Aladdin SW imaging exposure times
During P69 it was necessary to commission SW (JHK) imaging in theAladdin arm. This new mode is offered for P70 Phase II.
Here is a summary of information which will be useful to observers wishingto prepare P70 OBs using this mode. Information is also provided inthe User Manual (v1.10.1).
The recommended DIT/NDIT/total_exposure_time for Aladdin SW imagingis the same as that for Hawaii SW imaging and is given in Table 23 ofthe User Manual. The minimum DIT with the Aladdin is 0.3447s.It is not necessary to submit a waiver request to use the Aladdinminimum DIT (unlike when using the Hawaii). This is because the readout time with the Aladdin is negligible. This short read time makesobservations with the Aladdin more efficient. However data reductionwith the Aladdin is more complicated, and photometry less accurate,than with the Hawaii (see section 2.2.1 in the User Manual for a moredetailed comparison of the two modes).
The ETC has not yet been updated for Aladdin SW imaging. To helpwith calculation of exposure times, a comparison of Aladdin and Hawaiizero-points is given in the following table. As a rough guide theAladdin is ~1.2 times faster than the Hawaii.
|Aladdin||ZP (ADU)||ZP (e)||Hawaii||ZP (ADU)||ZP (e)|
We are still testing the effects of saturation in the Aladdin.Therefore, for P70 Phase II, the bright star limits for SW imaging with theAladdin have been kept the same as with the Hawaii, i.e. a waiverrequest should be submitted if the field contains stars brighter than11th magnitude.