6.3 Target Selection and Duplication Check

When planning a Spitzer observing proposal, the first consideration is whether the intended target has already been observed, or approved for observations, with Spitzer. To determine this, we use Leopard or visit the Spitzer Reserved Observations Catalog (ROC) at

http://ssc.spitzer.caltech.edu/roc/

and look for any instances of 3C 273 (or other observations at, or near, the target coordinates of RA = 12:29:06.7, DEC = +02:03:08.6). The ROC shows that our target is already selected for observation with the IRS in GTO program PID 105; the abstract for this program can be viewed at

http://ssc.spitzer.caltech.edu/geninfo/gto/abs/pid105,

and with MIPS in GTO program PID 82, which can be viewed at

http://ssc.spitzer.caltech.edu/geninfo/gto/abs/pid82.

The PID 105 observations are of most interest in determining potential conflicts with any new IRS program: these GTO observations at our target coordinates are planned to utilize both the SH and LH modules. If we were considering to write a new proposal for Spitzer observations, then these approved GTO observations could preclude new observations at the specified target position. In order to avoid being in conflict with these previous observations, as per the Spitzer Duplicate Observations Rules, which are available at

http://ssc.spitzer.caltech.edu/documents/rules/,

new observations would have to be designed in such a way that: (1) the integration time per pixel for each observation differs by more than a factor of two in sensitivity, and (2) the target positions are separated by more than one-half of the slit length of the relevant IRS module. Nevertheless, for the purpose of developing this Cookbook example, we will continue without worrying further about these considerations.