Data Products Guide
The Data Products Guide describes the contents and purpose of the Chandra data products used in data analysis.
For a more general overview of the Chandra data products, refer to the Introduction to the Data Products thread.
ACIS
Primary Products
The data products are rearranged such that the files necessary for most analyses are in the primary directory.
| Filename | Description | Content | Instrument | SDP Level |
|---|---|---|---|---|
| acis_evt2.fits | imaging event file | EVT2 | ACIS | L2 |
| acis_evt2.fits | grating event file | EVT2 | ACIS | L2 |
| acis_cntr_img2.fits | high-resolution image of the center of the field | HIRESIMG | ACIS | L2 |
| acis_full_img2.fits | full-field sky image | LORESIMG | ACIS | L2 |
| acis_pha2.fits | grating spectra | SPECTRUM | ACIS | L2 |
| acis_src2.fits [removed in DS 8.4] | imaging source list | SRC | ACIS | L2 |
| acis_bpix1.fits | bad pixel list | BADPIX | ACIS | L1 |
| acis_fov1.fits | field of view | FOV | ACIS | L1 |
| pcad_asol1.fits | aspect solution | ASPSOL | PCAD | L1 |
| orbit_eph1.fits | orbit ephemeris | ORBITEPHEM1 | ORBIT | L1 |
Secondary Products
If you are interested in reprocessing your data, you will also need the level=1 files, which are in the secondary directory.
| Filename | Description | Content | Instrument | SDP Level |
|---|---|---|---|---|
| acis_evt1.fits | event file | EVT1 | ACIS | L1 |
| acis_flt1.fits | good time intervals | GTI | ACIS | L1 |
| acis_mtl1.fits | mission timeline | MTL | ACIS | L1 |
| acis_bias0.fits | bias maps | BIAS0 | ACIS | L0 |
| acis_pbk0.fits | parameter block | PBK | ACIS | L0 |
| acis_stat1.fits † | exposure statistics | EXPSTATS | ACIS | L1 |
| acis_msk1.fits | detector mask | MSK | ACIS | L1 |
| acis_soff1.fits † [removed in DS 8.4] | alignment offsets | ALIGNMOFFS | ACIS | L1 |
| acis_aoff1.fits † [removed in DS 8.4] | aspect offsets | ASPOFFS | ACIS | L1 |
| pcad_aqual1.fits † | aspect quality | ASPQUAL | PCAD | L1 |
| pcad_osol1.fits † | on-board-computer (OBC) aspect solution | OBCSOL | PCAD | L1 |
| solar_eph1.fits † | solar ephemeris | SOLAREPHEM1 | SOLAR | L1 |
| lunar_eph1.fits † | lunar ephemeris | LUNAREPHEM1 | LUNAR | L1 |
| angles_eph1.fits † | viewing angles | ANGLEEPHEM | Angles | L1 |
|
† Most users will never need this file in their analysis. |
||||
Supporting Products
The pipeline-produced supporting products are generally not needed in data analysis.
| Filename | Description | Content | Instrument | SDP Level |
|---|---|---|---|---|
| acis_evt1a.fits | grating event file | TGEVT1 | ACIS | L1.5 |
| acis_src1a.fits | grating source list | TGSRC | ACIS | L1.5 |
HRC
Primary Products
The data products are rearranged such that the files necessary for most analyses are in the primary directory.
| Filename | Description | Content | Instrument | SDP Level |
|---|---|---|---|---|
| hrc_evt2.fits | imaging event file | EVT2 | HRC | L2 |
| hrc_evt2.fits | grating event file | EVT2 | HRC | L2 |
| hrc_cntr_img2.fits | high-resolution image of the center of the field | HIRESIMG | HRC | L2 |
| hrc_full_img2.fits | full-field sky image | LORESIMG | HRC | L2 |
| hrc_pha2.fits | grating spectra | SPECTRUM | HRC | L2 |
| hrc_src2.fits [removed in DS 8.4] | imaging source list | SRC | HRC | L2 |
| hrc_dtf1.fits | dead time factor | DTF | HRC | L1 |
| hrc_fov1.fits | field of view | FOV | HRC | L1 |
| pcad_asol1.fits | aspect solution | ASPSOL | PCAD | L1 |
| orbit_eph1.fits | orbit ephemeris | ORBITEPHEM1 | ORBIT | L1 |
Secondary Products
If you are interested in reprocessing your data, you will also need the level=1 files, which are in the secondary directory.
| Filename | Description | Content | Instrument | SDP Level |
|---|---|---|---|---|
| hrc_evt1.fits | event file | EVT1 | HRC | L1 |
| hrc_std_flt1.fits | good time intervals | GTI | HRC | L1 |
| hrc_bpix1.fits | bad pixel list | BADPIX | HRC | L1 |
| hrc_msk1.fits | detector mask | MSK | HRC | L1 |
| hrc_mtl1.fits | mission timeline | MTL | HRC | L1 |
| hrc_std_dtfstat1.fits † | dead time factor statistics | DTFSTATS | HRC | L1 |
| hrc_soff1.fits † [removed in DS 8.4] | alignment offsets | ALIGNMOFFS | HRC | L1 |
| hrc_aoff1.fits † [removed in DS 8.4] | aspect offsets | ASPOFFS | HRC | L1 |
| pcad_aqual1.fits † | aspect quality | ASPQUAL | PCAD | L1 |
| pcad_osol1.fits † | on-board-computer (OBC) aspect solution | OBCSOL | PCAD | L1 |
| solar_eph1.fits † | solar ephemeris | SOLAREPHEM1 | SOLAR | L1 |
| lunar_eph1.fits † | lunar ephemeris | LUNAREPHEM1 | LUNAR | L1 |
| angles_eph1.fits † | viewing angles | ANGLEEPHEM | Angles | L1 |
|
† Most users will never need this file in their analysis. |
||||
Supporting Products
The pipeline-produced supporting products are generally not needed in data analysis.
| Filename | Description | Content | Instrument | SDP Level |
|---|---|---|---|---|
| hrc_evt1a.fits | grating event file | TGEVT1 | HRC | L1.5 |
| hrc_src1a.fits | grating source list | TGSRC | HRC | L1.5 |