12 Request for NAO/Legacy Science Observing TimeTo complement the SIRTF observations, we propose to measure the optical colors of all of the point sources that we detect. The optical colors will be important place the stellar objects on an HR diagram and identify pre- and post-main sequence objects. In order to detect the optical counterparts of the 2 million sources that will be detected in the SEDI observations, we require optical photometry in V, R, and I bands to 23, 22.5, and 21.5 in the V, R, and I bands, respectively (as described earlier in this proposal). We propose to use the Mosaic camera on the NOAO 4-m telescope, with its ideal combination of sensitivity and wide field of view, to observe the SEDI fields accessible from Kitt Peak. For the southern sources (DEC < 25 deg.), we have already described the ESO observations that will be performed. This NOAO proposal is to cover the remaining 9 SEDI fields, which are listed in the Table below.
Table 4 SEDI fields to be observed at NOAO with the Mosaic camera. Using the time estimator on the NOAO web pages, we find that the times required to reach our sensitivity limits are 410 s, 280 s, and 190 s at V, R, and I, respectively, so the observing time required per Mosaic position, including 2.5 min overhead per exposure, is 22 min. For each 3 sq. deg. SEDI field to be observed at NOAO, we will observe 12 positions with Mosaic, which allows for small overlaps between the images and non-optimal matching of the Mosaic and SIRTF array orientations. For each SEDI field, we therefore require 4.4 hr of observing time. For the Cygnus Loop field, in addition to the standard broad-band colors, we will obtain narrow-band images in Halpha and S II to trace the distribution of shocked gas; these images will help disentangle sources and supernova remnant filaments, and they will be correlated with the IRAC and MIPS images to locate infrared emission from shocked gas. Assuming our fields are available for 6 hr of solid observing per night when the observations are scheduled (and good weather, efficient instrument setup and filter changes, and efficient standard star calibrations), we require 8 nights of observing time. The Table above shows the months when our targets are available from Kitt Peak. To cover the available targets, we request two observing runs, one in in the winter (Dec-Feb) for HD93521, Ursa, Polaris, Taurus, and California fields; and the other in the summer (Jun-Aug) for Cygnus Loop, 3C380, Ced201, and SAO50690. We request dark sky during our observing run because we will be performing absolute photometry on the sources we detect. We will reduce the data in IRAF using the NOAO Mosaic data reduction package. The point sources will be extracted from the Mosaic data using DAOPHOT with parameters coordinated with the ESO data reduction. The optical counterparts will be identified for each SEDI source and added to the SEDI catalog as described in the data analysis section (section 7.1.2) of this proposal. It is our intention to make the SEDI catalog (including the optical photometry) available to the public as rapidly as possible, as shown in our data release schedule (Table 2).
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