Principal: Chad Engelbracht
Deputy: Dean Hines, Dave Frayer, Almudena Alonso
Data Monkey: Eiichi Egami
Priority: Necessary
Downlink Priority: Normal
Analysis Time: 24h
Last Updated:
This is the 70µm flux calibration to be done at the beginning and end of every campaign after the instrument has been basically checked out and the telescope temperature has stabilized.
This is the standard campaign 70µm flux calibration. 1 flux standard will be observed using 3 cycles of the photometry AOR, using small-field mode and 3-second DCEs. The AOR mips-922 only calibrates the 70µm default-scale mode and will be used throughout most of IOC. If there are 70µm fine-scale or SED observations that need to be calibrated, which only happens in campaigns R, V, and W under the current schedule, AOR mips-922-a (which adds fine-scale and SED observations of the star) should be used. This task is intended to establish the DN to Jy conversion factor for the campaign. Other tasks perform a detailed characterization of the dependence of this factor on integration time (mips-251), background (mips-921), or flux (mips-350).
The current target is HD 50310. This star was chosen because it is near the CVZ (and thus has a large visibility window) and because it is about 0.7 Jy at 70µm, which makes it bright enough to measure at a high ratio of signal to noise but faint enough that it is only 1/2 well in a 3s exposure, and is thus very unlikely to saturate the detector.
The AOR listed here takes 397 seconds. If we have to use a fainter star for calibration, we'll use 10-second DCEs, pushing the total time up to 693 seconds, a little less than the 12 minutes allotted for this task.
The AOR version which includes fine-scale and SED observations (mips-922-a) requires more time, a total of 22 minutes.
The first time this task is run it will be in the same campaign as the 70µm first-light observation, mips-322, and so will provide additional data to assess the functionality of this array.
The standard AOR (mips-922) will generate 30 observations of the standard star.
Array Data Desired:
70 µm
Data Reformatting Option:
Special Instructions:
The first instance of this task is in the same campaign as the 70µm first light, so there are no particular dependencies for this task, aside from the basic requirement that the instrument is working. A long series of 24µm experiments prior to the task should have established that commanding, the CSMM, and the stimulators work. If they don't, we have much more replanning to do than could be captured in this cookbook.
The main goal of the analysis is to determine the flux conversion factor for this campaign. The data will be processed with both the SSC pipeline and the MIPS DAT (using default settings); the derived flux conversion factors will be compared to check for problems in the data processing. To derive the flux conversion factor, photometry will be performed on the mosaicked image. This must be done in such a way that corrects for distortion. The errors will be derived using the error images that accompany the BCDs. The assumed flux of the star (from the tables on the MIPS IST web page) will be divided by the measured counts (corrected from the measured aperture to the total star counts using an aperture correction) to compute the flux conversion factor.
A mosaic of the stellar images will be generated. This image will be examined visually for any obvious problems, such as poor matching of background levels between DCEs, missing data, asteroids in the field, unusual noise patterns in the mosaic (e.g., did 1 DCE get weighted much more than all the others?), etc. The mosaic may need to be regenerated if inappropriate data were used in the initial mosaic generation.
If the standard anomaly response actions do result in usable data, calibration can still be achieved using the redundant set of observations at the beginning or end of the campaign.