HXD-PIN Background (tuned) for V2.x and V3.0 Data


The HXD team has developed a different PIN-NXB model (so-called "bgd_d") than the previous one ("bgd_a"; METHOD=PINUDLCUNIT), based on the same method used to create the GSO-NXB (METHOD=LCFIT). Although this PIN-NXB model (METHOD=LCFITDT) generally shows a better reproducibility, it takes 1-2 months after the finish of pipeline processing to be released since this method needs the one month dataset of calibrated GSO events. Therefore, the HXD team regards the previous model as "quick" background for the purpose of immediate quick-look analysis and will continue to release them at "one week delay" timed, while this new model is regarded as "tuned" background for the final precise analysis. Please note that this new PIN-NXB files are also "dead-time corrected", and hence the analysis procedure is exactly the same between "quick" and "tuned".

The reproducibility of the (tuned) HXD-PIN background model for v2 products is described as a suzakumemo (2008-03).

The "tuned" PIN-NXB files are now available from the following location:

Observation date Directory METHOD * METHODV **
2005-09-02 to 2012-07-31***: pinnxb_ver2.0_tuned LCFITDT 2.0ver0804
After 2012-08-01****: pinnxb_ver2.2_tuned LCFITDT 2.2ver1403
*: FITS header keyword to distinguish the background modeling methods.
**: FITS header keyword to distinguish the minor revisions of the same model. (YYMM corresponds to the creation month of that file.)
***: There is no "tuned" background in the period from 2006-05-24 to 2006-05-29, when one of 64 PIN diodes showed an unusually high event rate probably caused by the radiation damege. Alternatively, you can use "quick" background by selecting with a condition of "UNITID>3".
Background files for the data from 2012-08-01 to 2013-11-30 are also prepared in this version, but please refer to the following description.
****: The HXD-PIN "tuned" background modeling (LCFITDT model in Fukazawa et al 2009, with 2.0ver0804 in the header keyword "METHODV") are found to be gradually underestimated by up to 3--4\% (as of 2013 December; see the quick report). Data analysis of bright sources are not affected, but some cautions must be taken for sources with a flux comparable to the PIN sensitivity. The HXD team has identified and fixed the cause and prepared a new version (2.2ver1403 in the header keyword "METHODV") for the data taken AFTER 2012 August. Please utilize them by considering your analysis situation. Note that there is no problems for the tuned background before 2012 July.

The directory is divided into subdirectories by month. For example, background files for observations carried out in 2006 August can be found in the subdirectory 2006_08. Within these monthly directories, individual background files are listed alphabetically. Note these files are named using the sequence number, e.g., ae100005010_hxd_pinbgd.evt.gz. These files should only be used with version 2.x processed data, and vice versa.

ISAS/JAXA Department of High Energy Astrophysics
Last Modified: Monday, 02-Jun-2014 16:00:07 JST