2030).

This observation is an Early Characterization Observation.

The existing data for this source are summarized in the following figure, which compares photometric measurements to a Kurucz model fit to those data (from Beth Holmes)

Data Collected

3 cycles of the photometry AOT in all 3 bands using 3 second DCEs.

Data Reformatting Requirements

Array Data Desired:

All Arrays.

Data Reformatting Option:

• NORMAL and
• NONE

Special Instructions:

Task Dependencies

• MIPS-914: 24 µm routine Scan Flat - Need to flatten images.
• MIPS-920: 24 µm flux standards - Need to compare MIPS fluxes to IRAS
• MIPS-915: 70 µm routine Scan IC - Need to remove stim IC from calibrated images.
• MIPS-922: 70 µm flux standards - Need to compare MIPS fluxes to IRAS
• MIPS-916: 160 µm routine Scan IC - Need to remove stim IC from calibrated images.
• MIPS-924: 160 µm flux standards - Need to compare MIPS fluxes to IRAS

Calibration Dependencies

• Darks, Flats/ICs, and Flux Calibration on all 3 arrays.
• As this target has a distincly non-photospheric emission, our knowledge of the MIPS color corrections will be tested by this experiment.

Output and Deliverable Products

• Coadded, dark-subtracted, flat-fielded, calibrated images at all 3 wavelengths based on processing via both the DAT and the SSC Pipeline.
• Monochromatic fluxes at all 3 wavelengths for the source, and comparison of those to the IRAS fluxes.

Data Analysis

• The reformatted data will be run through mips_sloper and mips_caler using the default settings to verify correct operation on Photometry AOR data for all three arrays. Final coadded images will be generated using mips_enhancer, and 'by hand' with IDP3 as a check.
• The BCD products from the SSC pipeline will be run through both the enhancer and IDP3 for producing fully co-added, calibrated images.
• Photometry will be done with IDP3 on the coadded images from both the DAT and the pipeline, and the results for the two compared directly to verify that they give the same answers for point sources.
• Final coadded images from the DAT and SSC Pipeline will also be compared by ratioing and/or differencing.
• We will prepare a figure comparing our derived monochromatic fluxes to the observed fluxes from IRAS, and the fitted photospheric SED for our target.
• The PSF will be compared to the STinyTim PSF at all 3 wavelengths to see if the source is extended. If it is, we will perform MEM and HIRES deconvolutions of the BCD level products from both the SSC pipeline and the DAT to see if we can bring out any structure in the disk.

Software Requirements

• DAT - mips_sloper, caler w/ no special flags to produce one set of BCD-level images.
• SSC pipeline to produce comparable BCD images.
• IDL - IDP3 for coadding imagas and doing photometry.
• DAT - mips_enhancer for producing coadded, calibrated images.
• SSC mosaicing tool for producing coadded, calibrated images.

Actions Following Analysis

• Disagreement between imaging and/or photometry results from the two pipelines.
  • Check data products at all possible intermediate stages.
• Disagreement with IRAS fluxes.
  • Contact calibration working group with the issue.

Additional Notes