During P69 it was necessary to commission SW (JHK) imaging in the Aladdin arm. This new mode is offered for P70 Phase II.
Here is a summary of information which will be useful to observers wishing to prepare P70 OBs using this mode. Information is also provided in the User Manual (v1.10.1).
The recommended DIT/NDIT/total_exposure_time for Aladdin SW imaging is the same as that for Hawaii SW imaging and is given in Table 23 of the User Manual. The minimum DIT with the Aladdin is 0.3447s. It is not necessary to submit a waiver request to use the Aladdin minimum DIT (unlike when using the Hawaii). This is because the read out time with the Aladdin is negligible. This short read time makes observations with the Aladdin more efficient. However data reduction with the Aladdin is more complicated, and photometry less accurate, than with the Hawaii (see section 2.2.1 in the User Manual for a more detailed comparison of the two modes).
The ETC has not yet been updated for Aladdin SW imaging. To help with calculation of exposure times, a comparison of Aladdin and Hawaii zero-points is given in the following table. As a rough guide the Aladdin 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 the Aladdin have been kept the same as with the Hawaii, i.e. a waiver request should be submitted if the field contains stars brighter than 11th magnitude.